Answers to Frequently Asked Questions (FAQs) About Various Billiards and Pool Topics
Categories
30-degree and 90-degree Rules
30-degree and 90-degree Rules for Cue Ball Control in Pool and Billiards
... how to predict cue ball motion to prevent scratches, aim break out shots, aim caroms, play position, and get through traffic.
30-degree rule
What is the 30-degree rule?
The 30-degree rule states that for a rolling-CB shot, over a wide range of cut angles, between a 1/4-ball and 3/4-ball hit, the CB will deflect by very close to 30° from its original direction after hitting the OB. If you want to be more precise, the angle is a little more (about 34 degrees) closer to a 1/2-ball hit and a little less (about 27 degrees) closer to a 1/4-ball or 3/4-ball hit. The rule is described and illustrated in the following video(YouTube)
... how to predict cue ball motion to prevent scratches, aim break out shots, aim caroms, play position, and get through traffic.
30-degree rule
What is the 30-degree rule?
The 30-degree rule states that for a rolling-CB shot, over a wide range of cut angles, between a 1/4-ball and 3/4-ball hit, the CB will deflect by very close to 30° from its original direction after hitting the OB. If you want to be more precise, the angle is a little more (about 34 degrees) closer to a 1/2-ball hit and a little less (about 27 degrees) closer to a 1/4-ball or 3/4-ball hit. The rule is described and illustrated in the following video(YouTube)
The Dr. Dave peace-sign technique is very useful in applying the 30-degree rule. Also, if you want to know how to account for speed effects, see "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (BD, June, 2005). And if you want to see how numbers change a little with typical pool equipment conditions, see "Rolling Cue Ball Deflection Angle Approximations" (Download) (BD, November, 2011).
Here a video demonstrations showing examples of how the 30-degree rule can be used in different shot situations:
Here a video demonstrations showing examples of how the 30-degree rule can be used in different shot situations:
The peace-sign technique can also be applied to draw shots using the trisect system.
How can you tell if your peace-sign is the correct angle?
See NV B.44.(YouTube) Also, here's a template (Download) useful for learning how to apply the 30-degree rule accurately. The template can be used to help you train and calibrate your hand peace-sign (see "The 30° rule: Part I - the basics" (Download) - BD, April, 2004 and "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) - BD, June, 2005).
One way to calibrate or check your peace sign at the table is to use your opposite hand index finger as a ruler to measure how much the tips of the "V" fingers should be spread. Using the 30-degree template (Download) or a 30-60-90 drafting triangle (available at office and arts and crafts stores), one can form the peace sign of the correct angles and then place the opposite-hand finger over the finger-tip gap, with the fingertip touching the tip of one of the fingers. Note where the second finger is relative to the other opposite-hand finger (e.g., just below the main knuckle, or at a certain wrinkle). Then (e.g., when you are playing), you can check your peace sign spread by recreating the same finger tip positions on your opposite hand.
Do people really use the 30-degree-rule peace-sign at the table?
If one has a critical shot close to a scratch, requiring precise caroms, needing ball break-up or avoidance, or with tight "traffic" of balls to negotiate, a well-calibrated peace sign can be extremely useful, allowing one to predict with confidence nearly exactly where the cue ball will go. One can adjust the peace sign slightly for the cut angle using the 30-degree rule angle template (external web-link) for help. One can also adjust for speed, as shown in "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (BD, June, 2005). Well-calibrated fingers can be much more accurate than intuition-based visualization.
How can you tell if your peace-sign is the correct angle?
See NV B.44.(YouTube) Also, here's a template (Download) useful for learning how to apply the 30-degree rule accurately. The template can be used to help you train and calibrate your hand peace-sign (see "The 30° rule: Part I - the basics" (Download) - BD, April, 2004 and "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) - BD, June, 2005).
One way to calibrate or check your peace sign at the table is to use your opposite hand index finger as a ruler to measure how much the tips of the "V" fingers should be spread. Using the 30-degree template (Download) or a 30-60-90 drafting triangle (available at office and arts and crafts stores), one can form the peace sign of the correct angles and then place the opposite-hand finger over the finger-tip gap, with the fingertip touching the tip of one of the fingers. Note where the second finger is relative to the other opposite-hand finger (e.g., just below the main knuckle, or at a certain wrinkle). Then (e.g., when you are playing), you can check your peace sign spread by recreating the same finger tip positions on your opposite hand.
Do people really use the 30-degree-rule peace-sign at the table?
If one has a critical shot close to a scratch, requiring precise caroms, needing ball break-up or avoidance, or with tight "traffic" of balls to negotiate, a well-calibrated peace sign can be extremely useful, allowing one to predict with confidence nearly exactly where the cue ball will go. One can adjust the peace sign slightly for the cut angle using the 30-degree rule angle template (external web-link) for help. One can also adjust for speed, as shown in "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (BD, June, 2005). Well-calibrated fingers can be much more accurate than intuition-based visualization.
Half-ball hit "gems"
Why is a 1/2-ball hit (30 degree cut angle) so useful?
Here are some excellent videos Mike Page put together on half-ball hit "gems:"
NV B.6 - Mike Page's half-ball hit gems (part 1) (YouTube)
NV B.6 - Mike Page's half-ball hit gems (part 2) (YouTube)
and here's a good summary article from Bob Jewett (BD, November, 2000). (Download)
The "natural angle" effect associated with a half-ball hit is one of the most important principles in pool and billiards. It has always surprised me how little (if any) coverage is dedicated to these subjects in commercially-available pool and billiards books and videos. These effects have been understood at least as early as 1835 (see Coriolis' book under physics of billiards). Maybe if we keep writing articles and posting videos on these topics, maybe they will become more "mainstream."
Gem #4 from the videos is the basis of the 30-degree rule, which states that for a rolling CB, the deflected angle is very close to 30 degrees for all cut angles between 1/4-ball and 3/4-ball hits (not just a 1/2-ball hit). This gem is the single most important and useful principle in pool, especially when used in conjunction with the peace-sign technique.
Why is a 1/2-ball hit (30 degree cut angle) so useful?
Here are some excellent videos Mike Page put together on half-ball hit "gems:"
NV B.6 - Mike Page's half-ball hit gems (part 1) (YouTube)
NV B.6 - Mike Page's half-ball hit gems (part 2) (YouTube)
and here's a good summary article from Bob Jewett (BD, November, 2000). (Download)
The "natural angle" effect associated with a half-ball hit is one of the most important principles in pool and billiards. It has always surprised me how little (if any) coverage is dedicated to these subjects in commercially-available pool and billiards books and videos. These effects have been understood at least as early as 1835 (see Coriolis' book under physics of billiards). Maybe if we keep writing articles and posting videos on these topics, maybe they will become more "mainstream."
Gem #4 from the videos is the basis of the 30-degree rule, which states that for a rolling CB, the deflected angle is very close to 30 degrees for all cut angles between 1/4-ball and 3/4-ball hits (not just a 1/2-ball hit). This gem is the single most important and useful principle in pool, especially when used in conjunction with the peace-sign technique.
.Gem #4 is an interesting proposition demonstration with the carom shot from the foot rail. NV A.1 (YouTube) shows a similar "sure-thing" proposition. The following article also illustrates and discusses the shot in "The 30° rule: Part III - carom vs. cut" (Download) (BD, June, 2004).
TP A.1 (Download) and TP A.2 (Download) present an error analysis and look at the effects of table size.
Gem #2 is explained and illustrated in detail in "Draw Shot Primer - Part I: physics" (Download) (BD, January, 2006). The concept can also extended into the trisect draw-shot aiming system. This is also a very useful "gem."
Many additional resources, with lots of illustrations, examples, and video links related to these principle, can be found here:
The 1/2-ball hit is a common shot, especially in the game of 9-ball, where you need to move the CB around the table a lot. With a 1/2-ball hit, the CB easily be given enough speed to travel significant distance. The CB's motion can also be killed fairly easily with a 1/2-ball hit. Also, side spin is very effective off the cushions with a 1/2-ball hit. For thinner hits, the faster ball speed reduces the effect of the side spin; and for fuller hits and the resulting slower speed of the CB, the spin doesn't grab as well, especially on new cloth.
Largest deflected angle
Does the cue ball deflect the most for a half-ball hit?
Close, but not precisely. See the bottom of TP 3.3. (Download) The maximum deflected angle (33.75 degrees) actually occurs at a cut angle of about 28 degrees, which corresponds to a 0.53 ball-hit fraction. These numbers are close to 30 degrees and a 1/2-ball hit, but not exact.
TP A.1 (Download) and TP A.2 (Download) present an error analysis and look at the effects of table size.
Gem #2 is explained and illustrated in detail in "Draw Shot Primer - Part I: physics" (Download) (BD, January, 2006). The concept can also extended into the trisect draw-shot aiming system. This is also a very useful "gem."
Many additional resources, with lots of illustrations, examples, and video links related to these principle, can be found here:
- 30-degree rule resource page (containing many additional resources and video demonstrations of how and when the rule is useful).
- collection of instructional articles on this topic: (Downloads)"The 90° rule: Part I - the basics" (BD, January, 2004).
- "The 90° rule: Part II - breakup and avoidance shots" (BD, February, 2004).
- "The 90° rule: Part III - carom and billiard shots" (BD, March, 2004).
- "90° and 30° rule review" (BD, July, 2004).
- "The 30° rule: Part I - the basics" (BD, April, 2004).
- "The 30° rule: Part II - examples" (BD, May, 2004).
- "The 30° rule: Part III - carom vs. cut" (BD, June, 2004).
- "90° and 30° Rule Follow-up - Part I" (BD, February, 2005).
- "90° and 30° Rule Follow-up - Part II: speed effects" (BD, March, 2005).
- "90° and 30° Rule Follow-up - Part III: inelasticity and friction effects" (BD, April, 2005).
- "90° and 30° Rule Follow-up - Part IV: sidespin effects" (BD, May, 2005).
- "90° and 30° Rule Follow-up - Part V: the final chapter" (BD, June, 2005).
- "Fundamentals - Part V: CB position control" (BD, January, 2009).
- "Fundamentals - Part VI: CB control examples" (BD, February, 2009).
- 30-degree rule and peace-sign technique one-page summary (Download) and the angle template. (Download)
- Math and physics backing up Gem #'s 2, 3, and 4 can be found in TP 3.3, TP A.4, and TP A.16. (Downloads)
The 1/2-ball hit is a common shot, especially in the game of 9-ball, where you need to move the CB around the table a lot. With a 1/2-ball hit, the CB easily be given enough speed to travel significant distance. The CB's motion can also be killed fairly easily with a 1/2-ball hit. Also, side spin is very effective off the cushions with a 1/2-ball hit. For thinner hits, the faster ball speed reduces the effect of the side spin; and for fuller hits and the resulting slower speed of the CB, the spin doesn't grab as well, especially on new cloth.
Largest deflected angle
Does the cue ball deflect the most for a half-ball hit?
Close, but not precisely. See the bottom of TP 3.3. (Download) The maximum deflected angle (33.75 degrees) actually occurs at a cut angle of about 28 degrees, which corresponds to a 0.53 ball-hit fraction. These numbers are close to 30 degrees and a 1/2-ball hit, but not exact.
Poetry
Are there easy ways to remember the 30 and 90 degree rules?
Here's some poetry:
30-degree rule:
If you let one finger stay,
The other finger points the way.
Peace.
90-degree rule:
When the ball has stun,
this is something you should not shun:
Point your finger, and the cue ball will follow the thumb.
If you do this, nobody will think you are dumb.
Are there easy ways to remember the 30 and 90 degree rules?
Here's some poetry:
30-degree rule:
If you let one finger stay,
The other finger points the way.
Peace.
90-degree rule:
When the ball has stun,
this is something you should not shun:
Point your finger, and the cue ball will follow the thumb.
If you do this, nobody will think you are dumb.
When the 30-degree rule applies
For what kinds of shots can the 30-degree rule be used?
The 30-degree rule is very useful for:
- scratch avoidance
- carom shot aiming
- cluster busting
- obstacle avoidance
- position play
- etc!
Here are some important things to keep in mind:
- the 30-degree rule applies only for natural roll shots.
- the 30-degree rule applies for the entire range of cut angles between 1/4-ball and 3/4-ball hits. This range includes the 1/2-ball hit (which is at the center of the range).
- the cue ball always leaves initially along the tangent line, which is 90 degrees away from (i.e., perpendicular to) the impact line (AKA object ball direction, line-of-centers, target line, etc.). However, for slow to medium speed natural roll shots, the cue ball deflects to the 30 degree direction almost immediately (i.e., the curve in the trajectory is almost imperceptible). Only at higher speeds does the travel down the tangent line become significant (e.g., see NV 3.8 (YouTube)). For more info, see the following demonstration from Disc I of the Video Encyclopedia of Pool Shots: (external web-link)
For what kinds of shots can the 30-degree rule be used?
The 30-degree rule is very useful for:
- scratch avoidance
- carom shot aiming
- cluster busting
- obstacle avoidance
- position play
- etc!
Here are some important things to keep in mind:
- the 30-degree rule applies only for natural roll shots.
- the 30-degree rule applies for the entire range of cut angles between 1/4-ball and 3/4-ball hits. This range includes the 1/2-ball hit (which is at the center of the range).
- the cue ball always leaves initially along the tangent line, which is 90 degrees away from (i.e., perpendicular to) the impact line (AKA object ball direction, line-of-centers, target line, etc.). However, for slow to medium speed natural roll shots, the cue ball deflects to the 30 degree direction almost immediately (i.e., the curve in the trajectory is almost imperceptible). Only at higher speeds does the travel down the tangent line become significant (e.g., see NV 3.8 (YouTube)). For more info, see the following demonstration from Disc I of the Video Encyclopedia of Pool Shots: (external web-link)
For more info, visit billiards.colostate.edu
Advice
Pool and Billiards Advice
... General advice about miscellaneous pool and billiards topics.
Alcohol effects
Why is it I sometimes play better when I drink alcohol?
First of all, you need to separate actual level of play from perceived level of play. Alcohol can affect both. For some people, a small amount of alcohol can actually increase relaxation and result in less tense (and better) play. For much more info, see "Beer-goggle effects" (Download) (BD, June, 2008).
Doing what feels "natural"
Should I do what feels natural, or try to change my stroke?
Concerning doing what is "natural," I don't think this is always the best advice. What many people do "naturally" doesn't always give the best results. For example, not dropping the elbow, or pausing in the final back swing, doesn't come naturally to many, but these changes can still help (some but not all people), even if it doesn't feel "natural." Now, with lots of practice, anything can be made to feel natural.
However, many people have stroke/stance/grip/bridge flaws that feel natural but cause inconsistency or inaccuracy. Sometimes, if these "natural" flaws are removed (through lots and lots of practice and maybe some instruction), improvement can result and the new technique (with the flaws removed) can become natural and relaxed (and more effective).
Improving your game
What can I do to make my game better?
The best way to improve is to practice (especially, if you work on your trouble areas. It might also help you to see an experienced and qualified instructor. They can often see problems or deficiencies with your mechanics and game that you might not know are there. They can also provide good advice for how to improve. Finally, if you haven't done so yet, you should read some books about pool. Improving your knowledge and understanding of the game might give you a wider arsenal of shots, help you be more creative at the table, help you be more aware of important factors for different types of shots, and help you improve with less practice.
from Bill Porter:
A couple of years ago I asked AZBers to single out the ONE IDEA that would most improve your pool game and they came up with a couple of dozen candidates. I narrowed those suggestions down to the eight you see below.
1. BE STILL over the shot, with as little movement of the head and body as possible.
2. STAY DOWN on the shot. Jimmy Reid once said he could tell who the good players were in a pool hall within a few minutes of entering the room. He said all he had to do was watch to see which players stayed down on their shots. Watching the cue ball contact the object ball is a good way to work on staying down on the shot as you stay down to watch the cue ball on its path to the object ball. This one is similar to #1, but deserves its own slot.
3. Treat EVERY SHOT with the same respect. "I quit missing those shots when I came to the realization that there is no such thing as an easy shot." (Luther "Wimpy" Lassiter)
4. Have a PRE-SHOT ROUTINE and follow it!
5. While standing up, decide on the shot (offense/defense, speed, side spin), then make a COMMITMENT to shoot the shot as you have decided to shoot it. Most shots are missed because of indecision. Another way to say this is to have a plan before every shot.
6. Do the highest percentage thing that YOU KNOW HOW to do (not what Efren would do).
7. Don?t let DISTRACTIONS cause you to lose focus on the shot. If something distracts you, stand up and go through your pre-shot routine from the beginning.
8. HAVE FUN! ? Your game may improve dramatically after reminding yourself that you are playing pool primarily to have fun.
Here's a suggestion for you. Take a small card, like a business card or an index card, and write a short version of the above suggestions on the card. Maybe the short versions would read something like this.
1) Be still
2) Stay down
3) Respect every shot
4) Follow the pre-shot routine
5) Commit to the shot
6) Play within your abilities
7) Defeat distractions, reset if necessary
8) Have fun!
Of course you may want to OMIT any of the 8 that really don't relate to your game. And you may want to ADD a few that are especially important for your game. Maybe you would add reminders to grip the cue lightly, pause at the end of your last back stroke, check your stance alignment, snug up your bridge, or whatever you have learned is useful for your game. If you carry that little card around with you, it will be handy to read over when you?re shooting poorly or in a slump.
From DeeMan, with a little humor thrown in:
Here are a few things to think about if you are really serious about improving and moving beyond banger status.
Some rules most don't have to think about but are impediments to playing well.
1) Don't shoot harder then you need for the shot and to gain position.
2) Know which direction your cue balls will go and think about how far it needs to travel.
3) Don't hit other balls on the table without a reason.
4) Learn to hit the center of the cue ball very precisely before worrying about hitting it off center.
5) Try not to leave the cue ball on a rail if not necessary.
6) Shoot balls first that clear the way for your other balls.
7) Identify packs and clusters and balls that won't "go" early and get a strategy to open then up or move them. To try to run out without this plan is foolish.
8) If you don't think you have a shot or safety you are playing Efren or just not looking hard enough.
9) Don't twirl the rack or do any other trick moves to impress people unless you are trying out for the circus.
10) Learn to stay level and shoot smoothly and don't think running boring balls rack after rack is something stupid or lucky.
11) Learn that draw and follow are for more than following or backing balls up.
12) Learn to "kill" the cue ball. NOTE: This does not involve a gun.
13) Don't put powder all over the table unless you are changing your opponent's diaper.
14) Don't show disappointment to your opponent when you mess up. That way, when you learn to intentionally miss, they won't know.
15) Don't whine, we have a guy named Earl that will handle that for you.
16) Chalk with your opposite hand.
17) Learn to read kisses. Not related to Madonna and Brittany.
18) Learn your limits and don't think your draw will all of a sudden resemble Cory's. That means learn to take your medicine and shoot the possible shot, the percentage shot.
19) Play the table (unless you are stalling).
20) Don't listen to guys on the internet giving you pool advice, especially DeeMan.
Selecting an instructor
How do I decide how to select an instructor?
I have met several "instructors" that were great pool players but terrible teachers. I have also met countless great players who would make terrible instructors. An instructor obviously must be knowledgeable and understand all of the intricacies of the game, and certainly have enough experience to appreciate those intricacies. An instructor must also be a good teacher and communicator and know how to connect with various types of people. Also, a great instructor should be a total "student of the game" (i.e., read everything, discuss and debate stuff on forums, communicate professionally and open-mindedly with other instructors and players, etc). Great instructors have too many things on their plate to be great players. To be a great player, one must have sharp eyes, a near-flawless stroke, and near-perfect speed control. That takes hours and hours of practice and play ... youth can also help. Only people completely dedicated to playing pool can put in the amount of time necessary to be great.
I don't think the true value a coach or instructor provides is information. Lots of great information can be found in good books and videos (and sometimes, even on the Internet). To me, the most important value an instructor offers is the ability and experience to work with a player as a unique individual, catering the instruction to best help that person improve.
FYI, a good list of well-respected and well-known instructors can be found here:
http://billiards.colostate.edu/links.html#Schools (external web-Link)
From Spider-man:
Talk to their former students. Ask them how the lessons were structured, did they feel it was worthwhile, and why. What was good, what was bad? Would they pay this instructor for more lessons in the future? Then ask yourself whether the described style of instruction is what you want.
Talk to as many as you can find, so that you're not captive to one person's glowing praise or damning complaint. You'll also learn how the instructor customizes his agenda to an individual student, or whether he has a "cookie-cutter" approach.
In other words, don't depend on the person selling you a service to tell you whether that service is good or bad. There's a huge temptation to tell you what you want to hear. Find the former students and get the story from the perspective of someone who was in the position you're about to be in. For a well-known instructor, or even a not-so-well known one that is local to you, there should be plenty of discussion available.
From Brian_in_VA:
I don't think a great teacher is necessarily a great player as they are two very different skill sets. Someone that is blessed with both is truly exceptional and may still not give a great lesson if the student isn't prepared to learn but then, that's the students fault.
A teacher has an abundant knowledge of the game, and knowledge of the mechanics for playing it properly and the willingness to share these.
A good teacher has that plus a methodology (often in the form of drills) for passing the knowledge to the student, for demonstrating the techniques and providing appropriate feedback to the student when first attempting them. This helps the student to build success with the new skill.
A great teacher has all that plus superior communication skills. This allows them to listen to the student, understand what the student is hearing and how they learn and then adapting their communication style to better fit that student. This provides a faster application of the new skill, a better cementing of it in the student's memory and a higher motivation to perform it correctly. The great teacher also assists the student in defining and developing reachable goals for their improvement. Without goals, there is little chance for long term success and application of what's been learned.
An excellent lesson, in my opinion, is 50% the responsibility of the student. If the student is anywhere above rank beginner, they should come prepared to learn with at least some idea of why they are taking a lesson, an initial goal, if you will. "I want to get better" is not a goal, it's a dream. "I want to improve my APA rating from a 4 to a 5" is better but it still is very results oriented. Best might be "I want to build a consistent enough stroke to be able to...."
What it takes to play like a pro
What does it take to play like a pro?
The main things top players have in common are:
... General advice about miscellaneous pool and billiards topics.
Alcohol effects
Why is it I sometimes play better when I drink alcohol?
First of all, you need to separate actual level of play from perceived level of play. Alcohol can affect both. For some people, a small amount of alcohol can actually increase relaxation and result in less tense (and better) play. For much more info, see "Beer-goggle effects" (Download) (BD, June, 2008).
Doing what feels "natural"
Should I do what feels natural, or try to change my stroke?
Concerning doing what is "natural," I don't think this is always the best advice. What many people do "naturally" doesn't always give the best results. For example, not dropping the elbow, or pausing in the final back swing, doesn't come naturally to many, but these changes can still help (some but not all people), even if it doesn't feel "natural." Now, with lots of practice, anything can be made to feel natural.
However, many people have stroke/stance/grip/bridge flaws that feel natural but cause inconsistency or inaccuracy. Sometimes, if these "natural" flaws are removed (through lots and lots of practice and maybe some instruction), improvement can result and the new technique (with the flaws removed) can become natural and relaxed (and more effective).
Improving your game
What can I do to make my game better?
The best way to improve is to practice (especially, if you work on your trouble areas. It might also help you to see an experienced and qualified instructor. They can often see problems or deficiencies with your mechanics and game that you might not know are there. They can also provide good advice for how to improve. Finally, if you haven't done so yet, you should read some books about pool. Improving your knowledge and understanding of the game might give you a wider arsenal of shots, help you be more creative at the table, help you be more aware of important factors for different types of shots, and help you improve with less practice.
from Bill Porter:
A couple of years ago I asked AZBers to single out the ONE IDEA that would most improve your pool game and they came up with a couple of dozen candidates. I narrowed those suggestions down to the eight you see below.
1. BE STILL over the shot, with as little movement of the head and body as possible.
2. STAY DOWN on the shot. Jimmy Reid once said he could tell who the good players were in a pool hall within a few minutes of entering the room. He said all he had to do was watch to see which players stayed down on their shots. Watching the cue ball contact the object ball is a good way to work on staying down on the shot as you stay down to watch the cue ball on its path to the object ball. This one is similar to #1, but deserves its own slot.
3. Treat EVERY SHOT with the same respect. "I quit missing those shots when I came to the realization that there is no such thing as an easy shot." (Luther "Wimpy" Lassiter)
4. Have a PRE-SHOT ROUTINE and follow it!
5. While standing up, decide on the shot (offense/defense, speed, side spin), then make a COMMITMENT to shoot the shot as you have decided to shoot it. Most shots are missed because of indecision. Another way to say this is to have a plan before every shot.
6. Do the highest percentage thing that YOU KNOW HOW to do (not what Efren would do).
7. Don?t let DISTRACTIONS cause you to lose focus on the shot. If something distracts you, stand up and go through your pre-shot routine from the beginning.
8. HAVE FUN! ? Your game may improve dramatically after reminding yourself that you are playing pool primarily to have fun.
Here's a suggestion for you. Take a small card, like a business card or an index card, and write a short version of the above suggestions on the card. Maybe the short versions would read something like this.
1) Be still
2) Stay down
3) Respect every shot
4) Follow the pre-shot routine
5) Commit to the shot
6) Play within your abilities
7) Defeat distractions, reset if necessary
8) Have fun!
Of course you may want to OMIT any of the 8 that really don't relate to your game. And you may want to ADD a few that are especially important for your game. Maybe you would add reminders to grip the cue lightly, pause at the end of your last back stroke, check your stance alignment, snug up your bridge, or whatever you have learned is useful for your game. If you carry that little card around with you, it will be handy to read over when you?re shooting poorly or in a slump.
From DeeMan, with a little humor thrown in:
Here are a few things to think about if you are really serious about improving and moving beyond banger status.
Some rules most don't have to think about but are impediments to playing well.
1) Don't shoot harder then you need for the shot and to gain position.
2) Know which direction your cue balls will go and think about how far it needs to travel.
3) Don't hit other balls on the table without a reason.
4) Learn to hit the center of the cue ball very precisely before worrying about hitting it off center.
5) Try not to leave the cue ball on a rail if not necessary.
6) Shoot balls first that clear the way for your other balls.
7) Identify packs and clusters and balls that won't "go" early and get a strategy to open then up or move them. To try to run out without this plan is foolish.
8) If you don't think you have a shot or safety you are playing Efren or just not looking hard enough.
9) Don't twirl the rack or do any other trick moves to impress people unless you are trying out for the circus.
10) Learn to stay level and shoot smoothly and don't think running boring balls rack after rack is something stupid or lucky.
11) Learn that draw and follow are for more than following or backing balls up.
12) Learn to "kill" the cue ball. NOTE: This does not involve a gun.
13) Don't put powder all over the table unless you are changing your opponent's diaper.
14) Don't show disappointment to your opponent when you mess up. That way, when you learn to intentionally miss, they won't know.
15) Don't whine, we have a guy named Earl that will handle that for you.
16) Chalk with your opposite hand.
17) Learn to read kisses. Not related to Madonna and Brittany.
18) Learn your limits and don't think your draw will all of a sudden resemble Cory's. That means learn to take your medicine and shoot the possible shot, the percentage shot.
19) Play the table (unless you are stalling).
20) Don't listen to guys on the internet giving you pool advice, especially DeeMan.
Selecting an instructor
How do I decide how to select an instructor?
I have met several "instructors" that were great pool players but terrible teachers. I have also met countless great players who would make terrible instructors. An instructor obviously must be knowledgeable and understand all of the intricacies of the game, and certainly have enough experience to appreciate those intricacies. An instructor must also be a good teacher and communicator and know how to connect with various types of people. Also, a great instructor should be a total "student of the game" (i.e., read everything, discuss and debate stuff on forums, communicate professionally and open-mindedly with other instructors and players, etc). Great instructors have too many things on their plate to be great players. To be a great player, one must have sharp eyes, a near-flawless stroke, and near-perfect speed control. That takes hours and hours of practice and play ... youth can also help. Only people completely dedicated to playing pool can put in the amount of time necessary to be great.
I don't think the true value a coach or instructor provides is information. Lots of great information can be found in good books and videos (and sometimes, even on the Internet). To me, the most important value an instructor offers is the ability and experience to work with a player as a unique individual, catering the instruction to best help that person improve.
FYI, a good list of well-respected and well-known instructors can be found here:
http://billiards.colostate.edu/links.html#Schools (external web-Link)
From Spider-man:
Talk to their former students. Ask them how the lessons were structured, did they feel it was worthwhile, and why. What was good, what was bad? Would they pay this instructor for more lessons in the future? Then ask yourself whether the described style of instruction is what you want.
Talk to as many as you can find, so that you're not captive to one person's glowing praise or damning complaint. You'll also learn how the instructor customizes his agenda to an individual student, or whether he has a "cookie-cutter" approach.
In other words, don't depend on the person selling you a service to tell you whether that service is good or bad. There's a huge temptation to tell you what you want to hear. Find the former students and get the story from the perspective of someone who was in the position you're about to be in. For a well-known instructor, or even a not-so-well known one that is local to you, there should be plenty of discussion available.
From Brian_in_VA:
I don't think a great teacher is necessarily a great player as they are two very different skill sets. Someone that is blessed with both is truly exceptional and may still not give a great lesson if the student isn't prepared to learn but then, that's the students fault.
A teacher has an abundant knowledge of the game, and knowledge of the mechanics for playing it properly and the willingness to share these.
A good teacher has that plus a methodology (often in the form of drills) for passing the knowledge to the student, for demonstrating the techniques and providing appropriate feedback to the student when first attempting them. This helps the student to build success with the new skill.
A great teacher has all that plus superior communication skills. This allows them to listen to the student, understand what the student is hearing and how they learn and then adapting their communication style to better fit that student. This provides a faster application of the new skill, a better cementing of it in the student's memory and a higher motivation to perform it correctly. The great teacher also assists the student in defining and developing reachable goals for their improvement. Without goals, there is little chance for long term success and application of what's been learned.
An excellent lesson, in my opinion, is 50% the responsibility of the student. If the student is anywhere above rank beginner, they should come prepared to learn with at least some idea of why they are taking a lesson, an initial goal, if you will. "I want to get better" is not a goal, it's a dream. "I want to improve my APA rating from a 4 to a 5" is better but it still is very results oriented. Best might be "I want to build a consistent enough stroke to be able to...."
What it takes to play like a pro
What does it take to play like a pro?
The main things top players have in common are:
- they have great vision and visual perception (i.e., they can clearly and consistently "see" the "angle of the shot" and the required line of aim).
- they have excellent "feel" for shot speed, spin, and position play.
- they are able to consistently and accurately deliver the cue along the desired line with the tip contact point and speed needed for the shot (even if their mechanics aren't always "textbook").
- they have tremendous focus and intensity and have a strong drive to improve and win
For more info, visit billiards.colostate.edu
Aiming
Aiming systems
How do different people aim?
"Fundamentals - Part II: aiming" (Download) (BD, October, 2008) and “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011) articles have some good illustrations and explanations related to aiming. See also: DAM aiming system. Aiming requires good visualization skills, precise body and cue alignment, accurate and consistent sighting, and an accurate and consistent stroke. And most importantly, it requires a lot of focus, and a lot of practice. There are no quick-fix solutions; although, "aiming systems" can help some people (for many reasons).
I personally use a combination of straight intuition (just "seeing the angle"), ghost-ball aiming, and contact point visualization (see DAM for more info). Bottom line: I just visualize the aim without using any kind of fractional-ball or fixed-reference compensation system. I certainly don't use any kind of math or numbers when I aim, like some people have suggested.
I think (but don't know) that if a scientific survey were done with all of the pro players, many (maybe even most) of them would say that aiming comes naturally (i.e., its "intuitive" or they just "see the angle"), because they have played so much. Some people might find the How the Pros Aim article (Download) interesting; although, it is not the result of a rigorous scientific study.
Here's a good introduction to aiming from Jerry Briesath. (YouTube)
from Patrick Johnson:
Many, maybe most, players learn to aim with no conscious technique, just by practice and repetition. Aiming techniques might make aiming easier for you, or you might be one of the many who use no technique. It isn't necessary to use them in order to play well. None of these techniques are better or worse than others, and it's not better or worse to use a technique or not. It's a personal choice.
Two general categories of aiming techniques are:
1. "Exact" techniques produce exact aim in theory, but are limited by our imperfect ability to visualize and execute them. They include:
2. "Align & Adjust" techniques begin by aiming at the same part of the object ball each time (center, contact point or edge) and adjust from there "by feel" to the actual aim for the shot. Common beginning alignments are ("CB" = cue ball; "OB" = object ball):
from Spider man:
You are correct, that is a fine article. But, as even that author concludes, it will never be "put to rest". Luckily, it doesn't really matter. The numerous pros interviewed used a vast and disparate array of aiming techniques. "Ghost Ball" seemed to be the only somewhat-recurring assertion, but not to a dominant extent. There were even one or two who claimed to aim by "feel".
Personally I use the "ghost ball" technique most often, but not to exclusion of others. I learned to play with no coaching, and "ghost ball" was something I thought I invented . I didn't learn what everyone else called it until I read "99 Critical Shots". Now on some simple shots I just let the subconscious handle aiming - all I visualize is the desired result, and it happens, right down to how much the CB path distorts from the draw, and how far it rolls after the second rail. On very thin cuts I may visualize actual ball-to-ball contact points. But on ALL caroms I fall back to an augmented ghost-ball alignment. Most players will hit caroms too thick if they rely on feel.
What I would like to stress from that article is the one thing that everyone interviewed DID have in common - "the balls went in" for them.
The fact that so many different methods will work, and work well, ensures that some will die convinced that "their" way is "the only" way. Clearly all brains are not wired alike, and no one technique is ever going to be a panacea. Use what works for you, as long as it makes sense.
from Bob_Jewett:
You may find one of the following articles useful. I included the article about finding the center of the pocket because if you don't know where that is, it's pretty hard to aim well. (Downloads)
http://www.sfbilliards.com/articles/1993.pdf (June) -- close ball aiming
http://www.sfbilliards.com/articles/1996.pdf (February) -- frozen ball aiming
http://www.sfbilliards.com/articles/1997.pdf (April) -- finding the center of the pocket
http://www.sfbilliards.com/articles/1999.pdf (November) -- a smorgasbord of systems
http://www.sfbilliards.com/articles/2000.pdf (June) -- analysis of three systems
http://www.sfbilliards.com/articles/2004.pdf (June) -- ferrule system, lights system, overlap system
http://www.sfbilliards.com/articles/2004.pdf (December) -- aiming devices
http://www.sfbilliards.com/articles/2005.pdf (January) -- some more devices
http://www.sfbilliards.com/articles/2005.pdf (June) -- a history of parallel aiming
How do different people aim?
"Fundamentals - Part II: aiming" (Download) (BD, October, 2008) and “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011) articles have some good illustrations and explanations related to aiming. See also: DAM aiming system. Aiming requires good visualization skills, precise body and cue alignment, accurate and consistent sighting, and an accurate and consistent stroke. And most importantly, it requires a lot of focus, and a lot of practice. There are no quick-fix solutions; although, "aiming systems" can help some people (for many reasons).
I personally use a combination of straight intuition (just "seeing the angle"), ghost-ball aiming, and contact point visualization (see DAM for more info). Bottom line: I just visualize the aim without using any kind of fractional-ball or fixed-reference compensation system. I certainly don't use any kind of math or numbers when I aim, like some people have suggested.
I think (but don't know) that if a scientific survey were done with all of the pro players, many (maybe even most) of them would say that aiming comes naturally (i.e., its "intuitive" or they just "see the angle"), because they have played so much. Some people might find the How the Pros Aim article (Download) interesting; although, it is not the result of a rigorous scientific study.
Here's a good introduction to aiming from Jerry Briesath. (YouTube)
from Patrick Johnson:
Many, maybe most, players learn to aim with no conscious technique, just by practice and repetition. Aiming techniques might make aiming easier for you, or you might be one of the many who use no technique. It isn't necessary to use them in order to play well. None of these techniques are better or worse than others, and it's not better or worse to use a technique or not. It's a personal choice.
Two general categories of aiming techniques are:
1. "Exact" techniques produce exact aim in theory, but are limited by our imperfect ability to visualize and execute them. They include:
- Ghost Ball
- Double Offset
- Parallel Lines
2. "Align & Adjust" techniques begin by aiming at the same part of the object ball each time (center, contact point or edge) and adjust from there "by feel" to the actual aim for the shot. Common beginning alignments are ("CB" = cue ball; "OB" = object ball):
- CB Center to OB Center
- CB Center to OB Edge
- CB Center to OB Contact Point
- Stick Edge to OB Contact Point
from Spider man:
You are correct, that is a fine article. But, as even that author concludes, it will never be "put to rest". Luckily, it doesn't really matter. The numerous pros interviewed used a vast and disparate array of aiming techniques. "Ghost Ball" seemed to be the only somewhat-recurring assertion, but not to a dominant extent. There were even one or two who claimed to aim by "feel".
Personally I use the "ghost ball" technique most often, but not to exclusion of others. I learned to play with no coaching, and "ghost ball" was something I thought I invented . I didn't learn what everyone else called it until I read "99 Critical Shots". Now on some simple shots I just let the subconscious handle aiming - all I visualize is the desired result, and it happens, right down to how much the CB path distorts from the draw, and how far it rolls after the second rail. On very thin cuts I may visualize actual ball-to-ball contact points. But on ALL caroms I fall back to an augmented ghost-ball alignment. Most players will hit caroms too thick if they rely on feel.
What I would like to stress from that article is the one thing that everyone interviewed DID have in common - "the balls went in" for them.
The fact that so many different methods will work, and work well, ensures that some will die convinced that "their" way is "the only" way. Clearly all brains are not wired alike, and no one technique is ever going to be a panacea. Use what works for you, as long as it makes sense.
from Bob_Jewett:
You may find one of the following articles useful. I included the article about finding the center of the pocket because if you don't know where that is, it's pretty hard to aim well. (Downloads)
http://www.sfbilliards.com/articles/1993.pdf (June) -- close ball aiming
http://www.sfbilliards.com/articles/1996.pdf (February) -- frozen ball aiming
http://www.sfbilliards.com/articles/1997.pdf (April) -- finding the center of the pocket
http://www.sfbilliards.com/articles/1999.pdf (November) -- a smorgasbord of systems
http://www.sfbilliards.com/articles/2000.pdf (June) -- analysis of three systems
http://www.sfbilliards.com/articles/2004.pdf (June) -- ferrule system, lights system, overlap system
http://www.sfbilliards.com/articles/2004.pdf (December) -- aiming devices
http://www.sfbilliards.com/articles/2005.pdf (January) -- some more devices
http://www.sfbilliards.com/articles/2005.pdf (June) -- a history of parallel aiming
Benefits of various aiming systems
Why are some basic cut shot "aiming systems" helpful and effective?
Any "system" that forces a person to focus on aim, alignment, and sighting consistently and with concentration will be beneficial to many people, especially people who currently don't focus well or long enough. It also helps to have a consistent and meaningful pre-shot routine, which the systems can help foster.
Concerning CTE, using the edge of the OB as a visual reference, and doing so consistently in setting up for every shot (e.g., by initially aligning with the CTE line), might help some people judge and visually learn/reinforce the amount of cut needed from one shot to the next. Also, focusing on the center of the CB (after the pivot) will help avoid unintentional side spin, which can cause squirt, swerve, and spin-induced throw, which can reduce accuracy and consistency. Also, placing the bridge hand down with the cue off angle (before the pivot) might allow some people to place their bridge hand more accurately because the pre-pivot cue might not disrupt the aiming line visual as much as when it is brought straight into the aiming line direction with the bridge.
From Colin Colenso (concerning 90/90 and CTE pivot-based systems):
I wanted to make a post listing what I perceive to be the strongest advantages of these systems.
I think these advantages are the main reason players often find great success aiming and shooting this way.
PLAUSIBLE CONTRIBUTING FACTORS:
1. Sighting point to point helps one to perceive an exact line and to take in the positions of the two balls relative to this line. In other words, they use a repeatable fixed method to visualize the ball positions.
2. These systems put you either right on line to begin with or in the ball park when used for appropriate shots.
3. In the pivot phase they move from this fixed line to another visual line that they perceive through the center of the CB. This finding of an aim line forces the mind to be decisive and exact. I believe forcing this decisiveness trains the mind not to wander and to make better decisions than just feeling around back and forth hoping to feel a ghost ball or contact point angle.
4. I suspect this one is the most powerful factor in these aiming methods. They force a player to commit to a pot line and then strike the cue dead straight through that line, rather than to swoop sideways on the shot as almost all beginners do. Because they focus hard on their pre-stroke alignment, they trust this line and stroke straight. If they do miss certain shots they will soon compensate with their aim until they learn to see the correct line. The normal player very often aims thick on their cut angles and swoops a little to make the cuts. When they try to bring speed or English into those shots they meet with many difficulties. So using any system that forces a player to adopt strict and accurate pre-alignment, followed by a straight stroke, should meet with considerable success and consistency after intensive practice.
5. Because players learn to trust their pre-alignment they begin to be able to relax during the actual stroke. This takes tension out of their arms and body and they can begin to execute with better speed and a more satisfactory feeling during execution. This may explain the feeling that they feel like they just pivot, bang and the ball goes in.
6. A system that requires a focus on the positioning of the cue may cause the player to be more highly aware of the line of cue. In standard aiming, some players may glance a little at the tip and CB but be mainly focused at the OB and therefore not getting much visual feedback from their cue, which is a straight line guide waiting to be used. Also, this cue position awareness may lead to a more constant positioning of the eyes over the cue. This is quite different to the normal play experience where there is a tendency to ride the ball into the hole. This occurs when players don't trust their alignment and tend to swoop a little to ride the cue ball to the correct point. This method of playing tends to make one have to work physically and mentally during the stroke. When pre-aligned well, the stroke is simply a matter of swinging the cue.
7. Using these systems may represent the most organized approach they have attempted for aiming. Several aspects have been compartmentalized so that each of these aspects can be focused on more clearly and developed individually. This organization may also assist in allowing the player to relax through the early implementation stage and then put their entire focus into the final alignment stage.
8. While sliding or shifting the cue into the final line of the shot, players may be incorporating a method that helps them to sight the required line of aim. This may be due to coming across the line, from left to right or vice versa, such that the sighter gets a feel for how the line of aim is moving relative to the position of the OB.
The only thing I don't agree with regarding these systems is that the systems find the aim line. I think it is the players that align themselves (via slight intuitive adjustments) to the correct aim line when need be. It will take them a little while to develop this ability for a wide range of shots.
From Mike Page (concerning pivot-based systems like CTE):
Various people report immediate improvement upon adopting a fractional ball approach. Others report immediate improvement upon adopting a "pivot" approach. Here's why. There are five independent "things" involved with aiming.
(1) the pocket
(2) the object ball
(3) the cue ball
(4) the stick
(5) the cyclopean eye
All 5 are necessary to get the job done. But the essence of determining the AIM LINE involves just three of these: the cyclopean eye, the cueball, and the object ball. The pocket should be considered BEFORE determining the AIM LINE The stick should be considered AFTER determining the aim line.
Many aiming perception problems involve, imo, either
(1) keeping the POCKET in the process too long or
(2) entering the STICK into the process too early
Those with problem (1) are helped by fractional ball approaches. Those with problem (2) are helped by pivot-style approaches.
A player MUST consider the pocket before determining the aim line. But once the pocket is considered to determine an object ball contact point or a ghost ball location or (along with the cue ball) a fullness of hit, there is no more information needed about the pocket. Many players suffer from being biased by the pocket when they're down on the shot. For those players, focusing on a ball overlap or on a cue ball aim point can help a lot.
Here's the other problem. When you are ready to pull the trigger, the STICK LINE and the AIM LINE are one and the same, and they need to be on the CORRECT AIM LINE. But before you are ready to pull the trigger, while you are just starting to get into position, all three are different. Imagine a red laser beam that is fixed on the CORRECT AIM LINE, and a green laser beam that is wherever you are looking, and a blue laser beam that goes through the center of the stick.
The CORRECT way to aim, imo, is first to get the green laser beam on the red one, and THEN to bring the blue one on board. If you don't do that, then you are biased by the stick line coming into view. The "almost right" stick line holds no value, but just like the fun-house almost straight walls and floors, we are drawn to them more than we should be.
So try aiming the shot by getting down into position with the stick off to the side and then with the ball-ball aim in view, bring the stick in from the side. Some people are helped a lot by this. It's a matter of not letting the tail wag the dog. So no, HOW you pivot doesn't matter. There are no magic rotating airpivoting receding hyperspheres. The emperor is naked.
From Mike Page:
If something seems to work or to help some people it IS important to many of us to understand WHY it helps. Part of this--most of us are here for fun when it comes down to it--is intellectual curiosity, but a big part of it is understanding what specific problems are solved by a particular approach to be able to incorporate and communicate those things directly and extend them to new situations.
There are reasons why beginning every shot the same way--looking full on or looking at the half-ball hit for instance--might be useful. The "SEEing it (from manual repetition)" you described above benefits from approaching the same shots the same way every time.
There are other reasons some of these approaches--whether it's one of Hal's methods or S.A.M. or whatever is being discussed here--help people. Get ready, because there's a big secret coming... These approaches cause people to do something they don't usually do. It's such an important thing that we have a name for it. It's called AIM. That's right.
If you look at the QUIET EYE studies, you will find one bit of consistency about the studies of pool, of putting, of basketball free throws, and of other aims involving stationary targets. Consistently a group of experts is compared to a group of wannabes. Consistently the group of experts GAZE at they target on average for a notably longer period of time in the "set" position. I'm talking maybe 2.5 seconds versus 1.5 seconds. It has become increasingly clear that this slightly longer gaze time--locking on your target for enough time-- is crucial for processing the information necessary to aim successfully.
Let's suppose many people suffer from inadequate GAZE time. IF true, then showing them a new method that forces them to lock in on the target (while following whatever the prescription is) will increase their success rate. Like the poop-on-the-swingset, the method might just be a mechanism to bring out the real solution (water/quiet-eye gaze time).
I point out in one of my aiming videos that I think another reason for any success people find with fractional ball aiming techniques is it causes them to sight parallel to the line the stick is moving. Many people don't. Many people sight from above the stick to the object ball contact point. This line is not parallel to the line of the stick or the cue ball motion.
Please understand that when someone suggests a method that SEEMS to not have the gaps filled in, that SEEMS to have shots that require two different angles to receive the same aim, that SEEMS to request the exact same aim for two sticks that we know squirt differently, it is like a giant bell going off for many of us.
Then if rather than taking off the system's clothes so that we can examine it honestly, the proponent points out that you really have to learn it in person or that such and such a world-class player uses it, it's like another giant bell going off.
... focusing on center-to-edge or edge-to-wherever gets your site line parallel to your stick. This could be a key for you to unlock the aim you really already have.
Or perhaps focusing on a shot from the edge of the cue ball and pivoting toward the center--like being discussed here--locks a person into an eye dominance that is different from what he would have done going straight down into the shot and gives him a perspective that works better for him.
My point is if these sorts of advice help certain people under certain circumstances pocket balls, then that's great. But it is very different from the aiming system "working." These people are actually finding their own aim; they're just approaching their own aim from a different angle.
From Joe W:
I suspect that aiming systems give people a reference point from which to think about the shot. Some players may or may not be aware of the idea that for some shots their subconscious makes adjustments.
On the one side aiming systems provide a zone of comfort for the player because they work in some (many) situations. This in turn leads to confidence when shooting and the player, over time, learns to compensate as needed.
On the other side it can be demonstrated that some aspects of these systems can not work as described. Proponents of the system seem to indicate that these systems take several weeks (?) to learn. However, the concepts are basically straightforward and could be briefly described and learned in a few hours. Weeks of training are required because the systems involve the development of "feel" though the user may not be aware of this aspect and therefore does not have to trust their natural sighting ability which is being developed within the system. For the present they have a system that can be relied upon.
In a sense, a player could be taught any of several systems and they all would work equally well if the player is willing to trust the system.
The conclusion is that one may seek the limits of the aiming system to learn what is useful for some particular shots from a physical basis and this may contribute to the development of a new, more advanced, system.
Why is aiming so difficult for some people?
Aiming is tough because it involves 3D visualization, visual perception, physical and visual alignment, and compensation for CIT (with no side spin) and/or squirt/swerve/throw with side spin.
From Patrick Johnson:
Aiming isn't a science, despite what some system [people] think. It involves many kinds of estimation:
- estimating where the OB contact point is by aligning it with the pocket, from a distance and an angle
- estimating how to adjust the OB contact point for throw
- estimating where the CB contact point is by imagining where it is on the "dark side" of the CB (this is part 1 of the subject of aiming systems)
- estimating how to align the CB and OB so the two contact points come together (this is part 2 of the subject of aiming systems)
- estimating how to position your head and eyes so all the above things are visualized correctly (this is part 2A of the subject of aiming systems)
This is only a partial list of the estimations required just for aiming (not stroking), and only for shots without side spin (don't get me started).
Even with a perfect stroke aiming isn't a simple, mechanically repeatable process.
From Colin Colenso:
I think that the biggest error that most players make when trying to become more accurate players is when they presume that their missed shots are caused by poor Stroke Mechanics, while they overlook the most common and significant cause which is poor Initial Alignment.
By Initial Alignment, I basically mean the positioning of the bridge point.
If you do not get your bridge to a point + or - a millimeter or less from the required line, then you are going to have to play an off center or sweeping stroke to pocket the OB as hoped.
In fact, it is common for players to subconsciously make this stroke adjustment when they feel that the shot is not going on line. This creates tension in their swing...their brain is fighting their heart is one way to describe it. So after they miss, they recall the sense of tension in the stroke, so confusedly start practicing their stroke, blaming their wrist action or some other aspect of stroke mechanics which is usually just a symptom of their poor Initial Alignment.
So to establish some proof for my contention, I set up a test.
A mechanical bridge was wedged into position. A piece of chalk sat under the rail as a firm point to keep the bridge from moving. CB and OB were put into positions that lined up for pocketing to the corner. Once established, I tapped the balls into place marked by a cross on the cloth. Hence I could replace the balls to almost identical positions each shot.
Using the bridge, fixed in place, my stroking did not feel very stable, yet I was able to pocket this shot 20 times in a row with very little variation in the pocketing accuracy. Not a single time did the OB hit the jaw.
Now I could make this shot miss by striking deliberately with English, but the point is, that it's not hard to hit the CB center ball accurately enough to provide satisfactory accuracy for most shots on the table.
The hard part is getting the bridge hand in perfect position for the shot...that is, to align perfectly
Why are some basic cut shot "aiming systems" helpful and effective?
Any "system" that forces a person to focus on aim, alignment, and sighting consistently and with concentration will be beneficial to many people, especially people who currently don't focus well or long enough. It also helps to have a consistent and meaningful pre-shot routine, which the systems can help foster.
Concerning CTE, using the edge of the OB as a visual reference, and doing so consistently in setting up for every shot (e.g., by initially aligning with the CTE line), might help some people judge and visually learn/reinforce the amount of cut needed from one shot to the next. Also, focusing on the center of the CB (after the pivot) will help avoid unintentional side spin, which can cause squirt, swerve, and spin-induced throw, which can reduce accuracy and consistency. Also, placing the bridge hand down with the cue off angle (before the pivot) might allow some people to place their bridge hand more accurately because the pre-pivot cue might not disrupt the aiming line visual as much as when it is brought straight into the aiming line direction with the bridge.
From Colin Colenso (concerning 90/90 and CTE pivot-based systems):
I wanted to make a post listing what I perceive to be the strongest advantages of these systems.
I think these advantages are the main reason players often find great success aiming and shooting this way.
PLAUSIBLE CONTRIBUTING FACTORS:
1. Sighting point to point helps one to perceive an exact line and to take in the positions of the two balls relative to this line. In other words, they use a repeatable fixed method to visualize the ball positions.
2. These systems put you either right on line to begin with or in the ball park when used for appropriate shots.
3. In the pivot phase they move from this fixed line to another visual line that they perceive through the center of the CB. This finding of an aim line forces the mind to be decisive and exact. I believe forcing this decisiveness trains the mind not to wander and to make better decisions than just feeling around back and forth hoping to feel a ghost ball or contact point angle.
4. I suspect this one is the most powerful factor in these aiming methods. They force a player to commit to a pot line and then strike the cue dead straight through that line, rather than to swoop sideways on the shot as almost all beginners do. Because they focus hard on their pre-stroke alignment, they trust this line and stroke straight. If they do miss certain shots they will soon compensate with their aim until they learn to see the correct line. The normal player very often aims thick on their cut angles and swoops a little to make the cuts. When they try to bring speed or English into those shots they meet with many difficulties. So using any system that forces a player to adopt strict and accurate pre-alignment, followed by a straight stroke, should meet with considerable success and consistency after intensive practice.
5. Because players learn to trust their pre-alignment they begin to be able to relax during the actual stroke. This takes tension out of their arms and body and they can begin to execute with better speed and a more satisfactory feeling during execution. This may explain the feeling that they feel like they just pivot, bang and the ball goes in.
6. A system that requires a focus on the positioning of the cue may cause the player to be more highly aware of the line of cue. In standard aiming, some players may glance a little at the tip and CB but be mainly focused at the OB and therefore not getting much visual feedback from their cue, which is a straight line guide waiting to be used. Also, this cue position awareness may lead to a more constant positioning of the eyes over the cue. This is quite different to the normal play experience where there is a tendency to ride the ball into the hole. This occurs when players don't trust their alignment and tend to swoop a little to ride the cue ball to the correct point. This method of playing tends to make one have to work physically and mentally during the stroke. When pre-aligned well, the stroke is simply a matter of swinging the cue.
7. Using these systems may represent the most organized approach they have attempted for aiming. Several aspects have been compartmentalized so that each of these aspects can be focused on more clearly and developed individually. This organization may also assist in allowing the player to relax through the early implementation stage and then put their entire focus into the final alignment stage.
8. While sliding or shifting the cue into the final line of the shot, players may be incorporating a method that helps them to sight the required line of aim. This may be due to coming across the line, from left to right or vice versa, such that the sighter gets a feel for how the line of aim is moving relative to the position of the OB.
The only thing I don't agree with regarding these systems is that the systems find the aim line. I think it is the players that align themselves (via slight intuitive adjustments) to the correct aim line when need be. It will take them a little while to develop this ability for a wide range of shots.
From Mike Page (concerning pivot-based systems like CTE):
Various people report immediate improvement upon adopting a fractional ball approach. Others report immediate improvement upon adopting a "pivot" approach. Here's why. There are five independent "things" involved with aiming.
(1) the pocket
(2) the object ball
(3) the cue ball
(4) the stick
(5) the cyclopean eye
All 5 are necessary to get the job done. But the essence of determining the AIM LINE involves just three of these: the cyclopean eye, the cueball, and the object ball. The pocket should be considered BEFORE determining the AIM LINE The stick should be considered AFTER determining the aim line.
Many aiming perception problems involve, imo, either
(1) keeping the POCKET in the process too long or
(2) entering the STICK into the process too early
Those with problem (1) are helped by fractional ball approaches. Those with problem (2) are helped by pivot-style approaches.
A player MUST consider the pocket before determining the aim line. But once the pocket is considered to determine an object ball contact point or a ghost ball location or (along with the cue ball) a fullness of hit, there is no more information needed about the pocket. Many players suffer from being biased by the pocket when they're down on the shot. For those players, focusing on a ball overlap or on a cue ball aim point can help a lot.
Here's the other problem. When you are ready to pull the trigger, the STICK LINE and the AIM LINE are one and the same, and they need to be on the CORRECT AIM LINE. But before you are ready to pull the trigger, while you are just starting to get into position, all three are different. Imagine a red laser beam that is fixed on the CORRECT AIM LINE, and a green laser beam that is wherever you are looking, and a blue laser beam that goes through the center of the stick.
The CORRECT way to aim, imo, is first to get the green laser beam on the red one, and THEN to bring the blue one on board. If you don't do that, then you are biased by the stick line coming into view. The "almost right" stick line holds no value, but just like the fun-house almost straight walls and floors, we are drawn to them more than we should be.
So try aiming the shot by getting down into position with the stick off to the side and then with the ball-ball aim in view, bring the stick in from the side. Some people are helped a lot by this. It's a matter of not letting the tail wag the dog. So no, HOW you pivot doesn't matter. There are no magic rotating airpivoting receding hyperspheres. The emperor is naked.
From Mike Page:
If something seems to work or to help some people it IS important to many of us to understand WHY it helps. Part of this--most of us are here for fun when it comes down to it--is intellectual curiosity, but a big part of it is understanding what specific problems are solved by a particular approach to be able to incorporate and communicate those things directly and extend them to new situations.
There are reasons why beginning every shot the same way--looking full on or looking at the half-ball hit for instance--might be useful. The "SEEing it (from manual repetition)" you described above benefits from approaching the same shots the same way every time.
There are other reasons some of these approaches--whether it's one of Hal's methods or S.A.M. or whatever is being discussed here--help people. Get ready, because there's a big secret coming... These approaches cause people to do something they don't usually do. It's such an important thing that we have a name for it. It's called AIM. That's right.
If you look at the QUIET EYE studies, you will find one bit of consistency about the studies of pool, of putting, of basketball free throws, and of other aims involving stationary targets. Consistently a group of experts is compared to a group of wannabes. Consistently the group of experts GAZE at they target on average for a notably longer period of time in the "set" position. I'm talking maybe 2.5 seconds versus 1.5 seconds. It has become increasingly clear that this slightly longer gaze time--locking on your target for enough time-- is crucial for processing the information necessary to aim successfully.
Let's suppose many people suffer from inadequate GAZE time. IF true, then showing them a new method that forces them to lock in on the target (while following whatever the prescription is) will increase their success rate. Like the poop-on-the-swingset, the method might just be a mechanism to bring out the real solution (water/quiet-eye gaze time).
I point out in one of my aiming videos that I think another reason for any success people find with fractional ball aiming techniques is it causes them to sight parallel to the line the stick is moving. Many people don't. Many people sight from above the stick to the object ball contact point. This line is not parallel to the line of the stick or the cue ball motion.
Please understand that when someone suggests a method that SEEMS to not have the gaps filled in, that SEEMS to have shots that require two different angles to receive the same aim, that SEEMS to request the exact same aim for two sticks that we know squirt differently, it is like a giant bell going off for many of us.
Then if rather than taking off the system's clothes so that we can examine it honestly, the proponent points out that you really have to learn it in person or that such and such a world-class player uses it, it's like another giant bell going off.
... focusing on center-to-edge or edge-to-wherever gets your site line parallel to your stick. This could be a key for you to unlock the aim you really already have.
Or perhaps focusing on a shot from the edge of the cue ball and pivoting toward the center--like being discussed here--locks a person into an eye dominance that is different from what he would have done going straight down into the shot and gives him a perspective that works better for him.
My point is if these sorts of advice help certain people under certain circumstances pocket balls, then that's great. But it is very different from the aiming system "working." These people are actually finding their own aim; they're just approaching their own aim from a different angle.
From Joe W:
I suspect that aiming systems give people a reference point from which to think about the shot. Some players may or may not be aware of the idea that for some shots their subconscious makes adjustments.
On the one side aiming systems provide a zone of comfort for the player because they work in some (many) situations. This in turn leads to confidence when shooting and the player, over time, learns to compensate as needed.
On the other side it can be demonstrated that some aspects of these systems can not work as described. Proponents of the system seem to indicate that these systems take several weeks (?) to learn. However, the concepts are basically straightforward and could be briefly described and learned in a few hours. Weeks of training are required because the systems involve the development of "feel" though the user may not be aware of this aspect and therefore does not have to trust their natural sighting ability which is being developed within the system. For the present they have a system that can be relied upon.
In a sense, a player could be taught any of several systems and they all would work equally well if the player is willing to trust the system.
The conclusion is that one may seek the limits of the aiming system to learn what is useful for some particular shots from a physical basis and this may contribute to the development of a new, more advanced, system.
Why is aiming so difficult for some people?
Aiming is tough because it involves 3D visualization, visual perception, physical and visual alignment, and compensation for CIT (with no side spin) and/or squirt/swerve/throw with side spin.
From Patrick Johnson:
Aiming isn't a science, despite what some system [people] think. It involves many kinds of estimation:
- estimating where the OB contact point is by aligning it with the pocket, from a distance and an angle
- estimating how to adjust the OB contact point for throw
- estimating where the CB contact point is by imagining where it is on the "dark side" of the CB (this is part 1 of the subject of aiming systems)
- estimating how to align the CB and OB so the two contact points come together (this is part 2 of the subject of aiming systems)
- estimating how to position your head and eyes so all the above things are visualized correctly (this is part 2A of the subject of aiming systems)
This is only a partial list of the estimations required just for aiming (not stroking), and only for shots without side spin (don't get me started).
Even with a perfect stroke aiming isn't a simple, mechanically repeatable process.
From Colin Colenso:
I think that the biggest error that most players make when trying to become more accurate players is when they presume that their missed shots are caused by poor Stroke Mechanics, while they overlook the most common and significant cause which is poor Initial Alignment.
By Initial Alignment, I basically mean the positioning of the bridge point.
If you do not get your bridge to a point + or - a millimeter or less from the required line, then you are going to have to play an off center or sweeping stroke to pocket the OB as hoped.
In fact, it is common for players to subconsciously make this stroke adjustment when they feel that the shot is not going on line. This creates tension in their swing...their brain is fighting their heart is one way to describe it. So after they miss, they recall the sense of tension in the stroke, so confusedly start practicing their stroke, blaming their wrist action or some other aspect of stroke mechanics which is usually just a symptom of their poor Initial Alignment.
So to establish some proof for my contention, I set up a test.
A mechanical bridge was wedged into position. A piece of chalk sat under the rail as a firm point to keep the bridge from moving. CB and OB were put into positions that lined up for pocketing to the corner. Once established, I tapped the balls into place marked by a cross on the cloth. Hence I could replace the balls to almost identical positions each shot.
Using the bridge, fixed in place, my stroking did not feel very stable, yet I was able to pocket this shot 20 times in a row with very little variation in the pocketing accuracy. Not a single time did the OB hit the jaw.
Now I could make this shot miss by striking deliberately with English, but the point is, that it's not hard to hit the CB center ball accurately enough to provide satisfactory accuracy for most shots on the table.
The hard part is getting the bridge hand in perfect position for the shot...that is, to align perfectly
From Patrick Johnson:
You'll always aim by feel; no system will change that. Even with the "systems" that show you exactly where to hit the OB ("ghost ball", "double overlap", "paralleling") you need to "feel" when you're lined up exactly right and "feel" how much adjustment to make for OB throw and CB squirt/swerve.
And most systems don't show you exactly where to hit the OB; they give you an approximate aim point (which you have to line up correctly by feel) and from that you have to adjust to the real aim point by feel. "Approximating" systems include all the systems that are not the well-known "exact" systems I named above.
"Approximating" systems include those taught by Hal Houle, Cue-Tech, RonV, Stan Shuffett, Joe Tucker and others, going by such names as "fractional aiming", "3-angles", "S.A.M.", "center-to-edge", "Pro 1", etc., etc. Some users and teachers of these systems will tell you that they are "exact" systems that need no adjustments, but they're wrong. All of them are approximation systems and all of them require you to adjust your aim by feel. The only one that I'm aware of that actually admits this fact openly is Joe Tucker's system.
Confidence is essential to increasing your "feel" for aiming, with or without an aiming system, and one of the main benefits of using a system is that it can help boost your confidence by narrowing down the range of choices you have to make by feel. Even players who don't think they use any system often use one (or more) unconsciously - for instance, when faced with a tough shot they might get a "second opinion" on their aim by imagining how "ghost ball" or "double overlap" aim would look. Many players use different systems for different kinds of shots - for instance, the "double overlap" system is especially useful for long thin cut shots.
Whether or not you use a system(s) and which one(s) you use are personal choices. Hopefully understanding exactly what aiming systems are and are not before you make those decisions will help you make the right ones for you.
Aim compensation for squirt (cue ball deflection), swerve, and throw
Is there a style of play (e.g., using aim-and-pivot aiming methods) that can compensate for all of the effects of squirt, swerve, and throw?
Background information on important related topics can be found here:
See also:
You'll always aim by feel; no system will change that. Even with the "systems" that show you exactly where to hit the OB ("ghost ball", "double overlap", "paralleling") you need to "feel" when you're lined up exactly right and "feel" how much adjustment to make for OB throw and CB squirt/swerve.
And most systems don't show you exactly where to hit the OB; they give you an approximate aim point (which you have to line up correctly by feel) and from that you have to adjust to the real aim point by feel. "Approximating" systems include all the systems that are not the well-known "exact" systems I named above.
"Approximating" systems include those taught by Hal Houle, Cue-Tech, RonV, Stan Shuffett, Joe Tucker and others, going by such names as "fractional aiming", "3-angles", "S.A.M.", "center-to-edge", "Pro 1", etc., etc. Some users and teachers of these systems will tell you that they are "exact" systems that need no adjustments, but they're wrong. All of them are approximation systems and all of them require you to adjust your aim by feel. The only one that I'm aware of that actually admits this fact openly is Joe Tucker's system.
Confidence is essential to increasing your "feel" for aiming, with or without an aiming system, and one of the main benefits of using a system is that it can help boost your confidence by narrowing down the range of choices you have to make by feel. Even players who don't think they use any system often use one (or more) unconsciously - for instance, when faced with a tough shot they might get a "second opinion" on their aim by imagining how "ghost ball" or "double overlap" aim would look. Many players use different systems for different kinds of shots - for instance, the "double overlap" system is especially useful for long thin cut shots.
Whether or not you use a system(s) and which one(s) you use are personal choices. Hopefully understanding exactly what aiming systems are and are not before you make those decisions will help you make the right ones for you.
Aim compensation for squirt (cue ball deflection), swerve, and throw
Is there a style of play (e.g., using aim-and-pivot aiming methods) that can compensate for all of the effects of squirt, swerve, and throw?
Background information on important related topics can be found here:
- back-hand English (BHE) and front-hand English (FHE)
- cue pivot length
- squirt, swerve, and throw effects
See also:
and here are some other more-detailed videos on the topic: (YouTube)
Squirt, swerve, and throw effects
What squirt (cue ball deflection), swerve, and throw effects do I need to be aware of?
A complete summary of all squirt (cue ball deflection), swerve, and throw effects and rules of thumb can be found below in the numbered list beneath the videos and illustration.
Here are some pertinent video demonstrations from the Video Encyclopedia of Pool Shots (VEPS): (external web-link)
- NV A.19 - Colin Colenso's back-hand-english saga (for squirt compensation)
- NV B.24 - Joe Tucker's squirt, swerve, and BHE/FHE combo (part 1)
- NV B.24 - Joe Tucker's squirt, swerve, and BHE/FHE combo (part 2)
- NV B.24 - Joe Tucker's squirt, swerve, and BHE/FHE combo (part 3)
Squirt, swerve, and throw effects
What squirt (cue ball deflection), swerve, and throw effects do I need to be aware of?
A complete summary of all squirt (cue ball deflection), swerve, and throw effects and rules of thumb can be found below in the numbered list beneath the videos and illustration.
Here are some pertinent video demonstrations from the Video Encyclopedia of Pool Shots (VEPS): (external web-link)
The numbered list below is a quick summary of important squirt (cue ball deflection), swerve, and throw effects, along with links to supporting resources. Let's start with a short glossary of definitions and an illustration of some of the terminology used in the effects list. More definitions can be found in the online glossary, (Download) and additional info and examples can be found in the linked resources.
BHE: back-hand English
CB: cue ball
CIT: cut-induced throw
FHE: front-hand English
gearing OE: the amount of outside English that results in no throwIE: inside English
OB: object ball
OE: outside English
SIT: spin-induced throw
squerve: combination of squirt and swerve
BHE: back-hand English
CB: cue ball
CIT: cut-induced throw
FHE: front-hand English
gearing OE: the amount of outside English that results in no throwIE: inside English
OB: object ball
OE: outside English
SIT: spin-induced throw
squerve: combination of squirt and swerve
Squirt (cue ball deflection), Swerve, and Throw Effects:
(everything you ever wanted to know about squirt, swerve, and throw)
from Colin Colenso:
It's little wonder that pros are adept at, and usually rely almost solely upon simply estimating how to align to any shot they want to make using English.
There really has been no other way to learn how to execute English for a wide range of shots. So they learn a huge range of shots by repetition and this gives them the intuitive feel to make, or get close to almost any shot they attempt with varying degrees of cut angle, speed and tip offset.
When I first learned about BHE a few years ago I thought it was some instant quick fix. But I soon learned that there were variables that affected the success on many shots quite significantly. These are:
1. The effective pivot point changes according to speed and distance traveled. (Swerve is the culprit).
2. The actual contact point required to make shots varies considerably with CB speed, cut angle and type and rate of spin on the CB.
So without knowing how much to adjust for all of these variables, BHE is only useful for a limited range of shots.
[Here is a method, with formulas, that can be used to select a bridge length to compensate for both squirt and swerve, assuming you have already adjusted your aim for any throw effects.]
PPe = PPi + DVK
PPe = required effective pivot point for any shot based on distance and shot speed.
D = Distance from CB to OB (or target) in feet.
V = Velocity Factor where 0 is maximum speed and 4 is slow, or one table length roll including bouncing off one rail (see below).
K = correction factor to account for cloth slickness given by:
K = (PPe* - PPi) / 15
PPi = The Intrinsic Pivot Point. Estimated by finding the effective pivot point for a shot over 5 feet hitting at maximum velocity, such that swerve has insignificant influence on the shot. My cue's PPi is 9.5 inches. Low squirt cues are 12 to 14 inches.
PPe* = the pivot point required for a 5 foot shot at speed factor 3, which is medium slow, enough to bounce 2 rails back to the original position. This figure will be different for each cue on each table. It brings the slickness variable into the formula.
My preferred cue on my table has PPe* = 13.7 inches. (This could change with humidity changes). It's PPi is 9.5 inches, so my K value for my cue on my table at the moment is (13.7 - 9.5)/15 = approx 0.28. 0.28 is the adjustment needed at distance 1 foot and speed factor 1. The number 15 is derived from the PPe* being at 5 foot at speed factor 3. 5x3 = 15. PPe* could use any shot as a basis with a different numerator, but 5 foot is a good number because it is about the length of the cue, it can be played with little elevation and it is long and slow enough to provide a decent difference with PPi, hence giving it a reasonable margin of error. PPe* can vary by around 2 inches depending on cloth slickness. It is a number that can be derived pretty accurately within half a dozen hits on a new table.
So for any shot my PPe = 9.5 + D x V x 0.28
So if I have a shot at speed factor 2 over 4 feet my PPe = 9.5 + 2.24 = approx 11.7 inches.
Below is a chart with PPe's for the full range of speeds and distances for my cue. You should be able to plug data into this formula and get PPe's that correspond to those in the chart. Note: The key to making this formula simple was creating the methodology of the speed factor. In the chart below, the speeds are divided into 6 markings, rather than the 5 for speed factors 0-4.
General Speed Factor (V) Rules are:
0 = Max speed, would bounce about 5 rails.
1 = Firm speed, would bounce 4 rails and back to starting position.
2 = Medium speed, would bounce 3 rails and back to starting position.
3 = Slow-Medium speed, would bounce 2 rails and back to starting position.
4 = Slow speed, would bounce 1 rail and back to starting position at center table.
(everything you ever wanted to know about squirt, swerve, and throw)
- Squirt increases with the amount of side spin.
- Squirt does not depend on shot speed (see squirt speed effects for more info).
- Squirt increases with the amount of shaft end mass (e.g., a low-squirt cue has less end mass and results in less squirt).
- Squirt is slightly less with a heavier CB (see CB weight effects).
- Squerve (net effect of squirt and swerve = net CB deflection) can be zero with certain speeds and cue elevations for a given shot distance, amount of side spin, and cue.
- Squerve is less for follow vs. draw shots (see squirt tip-contact-height effects).
- Squirt or squerve can be canceled using back-hand English (BHE) and/or front-hand English (FHE) aim-and-pivot methods.
- Swerve increases with cue elevation and the amount of side spin.
- Swerve occurs with practically all side spin shots because the cue must be elevated to clear the rails.
- Swerve is delayed with faster shot speed.
- Swerve occurs only while the CB is sliding; once rolling begins, the CB heads in a straight line.
- Swerve occurs earlier with sticky cloth and later on slick cloth.
- Swerve occurs earlier with a follow shot than with a draw shot (see "Squirt - Part VIII: squerve effects" (Download) - BD, March, 2008).
- Swerve angle is larger with a draw shot than with a follow shot (see "Squirt - Part VIII: squerve effects" (Download) - BD, March, 2008).
- Swerve angle can be predicted and visualized using the Coriolis masse-shot aiming method.
- For small cut angle shots (i.e., fuller hits), the amount of CIT does not vary with shot speed, but increases with cut angle (see NV B.86 (YouTube) and "Throw - Part II: results" (Download) - BD, September, 2006).
- For larger cut angle shots (i.e., thinner hits), the amount of CIT is significantly larger for slower speed shots as compared to faster speed shots (see "Throw - Part II: results" (Download) - BD, September, 2006, and Ball Motion Properties in Stun and Follow Shots, (external web-link)).
- The amount of CIT decreases some with larger cut angles, but not by much (especially for slower speed shots) (see "Throw - Part II: results" (Download) - BD, September, 2006).
- Maximum CIT occurs at close to a half-ball hit (30-degree cut angle) (see "Throw - Part II: results" (Download) - BD, September, 2006).
- In general, throw is larger at slower speeds, and for stun shots.
- Maximum throw, under typical conditions, is about 1 inch per foot of CB travel, which is about 5 degrees.
- Both follow and draw reduce throw, and they do so by the same amount (see "Throw - Part III: follow and draw effects" (Download) - BD, October, 2006).
- The largest discrepancy between throw values for stun and follow/draw shots occurs close to a half-ball hit (30-degree cut angle) (see "Throw - Part III: follow and draw effects" (Download) - BD, October, 2006).
- The difference between the throw of stun and follow/draw shots is not as great at larger cut angles (see "Throw - Part III: follow and draw effects" (Download) - BD, October, 2006).
- More side spin gives you more SIT only up to a point. Additional side spin beyond that point actually reduces the amount of SIT (i.e., more side spin doesn't always give you more throw) (see "Throw - Part V: SIT speed effects" (Download) - BD, December, 2006).
- SIT is largest for a slow stun shot with about 50% of maximum side spin (see see NV B.86 (YouTube) and "Throw - Part V: SIT speed effects" (Download) - BD, December, 2006).
- The amount of throw can increase significantly as a small amount of side spin is added, especially for a stun shot (see "Throw - Part IV: spin-induced throw" (Download) - BD, November, 2006).
- SIT is independent of speed (i.e., the throw is the same at all speeds) for small amounts of side spin (see "Throw - Part V: SIT speed effects" (Download) - BD, December, 2006).
- "Gearing" OE results in absolutely no throw. The amount of side spin required for "gearing" increases with cut angle. At a half-ball hit, the amount of side spin required is about 50% (see "Throw - Part VI: inside/outside English" (Download) - BD, January, 2007).
- At very small cut angles, IE and OE create similar amounts of throw (although, in opposite directions) (see "Throw - Part VII: CIT/SIT combo" (Download) - BD, February, 2007).
- For large cut angles, a small amount of OE can result in more throw than shots with no side spin (see see "Throw - Part VII: CIT/SIT combo" (Download) - BD, February, 2007).
- For large cut angles, IE results in less throw than shots with no side spin (see see "Throw - Part VII: CIT/SIT combo" (Download)- BD, February, 2007).
- IE increases throw at small cut angles, but actually reduces the amount of throw at larger cut angles (see see "Throw - Part VII: CIT/SIT combo" (Download) - BD, February, 2007).
- OE can cause throw in either direction depending on the amount of side spin and the cut angle (see "Throw - Part VI: inside/outside English" (Download) - BD, January, 2007).
- Even for large cut angle shots (thin hits), excess OE (more than the "gearing" amount) can be applied to throw the OB in the SIT direction (see "Throw - Part VI: inside/outside English" (Download) - BD, January, 2007).
- The amount of throw with IE can be much more consistent than with OE if the amount of side spin varies a little. In other words, the amount of throw varies more with tip placement for OE vs. IE. This might explain why some people prefer using IE on cut shots ... because they can better anticipate and adjust for the amount of throw.
- The least amount of throw, and the most throw consistency, occurs with fast IE shots.
from Colin Colenso:
It's little wonder that pros are adept at, and usually rely almost solely upon simply estimating how to align to any shot they want to make using English.
There really has been no other way to learn how to execute English for a wide range of shots. So they learn a huge range of shots by repetition and this gives them the intuitive feel to make, or get close to almost any shot they attempt with varying degrees of cut angle, speed and tip offset.
When I first learned about BHE a few years ago I thought it was some instant quick fix. But I soon learned that there were variables that affected the success on many shots quite significantly. These are:
1. The effective pivot point changes according to speed and distance traveled. (Swerve is the culprit).
2. The actual contact point required to make shots varies considerably with CB speed, cut angle and type and rate of spin on the CB.
So without knowing how much to adjust for all of these variables, BHE is only useful for a limited range of shots.
[Here is a method, with formulas, that can be used to select a bridge length to compensate for both squirt and swerve, assuming you have already adjusted your aim for any throw effects.]
PPe = PPi + DVK
PPe = required effective pivot point for any shot based on distance and shot speed.
D = Distance from CB to OB (or target) in feet.
V = Velocity Factor where 0 is maximum speed and 4 is slow, or one table length roll including bouncing off one rail (see below).
K = correction factor to account for cloth slickness given by:
K = (PPe* - PPi) / 15
PPi = The Intrinsic Pivot Point. Estimated by finding the effective pivot point for a shot over 5 feet hitting at maximum velocity, such that swerve has insignificant influence on the shot. My cue's PPi is 9.5 inches. Low squirt cues are 12 to 14 inches.
PPe* = the pivot point required for a 5 foot shot at speed factor 3, which is medium slow, enough to bounce 2 rails back to the original position. This figure will be different for each cue on each table. It brings the slickness variable into the formula.
My preferred cue on my table has PPe* = 13.7 inches. (This could change with humidity changes). It's PPi is 9.5 inches, so my K value for my cue on my table at the moment is (13.7 - 9.5)/15 = approx 0.28. 0.28 is the adjustment needed at distance 1 foot and speed factor 1. The number 15 is derived from the PPe* being at 5 foot at speed factor 3. 5x3 = 15. PPe* could use any shot as a basis with a different numerator, but 5 foot is a good number because it is about the length of the cue, it can be played with little elevation and it is long and slow enough to provide a decent difference with PPi, hence giving it a reasonable margin of error. PPe* can vary by around 2 inches depending on cloth slickness. It is a number that can be derived pretty accurately within half a dozen hits on a new table.
So for any shot my PPe = 9.5 + D x V x 0.28
So if I have a shot at speed factor 2 over 4 feet my PPe = 9.5 + 2.24 = approx 11.7 inches.
Below is a chart with PPe's for the full range of speeds and distances for my cue. You should be able to plug data into this formula and get PPe's that correspond to those in the chart. Note: The key to making this formula simple was creating the methodology of the speed factor. In the chart below, the speeds are divided into 6 markings, rather than the 5 for speed factors 0-4.
General Speed Factor (V) Rules are:
0 = Max speed, would bounce about 5 rails.
1 = Firm speed, would bounce 4 rails and back to starting position.
2 = Medium speed, would bounce 3 rails and back to starting position.
3 = Slow-Medium speed, would bounce 2 rails and back to starting position.
4 = Slow speed, would bounce 1 rail and back to starting position at center table.
[To compensate for how squerve changes for draw vs. follow shots (for more info, see "Squirt - Part VIII: squerve effects" (Download) - BD, March, 2008), we can also make an adjustment to the pivot point based on the height of the cue:]
Based on the above observation I was able, via some testing to establish a pivot point adjustment key depending on the height the cue ball is struck with English.
Strangely enough it seems to work pretty well independent of distance, speed or cue offset. Though this hasn't been tested comprehensively.
So the total PPe Effective Pivot Point formula, as it has been refined is:
PPe = PPi + DVK + H
H = Height of hit on CB using the numbers given below in the diagram.
(Note: In most practical cases we don't need to hit higher than the 1 range. Most draw shots fit into the -1 range.
For a low squirt cue, such as a Predator Z, I would increase the numbers in the below chart by about 33%. So they might range from 4 to -1.3. Current information suggests the Predator Z has a natural or intrinsic pivot point of between 12 and 13 inches, compared to a normal shaft which is in the 9 to 9.5 inch range.
Based on the above observation I was able, via some testing to establish a pivot point adjustment key depending on the height the cue ball is struck with English.
Strangely enough it seems to work pretty well independent of distance, speed or cue offset. Though this hasn't been tested comprehensively.
So the total PPe Effective Pivot Point formula, as it has been refined is:
PPe = PPi + DVK + H
H = Height of hit on CB using the numbers given below in the diagram.
(Note: In most practical cases we don't need to hit higher than the 1 range. Most draw shots fit into the -1 range.
For a low squirt cue, such as a Predator Z, I would increase the numbers in the below chart by about 33%. So they might range from 4 to -1.3. Current information suggests the Predator Z has a natural or intrinsic pivot point of between 12 and 13 inches, compared to a normal shaft which is in the 9 to 9.5 inch range.
Bisect-pivot-and-shift aiming system
How does the "bisect-pivot-and-shift" aiming system work?
from bluepepper:
Bottom-of-the-ball aiming
How does the "bottom-of-the-ball aiming" aiming system work?
"Bottom-of-the-ball" aiming is a way to visualize the required contact point on the object ball (assuming no throw). First visualize the required cut angle for the shot as shown in "a" in the diagram below. Then visualize this same angle on the face of the object ball, as shown in "b" below. If the vertex of the angle is on the edge of the ball, and one leg of the angle goes through the center of the ball with the other leg vertical, the necessary contact point (CP) is where the vertical leg crosses the ball's equator.
How does the "bisect-pivot-and-shift" aiming system work?
from bluepepper:
- Sighting for a straight in shot from behind the cue ball, place tip of cue on table midway between cue ball and object ball.
- Then locate contact point on object ball.
- Keeping tip in same spot on table move to the right or left until the cue is pointing directly at the contact point.
- From there, roll the cue, staying parallel to that line, until the center of the cue is hovering directly above the center of the cue ball. That's your aim line. Pick a spot along this line to aim at in order to pocket the shot.
Bottom-of-the-ball aiming
How does the "bottom-of-the-ball aiming" aiming system work?
"Bottom-of-the-ball" aiming is a way to visualize the required contact point on the object ball (assuming no throw). First visualize the required cut angle for the shot as shown in "a" in the diagram below. Then visualize this same angle on the face of the object ball, as shown in "b" below. If the vertex of the angle is on the edge of the ball, and one leg of the angle goes through the center of the ball with the other leg vertical, the necessary contact point (CP) is where the vertical leg crosses the ball's equator.
Below is an example for a 1/2-ball hit, 30-degree cut shot.
from Patrick Johnson:
from Patrick Johnson:
Contact-point-to-contact-point or parallel-lines system
How does the "contact-point-to-contact-point" or "parallel-lines" aiming system work?
It is described in detail in “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011). Here's a useful illustration from the article:
How does the "contact-point-to-contact-point" or "parallel-lines" aiming system work?
It is described in detail in “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011). Here's a useful illustration from the article:
and here's how it works:
1. Visualize a line through the center of the OB in the target direction. This locates the CP (red dot) on the OB.
2. Shift this line to the CB, keeping it parallel to the line in step one (see the blue lines). This defines the CP on the CB.
3. Visualize a line through the CB CP and the OB CP (see the red line).
4. Parallel shift this line to the center of the CB. The result is the required aiming direction (neglecting CIT, of course).
from Patrick Johnson:
1. Visualize a line through the center of the OB in the target direction. This locates the CP (red dot) on the OB.
2. Shift this line to the CB, keeping it parallel to the line in step one (see the blue lines). This defines the CP on the CB.
3. Visualize a line through the CB CP and the OB CP (see the red line).
4. Parallel shift this line to the center of the CB. The result is the required aiming direction (neglecting CIT, of course).
from Patrick Johnson:
TE aiming system
How does the Center-to-Edge (CTE) aiming system work?
CTE (Center-To-Edge) is an "align-and-pivot" pre-shot routine and "aiming system" that uses a line through the center of the CB and outside edge of the OB as a reference. There are several different versions and interpretations of CTE, but they are all based on establishing an initial "alignment" and then "pivoting" to the final aiming-line direction.
CTE Version 1 (an early and simplified "version" of CTE) - 3 lines of aim:
Here is a description of a version of the CTE, based on a video demonstration posted (and later removed) by eezbank, that he claimed was the version of CTE originally taught to him by Hal Houle:
For a “thick hit” (a small cut angle, less than about 15 degrees) to the left:
The way Hal teaches the system you pivot on every shot. So, the halfball info is wrong. Also, where I use the one tip reference Hal says it doesn't matter how many tips you use. You can start all the way to one side of the CB if that's what works with your pivot length.
CTE Version 2 (posted by Shawn Armstrong, as taught to him my Hal Houle) - 4 lines of aim:
The direction of the pivot, and the starting point, are determined by the angle of the cut. This is why you need to know the half ball hit angle. The alignment point on the object ball is always the outer edge. The starting point on the cueball is always the edge. However, it can be the inside or outside edge. That is determined by the cut angle.
For shots less than 30 degrees, line up the center of the cueball with the edge of the object ball. Start with the outside edge of your cue tip lined up with the outside edge of the cueball. Pivot towards center. Your pivot should be leading you towards the center of the object ball.
For cuts greater than 30 degrees, but less than 65, the pivot comes from the inside edge of the cueball. When you pivot to center, you should be going towards the outside edge of the object ball, away from the center.
For thin cuts, the pivots are edge to edge. For cuts between 65-80 degrees (thicker than 80), the pivot is towards center from the outside edge of the cueball. For cuts thinner than 80, the pivot is from the inside edge of the cueball.
Thinner than 80, pivot from outside edge to center on the cueball, with the starting alignment being cutting edge of cueball to the cutting edge of the object ball. For razor cuts, line up outside edge to outside edge, and pivot away from the edge.
CTE Version 3 (posted by Dave Segal on Spidey's blog (external blog-link)) - 2 lines of aim:
An excellent explanation and illustration of this approach, from mohrt, can be found here (external web-link).
Note: CTEL = Center-to-Edge Line = line through CB center and perceived OB outer edge.
BASIC CTE PIVOTS (as taught by Hal Houle):
For thick cuts: Your cue is parallel to the CTEL with your tip pointing at the outside edge of the CB (the edge of the CB that’s farthest from the pocket). You then pivot your tip towards the pocket until it reaches CB center.
For thin cuts: Your cue is parallel to the CTEL with your tip pointing at the inside edge of the CB (the side of the CB that’s closest to the pocket). You then pivot your tip away from the pocket until it reaches CB center.
If you’re not sure which side to pivot from, only one will work. One will look right – the other will not.
For straight-ins: It doesn’t matter which side of the CB you address, just make sure you perform a thick-cut pivot.
Here's a more recent clarification from Spidey (based on a phone conversation):
What qualifies as a "thick cut" or "thin cut" isn't strictly based on the cut angle needed for a shot. It also depends on the distance between the CB and OB. You develop a sense for this as you work with the system.
Stan Shuffett's version
CTE Version 4 (as interpreted by dr_dave from the description and examples on Stan Shuffett's Pro One DVD) - 6 lines of aim:
While standing, sight through the center of the CB and the outside edge of the OB (i.e., sight along the CTE line). Then, based on the type of cut (see the table below), shift your sighting to visualize a line through the inside edge of the CB to a given alignment point on the OB (see the table and figure below), while also maintaining the CTE visual. Then drop and slide into your stance straight toward the CB, placing your bridge to align the cue 1/2 tip off the CB's center (per the table and figure below). Now pivot the cue to the center of the CB with a fixed-bridge pivot. Here is a summary of the OB alignment points and pre-pivot tip positions for each type of cut:
How does the Center-to-Edge (CTE) aiming system work?
CTE (Center-To-Edge) is an "align-and-pivot" pre-shot routine and "aiming system" that uses a line through the center of the CB and outside edge of the OB as a reference. There are several different versions and interpretations of CTE, but they are all based on establishing an initial "alignment" and then "pivoting" to the final aiming-line direction.
CTE Version 1 (an early and simplified "version" of CTE) - 3 lines of aim:
Here is a description of a version of the CTE, based on a video demonstration posted (and later removed) by eezbank, that he claimed was the version of CTE originally taught to him by Hal Houle:
For a “thick hit” (a small cut angle, less than about 15 degrees) to the left:
- Align the cue 1 tip to the right of the CB center through the right edge of the OB.
- Place the bridge hand down with the cue along this line.
- Pivot the cue until the cue is pointed directly through the center of the CB.
- Stroke perfectly straight along this line.
- Align the cue through the center of the CB and through the right edge of the OB.
- Place the bridge hand down with the cue along this line.
- Stroke perfectly straight along this center-to-edge (CTE) line.
- Align the cue 1 tip to the left of the CB center through the right edge of the OB.
- Place the bridge hand down with the cue along this line.
- Pivot the cue until the cue is pointed directly through the center of the CB.
- Stroke perfectly straight along this line.
The way Hal teaches the system you pivot on every shot. So, the halfball info is wrong. Also, where I use the one tip reference Hal says it doesn't matter how many tips you use. You can start all the way to one side of the CB if that's what works with your pivot length.
CTE Version 2 (posted by Shawn Armstrong, as taught to him my Hal Houle) - 4 lines of aim:
The direction of the pivot, and the starting point, are determined by the angle of the cut. This is why you need to know the half ball hit angle. The alignment point on the object ball is always the outer edge. The starting point on the cueball is always the edge. However, it can be the inside or outside edge. That is determined by the cut angle.
For shots less than 30 degrees, line up the center of the cueball with the edge of the object ball. Start with the outside edge of your cue tip lined up with the outside edge of the cueball. Pivot towards center. Your pivot should be leading you towards the center of the object ball.
For cuts greater than 30 degrees, but less than 65, the pivot comes from the inside edge of the cueball. When you pivot to center, you should be going towards the outside edge of the object ball, away from the center.
For thin cuts, the pivots are edge to edge. For cuts between 65-80 degrees (thicker than 80), the pivot is towards center from the outside edge of the cueball. For cuts thinner than 80, the pivot is from the inside edge of the cueball.
Thinner than 80, pivot from outside edge to center on the cueball, with the starting alignment being cutting edge of cueball to the cutting edge of the object ball. For razor cuts, line up outside edge to outside edge, and pivot away from the edge.
CTE Version 3 (posted by Dave Segal on Spidey's blog (external blog-link)) - 2 lines of aim:
An excellent explanation and illustration of this approach, from mohrt, can be found here (external web-link).
Note: CTEL = Center-to-Edge Line = line through CB center and perceived OB outer edge.
BASIC CTE PIVOTS (as taught by Hal Houle):
For thick cuts: Your cue is parallel to the CTEL with your tip pointing at the outside edge of the CB (the edge of the CB that’s farthest from the pocket). You then pivot your tip towards the pocket until it reaches CB center.
For thin cuts: Your cue is parallel to the CTEL with your tip pointing at the inside edge of the CB (the side of the CB that’s closest to the pocket). You then pivot your tip away from the pocket until it reaches CB center.
If you’re not sure which side to pivot from, only one will work. One will look right – the other will not.
For straight-ins: It doesn’t matter which side of the CB you address, just make sure you perform a thick-cut pivot.
Here's a more recent clarification from Spidey (based on a phone conversation):
What qualifies as a "thick cut" or "thin cut" isn't strictly based on the cut angle needed for a shot. It also depends on the distance between the CB and OB. You develop a sense for this as you work with the system.
Stan Shuffett's version
CTE Version 4 (as interpreted by dr_dave from the description and examples on Stan Shuffett's Pro One DVD) - 6 lines of aim:
While standing, sight through the center of the CB and the outside edge of the OB (i.e., sight along the CTE line). Then, based on the type of cut (see the table below), shift your sighting to visualize a line through the inside edge of the CB to a given alignment point on the OB (see the table and figure below), while also maintaining the CTE visual. Then drop and slide into your stance straight toward the CB, placing your bridge to align the cue 1/2 tip off the CB's center (per the table and figure below). Now pivot the cue to the center of the CB with a fixed-bridge pivot. Here is a summary of the OB alignment points and pre-pivot tip positions for each type of cut:
Inside: on the side of the ball toward the cut (i.e., the left side for a cut to the left, the right side for a cut to the right)
outside: on the side of the ball away from the cut (i.e., the right side for a cut to the left, the left side for a cut to the right)
*: If the CB-OB distance is less than about 1', sight to "inside 1/8" instead of "inside 1/4."
**: For thin cuts, you ignore the CTE visual and just sight for the 1/8-ball overlap.
outside: on the side of the ball away from the cut (i.e., the right side for a cut to the left, the left side for a cut to the right)
*: If the CB-OB distance is less than about 1', sight to "inside 1/8" instead of "inside 1/4."
**: For thin cuts, you ignore the CTE visual and just sight for the 1/8-ball overlap.
Note - Stan uses the "A," "B," and "C" notation (see the illustration above) to refer to the inside, center, or outside of the OB. With a cut to the left, the inside is "A" and the outside is "C." With a cut to the right, the inside is "C" and the outside is "A." "B" is always the center. For example, with a "very thick" cut to the right, you align the right (inside) edge of the CB with point "C" (inside 1/4). With a "very thick" cut to the left, you align the left (inside) edge of the CB with point "A" (inside 1/4). Also, Stan indicates the pre-pivot cue alignment based on whether the cue tip is "left" or "right" of center. For example, with a cut to the left, if the pre-pivot cue tip alignment is to the right (outside) of the CB center, Stan calls this a "right pivot." If the pre-pivot tip alignment is instead to the left of center ("inside" for a cut to the left, or "outside" for a cut to the right), Stan calls this a "left pivot."
You develop a feel for the alignments and pivots required for different shots based on practice and experience (i.e., there is no direct guidance on how to judge and choose the proper cut category for a given shot). You can also vary the cut angle created with a given CB-OB distance and a given alignment choice by varying your eye position some, also based on practice and experience.
FYI, example shots using many of the alignments above (with Stan's notation) can be found here: www.ohrt.com/billiards/ProOnePractice.pdf (Download)
And here's a demonstration of how the pivots work. (YouTube)
from Stan Shuffett (from AZB post): (external web-Blog)
Previously, I added A and C as thin cut OB aimpoints. That was my first adjustment in 2 years to CTE PRO ONE.
After much study and consideration a FINAL adjustment in my CTE PRO ONE system is being implemented.
For shots at or near a zero angle and with CB and OB further apart than 1 diamond's distance, please note this change to your visuals.
Instead of using OBA or OBC as an aim point for the near zero angle shots, use CBE to OBE with a center to edge perception. All pivot information remains the same. Near zero angle shots can have slight left or right cuts.
This is my FINAL adjustment for any major system aspect of CTE PRO ONE.
CTE Evaluation and Analysis:
If you are good at judging the type of cut, version 4 above will generally work better than the others (without conscious or subconscious "adjustment") because it involves a larger number of lines of aim, which will offer better coverage over a wide range of cut angles. Also, because there is less pivot than with the other versions, there will be less variation in results with different bridge lengths and CB-OB distances (see more info below).
If you follow any of the procedures above literally and exactly (without conscious or subconscious "adjustment"), you will make shots within certain limited ranges of cut angles and CB-OB distances for each line of aim (see limited lines of aim). However, if you don't vary the alignment or pivot (see more below), you will miss shots outside of and between these ranges, unless the OB is close to the pocket or the pockets are large (providing a large margin for error).
Many "challenges" relating to "aiming systems" are described and illustrated in "Fundamentals - Part III: DAM aiming system" (Download) (BD, November, 2008) and "Fundamentals - Part IV: bridge length" (Download) (BD, December, 2008). These difficulties certainly apply to CTE. Here's a good experiment you can use to test whether or not you understand how to apply CTE (or any pivot-based aiming method) effectively:
You develop a feel for the alignments and pivots required for different shots based on practice and experience (i.e., there is no direct guidance on how to judge and choose the proper cut category for a given shot). You can also vary the cut angle created with a given CB-OB distance and a given alignment choice by varying your eye position some, also based on practice and experience.
FYI, example shots using many of the alignments above (with Stan's notation) can be found here: www.ohrt.com/billiards/ProOnePractice.pdf (Download)
And here's a demonstration of how the pivots work. (YouTube)
from Stan Shuffett (from AZB post): (external web-Blog)
Previously, I added A and C as thin cut OB aimpoints. That was my first adjustment in 2 years to CTE PRO ONE.
After much study and consideration a FINAL adjustment in my CTE PRO ONE system is being implemented.
For shots at or near a zero angle and with CB and OB further apart than 1 diamond's distance, please note this change to your visuals.
Instead of using OBA or OBC as an aim point for the near zero angle shots, use CBE to OBE with a center to edge perception. All pivot information remains the same. Near zero angle shots can have slight left or right cuts.
This is my FINAL adjustment for any major system aspect of CTE PRO ONE.
CTE Evaluation and Analysis:
If you are good at judging the type of cut, version 4 above will generally work better than the others (without conscious or subconscious "adjustment") because it involves a larger number of lines of aim, which will offer better coverage over a wide range of cut angles. Also, because there is less pivot than with the other versions, there will be less variation in results with different bridge lengths and CB-OB distances (see more info below).
If you follow any of the procedures above literally and exactly (without conscious or subconscious "adjustment"), you will make shots within certain limited ranges of cut angles and CB-OB distances for each line of aim (see limited lines of aim). However, if you don't vary the alignment or pivot (see more below), you will miss shots outside of and between these ranges, unless the OB is close to the pocket or the pockets are large (providing a large margin for error).
Many "challenges" relating to "aiming systems" are described and illustrated in "Fundamentals - Part III: DAM aiming system" (Download) (BD, November, 2008) and "Fundamentals - Part IV: bridge length" (Download) (BD, December, 2008). These difficulties certainly apply to CTE. Here's a good experiment you can use to test whether or not you understand how to apply CTE (or any pivot-based aiming method) effectively:
Shot "A" is about a 10-degree cut, shot "B" is about a 15-degree cut, and shot "C" is about a 20-degree cut. All three shots fit into the "thick cut" category of some versions of CTE. Also, the CB-to-OB distance is the same for all three shots. If the bridge length and pivot amount is the same for all three shots, a pertinent question is: What do you do differently with the alignment and/or pivot steps of CTE to pocket each of the three shots? There are several possible answers. You can:
1.) Change the initial alignment slightly (e.g., by shifting your eye alignment so the perceived cue alignment and/or parallel shift is different)
or
2.) Change the amount of the parallel shift (before the pivot) so you don't quite go all of the way to the perceived CB edge (e.g., shift a given number of "tips" instead)
or
3.) Pivot a slightly different amount (e.g., not quite to center, or just past center).
or
4.) Change the "effective pivot length" slightly (e.g., by adjusting your bridge length or by shifting/tilting your bridge during the pivot).
Options 1 and 4 are probably the most common approaches. The diagram below (from "Fundamentals - Part IV: bridge length" (Download) - BD, December, 2008) shows how a change in "effective pivot length" changes the amount of cut. The diagram shows two different bridge positions, but it could also represent two different "effective cue-pivot-points" created by a non-rigid-bridge pivot method (see more below).
1.) Change the initial alignment slightly (e.g., by shifting your eye alignment so the perceived cue alignment and/or parallel shift is different)
or
2.) Change the amount of the parallel shift (before the pivot) so you don't quite go all of the way to the perceived CB edge (e.g., shift a given number of "tips" instead)
or
3.) Pivot a slightly different amount (e.g., not quite to center, or just past center).
or
4.) Change the "effective pivot length" slightly (e.g., by adjusting your bridge length or by shifting/tilting your bridge during the pivot).
Options 1 and 4 are probably the most common approaches. The diagram below (from "Fundamentals - Part IV: bridge length" (Download) - BD, December, 2008) shows how a change in "effective pivot length" changes the amount of cut. The diagram shows two different bridge positions, but it could also represent two different "effective cue-pivot-points" created by a non-rigid-bridge pivot method (see more below).
If using a "mechanical pivot" (i.e., pivoting after placing the bridge hand down), one way to vary the "effective pivot length" is to vary the bridge length (as implied by the diagram). Another is to shift, rotate, tilt, or deform your bridge hand during the pivot as you shift your body (AKA "hip pivot"). Here's an example of this, posted by Colin Colenso, where the "effective pivot length" is much longer than the bridge length:
Another way is to use an "air pivot," where you pivot the cue and/or entire body before placing the bridge hand down. In this case, you can easily create any "effective pivot length" over an extremely wide range. Sometimes, the "effective pivot length" is referred to as the "shot arc." Here is a demonstration of how some forms of pivoting are used in conjunction with CTE and other pivot-based aiming methods: CTE pivot demonstration (YouTube). For more info concerning pivoting, "air pivot," and "shot arc," see Spidey's blog.(external blog-link)
The difficulty is in judging how much to change the initial alignment or "effective pivot length" to pocket balls requiring similar, but slightly different, amounts of cut. Many of the CTE proponents will say you don't need to know where the pocket is, or take into consideration the necessary amount of cut (other than to judge a "thin hit" vs. a "thick hit"), but this obviously cannot be the case. Maybe people who seem to use CTE effectively must at least sense where the pocket is (even if they don't look at it), or maybe they just have a feel for how much cut they need to pocket the ball. This sense or feel could influence their alignment or "pivot" in intangible ways that are difficult to describe or illustrate.
With all pivot-based aiming methods, the choice for "effective pivot length" must vary with the distance between the CB and OB, as illustrated by the following diagram from "Fundamentals - Part III: DAM aiming system" (Download) (BD, November, 2008). Note - the purpose for this diagram is simply to illustrate a general principle pertinent to all align-and-pivot systems like CTE and 90/90. The diagram is not meant to show a specific aiming example for any particular system or shot. The pre-pivot alignment shown is actually a 90/90 edge-to-edge (ETE) alignment, but again, this choice is not important for the point being made. With a fixed alignment (whatever alignment that might be) and a fixed "effective pivot length," the distance between the CB and OB has a huge effect on the resulting cut angle of the shot:
The difficulty is in judging how much to change the initial alignment or "effective pivot length" to pocket balls requiring similar, but slightly different, amounts of cut. Many of the CTE proponents will say you don't need to know where the pocket is, or take into consideration the necessary amount of cut (other than to judge a "thin hit" vs. a "thick hit"), but this obviously cannot be the case. Maybe people who seem to use CTE effectively must at least sense where the pocket is (even if they don't look at it), or maybe they just have a feel for how much cut they need to pocket the ball. This sense or feel could influence their alignment or "pivot" in intangible ways that are difficult to describe or illustrate.
With all pivot-based aiming methods, the choice for "effective pivot length" must vary with the distance between the CB and OB, as illustrated by the following diagram from "Fundamentals - Part III: DAM aiming system" (Download) (BD, November, 2008). Note - the purpose for this diagram is simply to illustrate a general principle pertinent to all align-and-pivot systems like CTE and 90/90. The diagram is not meant to show a specific aiming example for any particular system or shot. The pre-pivot alignment shown is actually a 90/90 edge-to-edge (ETE) alignment, but again, this choice is not important for the point being made. With a fixed alignment (whatever alignment that might be) and a fixed "effective pivot length," the distance between the CB and OB has a huge effect on the resulting cut angle of the shot:
Interestingly, with the exact same initial alignment and pivot, two of the three balls can be potted if the pocket happens to be at points "a," "b," or "c." This would actually be a good proposition shot. Approach somebody who doubts pivot-based aiming systems and bet him or her you can make two radically different shots (e.g., shots "A" and "B" in the diagram) with the exact same initial alignment and the exact same pivot. You can even have the doubter shoot the shots for you, as long as his alignment and stroke skills are reasonably good. If the balls are lined up to take advantage of the effect shown in the diagram (i.e., if the balls are lined up so the corner pocket is at point "a" relative to the balls), both shots will go and you will win the bet.
The diagram above begs the following question: Is there a pivot length that would allow all three balls to be sent to the same position (e.g., where a pocket is located)? Unfortunately, this is not possible in this case. With a shorter pivot, the ball-hit fraction on shot "C" reaches 0 before all of the lines can meet:
The diagram above begs the following question: Is there a pivot length that would allow all three balls to be sent to the same position (e.g., where a pocket is located)? Unfortunately, this is not possible in this case. With a shorter pivot, the ball-hit fraction on shot "C" reaches 0 before all of the lines can meet:
and with a longer pivot, the CB aiming line will be closer to parallel to the the original alignment line, creating smaller cut angles, but the lines still can't all meet at one point:
and with a true parallel shift (infinite pivot length), all of the cut angles would be identical and the OB lines would be exactly parallel (i.e., they wouldn't intersect at all).
Here's another way to explain the impact of the limited lines of aim created by a limited number of initial alignments and pivot directions, applied again to the following three shots:
Here's another way to explain the impact of the limited lines of aim created by a limited number of initial alignments and pivot directions, applied again to the following three shots:
Instead of just the three shots (A, B, and C), consider 15 shots equally spaced between shots A and C. Let's use Stan's version of CTE for this example. According to the system procedure, alignment and pivot choices change with shot cut angle. As the cut angle changes in small increments between shots A and C, the choices for alignment and pivot change at certain points in the range. For example, on Stan's DVD, he suggests an inside 1/8 OB alignment with with an inside cue tip position (for a left-to-right pivot) for shot "A," an inside 1/4 OB alignment (point A) with an inside cue tip position (for a 1/2-tip left-to-right pivot) for Shot "B," and a center OB alignment (point B) with an inside cue tip position (for a 1/2-tip left-to-right pivot) for Shot "C." At each point in the range of 15 shots where the alignment and/or pivots change, because neighboring shots of the group of 15 are so close together, different alignments and pivots would need to produce the same cut angle (e.g., to pocket the ball with an angle in between both choices). Also, the alignment and pivot will not change for certain ranges of shots within the 15. Therefore, a single alignment and pivot would need to create a range of cut angles. However, if you follow the procedure accurately and consistently for a selected alignment and pivot, with a given CB-OB distance and bridge length, assuming a rigid and fixed bridge, the procedure would result in the exact same cut angle every time (without conscious or subconscious "adjustments"). Obviously, this particular cut angle will work for some of the shots in the indicated range, and it won't work for others (depending on the distance to and size of the pocket), because every shot in the indicated range requires a different cut angle (assuming center-pocket aiming).
Now, does that mean you can't make CTE work for all shots at a table? Absolutely not. Four ways to make it work are summarized above. This is where "visual intelligence," "adjustment," "experience-based intuition," and "feel" come into play. And with enough practice, a person might be able to learn to apply one or more of the four techniques suggested, and do so naturally and even subconsciously ... to where they might not even know they are doing them.
BOTTOM LINE OF THE ANALYSIS
Any align-and-pivot system like CTE requires changes in alignment and/or effective pivot length as the cut angle and shot distance change.
DAM is still a much simpler approach to basic center-ball aiming than any pivot-based system; although, like anything, it does requires practice. Regardless of which "aiming system" you use (even if you just "see the angle"), you still need to practice to develop and improve your "visual intelligence" and consistency, and you need to actually focus on aiming the shot. It also helps to have an effective and consistent pre-shot routine. Many aiming systems can help some people do this (for more info, see benefits of "aiming systems"). Also, when you use side spin, you need to compensate your aim to account for squirt, swerve, and throw.
Now, does that mean you can't make CTE work for all shots at a table? Absolutely not. Four ways to make it work are summarized above. This is where "visual intelligence," "adjustment," "experience-based intuition," and "feel" come into play. And with enough practice, a person might be able to learn to apply one or more of the four techniques suggested, and do so naturally and even subconsciously ... to where they might not even know they are doing them.
BOTTOM LINE OF THE ANALYSIS
Any align-and-pivot system like CTE requires changes in alignment and/or effective pivot length as the cut angle and shot distance change.
DAM is still a much simpler approach to basic center-ball aiming than any pivot-based system; although, like anything, it does requires practice. Regardless of which "aiming system" you use (even if you just "see the angle"), you still need to practice to develop and improve your "visual intelligence" and consistency, and you need to actually focus on aiming the shot. It also helps to have an effective and consistent pre-shot routine. Many aiming systems can help some people do this (for more info, see benefits of "aiming systems"). Also, when you use side spin, you need to compensate your aim to account for squirt, swerve, and throw.
For more info, visit billiards.colostate.edu
Balls
Pool and Billiards Balls
... physical characteristics of pool balls.
Colors
Is there any rationale behind the choices for pool balls?
Every "solid" (balls 1-7) have a different color, and every "stripe" (balls 9-15) uses the same color as the corresponding "solid" (e.g., the 1-ball and 9-ball are both yellow).
If you arrange the balls in an 8-ball rack in a methodical way in color groupings (YouTube), all sorts of numerical consistencies also arise.
from Patrick Johnson:
... physical characteristics of pool balls.
Colors
Is there any rationale behind the choices for pool balls?
Every "solid" (balls 1-7) have a different color, and every "stripe" (balls 9-15) uses the same color as the corresponding "solid" (e.g., the 1-ball and 9-ball are both yellow).
If you arrange the balls in an 8-ball rack in a methodical way in color groupings (YouTube), all sorts of numerical consistencies also arise.
from Patrick Johnson:
Three primary colors:
1 & 9 = Yellow (primary)
2 & 10 = Blue (primary)
3 & 11 = Red (primary)
Three secondary colors:
4 & 12 = Purple (blue+red)
5 & 13 = Orange (red+yellow)
6 & 14 = Green (yellow+blue)
One tertiary color:
7 & 15 = Maroon (purple+red)
Two all-or-nothing colors:
8 = Black
Cue = White
Compression effects
Does the size of the contact patch between the CB and OB vary with cut angle and speed, and does this affect how I should aim shots?
The CB and OB do compress a small amount during the extremely brief contact time, and this does create a "contact patch" that varies in shape and size with cut angle and speed, but the effect of this compression is very small. The compression does increase the cut angle slightly due to the contact patch compressing past the initial point of contact between the balls (when contact is first initiated), and this does tend to counteract the effect of cut-induced throw (CIT) a small amount, but the ball-compression effect is very small and can be neglected for all practical purposes.
Contact time
How long are the CB and OB in contact during a collision?
Marlow did some experiments on this, and he reported numbers between 0.0001 and 0.0006 seconds (in "The Physics of Pocket Billiards," 1995). The balls do not stay in contact for very long.
DBKcues has also taken various measurements of ball properties and contact times. More info can be found here: DBKcues ball collision measurements. (external web-blog) They measured ball contact times in the 250-300 micro-second range (0.00025-0.0003 seconds).
Here's a super-slow-motion view showing how brief the balls remain in contact (and how little they compress):
1 & 9 = Yellow (primary)
2 & 10 = Blue (primary)
3 & 11 = Red (primary)
Three secondary colors:
4 & 12 = Purple (blue+red)
5 & 13 = Orange (red+yellow)
6 & 14 = Green (yellow+blue)
One tertiary color:
7 & 15 = Maroon (purple+red)
Two all-or-nothing colors:
8 = Black
Cue = White
Compression effects
Does the size of the contact patch between the CB and OB vary with cut angle and speed, and does this affect how I should aim shots?
The CB and OB do compress a small amount during the extremely brief contact time, and this does create a "contact patch" that varies in shape and size with cut angle and speed, but the effect of this compression is very small. The compression does increase the cut angle slightly due to the contact patch compressing past the initial point of contact between the balls (when contact is first initiated), and this does tend to counteract the effect of cut-induced throw (CIT) a small amount, but the ball-compression effect is very small and can be neglected for all practical purposes.
Contact time
How long are the CB and OB in contact during a collision?
Marlow did some experiments on this, and he reported numbers between 0.0001 and 0.0006 seconds (in "The Physics of Pocket Billiards," 1995). The balls do not stay in contact for very long.
DBKcues has also taken various measurements of ball properties and contact times. More info can be found here: DBKcues ball collision measurements. (external web-blog) They measured ball contact times in the 250-300 micro-second range (0.00025-0.0003 seconds).
Here's a super-slow-motion view showing how brief the balls remain in contact (and how little they compress):
Cue ball types
What are the differences among commonly used cue balls?
from sfleinen (in AZB post): (external web-forum)
In 1993 Dynamo began phasing out this ball in favor of a magnetic separator; and by 1995, all Dynamo coin tables used magnetic separation.
from DogsPlayingPool (in AZB post): (external web-forum)
Aramith CB information (Download)
According to this the Red Logo, Blue Circle, and Measle are all the same ball. They are made from the same resin (Super Aramith Pro) and obviously are all regulation size and weight.
from sfleinen (in AZB post): (external web-forum)
What's truly bizarre, is that only several years ago, all three of these cue balls were indeed different -- different weights and different compositions. You can just *look* at each of these three balls, and see the differences in opacity and color, never mind the obvious differences you notice when you put the cue balls on the scale.
What I think happened of late, is that the Saluc factory, in the spirit of absorbing their "acquisitions" (e.g. Brunswick's and Aramith's products), have decided to standardize all the products.
from sfleinen (in AZB post): (external web-forum)
... a lighter cue ball [is] undesirable in 14.1 (e.g. because of reduced ability to "hold" it [it "wants" to zing around], as well as the propensity to glance off the rack and clusters at weird angles).
Ball elasticity
What is ball elasticity, and how does it affect how pool balls play?
Elasticity (described by the physics term "coefficient of restitution") is a measure of how much energy is retained during a collision between two balls.
from Bob Jewett (in AZB post): (external web-forum)
Elasticity is how well a ball will transfer its energy to another ball. On a stop shot, we hope for the object ball to leave with 100% of the cue ball's incoming speed. If the balls are inelastic, the object ball will get only part of the cue ball's speed. A result of this, required by the laws of conservation of energy and momentum, is that the cue ball will retain some of its initial velocity, and be going forward slightly after the collision. This action is much more visible with ivory balls which are much less elastic than pool balls.
One way to measure elasticity is to bounce a ball off a very hard, heavy object, like a steel block. (This gives a situation just like two balls running at each other with the same speed, since neither ball will penetrate the point where they collide, just as the ball will not penetrate (significantly) the steel block.) Neglecting air resistance, the bounce height divided by the starting height gives the square of the "coefficient of restitution" of the collision, and gives a ratio of speeds before and after the collision. Wikipedia has several sections on this stuff.
If a cue ball is inelastic, it will follow well and draw poorly even though it is the same mass as the object ball.
Material and manufacturing
What are pool balls made of?
Here are some good resources explaining the history and current state of pool ball materials:
http://en.wikipedia.org/wiki/Billiard_ball (external web-link)
Here's a basic description of the manufacturing method:
http://www.ehow.com/facts_5844628_billiard-balls-manufactured_.html (external web-link)
Silicone spray effects
Does Silicone spray help you get more draw and masse action on the CB?
Yes. In fact, some trick shot artists sometimes use Silicone spray to help them create some of the magical shots they can execute.
I describe and demonstrate the effects of Silicone spray in this video (starting at the 0:40 point):
NV B.40 - Masse-draw billiard (carom) trick shot from the movie "The Hustler" (YouTube)
Here's another (at the 0:35 point):
NV B.41 - Coriolis masse shot aiming method with a large-curve example (YouTube)
It works like a charm, but it does wear off over time as it wipes off onto the cloth. It also leaves slippery residue on your hands when you handle the CB.
Smoothness and roundness
What does a pool ball's surface look like under extreme magnification, and how smooth and round is a pool ball compared to the Earth?
Here's a 1mm x 1mm area of a clean and smooth cue ball imaged with a scanning white light interferometer:
What are the differences among commonly used cue balls?
from sfleinen (in AZB post): (external web-forum)
- Blue Dot -- This is a generic "old time" cue ball ... be careful, because this ball is slightly lighter than the object balls, and is a bit "zingey" (especially with draw). The Blue Circle ball is better to use than the Blue Dot ball. Speaking of which...
- Blue Circle -- This is the cue ball delivered with a genuine set of Brunswick (Saluc) Centennials. This is probably the most favorite cue ball ... neck-and-neck with the Aramith Pro Cup (measles) cue ball
- Red Dot (also see the quote from Michael Gaughan below) -- this is a HEAVYWEIGHT (6.75 ounces!) cue ball used on [older] Dynamo barboxes (the ones that differentiated the cue ball from the object balls by its sheer weight). This cue ball is at least a full ounce HEAVIER than the object balls, so that it is able to trip the "trap door" inside the [older] Dynamo tables for the cue ball return. Because of this, perfect stop shots are IMPOSSIBLE with this cue ball, because of the "heavier mass hitting a lighter mass" physics problem -- the object ball is not heavy enough to absorb all the kinetic energy away from the cue ball, and thus the cue ball lunges forward a bit after contact with the object ball, even with a good stop-shot stroke, and even if a little bit of draw is applied (the cue ball will lunge forward a bit, then roll backwards with the draw spin).
- Red Circle (external web-link)-- It's properly known as the Aramith Red Circle cue ball. This is a standalone cue ball product from Aramith (it is offered standalone only, and is not bundled with any of Aramith's full ball sets). This cue ball is a bit lighter in weight than the object balls, and is therefore a favorite of 9-ballers, because "it makes it easier for them to move the rock around" (especially with draw).
- "Measles" ("red-dotted" or "red-spotted") ball -- This is the Aramith Pro Cup ball seen (and used) at tournaments, on TV, etc. This ball weighs exactly the same as the object balls, just like the Brunswick (Saluc) Centennial blue circle ball. ... Be careful, though, for there are "measles ball knockoffs" out there that are not the same thing. An easy way to tell the knockoffs, is that they usually have eight (8) red spots instead of Aramith's trademarked six (6) red spots.
In 1993 Dynamo began phasing out this ball in favor of a magnetic separator; and by 1995, all Dynamo coin tables used magnetic separation.
from DogsPlayingPool (in AZB post): (external web-forum)
Aramith CB information (Download)
According to this the Red Logo, Blue Circle, and Measle are all the same ball. They are made from the same resin (Super Aramith Pro) and obviously are all regulation size and weight.
from sfleinen (in AZB post): (external web-forum)
What's truly bizarre, is that only several years ago, all three of these cue balls were indeed different -- different weights and different compositions. You can just *look* at each of these three balls, and see the differences in opacity and color, never mind the obvious differences you notice when you put the cue balls on the scale.
What I think happened of late, is that the Saluc factory, in the spirit of absorbing their "acquisitions" (e.g. Brunswick's and Aramith's products), have decided to standardize all the products.
from sfleinen (in AZB post): (external web-forum)
... a lighter cue ball [is] undesirable in 14.1 (e.g. because of reduced ability to "hold" it [it "wants" to zing around], as well as the propensity to glance off the rack and clusters at weird angles).
Ball elasticity
What is ball elasticity, and how does it affect how pool balls play?
Elasticity (described by the physics term "coefficient of restitution") is a measure of how much energy is retained during a collision between two balls.
from Bob Jewett (in AZB post): (external web-forum)
Elasticity is how well a ball will transfer its energy to another ball. On a stop shot, we hope for the object ball to leave with 100% of the cue ball's incoming speed. If the balls are inelastic, the object ball will get only part of the cue ball's speed. A result of this, required by the laws of conservation of energy and momentum, is that the cue ball will retain some of its initial velocity, and be going forward slightly after the collision. This action is much more visible with ivory balls which are much less elastic than pool balls.
One way to measure elasticity is to bounce a ball off a very hard, heavy object, like a steel block. (This gives a situation just like two balls running at each other with the same speed, since neither ball will penetrate the point where they collide, just as the ball will not penetrate (significantly) the steel block.) Neglecting air resistance, the bounce height divided by the starting height gives the square of the "coefficient of restitution" of the collision, and gives a ratio of speeds before and after the collision. Wikipedia has several sections on this stuff.
If a cue ball is inelastic, it will follow well and draw poorly even though it is the same mass as the object ball.
Material and manufacturing
What are pool balls made of?
Here are some good resources explaining the history and current state of pool ball materials:
http://en.wikipedia.org/wiki/Billiard_ball (external web-link)
Here's a basic description of the manufacturing method:
http://www.ehow.com/facts_5844628_billiard-balls-manufactured_.html (external web-link)
Silicone spray effects
Does Silicone spray help you get more draw and masse action on the CB?
Yes. In fact, some trick shot artists sometimes use Silicone spray to help them create some of the magical shots they can execute.
I describe and demonstrate the effects of Silicone spray in this video (starting at the 0:40 point):
NV B.40 - Masse-draw billiard (carom) trick shot from the movie "The Hustler" (YouTube)
Here's another (at the 0:35 point):
NV B.41 - Coriolis masse shot aiming method with a large-curve example (YouTube)
It works like a charm, but it does wear off over time as it wipes off onto the cloth. It also leaves slippery residue on your hands when you handle the CB.
Smoothness and roundness
What does a pool ball's surface look like under extreme magnification, and how smooth and round is a pool ball compared to the Earth?
Here's a 1mm x 1mm area of a clean and smooth cue ball imaged with a scanning white light interferometer:
The plentiful scratches are from the polishing process during manufacturing. The blemishes are simply slight defects in the formed material. The following contour map shows the relative size of the small peaks and valleys on the surface:
The scale indicated on the image above is microns (micrometers = 10^-6 meters = 0.001 mm).
See “Is a Pool Ball Smoother Than the Earth?” (BD, June, 2013) (Download) for more images and analysis. The quote from Bob Jewett below also offers a good interpretation of the data. And here's another good article on this topic: Is the Earth Like a Billiard Ball or Not? (external web-link)
from Bob Jewett (in AZB post): (external forum-link)
So from Dr. Dave's picture we see a difference in heights of 1 micron (peak to valley) for spots that are within 1000 microns (1mm) of each other. Since the radius of a pool ball is about 28560 microns, the "local" roughness observed is about 1/30000 or about roughly 30 parts per million.
For a similar ratio on the surface of the Earth, consider the extreme of Mt. Whitney to Death Valley, which are pretty close to each other and differ in elevation by about three miles. Since the radius of the Earth is about 4000 miles, the "local" roughness of the Earth is about 1/1400 or 700 parts per million.
Measurements in Louisiana will give a different roughness. Driskill Mountain is 535 feet (or 0.1 mile, close enough) and the highest point in the state. 0.1/4000 is 1/40000 or slightly smoother than the polished ball Dr. Dave showed. If you look just at the oceans, the roughness is around 150 feet in the worst swells, but that would be quite a bit smoother than the polished pool ball.
Gouged pool balls -- from having been knocked onto the floor or against the wall -- might have pits 100 microns deep. Those would be rougher than California by a factor of 5 or so.
In my experience, Aramith balls out of the box are within 0.001 inch of the correct size and are rounder than that. That means that the non-roundness of a ball is less than 0.001/1.125 or 0.1% or about 1000PPM. The Earth is about 3300PPM out of round according to the above postings.
Bottom line: New, polished pool balls are much rounder than the Earth and somewhat smoother than the "geologically interesting" areas of the Earth. Old, worn pool balls are still much rounder than the Earth but depending on damage may be rougher than the roughest spots on the surface of the Earth.
Weight, size, and wear effects
Does the weight and size of the balls ever vary much, and does it have an effect?
The following video describes and demonstrates all effects related to using cue balls or object balls of different weights and sizes:
See “Is a Pool Ball Smoother Than the Earth?” (BD, June, 2013) (Download) for more images and analysis. The quote from Bob Jewett below also offers a good interpretation of the data. And here's another good article on this topic: Is the Earth Like a Billiard Ball or Not? (external web-link)
from Bob Jewett (in AZB post): (external forum-link)
So from Dr. Dave's picture we see a difference in heights of 1 micron (peak to valley) for spots that are within 1000 microns (1mm) of each other. Since the radius of a pool ball is about 28560 microns, the "local" roughness observed is about 1/30000 or about roughly 30 parts per million.
For a similar ratio on the surface of the Earth, consider the extreme of Mt. Whitney to Death Valley, which are pretty close to each other and differ in elevation by about three miles. Since the radius of the Earth is about 4000 miles, the "local" roughness of the Earth is about 1/1400 or 700 parts per million.
Measurements in Louisiana will give a different roughness. Driskill Mountain is 535 feet (or 0.1 mile, close enough) and the highest point in the state. 0.1/4000 is 1/40000 or slightly smoother than the polished ball Dr. Dave showed. If you look just at the oceans, the roughness is around 150 feet in the worst swells, but that would be quite a bit smoother than the polished pool ball.
Gouged pool balls -- from having been knocked onto the floor or against the wall -- might have pits 100 microns deep. Those would be rougher than California by a factor of 5 or so.
In my experience, Aramith balls out of the box are within 0.001 inch of the correct size and are rounder than that. That means that the non-roundness of a ball is less than 0.001/1.125 or 0.1% or about 1000PPM. The Earth is about 3300PPM out of round according to the above postings.
Bottom line: New, polished pool balls are much rounder than the Earth and somewhat smoother than the "geologically interesting" areas of the Earth. Old, worn pool balls are still much rounder than the Earth but depending on damage may be rougher than the roughest spots on the surface of the Earth.
Weight, size, and wear effects
Does the weight and size of the balls ever vary much, and does it have an effect?
The following video describes and demonstrates all effects related to using cue balls or object balls of different weights and sizes:
"Ball Weight and Size Difference Effects – Part I" (Download) (BD, February, 2012) and "Ball Weight and Size Difference Effects – Part II" (Download) (BD, March, 2012) also cover ball-weight-difference effects in detail. Here's another article from Bob Jewett (BD, December '05) (Download) on the topic.
Generally, with older balls, the cue ball (CB) will be slightly smaller and lighter than the object balls (OBs) because it takes more abuse and wears faster as a result. However, if a new CB is used with an older set of OBs, the CB will be slightly heavier because only the OBs will have wear. On many coin-operated tables in bars (i.e., "bar boxes"), the CB is often heavier and/or larger than the other balls to help the ball-return mechanism distinguish the CB from the others.
When the CB is heavier, it is easier to follow and tougher to draw. With a cut shot, the CB will go forward of the tangent line; and with a stop shot, the CB will drift forward some. A heavier CB will also squirt slightly less.
When the CB is lighter, it is easier to draw the CB and tougher to follow. With a cut shot, the CB will pull back from the tangent line; also, with a stop shot, the CB will bounce back some. A lighter CB will also squirt slightly more.
When the CB is smaller or larger, the contact point on the OB will not be at the equator, the balls will also tend to hop a little, especially with faster speed. With cut shots, the cut angle will also be off slightly (see the question and answer below), but this is an extremely small effect.
Worn OBs will also not rack as well as new high-quality balls. Slight mismatches in size and non-spherical shape (due to non-uniform wear) will result in less-tight racks and poor break action (bad spread, more clusters, fewer balls made).
Do CB and OB weight and size differences affect cut angle and throw?
Assuming the ball surfaces have the same friction properties in a comparison, and assuming the same line-of-centers hits are being created in a comparison, then the amount of throw should not vary with CB or OB weight or size. However, if the weight difference is due to size differences, and a person aims the same way they normally do (with equal-size balls), then there will be different amounts of perceived throw. For example, a larger CB will create a slightly fuller hit than expected (with normal aim), and this will give the perception that the OB is being thrown more (even though it isn't).
With a larger CB, there is a downward component of force (which can make the CB and/or OB hop and result in slower OB motion), but this would not change the OB direction (i.e., the amount of throw). Interaction between the bottom of the OB and the cloth has nothing to do with throw. Although, having the CB contact the OB above the equator does change the effective cut angle of the shot, just as it does with jump shots where the CB hits the OB while airborne (and some people might perceive this as a throw effect, but it isn't). For more info and demonstrations of overcutting with an above-equator hit, see the jump-shot over-cut resource page.
Because the ball material is so stiff compared to the cloth, a downward CB-to-OB collision at a modest angle is really unaffected by the resulting OB-to-table collision. Per the ball-contact-time resource page, a ball-to-ball collision occurs in about 0.0003 seconds (300 microseconds). Per HSV B.44 - cloth compression and cue ball trajectory for draw shots of various elevations (YouTube), an OB takes about 0.002 seconds to compress the cloth and rebound off the slate at an angle ... about 7-times longer than the ball-ball collision. Therefore, the CB-to-OB collision is mostly done before any significant force builds up between the OB and the cloth.
Even though a larger CB will hit the OB above the equator, which increases the effective cut angle some (creating a thinner hit), the larger size of the CB causes a sooner hit, which decreases the effective cut angle some (creating a fuller hit). The 2nd effect is bigger than the first, creating a fuller hit than expected. If you are not convinced, draw a top view of a half-ball hit with both an equal-size CB and a larger CB (along the same CTE line). The point of contact between the balls must lie on the line-of-centers between the balls. The line-of-centers for the larger ball creates a smaller cut angle and fuller hit (even with the above-equator hit effect). Although, any reasonable and typical size differences between the CB and OBs will probably be too small to notice any cut-angle-change effects, unless you are playing on an old "bar box" with a large CB, in which case it might be noticeable to a good player.
Generally, with older balls, the cue ball (CB) will be slightly smaller and lighter than the object balls (OBs) because it takes more abuse and wears faster as a result. However, if a new CB is used with an older set of OBs, the CB will be slightly heavier because only the OBs will have wear. On many coin-operated tables in bars (i.e., "bar boxes"), the CB is often heavier and/or larger than the other balls to help the ball-return mechanism distinguish the CB from the others.
When the CB is heavier, it is easier to follow and tougher to draw. With a cut shot, the CB will go forward of the tangent line; and with a stop shot, the CB will drift forward some. A heavier CB will also squirt slightly less.
When the CB is lighter, it is easier to draw the CB and tougher to follow. With a cut shot, the CB will pull back from the tangent line; also, with a stop shot, the CB will bounce back some. A lighter CB will also squirt slightly more.
When the CB is smaller or larger, the contact point on the OB will not be at the equator, the balls will also tend to hop a little, especially with faster speed. With cut shots, the cut angle will also be off slightly (see the question and answer below), but this is an extremely small effect.
Worn OBs will also not rack as well as new high-quality balls. Slight mismatches in size and non-spherical shape (due to non-uniform wear) will result in less-tight racks and poor break action (bad spread, more clusters, fewer balls made).
Do CB and OB weight and size differences affect cut angle and throw?
Assuming the ball surfaces have the same friction properties in a comparison, and assuming the same line-of-centers hits are being created in a comparison, then the amount of throw should not vary with CB or OB weight or size. However, if the weight difference is due to size differences, and a person aims the same way they normally do (with equal-size balls), then there will be different amounts of perceived throw. For example, a larger CB will create a slightly fuller hit than expected (with normal aim), and this will give the perception that the OB is being thrown more (even though it isn't).
With a larger CB, there is a downward component of force (which can make the CB and/or OB hop and result in slower OB motion), but this would not change the OB direction (i.e., the amount of throw). Interaction between the bottom of the OB and the cloth has nothing to do with throw. Although, having the CB contact the OB above the equator does change the effective cut angle of the shot, just as it does with jump shots where the CB hits the OB while airborne (and some people might perceive this as a throw effect, but it isn't). For more info and demonstrations of overcutting with an above-equator hit, see the jump-shot over-cut resource page.
Because the ball material is so stiff compared to the cloth, a downward CB-to-OB collision at a modest angle is really unaffected by the resulting OB-to-table collision. Per the ball-contact-time resource page, a ball-to-ball collision occurs in about 0.0003 seconds (300 microseconds). Per HSV B.44 - cloth compression and cue ball trajectory for draw shots of various elevations (YouTube), an OB takes about 0.002 seconds to compress the cloth and rebound off the slate at an angle ... about 7-times longer than the ball-ball collision. Therefore, the CB-to-OB collision is mostly done before any significant force builds up between the OB and the cloth.
Even though a larger CB will hit the OB above the equator, which increases the effective cut angle some (creating a thinner hit), the larger size of the CB causes a sooner hit, which decreases the effective cut angle some (creating a fuller hit). The 2nd effect is bigger than the first, creating a fuller hit than expected. If you are not convinced, draw a top view of a half-ball hit with both an equal-size CB and a larger CB (along the same CTE line). The point of contact between the balls must lie on the line-of-centers between the balls. The line-of-centers for the larger ball creates a smaller cut angle and fuller hit (even with the above-equator hit effect). Although, any reasonable and typical size differences between the CB and OBs will probably be too small to notice any cut-angle-change effects, unless you are playing on an old "bar box" with a large CB, in which case it might be noticeable to a good player.
For more info, visit billiards.colostate.edu
Bank and Kick Shots
Banks and Kicks in Pool and Billiards
...how to use diamond systems to aim kick and bank shots in pool
(external web-links) for more information:
see Chapter 6 and Sections 7.06-7.08 in The Illustrated Principles of Pool and Billiards.
Disc IV of the Video Encyclopedia of Pool Shots (VEPS) , and Disc IV of the Video Encyclopedia of Pool Practice (VEPP)
Advantages of fast speed
Why do many top bankers use fast speed?
With faster speed, there is much less variation from table to table and from shot to shot. The OB will pick up less roll, and this (combined with the post rebound speed) will minimize how much the OB curves after rebound. As a result the ball will bank in a more consistent direction.
Also, there are many variables that affect how a ball banks (cloth friction, cushion friction and coefficients of restitution, OB spin transfer, and table roll-off). At faster speed, these variables don't change the shot as much with slight changes in speed as they do with similar speed changes at slower speeds. This is another advantage of using faster speed for banks.
At slower speeds, the path and final target of the rebounding ball varies a lot with small changes in speed. The disadvantage of faster speed is the reduced effective "size" of the pocket.
Faster speed can also help reduce the chance for a double kiss at certain approach angles. See:
...how to use diamond systems to aim kick and bank shots in pool
(external web-links) for more information:
see Chapter 6 and Sections 7.06-7.08 in The Illustrated Principles of Pool and Billiards.
Disc IV of the Video Encyclopedia of Pool Shots (VEPS) , and Disc IV of the Video Encyclopedia of Pool Practice (VEPP)
Advantages of fast speed
Why do many top bankers use fast speed?
With faster speed, there is much less variation from table to table and from shot to shot. The OB will pick up less roll, and this (combined with the post rebound speed) will minimize how much the OB curves after rebound. As a result the ball will bank in a more consistent direction.
Also, there are many variables that affect how a ball banks (cloth friction, cushion friction and coefficients of restitution, OB spin transfer, and table roll-off). At faster speed, these variables don't change the shot as much with slight changes in speed as they do with similar speed changes at slower speeds. This is another advantage of using faster speed for banks.
At slower speeds, the path and final target of the rebounding ball varies a lot with small changes in speed. The disadvantage of faster speed is the reduced effective "size" of the pocket.
Faster speed can also help reduce the chance for a double kiss at certain approach angles. See:
Contact-point mirror system for aiming shallow-angle, rolling kick shots
How do you aim to kick at balls close to a rail at a shallow angle into the rail?
For shallow angles into the rail, where the OB is fairly close to the rail, the contact-point-mirror-kick method works well. It is described in "VEPS GEMS - Part VII: Contact-Point Mirror Kick" (Download) (BD, July, 2010) and “VEPP – Part X: Shallow One-rail Kicks” (Download) (BD, January, 2013), and here are video demonstrations with a complete explanations:
How do you aim to kick at balls close to a rail at a shallow angle into the rail?
For shallow angles into the rail, where the OB is fairly close to the rail, the contact-point-mirror-kick method works well. It is described in "VEPS GEMS - Part VII: Contact-Point Mirror Kick" (Download) (BD, July, 2010) and “VEPP – Part X: Shallow One-rail Kicks” (Download) (BD, January, 2013), and here are video demonstrations with a complete explanations:
Corner 5 System for aiming two-, three-, and four-rail kicks off a long rail
How does the "Corner 5" System work?
It is illustrated and explained, with examples, in the following articles: (Downloads)
"VEPS GEMS - Part XI: Corner-5 System Intro" (BD, November, 2010).
"VEPS GEMS - Part XII: Corner-5 System Example and Benchmark" (BD, December, 2010).
"VEPS GEMS - Part XIII: Corner-5 System Adjustments" (BD, January, 2011).
Here's a demo starring Donald Duck: "Donald in MathMagic Land" 3-cushioin billiards demo (YouTube). Here's a complete demonstration and explanation of the Corner-5 system, with lots of examples of how it is applied:
How does the "Corner 5" System work?
It is illustrated and explained, with examples, in the following articles: (Downloads)
"VEPS GEMS - Part XI: Corner-5 System Intro" (BD, November, 2010).
"VEPS GEMS - Part XII: Corner-5 System Example and Benchmark" (BD, December, 2010).
"VEPS GEMS - Part XIII: Corner-5 System Adjustments" (BD, January, 2011).
Here's a demo starring Donald Duck: "Donald in MathMagic Land" 3-cushioin billiards demo (YouTube). Here's a complete demonstration and explanation of the Corner-5 system, with lots of examples of how it is applied:
from AtLarge:
I think this will be extremely easy to remember. Notice that for each of the cases you cited, the number of diamonds of separation plus the 4th-rail convergence diamond (counting from the pocket as zero) totals 6. That is, 6+0=6. 5+1=6. 4+2=6. 3+3=6. So we could call it the "Sixes System" for three-rail kicks.
Diamond systems for aiming kick shots
How do diamond systems work?
All of the most common and useful banking and kicking systems (those listed below, and others) are described, illustrated, and demonstrated on Disc IV of the Video Encyclopedia of Pool Shots. (external web-link)
The simplest diamond systems are the equal-distance mirror system and the through-diamond rolling-ball system.
For shallow angles into the rail, where the OB is fairly close to the rail, the contact-point mirror system for shallow-angle, rolling kick shots works well.
The most famous"diamond system" is the Corner 5 System for aiming three-rail kicks off long rail.
Another famous diamond system is the Plus System for two-rail kicks off short rail.
from DeadAim:
complete "kicking academy" document describing and illustrating many diamond systems for kick shots. (Download)
Double kiss detection and avoidance with a cross-corner bank shot
How do you know if a bank shot will cause a double-kiss, and how can you avoid it?
Watch the videos below on YouTube for more details
Video one
Video two
Video three
Video four
Video five
I think this will be extremely easy to remember. Notice that for each of the cases you cited, the number of diamonds of separation plus the 4th-rail convergence diamond (counting from the pocket as zero) totals 6. That is, 6+0=6. 5+1=6. 4+2=6. 3+3=6. So we could call it the "Sixes System" for three-rail kicks.
Diamond systems for aiming kick shots
How do diamond systems work?
All of the most common and useful banking and kicking systems (those listed below, and others) are described, illustrated, and demonstrated on Disc IV of the Video Encyclopedia of Pool Shots. (external web-link)
The simplest diamond systems are the equal-distance mirror system and the through-diamond rolling-ball system.
For shallow angles into the rail, where the OB is fairly close to the rail, the contact-point mirror system for shallow-angle, rolling kick shots works well.
The most famous"diamond system" is the Corner 5 System for aiming three-rail kicks off long rail.
Another famous diamond system is the Plus System for two-rail kicks off short rail.
from DeadAim:
complete "kicking academy" document describing and illustrating many diamond systems for kick shots. (Download)
Double kiss detection and avoidance with a cross-corner bank shot
How do you know if a bank shot will cause a double-kiss, and how can you avoid it?
Watch the videos below on YouTube for more details
Video one
Video two
Video three
Video four
Video five
Effects and factors to consider
What effects does one need to adjust for when aiming bank and kick shots?
First, "VEPS GEMS - Part XVII: Trick and Proposition Shots" (Download) (BD, May, 2011) and the video below illustrate, describe, and demonstrate basic terminology for bank and kick shots:
What effects does one need to adjust for when aiming bank and kick shots?
First, "VEPS GEMS - Part XVII: Trick and Proposition Shots" (Download) (BD, May, 2011) and the video below illustrate, describe, and demonstrate basic terminology for bank and kick shots:
The basic mirror (angle in equals angle out) systems provide a point of reference only. Your aim with a given shot depends on many effects. The effects that require aim adjustment include:
- In general, more speed shortens the rebound and less speed lengthens the rebound (see NV 6.7); however, see HSV B.41 (YouTube) and NV B.95 (YouTube). One reason faster speed shortens a rolling-CB, angled kick is that the post-rebound curve is delayed by the speed. With a fast-speed, small-angle bank, the OB has near stun into the cushion and picks up topspin off the rail (see HSV B.15 (YouTube)), which curves the OB short.
- Less ball topspin roll (due to faster speed or closeness to rail) means shorter rebound.
- Running English lengthens rebound, and reverse English shortens the rebound. This effect is greatest with the ball heading straight into the rail (i.e., with no approach angle).
- Running English results in more CB speed after rebound, and reverse English results in less CB speed after rebound. The difference is greatest at a moderate approach angle in the rail (i.e., about 20-40 degrees from the rail perpendicular).
- Follow lengthens kick rebound, draw shortens it (e.g., see NV B.29 (YouTube) and NV B.57 (YouTube)).
- English has little effect at large approach angles, where the ball is heading fairly parallel to the rail. However, the English will have a large effect off the second rail, where the approach angle will be small, with the ball heading fairly perpendicular to the rail.
- An outside cut shortens a bank, an inside cut lengthens it. See: NV C.14 (YouTube).
- Bank direction consistency is generally better at faster speeds.
- Spin transfer can significantly affect banks (e.g., left spin on the CB can transfer right spin to the OB which shifts the rebound to the right).
- If the CB has a "natural English" amount (similar to "gearing English" for a cut shot), the side spin won't change off the cushion. With less side spin (including "negative" or reverse English), the cushion will increase the amount of spin, and the angle will shorten and for more English, the spin will decrease off the cushion, and the angle will lengthen.
- The cushion imparts spin (and can even reverse the spin direction) on a kicked or banked ball.
- Cut and spin transfer effects are related to throw effects, so a complete understanding of throw helps too.
- Kicks and banks generally go longer on new and clean in a dry environment (see cloth effects for more info).
For kick shots with small approach angles (i.e., almost straight into the rail), it sometimes helps to know how topspin and bottom-spin change off the rebound. For more information and examples, see:
Equal-distance mirror system for aiming bank and kick shots
How does the basic mirror system work?
"VEPS GEMS - Part V: Banks and Kicks" (Download) (BD, May, 2010) and the video below illustrate, describes and demonstrates the basic terminology for bank and kick shots, and explains the basic equal-rail-distance mirror system and
The basic mirror (angle in equals angle out) systems provide a point of reference only. You must compensate your aim for a given shot based on the many effects and factors to consider.
For shallow angle kicks, where the object ball is close to the rail, the following mirror system works quite well:
Pool bank and kick terminology and aiming system(YouTube)
Shallow angle contact point mirror image kick shot(YouTube)
Kick shot aiming system(YouTube)
- HSV B.15 - straight-on kick shot rebound losses and spin changes for roll, stun, and draw shots
- NV B.18 - Kick shot cue ball hold shot example with Tom Ross (YouTube)
Equal-distance mirror system for aiming bank and kick shots
How does the basic mirror system work?
"VEPS GEMS - Part V: Banks and Kicks" (Download) (BD, May, 2010) and the video below illustrate, describes and demonstrates the basic terminology for bank and kick shots, and explains the basic equal-rail-distance mirror system and
The basic mirror (angle in equals angle out) systems provide a point of reference only. You must compensate your aim for a given shot based on the many effects and factors to consider.
For shallow angle kicks, where the object ball is close to the rail, the following mirror system works quite well:
Pool bank and kick terminology and aiming system(YouTube)
Shallow angle contact point mirror image kick shot(YouTube)
Kick shot aiming system(YouTube)
For more information, see: "Billiard University (BU) - Part IX: Kicks (Download)," (April, 2014).
Fast-speed mirror-system adjustment
How do adjust your aim for a fast-speed bank?
The simplest approach is to use the basic mirror system and shift the butt of the cue by about 1/3 diamond, as described in "VEPS GEMS - Part V: Banks and Kicks" (Download) (BD, May, 2010).
The butt shift alone works only when the OB is fairly close to the banking rail. But regardless of the distance to the rail, after adjusting the mirror aim, the line of action of the OB should cross the origination rail groove at a point about 1/3 to 1/2 diamond more than twice the distance on the banking rail. In the example above, the final line of the OB should be aimed at about 1.9 and originate from about 4.3 (2*1.9 + 0.5). The exact amount of adjustment needed will vary with conditions and the angle of the bank, but 1/3 of a diamond is a good general benchmark reference.
Another useful fast-speed banking reference is the 3-to-1 line. On most tables, shooting through 1 from 3 with very fast speed pockets the ball.
An alternative to the 1/3-diamond system described above is a through-diamond system described in the following video: Ekert's bank shot reference lines (YouTube). It can be described concisely as the "2x-to-3/4x-through-diamond system" as opposed to the "(2x+1/3)-to-x rail-grove system" described above. Both systems are described and illustrated in detail in: “Fast Speed Banks”(Download) (BD, July, 2013).
In addition to being able to use the aiming systems above, there are advantages to using fast speed with bank shots. For more info, see: advantages of fast speed.
Magic spot three-rail mirror-image kick shot aiming system
How do you find and use the "magic spot" for three-rail kick shots?
See the following document from Marcel Elfers: Pool Magic Spot. (Download)
Plus System for aiming two-rail kicks off a short rail
How does the Plus System (AKA Plus Two System, AKA "Plus 2 System") work?
It is described and illustrated in detail in the following instructional articles: (Downloads)
"VEPS GEMS - Part VIII: Plus System Intro" (BD, August, 2010).
"VEPS GEMS - Part IX: Plus System Adjustments" (BD, September, 2010).
"VEPS GEMS - Part X: Plus System Examples" (BD, October, 2010).
Shallow-angle contact-point-mirror-image kick-shot aiming system
How do you aim shallow-angle kick shots where the object ball is close to the rail?
When the object ball is close to a ball away from the rail, the following mirror system, from Disc IV of the Video Encyclopedia of Pool Shots (VEPS) (Download) is very effective.
For more information, see: "VEPS GEMS - Part VII: Contact-Point Mirror Kick" (Download) (BD, July, 2010) and “VEPP - Part X: Shallow One-rail Kicks,” (Download) (BD, January, 2013).
Sid System for aiming steep two-rail kicks off a short rail
What is the "Sid System" and how does it work?
from Bob Jewett (from AZB post):(external forum-link)
For those who are wondering what "System Sid" is, here is the diagram from Walt Harris's book, "Billiard Atlas". To hit a spot on the second cushion, multiply the number for the spot by how many diamonds the cue ball is from point X. In the example, the target is 2.5 and the cue ball (Q) is 3 diamonds from X so the target is 7.5 on the short rail. Note that the short rail (M) is numbered 10 to the diamond, the second rail has a variable numbering that you have to memorize, and the rail you are shooting from (O) is numbered in units to multiply with. Harris recommends renumbering the O rail according to the second rail number, so in the example it would be numbered 0, 2.5, 5.0 and 7.5 starting from X.
If you work out the geometry in detail, the numbers on the second rail are off a little but as listed they are easy to remember.
Spin transfer bank shots
Is spin transfer required to make certain bank shots?
Yes. See NV B.20 (YouTube) for two important examples. For more information, and another example, see "Throw - Part VIII: spin transfer" (Download) (BD, March, 2007).
Spot-on-the-wall kick shot aiming system
How do "spot-on-the-wall" kicking systems work?
The three-rail Corner-5, two-rail Plus-2, and one-rail kick "spot-on-the-wall" systems are described and demonstrated here:
Fast-speed mirror-system adjustment
How do adjust your aim for a fast-speed bank?
The simplest approach is to use the basic mirror system and shift the butt of the cue by about 1/3 diamond, as described in "VEPS GEMS - Part V: Banks and Kicks" (Download) (BD, May, 2010).
The butt shift alone works only when the OB is fairly close to the banking rail. But regardless of the distance to the rail, after adjusting the mirror aim, the line of action of the OB should cross the origination rail groove at a point about 1/3 to 1/2 diamond more than twice the distance on the banking rail. In the example above, the final line of the OB should be aimed at about 1.9 and originate from about 4.3 (2*1.9 + 0.5). The exact amount of adjustment needed will vary with conditions and the angle of the bank, but 1/3 of a diamond is a good general benchmark reference.
Another useful fast-speed banking reference is the 3-to-1 line. On most tables, shooting through 1 from 3 with very fast speed pockets the ball.
An alternative to the 1/3-diamond system described above is a through-diamond system described in the following video: Ekert's bank shot reference lines (YouTube). It can be described concisely as the "2x-to-3/4x-through-diamond system" as opposed to the "(2x+1/3)-to-x rail-grove system" described above. Both systems are described and illustrated in detail in: “Fast Speed Banks”(Download) (BD, July, 2013).
In addition to being able to use the aiming systems above, there are advantages to using fast speed with bank shots. For more info, see: advantages of fast speed.
Magic spot three-rail mirror-image kick shot aiming system
How do you find and use the "magic spot" for three-rail kick shots?
See the following document from Marcel Elfers: Pool Magic Spot. (Download)
Plus System for aiming two-rail kicks off a short rail
How does the Plus System (AKA Plus Two System, AKA "Plus 2 System") work?
It is described and illustrated in detail in the following instructional articles: (Downloads)
"VEPS GEMS - Part VIII: Plus System Intro" (BD, August, 2010).
"VEPS GEMS - Part IX: Plus System Adjustments" (BD, September, 2010).
"VEPS GEMS - Part X: Plus System Examples" (BD, October, 2010).
Shallow-angle contact-point-mirror-image kick-shot aiming system
How do you aim shallow-angle kick shots where the object ball is close to the rail?
When the object ball is close to a ball away from the rail, the following mirror system, from Disc IV of the Video Encyclopedia of Pool Shots (VEPS) (Download) is very effective.
For more information, see: "VEPS GEMS - Part VII: Contact-Point Mirror Kick" (Download) (BD, July, 2010) and “VEPP - Part X: Shallow One-rail Kicks,” (Download) (BD, January, 2013).
Sid System for aiming steep two-rail kicks off a short rail
What is the "Sid System" and how does it work?
from Bob Jewett (from AZB post):(external forum-link)
For those who are wondering what "System Sid" is, here is the diagram from Walt Harris's book, "Billiard Atlas". To hit a spot on the second cushion, multiply the number for the spot by how many diamonds the cue ball is from point X. In the example, the target is 2.5 and the cue ball (Q) is 3 diamonds from X so the target is 7.5 on the short rail. Note that the short rail (M) is numbered 10 to the diamond, the second rail has a variable numbering that you have to memorize, and the rail you are shooting from (O) is numbered in units to multiply with. Harris recommends renumbering the O rail according to the second rail number, so in the example it would be numbered 0, 2.5, 5.0 and 7.5 starting from X.
If you work out the geometry in detail, the numbers on the second rail are off a little but as listed they are easy to remember.
Spin transfer bank shots
Is spin transfer required to make certain bank shots?
Yes. See NV B.20 (YouTube) for two important examples. For more information, and another example, see "Throw - Part VIII: spin transfer" (Download) (BD, March, 2007).
Spot-on-the-wall kick shot aiming system
How do "spot-on-the-wall" kicking systems work?
The three-rail Corner-5, two-rail Plus-2, and one-rail kick "spot-on-the-wall" systems are described and demonstrated here:
More information, including guidelines on how far the spot would be from the table, can be found in "VEPS GEMS - Part XIV: 'Spot-on-the-Wall' System" (Download) (BD, February, 2011).
There are different "rules of thumb" for estimating the best distance to the spot on the wall, but they don't always match the results in the article (Download) very well. Here's a common rule that does a decent job (although, it predicts a distance longer than recommended for a 3-rail shot and a distance shorter than recommended for a 1-rail shot):
from Monte Ohrt:
For any given spot-on-the-wall kick shot, the exact optimal distance from the first rail to the spot is the distance the cue ball travels after it hits the first rail to the target. For a one-rail kick, this is simply the distance from rail 1 to the target. For a two-rail kick, it is the distance between rail 1 and 2, and also add the distance between rail 2 and the target point. For a three rail kick, it is the distance between rails 1 and 2, 2 and 3, and 3 to the target point ... and so on for 4 rails, 5 rails, etc. After about 3 rails the point of convergence is so narrow that it normally doesn't make any difference, just pick a spot at least 3 tables away.
Through-diamond rolling-cue-ball one-rail kick and bank shot aiming system
How does the through-diamond rolling-cue-ball one-rail kick system work?
It is described in "VEPS GEMS - Part VI: One-Rail Kicks" (Download) (BD, June, 2010). Here's a video demonstration, from Disc IV of the Video Encyclopedia of Pool Shots (VEPS) (external web-link), with a complete explanation:
See videos on YouTube at:
Diamond System for aiming
Here's another useful video, from Disc III of the Billiard University (BU) Instructional DVD series: (external web-link): YouTube Link
Two-rail bank shot aiming system
Is there an aiming system for two-rail bank shots off the short rail?
You can use the Plus System for aiming two-rail banks off the short rail, but it will require practice to learn how to adjust for the lack of running English and forward roll on the OB into the first cushion which varies with distance and shot speed.
If the OB is fairly close to or frozen to the short rail, the systems below from Freddy Bentivegna work fairly well.
from freddy the beard AZB post: (external forum-link).
Two-rail parallel-line kick shot aiming system
Dr. Dave, I have been practicing the 2-rail parallel line kick shots you show in your book on pages 229 & 230 and demonstrated in NV 7.9. It works fine if I set up the balls similar to what you show in your book but I am having difficulty envisioning the same shot from other set ups. I don't think I fully understand how to determine the center line between the 2 parallel lines. Can you elaborate on this idea?
The following video, from Disc III of the Billiard University (BU) Instructional DVD series (external web-link)
Unfortunately, the action of this shot depends on English, shot speed, and table (especially cushion) conditions. Obviously, when practicing, you need to try to use consistent English and speed on a given table to see how the cue ball responds at different angles.
For more information and demonstrations, see Shots 514 and 515 on Disc IV of the Video Encyclopedia of Pool Shots. (external web-link)
Two-times-across and three-times across bank shots
What are "two-times" and "three-times" across bank shots, and how do they work?
Watch video(YouTube)
There are different "rules of thumb" for estimating the best distance to the spot on the wall, but they don't always match the results in the article (Download) very well. Here's a common rule that does a decent job (although, it predicts a distance longer than recommended for a 3-rail shot and a distance shorter than recommended for a 1-rail shot):
from Monte Ohrt:
For any given spot-on-the-wall kick shot, the exact optimal distance from the first rail to the spot is the distance the cue ball travels after it hits the first rail to the target. For a one-rail kick, this is simply the distance from rail 1 to the target. For a two-rail kick, it is the distance between rail 1 and 2, and also add the distance between rail 2 and the target point. For a three rail kick, it is the distance between rails 1 and 2, 2 and 3, and 3 to the target point ... and so on for 4 rails, 5 rails, etc. After about 3 rails the point of convergence is so narrow that it normally doesn't make any difference, just pick a spot at least 3 tables away.
Through-diamond rolling-cue-ball one-rail kick and bank shot aiming system
How does the through-diamond rolling-cue-ball one-rail kick system work?
It is described in "VEPS GEMS - Part VI: One-Rail Kicks" (Download) (BD, June, 2010). Here's a video demonstration, from Disc IV of the Video Encyclopedia of Pool Shots (VEPS) (external web-link), with a complete explanation:
See videos on YouTube at:
Diamond System for aiming
Here's another useful video, from Disc III of the Billiard University (BU) Instructional DVD series: (external web-link): YouTube Link
Two-rail bank shot aiming system
Is there an aiming system for two-rail bank shots off the short rail?
You can use the Plus System for aiming two-rail banks off the short rail, but it will require practice to learn how to adjust for the lack of running English and forward roll on the OB into the first cushion which varies with distance and shot speed.
If the OB is fairly close to or frozen to the short rail, the systems below from Freddy Bentivegna work fairly well.
from freddy the beard AZB post: (external forum-link).
Two-rail parallel-line kick shot aiming system
Dr. Dave, I have been practicing the 2-rail parallel line kick shots you show in your book on pages 229 & 230 and demonstrated in NV 7.9. It works fine if I set up the balls similar to what you show in your book but I am having difficulty envisioning the same shot from other set ups. I don't think I fully understand how to determine the center line between the 2 parallel lines. Can you elaborate on this idea?
The following video, from Disc III of the Billiard University (BU) Instructional DVD series (external web-link)
Unfortunately, the action of this shot depends on English, shot speed, and table (especially cushion) conditions. Obviously, when practicing, you need to try to use consistent English and speed on a given table to see how the cue ball responds at different angles.
For more information and demonstrations, see Shots 514 and 515 on Disc IV of the Video Encyclopedia of Pool Shots. (external web-link)
Two-times-across and three-times across bank shots
What are "two-times" and "three-times" across bank shots, and how do they work?
Watch video(YouTube)
from Patrick Johnson:
It's a series of spin events:
1. The CB colliding with the OB puts some "holdup" spin on the OB, which shortens the angle off the first rail.
2. The OB colliding with the first rail at an angle reverses the spin that was put on by the CB (just like any ball picks up "running" spin when it hits the rail).
3. The reversed spin throws the OB toward the side pocket off the second rail.
It's a series of spin events:
1. The CB colliding with the OB puts some "holdup" spin on the OB, which shortens the angle off the first rail.
2. The OB colliding with the first rail at an angle reverses the spin that was put on by the CB (just like any ball picks up "running" spin when it hits the rail).
3. The reversed spin throws the OB toward the side pocket off the second rail.
For more info, visit billiards.colostate.edu
Books
Billiards and Pool Books
... information and reviews dealing with pool and billiards instructional books.
Physics of pool
What books are available concerning the physics of pool?
See pool and billiards physics resources.(external web-link) It lists and provides links to many general interest and technical articles and books dealing with the physics and understanding of pool principles.
Mental side of the game
What are some good books dealing with the mental side or mental game of pool?
"The Pleasures of Small Motions" by Bob Fancher
"The Inner Game of Tennis" by W. Timothy Gallwey, Zach Kleiman, and Pete Carroll
"Mental Toughness Training for Sports: Achieving Athletic Excellence" by James Loehr
" The Talent Code: Greatness Isn't Born. It's Grown. Here's How." by Daniel Coyle
Also, Volume II of Tom Ross' Complete Instructional Works CD-ROM series dealing with the mental aspects of pool (external web-link) is excellent.
Also, there are many useful online resources dealing with this mental side or mental game of pool, including Joe Waldron's excellent collection of articles on this topic.(external web-link)
Recommended books
What are the best pool instructional books available?
from PoolMaster (on Amazon.com):
I would add the following to this list:
"Play Great Pool" by Mark Wilson
best coverage of mechanics and fundamentals, also with good coverage of mental aspects of the game
"The Eight Ball Bible" by R. Givens
best book dealing with 8-ball strategy, especially bar-box 8-ball
"Banking with the Beard" by Freddy Bentivegna
best book dealing with kick and bank shot aiming systems
"Pool & Billiards for Dummies" by N. Leider
excellent all-around introductory book
Reviews of Dr. Dave's book
Information dealing with Dr. Dave's book can be found here: The Illustrated Principles of Pool and Billiards (external web-link)
Reviews for Dr. Dave's DVDs can be found here: Dr Dave's Videos and DVDs review
from George Fels' Billiards Digest May '08 article: (Download)
[The article starts with a review of Freddy "The Beard" Bentivegna's stuff.]
The other instructional opus highly deserving of "props" this month is "The Illustrated Principles of Pool and Billiards," by BD's own David "Dr. Dave" Alciatore, a mechanical engineering professor. Dr. Dave is one of our most popular instructional columnists and one of the leading posters on the "Cue Chalk Board" forum on BD's Web site, no doubt due to his incredible generosity when it comes to sharing his knowledge. (How many cue-game publications do you suppose there are whose writing staffs include a physicist, a lawyer, and two graduate engineers?) Except for their apparent mutual Italian heritage and love of pool, he has nothing in common with Bentivegna. The latter's instruction comes from decades of high-stakes play, instincts, observations, and the teachings of older players. Alciatore's work, by contrast, largely depends on good old-fashioned science. The nuances of spin, cling, squirt, swerve, and "squerve" (the dreaded combination of squirt and swerve) have never been analyzed and explained as masterfully.
Because my father hounded me about taking physics all the way through high school, I avoided the subject as though it were snake venom, and am thus probably not the ideal subject for teaching on this plane. Dr. Dave writes well on pool's basics, but it's not until Chapter 4, "Spin and English," that his instruction really begins to sing. And he's equally masterful at integrating his scientific knowledge with on-the-table playing instruction. "Illustrated Principles" introduces over 80 playing principles, plus more than 250 illustrations and photographs. There's also a companion CD, with the same title, containing over 150 video clips and 20 technical proofs of his teachings.
I've lost track of all the stories I've heard of players who got angry with other players for sharing the game's secrets. The late Charlie Cacciapaglia of Rockford, Ill., one-time mentor to Hall-of-Famer Dallas West, was furious with his charge for becoming a successful pool teacher. And the immortal Willie Mosconi, who spent his entire adolescence in the Great Depression and needed the suckers to stay ignorant so he could help keep his family afloat, was notoriously closed-mouthed about dispensing advice; indeed, "always play with better players" and "practice the circle drill" are his only known instructions after all those years in the limelight. Those were two Italians who clearly didn't want to share the joy. Be glad that today we have two who do.
from Amazon.com:
If you think the best pool players are leather-jacketed badasses who quit school at 12 to shark sailors out of their paychecks, think again. Pool involves complex physical principles that aren't taught until long after the delinquents have departed the academy. "Dr. Dave," both a professor of mechanical engineering and a Billiards Digest columnist, has written a textbook-style how-to that focuses on the game's fundamental principles. It's loaded with excellent color diagrams, decent photographs, and useful sidebars. He's a Web geek, too--there are dozens of cross-references to his site, where free videos demonstrate the lessons on the page. (The site even offers technical proofs!) There's so much information packed in here that learners who prefer a prosy approach may be put off. It's written clearly, though, and for the nuts-and-bolts crowd--make that the graphing-calculator and circuit-board set--it's hard to imagine a better primer. Reminiscent of Jack Koehler's excellent The Science of Pocket Billiards (1989). Pool is for nerds--and that's cool.
See also: Amazon.com customer reviews. (external shopping-link)
from David "Blackjack" Sapolis:
Great book with a lot of hard work and research behind it. It is a must have for your collection.
from BigRigTom:
Dr. Dave's Book is THE BEST POOL BOOK I have ever read. It is one of the few that combined with Dr. Dave's website can claim the right to say it is the RIGHT way to view many of the concepts in pool physics. I don't know if Dr. Dave was the 1st to recognize the 30 degree rule but his book was the 1st time I had ever heard it and like Billy Bob I had to try it a few times to really understand it but once I did get it through my thick head ....WOW!...what a difference it has made. I too recommend that book and the web site to others when I see them actively pursuing the improvement that we all strive for.
I remember telling Dr. Dave directly that his book put an end to a lot of searching by me for the CORRECT way to shoot many of the shots in pool. I still only get it right sometimes but thank to Dr. Dave I know when I have done it wrong. I can not say enough good things about the information Dr. Dave has made available to the world of pool and billiards players and when people disagree with his points he has always displayed the patience of a saint while respecting the views and opinions of others...regardless of how ridiculous some of those views have been at times.
Keep up the good work Dr. Dave, you are an inspiration to us all.....well most of us. There are still a few knuckleheads out there like those guys that laughed at Columbus when he sailed off into the sunset.
from poolstudent.com:
David (Dr Dave) G. Alciatore’s book The Illustrated Principles of Pool and Billiards explains what happens on the pool table from a scientific or engineering perspective. By explaining the underlying forces, the cause and effect of the where balls go and why, Dr Dave will enable you to understand pool at a fundamental level.
Hopefully that didn’t scare you off, because this book is written for ordinary people in plain and clear language. I wish there were such lucid explanations for everything else in the world.
The book is jam packed with excellent photos, clear and useful illustrations and enumerated principles in the form of bullet lists. These do a fine job of supporting the text and enhancing understanding.
Starting out, the coverage of fundamentals is easy to grasp and covers the topic well. It’s difficult to make this stuff interesting but Dave’s done what he could.
Basic shot making comes in for a detailed treatment. There are 45 pages covering everything you need to learn how to aim and successfully make pool shots. Using his website at Colorado State as an additional resource, Dr Dave has included links to view videos of every point he discusses. Where appropriate he even has ultra-slow motion video of things that happen so fast you can’t ordinarily see them. Though you don’t have to buy the book to see these videos on-line, the book provides the context to get the most out of them. I encourage you to buy this book and support Dr Dave’s gifts to the pool community.
Warranting special mention here as an example of the way this book explains fundamental principles, the 90° rule (tangent rule) comes in for a lot of explanation. How it can easily be used to help you understand exactly what draw and follow do to the resulting path of the cue ball. It can turn on the lights to let you see the pool world in a totally new and extremely useful light. His addition of the 30° rule to the basic set of principles has helped many to play much better pool.
Spin and english come in for the treatment next. With clarity and precision, Dr Dave elucidates the underlying and seemingly mysterious principles that add the next level of complexity to the game. Remember when you were in school and every year you’d learn that what you learned last year was only mostly correct, and needed a little additional info to make it correct. Well, this chapter is what does that to the basics of pool. This is critical information, and without really getting it parts of the game will always be a mystery. The explanations here are as good as they get. Study this chapter, because after a good stroke knowledge of these subtleties is the most valuable thing you can do to improve your pool game.
The rest of the book is dedicated to using the fundamentals to explain how to play pool well. There’s coverage of how to get position, how to make banks and kicks, advanced techniques, etc.
This book is highly recommended and is one of my favorites.
from av84fun (Jim):
I have recently finished my long overdue reading of Dr. Dave Alciatore's book, The Illustrated Principles of Pool and Billiards. Bottom line, it is a must have book.
I have a large library of pool instructional texts and would rank this book in the top echelon of the lot. There may be another text that is accompanied via DVD or on-line with illustrative video clips, including super slo mo video of many salient points but I am not aware of one.
Pictures are, in many cases, worth a thousand words and there are LOTS of pictures (and diagrams) in the book which, when accompanied by the archive of other videos and texts renders Dave's work to be of exceptional value. He, quite correctly, formats the book in a "building block" and very clearly describes all of the most essential ingredients required to climb the ladder of pool knowledge.
Since most rungs on the ladder are given space, this is not a work devoted entirely to advanced players which is not a criticism. Even some advanced players couldn't explain why they do certain rather fundamental things...and many wouldn't care to but we cannot impose upon the author, knowledge of what his readers know and do not know. Clearly, even quite advanced players will learn enough from this book to justify its price. On the other end of the spectrum, I think it would be an excellent idea for professional instructors to use the book as a "lesson plan" model.
Again, accompanied as the text is with excellent and in some cases, unique video, the use of the book/video entity can hardly help but accelerate the student's learning curve. One objective standard I use to rate such books is the number of Post-it-Notes stuck between their pages. I have LOTS of them in Dave's book....which, by the way...is a technique I would recommend to all. I review my noted pages in almost all my instructional texts annually or very nearly so and always have. And there has been not one single such pass in which I have not been reminded of something important. (Possibly because my memory sucks but that is another story.)
Finally, while Dave is a self-admitted physics geek (in the loving sense of that word) he never talks down or tries to dazzle his readers with technical jargon. There are a number of "technical proofs" for those who are interested in them but the basic text is quite conversational.
Well done Dr. Dave.
from caedos (Carl):
This may be hands down the best physical presentation of a pool text I've ever seen. By that I mean this: paper weight and gloss, sectioning, cross-referencing, supporting online media, graphics, and a separation of text in pieces directed to different reader needs (not unlike the 'For Dummies' where a section is for a 'rule of thumb' or 'important!' note).
from JB Cases:
I have read it and watched the DVDs. It's a lot of good solid information for the money.
One thing I like about it better than most other basic instruction books is that it's backed up by free video examples that compliment the book. So you can always go to the website and look up the videos.
... it's pretty much a must have on any pool enthusiast's shelf.
from New2Pool:
Dave's book is easy to understand and the style suites me very well. I like to know how things work and his book does a good job of explaining what is going on to make a shot work. One thing I was surprised at was the aesthetic quality of the book. Dave's book looks and feels better than most books. The paper quality is superb and the illustrations are very clear.
... information and reviews dealing with pool and billiards instructional books.
Physics of pool
What books are available concerning the physics of pool?
See pool and billiards physics resources.(external web-link) It lists and provides links to many general interest and technical articles and books dealing with the physics and understanding of pool principles.
Mental side of the game
What are some good books dealing with the mental side or mental game of pool?
"The Pleasures of Small Motions" by Bob Fancher
"The Inner Game of Tennis" by W. Timothy Gallwey, Zach Kleiman, and Pete Carroll
"Mental Toughness Training for Sports: Achieving Athletic Excellence" by James Loehr
" The Talent Code: Greatness Isn't Born. It's Grown. Here's How." by Daniel Coyle
Also, Volume II of Tom Ross' Complete Instructional Works CD-ROM series dealing with the mental aspects of pool (external web-link) is excellent.
Also, there are many useful online resources dealing with this mental side or mental game of pool, including Joe Waldron's excellent collection of articles on this topic.(external web-link)
Recommended books
What are the best pool instructional books available?
from PoolMaster (on Amazon.com):
- "The Illustrated Principles of Pool and Billiards" (external web-link) by David G. Alciatore
best all-round book with best illustrations and web resources - "Byrne's Complete Book of Pool Shots: 350 Moves Every Player Should Know" by Robert Byrne
comprehensive set of examples of every type of shot - "The 99 Critical Shots in Pool: Everything You Need to Know to Learn and Master the Game" by Ray Martin
99 of the best examples of types of shots - "Byrne's New Standard Book of Pool and Billiards" by Robert Byrne
great all-around intro book - "Pleasures of Small Motions: Mastering the Mental Game of Pocket Billiards" by Bob Fancher
great coverage of the mental side of the game - "Play Your Best Pool" by Philip B. Capelle
good all-around book for beginners - "Mike Massey's World of Trick Shots" by Mike Massey
best book dealing with trick shots, by the master
I would add the following to this list:
"Play Great Pool" by Mark Wilson
best coverage of mechanics and fundamentals, also with good coverage of mental aspects of the game
"The Eight Ball Bible" by R. Givens
best book dealing with 8-ball strategy, especially bar-box 8-ball
"Banking with the Beard" by Freddy Bentivegna
best book dealing with kick and bank shot aiming systems
"Pool & Billiards for Dummies" by N. Leider
excellent all-around introductory book
Reviews of Dr. Dave's book
Information dealing with Dr. Dave's book can be found here: The Illustrated Principles of Pool and Billiards (external web-link)
Reviews for Dr. Dave's DVDs can be found here: Dr Dave's Videos and DVDs review
from George Fels' Billiards Digest May '08 article: (Download)
[The article starts with a review of Freddy "The Beard" Bentivegna's stuff.]
The other instructional opus highly deserving of "props" this month is "The Illustrated Principles of Pool and Billiards," by BD's own David "Dr. Dave" Alciatore, a mechanical engineering professor. Dr. Dave is one of our most popular instructional columnists and one of the leading posters on the "Cue Chalk Board" forum on BD's Web site, no doubt due to his incredible generosity when it comes to sharing his knowledge. (How many cue-game publications do you suppose there are whose writing staffs include a physicist, a lawyer, and two graduate engineers?) Except for their apparent mutual Italian heritage and love of pool, he has nothing in common with Bentivegna. The latter's instruction comes from decades of high-stakes play, instincts, observations, and the teachings of older players. Alciatore's work, by contrast, largely depends on good old-fashioned science. The nuances of spin, cling, squirt, swerve, and "squerve" (the dreaded combination of squirt and swerve) have never been analyzed and explained as masterfully.
Because my father hounded me about taking physics all the way through high school, I avoided the subject as though it were snake venom, and am thus probably not the ideal subject for teaching on this plane. Dr. Dave writes well on pool's basics, but it's not until Chapter 4, "Spin and English," that his instruction really begins to sing. And he's equally masterful at integrating his scientific knowledge with on-the-table playing instruction. "Illustrated Principles" introduces over 80 playing principles, plus more than 250 illustrations and photographs. There's also a companion CD, with the same title, containing over 150 video clips and 20 technical proofs of his teachings.
I've lost track of all the stories I've heard of players who got angry with other players for sharing the game's secrets. The late Charlie Cacciapaglia of Rockford, Ill., one-time mentor to Hall-of-Famer Dallas West, was furious with his charge for becoming a successful pool teacher. And the immortal Willie Mosconi, who spent his entire adolescence in the Great Depression and needed the suckers to stay ignorant so he could help keep his family afloat, was notoriously closed-mouthed about dispensing advice; indeed, "always play with better players" and "practice the circle drill" are his only known instructions after all those years in the limelight. Those were two Italians who clearly didn't want to share the joy. Be glad that today we have two who do.
from Amazon.com:
If you think the best pool players are leather-jacketed badasses who quit school at 12 to shark sailors out of their paychecks, think again. Pool involves complex physical principles that aren't taught until long after the delinquents have departed the academy. "Dr. Dave," both a professor of mechanical engineering and a Billiards Digest columnist, has written a textbook-style how-to that focuses on the game's fundamental principles. It's loaded with excellent color diagrams, decent photographs, and useful sidebars. He's a Web geek, too--there are dozens of cross-references to his site, where free videos demonstrate the lessons on the page. (The site even offers technical proofs!) There's so much information packed in here that learners who prefer a prosy approach may be put off. It's written clearly, though, and for the nuts-and-bolts crowd--make that the graphing-calculator and circuit-board set--it's hard to imagine a better primer. Reminiscent of Jack Koehler's excellent The Science of Pocket Billiards (1989). Pool is for nerds--and that's cool.
See also: Amazon.com customer reviews. (external shopping-link)
from David "Blackjack" Sapolis:
Great book with a lot of hard work and research behind it. It is a must have for your collection.
from BigRigTom:
Dr. Dave's Book is THE BEST POOL BOOK I have ever read. It is one of the few that combined with Dr. Dave's website can claim the right to say it is the RIGHT way to view many of the concepts in pool physics. I don't know if Dr. Dave was the 1st to recognize the 30 degree rule but his book was the 1st time I had ever heard it and like Billy Bob I had to try it a few times to really understand it but once I did get it through my thick head ....WOW!...what a difference it has made. I too recommend that book and the web site to others when I see them actively pursuing the improvement that we all strive for.
I remember telling Dr. Dave directly that his book put an end to a lot of searching by me for the CORRECT way to shoot many of the shots in pool. I still only get it right sometimes but thank to Dr. Dave I know when I have done it wrong. I can not say enough good things about the information Dr. Dave has made available to the world of pool and billiards players and when people disagree with his points he has always displayed the patience of a saint while respecting the views and opinions of others...regardless of how ridiculous some of those views have been at times.
Keep up the good work Dr. Dave, you are an inspiration to us all.....well most of us. There are still a few knuckleheads out there like those guys that laughed at Columbus when he sailed off into the sunset.
from poolstudent.com:
David (Dr Dave) G. Alciatore’s book The Illustrated Principles of Pool and Billiards explains what happens on the pool table from a scientific or engineering perspective. By explaining the underlying forces, the cause and effect of the where balls go and why, Dr Dave will enable you to understand pool at a fundamental level.
Hopefully that didn’t scare you off, because this book is written for ordinary people in plain and clear language. I wish there were such lucid explanations for everything else in the world.
The book is jam packed with excellent photos, clear and useful illustrations and enumerated principles in the form of bullet lists. These do a fine job of supporting the text and enhancing understanding.
Starting out, the coverage of fundamentals is easy to grasp and covers the topic well. It’s difficult to make this stuff interesting but Dave’s done what he could.
Basic shot making comes in for a detailed treatment. There are 45 pages covering everything you need to learn how to aim and successfully make pool shots. Using his website at Colorado State as an additional resource, Dr Dave has included links to view videos of every point he discusses. Where appropriate he even has ultra-slow motion video of things that happen so fast you can’t ordinarily see them. Though you don’t have to buy the book to see these videos on-line, the book provides the context to get the most out of them. I encourage you to buy this book and support Dr Dave’s gifts to the pool community.
Warranting special mention here as an example of the way this book explains fundamental principles, the 90° rule (tangent rule) comes in for a lot of explanation. How it can easily be used to help you understand exactly what draw and follow do to the resulting path of the cue ball. It can turn on the lights to let you see the pool world in a totally new and extremely useful light. His addition of the 30° rule to the basic set of principles has helped many to play much better pool.
Spin and english come in for the treatment next. With clarity and precision, Dr Dave elucidates the underlying and seemingly mysterious principles that add the next level of complexity to the game. Remember when you were in school and every year you’d learn that what you learned last year was only mostly correct, and needed a little additional info to make it correct. Well, this chapter is what does that to the basics of pool. This is critical information, and without really getting it parts of the game will always be a mystery. The explanations here are as good as they get. Study this chapter, because after a good stroke knowledge of these subtleties is the most valuable thing you can do to improve your pool game.
The rest of the book is dedicated to using the fundamentals to explain how to play pool well. There’s coverage of how to get position, how to make banks and kicks, advanced techniques, etc.
This book is highly recommended and is one of my favorites.
from av84fun (Jim):
I have recently finished my long overdue reading of Dr. Dave Alciatore's book, The Illustrated Principles of Pool and Billiards. Bottom line, it is a must have book.
I have a large library of pool instructional texts and would rank this book in the top echelon of the lot. There may be another text that is accompanied via DVD or on-line with illustrative video clips, including super slo mo video of many salient points but I am not aware of one.
Pictures are, in many cases, worth a thousand words and there are LOTS of pictures (and diagrams) in the book which, when accompanied by the archive of other videos and texts renders Dave's work to be of exceptional value. He, quite correctly, formats the book in a "building block" and very clearly describes all of the most essential ingredients required to climb the ladder of pool knowledge.
Since most rungs on the ladder are given space, this is not a work devoted entirely to advanced players which is not a criticism. Even some advanced players couldn't explain why they do certain rather fundamental things...and many wouldn't care to but we cannot impose upon the author, knowledge of what his readers know and do not know. Clearly, even quite advanced players will learn enough from this book to justify its price. On the other end of the spectrum, I think it would be an excellent idea for professional instructors to use the book as a "lesson plan" model.
Again, accompanied as the text is with excellent and in some cases, unique video, the use of the book/video entity can hardly help but accelerate the student's learning curve. One objective standard I use to rate such books is the number of Post-it-Notes stuck between their pages. I have LOTS of them in Dave's book....which, by the way...is a technique I would recommend to all. I review my noted pages in almost all my instructional texts annually or very nearly so and always have. And there has been not one single such pass in which I have not been reminded of something important. (Possibly because my memory sucks but that is another story.)
Finally, while Dave is a self-admitted physics geek (in the loving sense of that word) he never talks down or tries to dazzle his readers with technical jargon. There are a number of "technical proofs" for those who are interested in them but the basic text is quite conversational.
Well done Dr. Dave.
from caedos (Carl):
This may be hands down the best physical presentation of a pool text I've ever seen. By that I mean this: paper weight and gloss, sectioning, cross-referencing, supporting online media, graphics, and a separation of text in pieces directed to different reader needs (not unlike the 'For Dummies' where a section is for a 'rule of thumb' or 'important!' note).
from JB Cases:
I have read it and watched the DVDs. It's a lot of good solid information for the money.
One thing I like about it better than most other basic instruction books is that it's backed up by free video examples that compliment the book. So you can always go to the website and look up the videos.
... it's pretty much a must have on any pool enthusiast's shelf.
from New2Pool:
Dave's book is easy to understand and the style suites me very well. I like to know how things work and his book does a good job of explaining what is going on to make a shot work. One thing I was surprised at was the aesthetic quality of the book. Dave's book looks and feels better than most books. The paper quality is superb and the illustrations are very clear.
For more info, visit billiards.colostate.edu
Break
(external web-links) for more information:
see Section 7.05 in The Illustrated Principles of Pool and Billiards
and Disc II and Disc V of the Video Encyclopedia of Pool Shots (VEPS)
Ball squat and hop
How do you make the CB squat on the break, and why does the cue ball sometimes hop in the air and/or off the table?
To make the CB "squat" (come to rest near the center of the table) after hitting the rack of balls, it needs to have slight topspin. The larger effective mass of the rack of balls makes the CB bounce back, so slight follow is required to stop that motion. However, due to the force of the power break shot, only slight follow should be used (i.e., the tip should contact the CB only a small amount above center). The following videos illustrate some of the physics involved:
So with a firm break shot, the CB will always be hopping on the way to the rack, and if the CB hits the rack while airborne, it will hop in the air after hitting the lead ball. This is not something one should try to create (e.g., by elevating the cue even more than normal). However, with a well-struck break (i.e., a square hit with significant speed), it is difficult to avoid the hop. The best scenario is if the CB lands exactly at the same time it hits the 1-ball. Then the most energy possible will be delivered to the rack, and the CB hop will be as small as possible. Although, even in this case, the CB will still hop slightly because the CB will still have a downward motion component when it lands at the 1-ball.
One should hit the CB with the cue as level as possible to minimize how much the CB hops on the way to the rack of balls to deliver as much power as possible to the balls. If the cue is elevated more than it needs to be to clear the rail, the CB would jump and skip more on the way to the rack, possibly causing it to hit the 1-ball even more airborne, which would cause it to hop even higher. But this would not be good because less energy would be delivered to the rack (due to the losses during the initial and any subsequent hops).
Now, if you hit the lead ball very squarely with significant CB speed, the CB will most likely hop. However, the hop is really not a good thing ... it is just the result of an accurate and powerful break.
Significant hop can occur only if the CB is airborne when it hits the lead ball. This can occur if the cue is elevated too much and/or if too much speed is used. The CB can also "climb" the lead ball a small amount with topspin from an above-center hit, but this effect is not significant.
If you hit the lead ball squarely (as you should with a good break), the cue ball hop is not a problem (unless it is high enough to hit the light fixture above the table). However, with hop and a non-square hit, the cue ball can easily fly off the table.
To reduce the amount of hop, try keeping the cue as level as possible at impact with the CB. Also, try to reduce how much you are hitting the CB above center, especially if the CB has too much follow action after landing.
You can also reduce the effect of hop by adjusting your break position so the distance to the rack is just right, where the CB lands just as it hits the lead ball of the rack. By moving your CB starting position left or right or forward or backward in the kitchen, you can control where the hop occurs (for a given break speed, cue elevation, and tip contact point).
Drill
What is a good drill from improving my break shot?
Disc V of the Video Encyclopedia of Pool Practice (VEPP) (external web-link) has a good 9-ball break drill for evaluating and improving your 9-ball break.
from Patrick Johnson:
The idea is to learn to aim the break shot as accurately as any other shot so you can consistently hit the head ball dead square, getting maximum power transfer into the rack and planting the cue ball in the middle of the table. It comes from a piece of advice I heard once and have repeated often to players who are learning to break:
Your break speed should be the maximum speed at which you can consistently pocket a straight-in shot with the cue ball on the head string and the object ball on the foot string, and stop the cue ball dead.
And that pretty much describes the drill:
1. place the cue ball in its normal breaking position
2. place a single object ball on the foot string directly in line with a corner pocket
3. shoot the OB straight into the pocket with a stop shot
4. hit the shot as hard as you think you can, but if you miss the pocket or the cue ball doesn't stop dead, slow the next shot down
5. only speed the shot up again when you've made several successful stop shots in a row
6. gradually build your speed up following the above rule
8-ball break
What are possible strategies for breaking in 8-ball?
First of all, follow the advice in the break technique section.
An alternative to hitting the lead ball on the break is hitting the 2nd-ball or 3rd-ball squarely instead by breaking from the side rail. These breaks can be very effective. They spread the balls well and often result in pocketing a ball. It is also easier to control the CB since less power is required. One disadvantage with a 2nd-ball break is sometimes the balls tend to cluster on the breaking side of the table.
If pattern racking is not prohibited, you might want to use the Corey Deuel approach (see below).
Should I put balls in certain positions when I am racking for 8-ball?
from CreeDo (in AZB post): (external forum-blog)
Interesting pattern Corey [Deuel] has come up with for 8b. It not only ensures an even spread for his chosen group, it leaves an ugly cluster for the opponent's group.
He breaks from the corner, hitting the 2nd row ball squarely, maybe 15-17 mph.
In the diagram it's the stripes that spread and the solids that cluster.
Two images below show how it was racked and what the results were after the break shot. On the 2nd image you can see: This is what he was left after the break on his own racks. You can see what's happening near the right side of the rack area. Not hard to guess which group he chose in each example.
see Section 7.05 in The Illustrated Principles of Pool and Billiards
and Disc II and Disc V of the Video Encyclopedia of Pool Shots (VEPS)
Ball squat and hop
How do you make the CB squat on the break, and why does the cue ball sometimes hop in the air and/or off the table?
To make the CB "squat" (come to rest near the center of the table) after hitting the rack of balls, it needs to have slight topspin. The larger effective mass of the rack of balls makes the CB bounce back, so slight follow is required to stop that motion. However, due to the force of the power break shot, only slight follow should be used (i.e., the tip should contact the CB only a small amount above center). The following videos illustrate some of the physics involved:
- HSV B.43 - break squat
- HSV A.123 - power break -- cue ball reactions for draw, follow, and skip
- NV D.14 - Pool Break Technique Advice - from Vol-III of the Billiard University instructional DVD series
So with a firm break shot, the CB will always be hopping on the way to the rack, and if the CB hits the rack while airborne, it will hop in the air after hitting the lead ball. This is not something one should try to create (e.g., by elevating the cue even more than normal). However, with a well-struck break (i.e., a square hit with significant speed), it is difficult to avoid the hop. The best scenario is if the CB lands exactly at the same time it hits the 1-ball. Then the most energy possible will be delivered to the rack, and the CB hop will be as small as possible. Although, even in this case, the CB will still hop slightly because the CB will still have a downward motion component when it lands at the 1-ball.
One should hit the CB with the cue as level as possible to minimize how much the CB hops on the way to the rack of balls to deliver as much power as possible to the balls. If the cue is elevated more than it needs to be to clear the rail, the CB would jump and skip more on the way to the rack, possibly causing it to hit the 1-ball even more airborne, which would cause it to hop even higher. But this would not be good because less energy would be delivered to the rack (due to the losses during the initial and any subsequent hops).
Now, if you hit the lead ball very squarely with significant CB speed, the CB will most likely hop. However, the hop is really not a good thing ... it is just the result of an accurate and powerful break.
Significant hop can occur only if the CB is airborne when it hits the lead ball. This can occur if the cue is elevated too much and/or if too much speed is used. The CB can also "climb" the lead ball a small amount with topspin from an above-center hit, but this effect is not significant.
If you hit the lead ball squarely (as you should with a good break), the cue ball hop is not a problem (unless it is high enough to hit the light fixture above the table). However, with hop and a non-square hit, the cue ball can easily fly off the table.
To reduce the amount of hop, try keeping the cue as level as possible at impact with the CB. Also, try to reduce how much you are hitting the CB above center, especially if the CB has too much follow action after landing.
You can also reduce the effect of hop by adjusting your break position so the distance to the rack is just right, where the CB lands just as it hits the lead ball of the rack. By moving your CB starting position left or right or forward or backward in the kitchen, you can control where the hop occurs (for a given break speed, cue elevation, and tip contact point).
Drill
What is a good drill from improving my break shot?
Disc V of the Video Encyclopedia of Pool Practice (VEPP) (external web-link) has a good 9-ball break drill for evaluating and improving your 9-ball break.
from Patrick Johnson:
The idea is to learn to aim the break shot as accurately as any other shot so you can consistently hit the head ball dead square, getting maximum power transfer into the rack and planting the cue ball in the middle of the table. It comes from a piece of advice I heard once and have repeated often to players who are learning to break:
Your break speed should be the maximum speed at which you can consistently pocket a straight-in shot with the cue ball on the head string and the object ball on the foot string, and stop the cue ball dead.
And that pretty much describes the drill:
1. place the cue ball in its normal breaking position
2. place a single object ball on the foot string directly in line with a corner pocket
3. shoot the OB straight into the pocket with a stop shot
4. hit the shot as hard as you think you can, but if you miss the pocket or the cue ball doesn't stop dead, slow the next shot down
5. only speed the shot up again when you've made several successful stop shots in a row
6. gradually build your speed up following the above rule
8-ball break
What are possible strategies for breaking in 8-ball?
First of all, follow the advice in the break technique section.
An alternative to hitting the lead ball on the break is hitting the 2nd-ball or 3rd-ball squarely instead by breaking from the side rail. These breaks can be very effective. They spread the balls well and often result in pocketing a ball. It is also easier to control the CB since less power is required. One disadvantage with a 2nd-ball break is sometimes the balls tend to cluster on the breaking side of the table.
If pattern racking is not prohibited, you might want to use the Corey Deuel approach (see below).
Should I put balls in certain positions when I am racking for 8-ball?
from CreeDo (in AZB post): (external forum-blog)
Interesting pattern Corey [Deuel] has come up with for 8b. It not only ensures an even spread for his chosen group, it leaves an ugly cluster for the opponent's group.
He breaks from the corner, hitting the 2nd row ball squarely, maybe 15-17 mph.
In the diagram it's the stripes that spread and the solids that cluster.
Two images below show how it was racked and what the results were after the break shot. On the 2nd image you can see: This is what he was left after the break on his own racks. You can see what's happening near the right side of the rack area. Not hard to guess which group he chose in each example.
Follow-through
Should I use an extended follow through on the break shot?
This is a question of cause and effect. A follow-through strictly has no influence on the cue ball because the cue tip is in contact with the cue ball for only a very short amount of time (approximately 0.001 seconds). The only things that significantly affect the breaking power for a given cue stick are cue stick speed at impact, tip offset (distance away from a center ball hit), and the squareness of the hit on the lead ball. However, if a powerful stroke does not exhibit a big follow-through, it is either not very powerful, or effort is being made to limit the follow-through. If one tries to constrain the follow-through, one will probably not achieve maximum speed at impact. Many authors and instructors recommend trying to "accelerate through the ball" for power shots. This thinking often helps one create good power, and it results in significant follow-through.
Follow-through can also be important in achieving good action on draw shots (although, not always for the reasons people think). For more info, see "Draw Shot Primer - Part V: how to achieve good draw action" (Download) (BD, May, 2006). In particular, see item "b" under "other advice" and item "5" under "stroke best practices." I think these points apply equally well to both a power break and a power draw.
from Fran Crimi:
Besides making sure the rack is tight, you MUST exaggerate your follow-through. Even if you think you are following through enough, push through even more. Watch Strickland's follow-through. The cue literally comes out of his bridge hand and is extended all the way down the table. It's difficult to master that letting-go technique with accuracy but with lots of practice, it will pay off in spades.
The other option is to leave the cue in your bridge hand but with an over-extended follow-through, if you lean into the break shot, you will definitely bend the shaft and possibly crack or break it like some other players do.
I prefer the letting-go technique.
Making the 8-ball
How can I increase my chances of making the 8-ball on the break?
Not all leagues and tournaments award a game victory for making the 8-ball on the break; but if they do, it is wise to try to increase your chances for pocketing the 8-ball. A good technique for this is to place the CB close to the side rail on the head string, and hit the 2nd ball in the rack squarely. The 8-ball will often head toward the opposite side pocket, and the balls will usually disperse well. Clips HSV 7.8-7.11 (external web-link) show how it works. For illustrations and more information, see Section 7.05 in The Illustrated Principles of Pool and Billiards. (external web-link)
Measuring your own break speed
Is there an easy way to measure your break shot speed without a fancy radar gun?
Here's a phone app that works very well:
http://www.mybreakspeed.com/ (external web-link)
You can also measure your break speed with any computer containing a microphone (see below).
from Runnin8:
To find your own break speed:
1) Measure the distance between where your cue ball rests on the table for a normal break and the head spot, subtract 2.25" for one ball diameter.
2) Use sound recorder on a PC to record the sound of your break. We used a laptop with it next to the table. Most PCs can record at 44Khz, or 44 thousand times a second, more than accurate enough. Also, forget about having to get it right in the middle. Unless your break speed is near the speed of sound its a nit. Use a sound program like Wave pad (external web-link) to open the file and identify the peak where the cue strikes the cueball and then the peak at rack contact. If you highlight with Wave pad it will tell you to the thousandth of a second.
3) Your break speed in mph is:
(distance-2.25) / 12*60/88 / (measured time)
9-ball break
What are possible strategies for breaking in 9-ball?
First of all, follow the advice in the break technique section.
If pattern racking is not prohibited, you might want to take advantage of those approaches (maybe in combination with a soft break per the Corey Deuel example below).
Should I put balls in certain positions when I am racking for 9-ball?
from CreeDo (in AZB post): (external forum-link)
Corey will not be satisfied until he completely breaks 9 ball.
First he figured out how to make a ball on the break every time and get a look at the 1. Then he figured out how to get an easy layout so he can run the whole rack every time. Now he's figured out how to leave himself a wired 9 ball combo after running just 2 or 3 balls:
YouTube Clip
Pattern racking strategy
Should I put balls in certain positions when I am racking for 9-ball?
There are certain ball-motion patterns you can take advantage of, whether you are racking for an opponent or racking for yourself. Some of the basics are covered in this video from Disc V of the Video Encyclopedia of Pool Shots:(external web-link)
See video example on YouTube on 9 ball pool racking strategy
2.2 Nine Ball Rack
The object balls are racked as tightly as possible in a diamond shape, with the one ball at the apex of the diamond and on the foot spot and the nine ball in the middle of the diamond. The other balls will be placed in the diamond without purposeful or intentional pattern.
Obviously, a strict interpretation and strict enforcement of this rule prohibits "pattern racking," where you place certain balls in certain positions for an advantage. However, the rule isn't usually interpreted so strictly. Often (e.g., in most leagues and tournaments), the last sentence is interpreted: It doesn't matter where the other balls are placed. Also, somebody can easily "pattern rack" without it seeming "intentional" or "purposeful." However, a ref or opponent has the right to protest if certain "patterns" are obviously being used (e.g., always placing the 2-ball in the back of the rack).
Obviously, the best solution is to have a neutral party rack the balls (which is done in the WPBA TV events). With "rack your own" or "opponent racking," "pattern racking" is always likely to occur unless each ball is required to be in an exact position, but this would require a rules change and would result in repetitious run-out patterns (especially with new balls on a "trained" table with consistently good racks).
I personally recommend that everyone (including all leagues and tournaments) use the "No Conflict Rules" for racking and breaking in 8 ball, 9 ball, and 10 ball. (external web-link)
Even if the balls are truly racked randomly, the balls will still be in a certain pattern in a given rack. And it can sometimes be useful to know where balls in certain positions tend to go.
Side spin
The short answer is:
NO, you should not use side spin on a break.
Here's the long answer:
If you hit the CB off center, some of the cue's energy will go into spinning the CB and less will go into moving the CB forward. Therefore, for a given stroke speed, the CB will have less forward speed when sidespin is used (i.e., you will have less breaking power). Also, if using sidespin, you need to adjust your aim for squirt; otherwise, you won't get a square hit on the lead ball, which is very important for power. Luckily, with a power break shot, swerve is not a significant factor, so if you have a breaking cue with a natural pivot length well matched to your preferred break bridge length, squirt compensation can be automatic for both intentional sidespin (if you use BHE) and unintentional sidespin. For more info, see Diagram 4 (and the related discussion) in "Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007).
Statistics
How often to pros make a ball on a break, and how often do they run out?
from AtLarge AZB post:(external forum-link)
Here are some break statistics from the 2014 Diamond Bigfoot 10-Ball Challenge streamed by Accu-Stats from the Derby City Classic. This was an invitational 16-man, single-elimination event.
The conditions for this event included: Diamond 10-foot table with 4 7/16" (I think) corner pockets, Simonis cloth, Diamond wooden rack, Cyclop TV balls, winner breaks, rack your own (2-ball and 3-ball on the back corners), break from anywhere behind the line, no jump cues allowed, all slop counts (except spot any 10-ball made on the break), and a 40-second shot clock (one extension per player per rack unless at hill/hill, then two extensions per player).
The 15 matches (267 games), all of which were streamed from the same table, were as follows. The figures in parentheses are the Accu-Stats Total Performance Averages (TPA), as calculated by Accu-Stats:
Overall results -- The breaker made at least one ball (and did not foul) 58% of the time (155 of 267), won 52% of the games (139 of 267), and broke and ran 16% of the games (44 of 267).
Here's a more detailed breakdown of the 267 games.
Breaker made at least one ball and did not foul:
10-balls on the break: The 10-ball was made on the break 6 times without scratching (2.2% of the 267 breaks), but it was spotted (with the breaker continuing to shoot) rather than counting as a win.
from AtLarge AZB post: (external forum-link)
Here are the aggregate break statistics from 34 of the 36 9-Ball matches streamed by Accu-Stats from the 2013 U.S. Open 9-Ball Championship in Chesapeake, VA.
The conditions for this event included: Diamond 9-foot table with pro-cut pockets, Simonis 860 cloth, Diamond wooden rack, Aramith Tournament balls, measles cue ball, winner breaks, breaker racks for himself with the 2-ball at the back of the rack, break from the box (a bit narrower than 2 diamonds wide), a 9-ball made on the break spots up if it went in either of the two foot-rail pockets, no soft breaking (at least 3 balls must pass mid-table or be pocketed), cue-ball fouls only, jump cues are allowed, and all slop counts (except as stated for 9-balls on the break). A 40-sec. shot clock (with one extension per rack) was used on most of the full-production matches beginning with the third match on Wednesday.
Overall results -- The breaker made at least one ball (and did not foul) 63% of the time (370 of 585), won 56% of the games (326 of 585), and broke and ran 21% of the games (124 of 585).
Here's a little more detailed breakdown of the 585 games.
Breaker made at least one ball and did not foul:
The 124 break-and-run games included just 3 9-balls on the break (0.5% of the 585 breaks). In addition, 18 9-balls (3.1% of the breaks) were made that went in one of the two bottom pockets and had to be spotted rather than counting as wins.
from AtLarge AZB post: (external forum-link)
Here are the break statistics from fifteen 9-ball matches streamed by Accu-Stats from the 2013 Southern Classic in Tunica, MS.
The conditions for this event included: Diamond 9-foot table with pro-cut pockets, Simonis cloth, Diamond wooden rack, winner breaks, rack your own, break from anywhere behind the line, no jump cues allowed, all slop counts (except 9 on the break in either foot-rail pocket), and a 40-second shot clock with one extension allowed per rack.
Overall results -- The breaker made at least one ball (and did not foul) 76% of the time (157 of 207 games), won 58% of the games (120 of 207), and broke and ran 35% of the games (73 of 207).
Here's a little more detailed breakdown of the 207 games.
Breaker made at least one ball and did not foul:
- He won 64% (100 of 157) of the games in which he made at least one ball on the break and did not foul.
- He won 13% (1 of 8) of the games in which he fouled on the break.
- He won 45% (19 of 42) of the games in which he broke dry but did not foul.
- He won 40% (20 of 50) of the games in which he either fouled on the break or broke dry without fouling.
9-balls on the break: The 73 break-and-run games included three 9-balls on the break (1.4% of the 207 breaks) that counted as wins. The 9-ball was also made and had to be spotted one time.
from AtLarge AZB post: (external forum-link)
Here are some break statistics for all 9 of the Diamond Bigfoot 10-Ball Challenge matches streamed by Inside Pool and Accu-Stats from the 2013 Southern Classic in Tunica, MS.
The conditions for this event included: Diamond 10-foot tables with approx. 4 1/2" (4 7/16"?) corner pockets, Simonis cloth, Diamond wooden rack, winner breaks, rack your own, break from anywhere behind the line, no jump cues allowed, all slop counts except spot any 10-ball made on the break in either foot-rail pocket, and a 40-second shot clock (last 3 matches only).
Overall results -- The breaker made at least one ball (and did not foul) 56% of the time (89 of 159), won 53% of the games (85 of 159), and broke and ran 19% of the games (30 of 159).
Here's a little more detailed breakdown of the 159 games.
Breaker made at least one ball and did not foul:
- He won 62% (55 of 89) of the games in which he made at least one ball on the break and did not foul.
- He won 33% (5 of 15) of the games in which he fouled on the break.
- He won 45% (25 of 55) of the games in which he broke dry but did not foul.
- He won 43% (30 of 70) of the games in which he either fouled on the break or broke dry without fouling.
10-balls on the break: One that counted as a win; eleven that were spotted. Ten of those spotted 10-balls occurred in the last three matches on Tuesday.
from AtLarge AZB post (external forum-link) for data from the 2012 US Open:
The conditions for this event included: 9-foot Diamond Pro-Am table, Simonis cloth, Delta-13 rack, winner breaks, breaker racks for himself, 2-ball must be racked at the back of the rack, break from the box, a 9-ball made on the break spots up if it went in either of the two foot-rail pockets, no soft breaking (at least 3 balls must pass mid-table or be pocketed), cue-ball fouls only, jump cues are allowed, and all slop counts (except as stated for 9-balls on the break).
The breaking results were as follows:
Breaker made at least one ball on the break and did not foul:
Day 1 -- 51 of 87 (59%)
Day 2 -- 60 of 99 (61%)
Day 3 -- 42 of 90 (47%)
Day 4 -- 85 of 110 (77%)
Day 5 -- 64 of 105 (61%)
Day 6 -- 52 of 93 (56%)
Day 7 -- 41 of 54 (76%)
7-day total -- 395 of 638 (62%)Breaker won the game:Day 1 -- 45 of 87 (52%)
Day 2 -- 53 of 99 (54%)
Day 3 -- 57 of 90 (63%)
Day 4 -- 72 of 110 (65%)
Day 5 -- 50 of 105 (48%)
Day 6 -- 43 of 93 (45%)
Day 7 -- 34 of 54 (63%)
7-day total -- 354 of 638 (55%)Break-and-run games:Day 1 -- 13 of 87 (15%)
Day 2 -- 16 of 99 (16%)
Day 3 -- 14 of 90 (16%)
Day 4 -- 36 of 110 (33%)
Day 5 -- 24 of 105 (23%)
Day 6 -- 19 of 93 (20%)
Day 7 -- 23 of 54 (43%)
6-day total -- 145 of 638 (23%)9-balls on the break:
The 145 B&R games include 4 9-balls on the break (0.6% of the 638 breaks). In addition, 5 9-balls (0.8%) were made that went in the two bottom pockets and had to be spotted rather than counting as wins.
Technique and equipment advice
What is some important basic advice about the break shot?
Here's a video demonstration of recommended "best practices" for break technique, from Disc III of the Billiard University (BU) Instructional DVD series: (external web-link)
Check out this YouTube link on: Pool Break Shot Technique Advice
For more info, see: “Billiard University (BU) - Part X: The Break Shot” (Download) (BD, May, 2014).
And here's another helpful video from Colin Colenso (see the quotes below also): NV A.20 - Colin Colenso's power break instructional video (YouTube)
The most important thing to remember is: an accurate (square) hit on the lead ball is the most important factor for a good break. Only use as much power as you can control. In general, you want to use a longer bridge length and stroke for shots with more power (e.g., the break). Make sure your bridge hand is stable and still during the forward stroke (or at least until CB impact), and follow through as straight as possible. Also keep your grip hand as relaxed as possible, and keep the cue as level as possible. In general, try to follow stroke "best practices," (Download) even on the break shot.
It is advisable to use a break cue with a "natural pivot length" well matched to your break bridge length. This will allow squirt to exactly cancel stroking errors that cause the tip to hit left or right of center ball, assuming your initial center-ball aim is accurate. For more information, see "Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007). Also, see the following video from Disc II of The Video Encyclopedia of Pool Shots: (external web-link)
Check out this YouTube video: Back-hand English (BHE) for English (side spin) deflection (squirt), from VEPS II (NV B.71)
It also helps to use a hard (e.g., phenolic) tip. This results in more CB speed for the same cue speed.
Many people raise their body during the break because they also straighten their arm and/or drop their elbow. These two motions counteract each other, keeping the cue close to level at impact. Also, straightening the arm can allow many people to generate more cue speed by getting more of the shoulder muscles involved. However, accuracy (a center-ball hit on the CB and a square hit on the rack lead ball) are much more important than a little extra power, so body motion should be kept to a minimum if accuracy suffers as a result.
For more info, see BD's breaking tips of the pros (external web-link) and Disc V of the Video Encyclopedia of Pool Shots (VEPS). (external web-link)
Here's a slow-motion video of Shane Van Boening's 10-ball break (YouTube). Shane's break is very consistent and effective, creating power seemingly effortlessly.
from Colin Colenso:
There are a few concrete physical / bio-mechanical contributors which can add velocity to the cue and hence make for bigger breaks. I'll discuss the main ones in order of what I consider to be the most important.
1. Long Lever: By standing higher during the shot, the effective length of the lever is increased. So just as long golf clubs have higher head speeds, a longer arm allows higher cue speed. One doesn't necessarily have to lunge upward to achieve this, but starting low and then raising the body may seem more conducive to better aiming.
2. Centripetal Force: The lunge upward of the shooting shoulder also produces a force at right angles to the direction of the cue movement. This centripetal force accelerates the cue, in the same way that hammer throwers accelerate the hammer by pulling at 90 degrees against it as it rotates.
3. Forward Lunge: Forward lunging creates additional cue speed also, just as shot putters can throw further with a glide throw rather than just a standing throw. One may be able to lunge at 2-3 mph and this component can be added to the overall cue speed.
The trick is working out the technique of these various factors such that they can all contribute with minimal loss of control.
I do believe a good wrist flick can contribute as much speed as the 3 effects above combined and it becomes hard to execute that as well while lunging, so a well timed stroke with minimum movement and with a reasonable length of lever can produce some very powerful controlled breaks.
That said, if one wants to break a world record, they might need to add a lunge to their technique.
from Colin Colenso:
some people can add 2-3 mph to their break by shortening their back hand position. There are two possible advantages of doing this.
1. With a longer arm (lever) on breaking due to being more upright, moving the hand towards the bridge brings it more into a right angled position which makes it more effective (and effectively longer), than having a longer back arm which is at a shallower angle to the cue. Imagine if the arm were stretched to the back of a 7 foot cue and you can visualize that the force is being applied at an inefficient angle.
2. Maybe the main reason is that shortening the back hand means that the pectoral (chest) muscle and front deltoid (shoulder) muscles (which are the source of most of the power) are put in a neutral / mid position in regard to extension / contraction. This is where muscles are at their strongest and can accelerate with more force, allowing a powerful punch with a limited back swing.
To get the feel for how this works, try a Bruce Lee 1" punch, first with arm almost fully extended, next with fist almost contracted back near your shoulder and one midway. The midway position is much stronger at applying a rapid burst of force. Different muscles involved, but you'll get the idea of what I mean by mid/extension power.
from mosconiac (in AZB post): (external forum-link)
There is a limit that most players reach (expressed in mph) due to lack of timing, leverage, & weight transfer. Older men & most women seem to plateau around 18-20 mph. Most males plateau around 22-24 mph. Yes, there are freaks of nature that inherently hit 30+mph, but those guys aren’t reading this thread, I suppose.
To get to the next level, players need to add a seemingly unnatural movement (really a series of movements coalesced into one) to the break routine. Most that try it end up striking the CB erratically and give up. Those that can get past that acclimation stage (through practice) will be rewarded.
All great breakers share these tendencies:
My break analysis videos: (YouTube Links)
Hillbilly: http://www.youtube.com/watch?v=N2b7D4DYwjI
Nevel: http://www.youtube.com/watch?v=l0quThyaBeg
Morra: http://www.youtube.com/watch?v=EqjOVOUl1qw
See any similarities in my other videos?:(YouTube Links)
Buste 1: http://www.youtube.com/watch?v=o1lGmxqPNd8
Buste 2: http://www.youtube.com/watch?v=Ysrxi_w6_B4
Archer 1: http://www.youtube.com/watch?v=NXTA2n-qkwY
Archer 2: http://www.youtube.com/watch?v=EmWyiZ73ymg
from Patrick Johnson:
As with other major breakers, it appears to me that the crucial feature in Larry's powerful break is the involvement of his upper arm. The elbow drop and standing up are both integral to getting a full-arm swing.
Much is made of the "lunge" of these power breakers, and I'm sure that contributes significantly, but I believe the straightening of the arm for the full-arm swing is the most important element in getting more power - and, of course, the main difficulty in hitting the CB accurately.
from sfleinen:
Here's of one of the most powerful (and controlled) breakers in the world -- the mighty Russian, Evgeny Stalev:
http://youtube.com/watch?v=PkCG3q2PDa4#t=560 (YouTube)
He's all of 150lbs soaking wet, yet clocks in 35+ mph breaks (he was averaging that in the U.S. Open the video above was taken from). Evgeny (pronounced "yev genny" with a hard "g" sound in the second syllable, for those Russian-pronunciation-challenged like us Americans) uses shoulder, elbow, and his pectoral (chest) muscle to achieve this power. You'll notice he doesn't use any "lunging" motion at all, but rather a very smooth "forward drift" motion in his stance. ... And he does all this with his playing cue!
In my opinion, Evgeny's got one of the smoothest, most powerful, and, for what's going on in his arm, accurate breaks around. Ask yourself, have you ever heard that kind of sound from a break? It's one thing to hear it in this video; quite another to hear it in person (the video lacks some of the auditory fireworks that seeing/hearing this live gives).
from KMRUNOUT:
Having studied the break for some time now, I've watched most of the great breakers. You might notice that Evgeny Stalev is remarkably similar to Shane Van Boening. They both have that "forward drift" thing going on. However, both also gently stand up as they *back stroke*. Another similarity is that they both keep their bridge hand pretty well anchored to the table. The result is a setup that allows for a very gentle relaxed building of power. This, I think, is the reason why they are able to consistently hit the rack so square and control the cue ball.
As for the body movement, here are my thoughts: can someone hit the rack in the high 20 mph range using just the arm, without moving the body? Not too likely. However, even if they could, it would seem to have to be a very aggressive movement. It would certainly be a very *short* lever and would require explosive power and speed. Remember that this power does not occur in a vacuum-there will be an equal and opposite force acting somewhere. This will require effort to keep the shoulder and the elbow from moving, and I think this can cost accuracy. By rotating the body slightly (the hips then the shoulders, like in a golf or baseball swing), you can provide a (moving) platform from which to execute this arm swing. You will notice a lot of breakers kick their leg back. This really has little to do with generating power. It is a *counterbalance*. The leg is rotating around the body in the opposite direction as the shoulders. This makes it easier to keep the spine in the same location as the shoulders (and leg) rotate around it. This can be practiced. The trade off is that initially you will have less cue ball control on the break. Soon, though, the benefit will be that it is *easier* (requires less effort) to swing the cue fast. So if you wish to break at, say, 25 mph...you *might* be able to achieve this with an arm-only swing (highly doubtful), but I would really like to see that motion result in quality cue ball control, because I doubt I would see that. If your goal is to break at 18 mph, then sure, use only your arm and you can have great cue ball control. 18 mph, though, is not always the best speed for a given table, especially in 8-ball.
I guess in summary what I am saying is that while you may get decent cue ball control at lower speeds with an arm only motion, I believe it is easier to develop good control at higher speeds using a more effortless technique, more like Stalev and VanBoening.
from Cornerman:
I notice that players that are stronger in the arm can break big with a short bridge. Others get great control with a super long bridge. Anyone who discourages the long bridge needs to step back and really really really make sure they understand the mechanic and why some players can indeed get better control with a longer bridge.
The longer bridge allows you to get to a higher speed while maintaining a lower acceleration. That is, you might be under more control with a longer bridge in getting the final desired stick speed. The shorter bridge, you'll need to have a higher acceleration for the same final stick speed. And that will need more arm strength to keep under control.
At the [2006] Derby City, I watched intensely some of the hardest breakers. The timing and coordination is something that if it's not natural, it would take some work. Again, add a few things at a time, and it could work wonders.
Elbow
There are two distinct power breaks that I've seen: Elbow Drop and Elbow Rise.
Elbow Drop Breakers: most hard breakers. For pros, this might include Bustamante, Sigel, Strickland, etc.
Elbow Rise Breakers: Archer, Breedlove, Lil John, Sparky Ferrule, Sarah Rousey.
In either case, the elbow drops, but since the Risers rise, the tip dips down on the back stroke, and shoots up on the final stroke. So, Elbow Risers aim at the center or a hair high on their setup.
For Droppers, most will aim low. Really low. Some aim right to the base of the ball or lower. Since they do this, and they get good contact, I assume the elbow is dropping before the tip contacts the ball.
Tip
Most of the hard breakers seem to be able to take that tip all the way to the bridge loop, often actually passing through it. This ensures the longest travel to get up to higher speed, without having to bully the stroke.
Back swing/Pause
I notice that most hard breakers take the final back swing relatively slowly, like they're drawing a bow. Players like Sarah will actually pull it back to the loop and almost freeze with her raised elbow high in the air. Archer also freezes with the elbow higher, but not nearly as high as Sarah's nor for as long a time.
Hips
There is definitely something to be said about rocking your hips back slowly on your final back swing and then leading with the hips on the final stroke before you start the forward swing. Pagulayan is a good example of this. On video, this might cause you to think he's pausing his stroke because the stick stop at the full back position while his hips start their move forward. This is probably the most difficult timing transition. The hip lead is part of the aforementioned freeze.
Follow Through
A lot of today's breakers follow through by letting go of the bridge hand, and bring the cue forward past the center of the table (if they can reach). I don't know if this really helps, but the act of following through helps to not check up your stroke. I still follow through to the table like Sigel, but not so pronounced.
So, even if you do any of the above in small controlled doses, rather than the wild lunge like Breedlove or Sarah, it will add power.
Whatever you do, if you find the cueball going forward after hitting the rack, either lowering your tip at address, or raising your elbow during the backswing can prove helpful.
from Colin Colenso:
Firstly, the long bridge will help but so can these, but they may be tricky to control for accuracy until you practice it a bit.
Firstly, transfer some of the force to the more powerful muscles, the pectorals. You can do this in three ways.
Turn your body more side on to the shot.
Stand up a little higher.
Move your body away from the cue an extra inch.
You'll start to get a slight discus version of a swing which can produce much more power than standard cue-ing which relies a lot on the biceps.
Also, relax you wrist and focus on letting it flex back in the early part of your forward delivery.
When I put these together and time the wrist, my biggest problem is keeping the CB on the table. The CB can land by the center pocket and bounce off the table from being only a fraction off center on the break.
But give it a try, coz at even 80% effort, if you can time these things using more of the pecs and wrist, you'll get plenty of power and can still control the accuracy.
from Jal:
You want the cue ball to have some topspin when it meets the rack. This will act like a brake and stop it from rebounding back too far.
It doesn't necessarily mean hitting above center. The cue ball will tend to pick up some topspin after it leaves your tip, even if it sails all the way to the rack. It gets it from the first bounce off the bed just after tip/ball impact, and of course, any subsequent bounces. (In fact, to my understanding, if it is airborne all the way, it should pick up more topspin from the one bounce than if it slid along the surface the entire way.)
Exactly where to strike to get the right amount of topspin depends on ball speed, cue elevation and cloth/ball conditions. But, it's going to be near center ball.
The adjustment, in theory, is very simple. If the cue ball is following too far forward, hit lower; if it's rebounding back too far, hit higher. If it's badly inconsistent, shorten your bridge length and/or slow down some until you get better control.
Theoretical simulation
If all of the balls were perfect and racked perfectly, how would the balls move after a perfect break?
Here is an interesting analysis and simulation showing the results of a perfect break with perfect balls (external web-link) by Jim Belk.
Should I use an extended follow through on the break shot?
This is a question of cause and effect. A follow-through strictly has no influence on the cue ball because the cue tip is in contact with the cue ball for only a very short amount of time (approximately 0.001 seconds). The only things that significantly affect the breaking power for a given cue stick are cue stick speed at impact, tip offset (distance away from a center ball hit), and the squareness of the hit on the lead ball. However, if a powerful stroke does not exhibit a big follow-through, it is either not very powerful, or effort is being made to limit the follow-through. If one tries to constrain the follow-through, one will probably not achieve maximum speed at impact. Many authors and instructors recommend trying to "accelerate through the ball" for power shots. This thinking often helps one create good power, and it results in significant follow-through.
Follow-through can also be important in achieving good action on draw shots (although, not always for the reasons people think). For more info, see "Draw Shot Primer - Part V: how to achieve good draw action" (Download) (BD, May, 2006). In particular, see item "b" under "other advice" and item "5" under "stroke best practices." I think these points apply equally well to both a power break and a power draw.
from Fran Crimi:
Besides making sure the rack is tight, you MUST exaggerate your follow-through. Even if you think you are following through enough, push through even more. Watch Strickland's follow-through. The cue literally comes out of his bridge hand and is extended all the way down the table. It's difficult to master that letting-go technique with accuracy but with lots of practice, it will pay off in spades.
The other option is to leave the cue in your bridge hand but with an over-extended follow-through, if you lean into the break shot, you will definitely bend the shaft and possibly crack or break it like some other players do.
I prefer the letting-go technique.
Making the 8-ball
How can I increase my chances of making the 8-ball on the break?
Not all leagues and tournaments award a game victory for making the 8-ball on the break; but if they do, it is wise to try to increase your chances for pocketing the 8-ball. A good technique for this is to place the CB close to the side rail on the head string, and hit the 2nd ball in the rack squarely. The 8-ball will often head toward the opposite side pocket, and the balls will usually disperse well. Clips HSV 7.8-7.11 (external web-link) show how it works. For illustrations and more information, see Section 7.05 in The Illustrated Principles of Pool and Billiards. (external web-link)
Measuring your own break speed
Is there an easy way to measure your break shot speed without a fancy radar gun?
Here's a phone app that works very well:
http://www.mybreakspeed.com/ (external web-link)
You can also measure your break speed with any computer containing a microphone (see below).
from Runnin8:
To find your own break speed:
1) Measure the distance between where your cue ball rests on the table for a normal break and the head spot, subtract 2.25" for one ball diameter.
2) Use sound recorder on a PC to record the sound of your break. We used a laptop with it next to the table. Most PCs can record at 44Khz, or 44 thousand times a second, more than accurate enough. Also, forget about having to get it right in the middle. Unless your break speed is near the speed of sound its a nit. Use a sound program like Wave pad (external web-link) to open the file and identify the peak where the cue strikes the cueball and then the peak at rack contact. If you highlight with Wave pad it will tell you to the thousandth of a second.
3) Your break speed in mph is:
(distance-2.25) / 12*60/88 / (measured time)
9-ball break
What are possible strategies for breaking in 9-ball?
First of all, follow the advice in the break technique section.
If pattern racking is not prohibited, you might want to take advantage of those approaches (maybe in combination with a soft break per the Corey Deuel example below).
Should I put balls in certain positions when I am racking for 9-ball?
from CreeDo (in AZB post): (external forum-link)
Corey will not be satisfied until he completely breaks 9 ball.
First he figured out how to make a ball on the break every time and get a look at the 1. Then he figured out how to get an easy layout so he can run the whole rack every time. Now he's figured out how to leave himself a wired 9 ball combo after running just 2 or 3 balls:
YouTube Clip
Pattern racking strategy
Should I put balls in certain positions when I am racking for 9-ball?
There are certain ball-motion patterns you can take advantage of, whether you are racking for an opponent or racking for yourself. Some of the basics are covered in this video from Disc V of the Video Encyclopedia of Pool Shots:(external web-link)
See video example on YouTube on 9 ball pool racking strategy
2.2 Nine Ball Rack
The object balls are racked as tightly as possible in a diamond shape, with the one ball at the apex of the diamond and on the foot spot and the nine ball in the middle of the diamond. The other balls will be placed in the diamond without purposeful or intentional pattern.
Obviously, a strict interpretation and strict enforcement of this rule prohibits "pattern racking," where you place certain balls in certain positions for an advantage. However, the rule isn't usually interpreted so strictly. Often (e.g., in most leagues and tournaments), the last sentence is interpreted: It doesn't matter where the other balls are placed. Also, somebody can easily "pattern rack" without it seeming "intentional" or "purposeful." However, a ref or opponent has the right to protest if certain "patterns" are obviously being used (e.g., always placing the 2-ball in the back of the rack).
Obviously, the best solution is to have a neutral party rack the balls (which is done in the WPBA TV events). With "rack your own" or "opponent racking," "pattern racking" is always likely to occur unless each ball is required to be in an exact position, but this would require a rules change and would result in repetitious run-out patterns (especially with new balls on a "trained" table with consistently good racks).
I personally recommend that everyone (including all leagues and tournaments) use the "No Conflict Rules" for racking and breaking in 8 ball, 9 ball, and 10 ball. (external web-link)
Even if the balls are truly racked randomly, the balls will still be in a certain pattern in a given rack. And it can sometimes be useful to know where balls in certain positions tend to go.
Side spin
The short answer is:
NO, you should not use side spin on a break.
Here's the long answer:
If you hit the CB off center, some of the cue's energy will go into spinning the CB and less will go into moving the CB forward. Therefore, for a given stroke speed, the CB will have less forward speed when sidespin is used (i.e., you will have less breaking power). Also, if using sidespin, you need to adjust your aim for squirt; otherwise, you won't get a square hit on the lead ball, which is very important for power. Luckily, with a power break shot, swerve is not a significant factor, so if you have a breaking cue with a natural pivot length well matched to your preferred break bridge length, squirt compensation can be automatic for both intentional sidespin (if you use BHE) and unintentional sidespin. For more info, see Diagram 4 (and the related discussion) in "Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007).
Statistics
How often to pros make a ball on a break, and how often do they run out?
from AtLarge AZB post:(external forum-link)
Here are some break statistics from the 2014 Diamond Bigfoot 10-Ball Challenge streamed by Accu-Stats from the Derby City Classic. This was an invitational 16-man, single-elimination event.
The conditions for this event included: Diamond 10-foot table with 4 7/16" (I think) corner pockets, Simonis cloth, Diamond wooden rack, Cyclop TV balls, winner breaks, rack your own (2-ball and 3-ball on the back corners), break from anywhere behind the line, no jump cues allowed, all slop counts (except spot any 10-ball made on the break), and a 40-second shot clock (one extension per player per rack unless at hill/hill, then two extensions per player).
The 15 matches (267 games), all of which were streamed from the same table, were as follows. The figures in parentheses are the Accu-Stats Total Performance Averages (TPA), as calculated by Accu-Stats:
Overall results -- The breaker made at least one ball (and did not foul) 58% of the time (155 of 267), won 52% of the games (139 of 267), and broke and ran 16% of the games (44 of 267).
Here's a more detailed breakdown of the 267 games.
Breaker made at least one ball and did not foul:
- Breaker won the game: 97 (36% of the 267 games)
- Breaker lost the game: 58 (22%)
- Breaker won the game: 6 (2%)
- Breaker lost the game: 17 (6%)
- Breaker won the game: 36 (13%)
- Breaker lost the game: 53 (20%)
- He won 63% (97 of 155) of the games in which he made at least one ball on the break and did not foul.
- He won 26% (6 of 23) of the games in which he fouled on the break.
- He won 40% (36 of 89) of the games in which he broke dry but did not foul.
- He won 38% (42 of 112) of the games in which he either fouled on the break or broke dry without fouling.
10-balls on the break: The 10-ball was made on the break 6 times without scratching (2.2% of the 267 breaks), but it was spotted (with the breaker continuing to shoot) rather than counting as a win.
from AtLarge AZB post: (external forum-link)
Here are the aggregate break statistics from 34 of the 36 9-Ball matches streamed by Accu-Stats from the 2013 U.S. Open 9-Ball Championship in Chesapeake, VA.
The conditions for this event included: Diamond 9-foot table with pro-cut pockets, Simonis 860 cloth, Diamond wooden rack, Aramith Tournament balls, measles cue ball, winner breaks, breaker racks for himself with the 2-ball at the back of the rack, break from the box (a bit narrower than 2 diamonds wide), a 9-ball made on the break spots up if it went in either of the two foot-rail pockets, no soft breaking (at least 3 balls must pass mid-table or be pocketed), cue-ball fouls only, jump cues are allowed, and all slop counts (except as stated for 9-balls on the break). A 40-sec. shot clock (with one extension per rack) was used on most of the full-production matches beginning with the third match on Wednesday.
Overall results -- The breaker made at least one ball (and did not foul) 63% of the time (370 of 585), won 56% of the games (326 of 585), and broke and ran 21% of the games (124 of 585).
Here's a little more detailed breakdown of the 585 games.
Breaker made at least one ball and did not foul:
- Breaker won the game: 241 (41% of the 585 games)
- Breaker lost the game: 129 (22%)
- Breaker won the game: 9 (2%)
- Breaker lost the game: 24 (4%)
- Breaker won the game: 76 (13%)
- Breaker lost the game: 106 (18%)
- He won 65% (241 of 370) of the games in which he made at least one ball on the break and did not foul.
- He won 27% (9 of 33) of the games in which he fouled on the break.
- He won 42% (76 of 182) of the games in which he broke dry but did not foul.
- He won 40% (85 of 215) of the games in which he either fouled on the break or broke dry without fouling.
The 124 break-and-run games included just 3 9-balls on the break (0.5% of the 585 breaks). In addition, 18 9-balls (3.1% of the breaks) were made that went in one of the two bottom pockets and had to be spotted rather than counting as wins.
from AtLarge AZB post: (external forum-link)
Here are the break statistics from fifteen 9-ball matches streamed by Accu-Stats from the 2013 Southern Classic in Tunica, MS.
The conditions for this event included: Diamond 9-foot table with pro-cut pockets, Simonis cloth, Diamond wooden rack, winner breaks, rack your own, break from anywhere behind the line, no jump cues allowed, all slop counts (except 9 on the break in either foot-rail pocket), and a 40-second shot clock with one extension allowed per rack.
Overall results -- The breaker made at least one ball (and did not foul) 76% of the time (157 of 207 games), won 58% of the games (120 of 207), and broke and ran 35% of the games (73 of 207).
Here's a little more detailed breakdown of the 207 games.
Breaker made at least one ball and did not foul:
- Breaker won the game: 100 (48% of the 207 games)
- Breaker lost the game: 57 (28%)
- Breaker won the game: 1 (0%)
- Breaker lost the game: 7 (3%)
- Breaker won the game: 19 (9%)
- Breaker lost the game: 23 (11%)
- He won 64% (100 of 157) of the games in which he made at least one ball on the break and did not foul.
- He won 13% (1 of 8) of the games in which he fouled on the break.
- He won 45% (19 of 42) of the games in which he broke dry but did not foul.
- He won 40% (20 of 50) of the games in which he either fouled on the break or broke dry without fouling.
9-balls on the break: The 73 break-and-run games included three 9-balls on the break (1.4% of the 207 breaks) that counted as wins. The 9-ball was also made and had to be spotted one time.
from AtLarge AZB post: (external forum-link)
Here are some break statistics for all 9 of the Diamond Bigfoot 10-Ball Challenge matches streamed by Inside Pool and Accu-Stats from the 2013 Southern Classic in Tunica, MS.
The conditions for this event included: Diamond 10-foot tables with approx. 4 1/2" (4 7/16"?) corner pockets, Simonis cloth, Diamond wooden rack, winner breaks, rack your own, break from anywhere behind the line, no jump cues allowed, all slop counts except spot any 10-ball made on the break in either foot-rail pocket, and a 40-second shot clock (last 3 matches only).
Overall results -- The breaker made at least one ball (and did not foul) 56% of the time (89 of 159), won 53% of the games (85 of 159), and broke and ran 19% of the games (30 of 159).
Here's a little more detailed breakdown of the 159 games.
Breaker made at least one ball and did not foul:
- Breaker won the game: 55 (35% of the 159 games)
- Breaker lost the game: 34 (21%)
- Breaker won the game: 5 (3%)
- Breaker lost the game: 10 (6%)
- Breaker won the game: 25 (16%)
- Breaker lost the game: 30 (19%)
- He won 62% (55 of 89) of the games in which he made at least one ball on the break and did not foul.
- He won 33% (5 of 15) of the games in which he fouled on the break.
- He won 45% (25 of 55) of the games in which he broke dry but did not foul.
- He won 43% (30 of 70) of the games in which he either fouled on the break or broke dry without fouling.
10-balls on the break: One that counted as a win; eleven that were spotted. Ten of those spotted 10-balls occurred in the last three matches on Tuesday.
from AtLarge AZB post (external forum-link) for data from the 2012 US Open:
The conditions for this event included: 9-foot Diamond Pro-Am table, Simonis cloth, Delta-13 rack, winner breaks, breaker racks for himself, 2-ball must be racked at the back of the rack, break from the box, a 9-ball made on the break spots up if it went in either of the two foot-rail pockets, no soft breaking (at least 3 balls must pass mid-table or be pocketed), cue-ball fouls only, jump cues are allowed, and all slop counts (except as stated for 9-balls on the break).
The breaking results were as follows:
Breaker made at least one ball on the break and did not foul:
Day 1 -- 51 of 87 (59%)
Day 2 -- 60 of 99 (61%)
Day 3 -- 42 of 90 (47%)
Day 4 -- 85 of 110 (77%)
Day 5 -- 64 of 105 (61%)
Day 6 -- 52 of 93 (56%)
Day 7 -- 41 of 54 (76%)
7-day total -- 395 of 638 (62%)Breaker won the game:Day 1 -- 45 of 87 (52%)
Day 2 -- 53 of 99 (54%)
Day 3 -- 57 of 90 (63%)
Day 4 -- 72 of 110 (65%)
Day 5 -- 50 of 105 (48%)
Day 6 -- 43 of 93 (45%)
Day 7 -- 34 of 54 (63%)
7-day total -- 354 of 638 (55%)Break-and-run games:Day 1 -- 13 of 87 (15%)
Day 2 -- 16 of 99 (16%)
Day 3 -- 14 of 90 (16%)
Day 4 -- 36 of 110 (33%)
Day 5 -- 24 of 105 (23%)
Day 6 -- 19 of 93 (20%)
Day 7 -- 23 of 54 (43%)
6-day total -- 145 of 638 (23%)9-balls on the break:
The 145 B&R games include 4 9-balls on the break (0.6% of the 638 breaks). In addition, 5 9-balls (0.8%) were made that went in the two bottom pockets and had to be spotted rather than counting as wins.
Technique and equipment advice
What is some important basic advice about the break shot?
Here's a video demonstration of recommended "best practices" for break technique, from Disc III of the Billiard University (BU) Instructional DVD series: (external web-link)
Check out this YouTube link on: Pool Break Shot Technique Advice
For more info, see: “Billiard University (BU) - Part X: The Break Shot” (Download) (BD, May, 2014).
And here's another helpful video from Colin Colenso (see the quotes below also): NV A.20 - Colin Colenso's power break instructional video (YouTube)
The most important thing to remember is: an accurate (square) hit on the lead ball is the most important factor for a good break. Only use as much power as you can control. In general, you want to use a longer bridge length and stroke for shots with more power (e.g., the break). Make sure your bridge hand is stable and still during the forward stroke (or at least until CB impact), and follow through as straight as possible. Also keep your grip hand as relaxed as possible, and keep the cue as level as possible. In general, try to follow stroke "best practices," (Download) even on the break shot.
It is advisable to use a break cue with a "natural pivot length" well matched to your break bridge length. This will allow squirt to exactly cancel stroking errors that cause the tip to hit left or right of center ball, assuming your initial center-ball aim is accurate. For more information, see "Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007). Also, see the following video from Disc II of The Video Encyclopedia of Pool Shots: (external web-link)
Check out this YouTube video: Back-hand English (BHE) for English (side spin) deflection (squirt), from VEPS II (NV B.71)
It also helps to use a hard (e.g., phenolic) tip. This results in more CB speed for the same cue speed.
Many people raise their body during the break because they also straighten their arm and/or drop their elbow. These two motions counteract each other, keeping the cue close to level at impact. Also, straightening the arm can allow many people to generate more cue speed by getting more of the shoulder muscles involved. However, accuracy (a center-ball hit on the CB and a square hit on the rack lead ball) are much more important than a little extra power, so body motion should be kept to a minimum if accuracy suffers as a result.
For more info, see BD's breaking tips of the pros (external web-link) and Disc V of the Video Encyclopedia of Pool Shots (VEPS). (external web-link)
Here's a slow-motion video of Shane Van Boening's 10-ball break (YouTube). Shane's break is very consistent and effective, creating power seemingly effortlessly.
from Colin Colenso:
There are a few concrete physical / bio-mechanical contributors which can add velocity to the cue and hence make for bigger breaks. I'll discuss the main ones in order of what I consider to be the most important.
1. Long Lever: By standing higher during the shot, the effective length of the lever is increased. So just as long golf clubs have higher head speeds, a longer arm allows higher cue speed. One doesn't necessarily have to lunge upward to achieve this, but starting low and then raising the body may seem more conducive to better aiming.
2. Centripetal Force: The lunge upward of the shooting shoulder also produces a force at right angles to the direction of the cue movement. This centripetal force accelerates the cue, in the same way that hammer throwers accelerate the hammer by pulling at 90 degrees against it as it rotates.
3. Forward Lunge: Forward lunging creates additional cue speed also, just as shot putters can throw further with a glide throw rather than just a standing throw. One may be able to lunge at 2-3 mph and this component can be added to the overall cue speed.
The trick is working out the technique of these various factors such that they can all contribute with minimal loss of control.
I do believe a good wrist flick can contribute as much speed as the 3 effects above combined and it becomes hard to execute that as well while lunging, so a well timed stroke with minimum movement and with a reasonable length of lever can produce some very powerful controlled breaks.
That said, if one wants to break a world record, they might need to add a lunge to their technique.
from Colin Colenso:
some people can add 2-3 mph to their break by shortening their back hand position. There are two possible advantages of doing this.
1. With a longer arm (lever) on breaking due to being more upright, moving the hand towards the bridge brings it more into a right angled position which makes it more effective (and effectively longer), than having a longer back arm which is at a shallower angle to the cue. Imagine if the arm were stretched to the back of a 7 foot cue and you can visualize that the force is being applied at an inefficient angle.
2. Maybe the main reason is that shortening the back hand means that the pectoral (chest) muscle and front deltoid (shoulder) muscles (which are the source of most of the power) are put in a neutral / mid position in regard to extension / contraction. This is where muscles are at their strongest and can accelerate with more force, allowing a powerful punch with a limited back swing.
To get the feel for how this works, try a Bruce Lee 1" punch, first with arm almost fully extended, next with fist almost contracted back near your shoulder and one midway. The midway position is much stronger at applying a rapid burst of force. Different muscles involved, but you'll get the idea of what I mean by mid/extension power.
from mosconiac (in AZB post): (external forum-link)
There is a limit that most players reach (expressed in mph) due to lack of timing, leverage, & weight transfer. Older men & most women seem to plateau around 18-20 mph. Most males plateau around 22-24 mph. Yes, there are freaks of nature that inherently hit 30+mph, but those guys aren’t reading this thread, I suppose.
To get to the next level, players need to add a seemingly unnatural movement (really a series of movements coalesced into one) to the break routine. Most that try it end up striking the CB erratically and give up. Those that can get past that acclimation stage (through practice) will be rewarded.
All great breakers share these tendencies:
- Low initial body position (aids upward body movement) with compact stance (aids weight transfer) & forward hand position (aids final alignment/delivery of cue)
- Abruptly raise cue at end of back swing (stores energy in arm & shoulder) and cock elbow behind body (stores more energy)
- Upper body releases (forward & up) with hips driving forward (sometimes with a turning motion like a golf swing)
- Elbow begins driving down & thru (cue returning to pre-shot alignment)…arm release lags behind body release
- At impact, upper body & hips are fully released (driven by rear foot), elbow is fully dropped (& driving forward), and weight shift causes rear leg to rise up for counter-balance.
My break analysis videos: (YouTube Links)
Hillbilly: http://www.youtube.com/watch?v=N2b7D4DYwjI
Nevel: http://www.youtube.com/watch?v=l0quThyaBeg
Morra: http://www.youtube.com/watch?v=EqjOVOUl1qw
See any similarities in my other videos?:(YouTube Links)
Buste 1: http://www.youtube.com/watch?v=o1lGmxqPNd8
Buste 2: http://www.youtube.com/watch?v=Ysrxi_w6_B4
Archer 1: http://www.youtube.com/watch?v=NXTA2n-qkwY
Archer 2: http://www.youtube.com/watch?v=EmWyiZ73ymg
from Patrick Johnson:
As with other major breakers, it appears to me that the crucial feature in Larry's powerful break is the involvement of his upper arm. The elbow drop and standing up are both integral to getting a full-arm swing.
Much is made of the "lunge" of these power breakers, and I'm sure that contributes significantly, but I believe the straightening of the arm for the full-arm swing is the most important element in getting more power - and, of course, the main difficulty in hitting the CB accurately.
from sfleinen:
Here's of one of the most powerful (and controlled) breakers in the world -- the mighty Russian, Evgeny Stalev:
http://youtube.com/watch?v=PkCG3q2PDa4#t=560 (YouTube)
He's all of 150lbs soaking wet, yet clocks in 35+ mph breaks (he was averaging that in the U.S. Open the video above was taken from). Evgeny (pronounced "yev genny" with a hard "g" sound in the second syllable, for those Russian-pronunciation-challenged like us Americans) uses shoulder, elbow, and his pectoral (chest) muscle to achieve this power. You'll notice he doesn't use any "lunging" motion at all, but rather a very smooth "forward drift" motion in his stance. ... And he does all this with his playing cue!
In my opinion, Evgeny's got one of the smoothest, most powerful, and, for what's going on in his arm, accurate breaks around. Ask yourself, have you ever heard that kind of sound from a break? It's one thing to hear it in this video; quite another to hear it in person (the video lacks some of the auditory fireworks that seeing/hearing this live gives).
from KMRUNOUT:
Having studied the break for some time now, I've watched most of the great breakers. You might notice that Evgeny Stalev is remarkably similar to Shane Van Boening. They both have that "forward drift" thing going on. However, both also gently stand up as they *back stroke*. Another similarity is that they both keep their bridge hand pretty well anchored to the table. The result is a setup that allows for a very gentle relaxed building of power. This, I think, is the reason why they are able to consistently hit the rack so square and control the cue ball.
As for the body movement, here are my thoughts: can someone hit the rack in the high 20 mph range using just the arm, without moving the body? Not too likely. However, even if they could, it would seem to have to be a very aggressive movement. It would certainly be a very *short* lever and would require explosive power and speed. Remember that this power does not occur in a vacuum-there will be an equal and opposite force acting somewhere. This will require effort to keep the shoulder and the elbow from moving, and I think this can cost accuracy. By rotating the body slightly (the hips then the shoulders, like in a golf or baseball swing), you can provide a (moving) platform from which to execute this arm swing. You will notice a lot of breakers kick their leg back. This really has little to do with generating power. It is a *counterbalance*. The leg is rotating around the body in the opposite direction as the shoulders. This makes it easier to keep the spine in the same location as the shoulders (and leg) rotate around it. This can be practiced. The trade off is that initially you will have less cue ball control on the break. Soon, though, the benefit will be that it is *easier* (requires less effort) to swing the cue fast. So if you wish to break at, say, 25 mph...you *might* be able to achieve this with an arm-only swing (highly doubtful), but I would really like to see that motion result in quality cue ball control, because I doubt I would see that. If your goal is to break at 18 mph, then sure, use only your arm and you can have great cue ball control. 18 mph, though, is not always the best speed for a given table, especially in 8-ball.
I guess in summary what I am saying is that while you may get decent cue ball control at lower speeds with an arm only motion, I believe it is easier to develop good control at higher speeds using a more effortless technique, more like Stalev and VanBoening.
from Cornerman:
I notice that players that are stronger in the arm can break big with a short bridge. Others get great control with a super long bridge. Anyone who discourages the long bridge needs to step back and really really really make sure they understand the mechanic and why some players can indeed get better control with a longer bridge.
The longer bridge allows you to get to a higher speed while maintaining a lower acceleration. That is, you might be under more control with a longer bridge in getting the final desired stick speed. The shorter bridge, you'll need to have a higher acceleration for the same final stick speed. And that will need more arm strength to keep under control.
At the [2006] Derby City, I watched intensely some of the hardest breakers. The timing and coordination is something that if it's not natural, it would take some work. Again, add a few things at a time, and it could work wonders.
Elbow
There are two distinct power breaks that I've seen: Elbow Drop and Elbow Rise.
Elbow Drop Breakers: most hard breakers. For pros, this might include Bustamante, Sigel, Strickland, etc.
Elbow Rise Breakers: Archer, Breedlove, Lil John, Sparky Ferrule, Sarah Rousey.
In either case, the elbow drops, but since the Risers rise, the tip dips down on the back stroke, and shoots up on the final stroke. So, Elbow Risers aim at the center or a hair high on their setup.
For Droppers, most will aim low. Really low. Some aim right to the base of the ball or lower. Since they do this, and they get good contact, I assume the elbow is dropping before the tip contacts the ball.
Tip
Most of the hard breakers seem to be able to take that tip all the way to the bridge loop, often actually passing through it. This ensures the longest travel to get up to higher speed, without having to bully the stroke.
Back swing/Pause
I notice that most hard breakers take the final back swing relatively slowly, like they're drawing a bow. Players like Sarah will actually pull it back to the loop and almost freeze with her raised elbow high in the air. Archer also freezes with the elbow higher, but not nearly as high as Sarah's nor for as long a time.
Hips
There is definitely something to be said about rocking your hips back slowly on your final back swing and then leading with the hips on the final stroke before you start the forward swing. Pagulayan is a good example of this. On video, this might cause you to think he's pausing his stroke because the stick stop at the full back position while his hips start their move forward. This is probably the most difficult timing transition. The hip lead is part of the aforementioned freeze.
Follow Through
A lot of today's breakers follow through by letting go of the bridge hand, and bring the cue forward past the center of the table (if they can reach). I don't know if this really helps, but the act of following through helps to not check up your stroke. I still follow through to the table like Sigel, but not so pronounced.
So, even if you do any of the above in small controlled doses, rather than the wild lunge like Breedlove or Sarah, it will add power.
Whatever you do, if you find the cueball going forward after hitting the rack, either lowering your tip at address, or raising your elbow during the backswing can prove helpful.
from Colin Colenso:
Firstly, the long bridge will help but so can these, but they may be tricky to control for accuracy until you practice it a bit.
Firstly, transfer some of the force to the more powerful muscles, the pectorals. You can do this in three ways.
Turn your body more side on to the shot.
Stand up a little higher.
Move your body away from the cue an extra inch.
You'll start to get a slight discus version of a swing which can produce much more power than standard cue-ing which relies a lot on the biceps.
Also, relax you wrist and focus on letting it flex back in the early part of your forward delivery.
When I put these together and time the wrist, my biggest problem is keeping the CB on the table. The CB can land by the center pocket and bounce off the table from being only a fraction off center on the break.
But give it a try, coz at even 80% effort, if you can time these things using more of the pecs and wrist, you'll get plenty of power and can still control the accuracy.
from Jal:
You want the cue ball to have some topspin when it meets the rack. This will act like a brake and stop it from rebounding back too far.
It doesn't necessarily mean hitting above center. The cue ball will tend to pick up some topspin after it leaves your tip, even if it sails all the way to the rack. It gets it from the first bounce off the bed just after tip/ball impact, and of course, any subsequent bounces. (In fact, to my understanding, if it is airborne all the way, it should pick up more topspin from the one bounce than if it slid along the surface the entire way.)
Exactly where to strike to get the right amount of topspin depends on ball speed, cue elevation and cloth/ball conditions. But, it's going to be near center ball.
The adjustment, in theory, is very simple. If the cue ball is following too far forward, hit lower; if it's rebounding back too far, hit higher. If it's badly inconsistent, shorten your bridge length and/or slow down some until you get better control.
Theoretical simulation
If all of the balls were perfect and racked perfectly, how would the balls move after a perfect break?
Here is an interesting analysis and simulation showing the results of a perfect break with perfect balls (external web-link) by Jim Belk.
For more info, visit billiards.colostate.edu
Bridge
Pool and Billiards Bridge
... how the type of bridge affects a pool shot.
(external web-link) for more information:
see Sections 2.03, 7.09, and 7.10 in The Illustrated Principles of Pool and Billiards
Closed bridge variations
Where should the index finger be with a closed bridge?
Many bridge variations are shown in the following video:
... how the type of bridge affects a pool shot.
(external web-link) for more information:
see Sections 2.03, 7.09, and 7.10 in The Illustrated Principles of Pool and Billiards
Closed bridge variations
Where should the index finger be with a closed bridge?
Many bridge variations are shown in the following video:
from sfleinen:
You guys did miss presentation of the most popular closed bridge, which is the Filipino-style, index-finger-pressing-down-upon-middle-finger closed bridge, with the thumb pressing against the side of the middle finger (it's basically "along for the ride" -- most of the clamping work is done by the index finger upon the middle finger). You'll notice most of the pros have now adopted this style closed bridge, with the "pure loop" style closed bridge (as taught in Mosconi's little red book) being quite rarely seen in pros these days.
Another closed bridge that is extremely stable is the Willie Hoppe style closed bridge, as shown here:
http://youtube.com/watch?v=sc4iaJWu8Ak#t=155s
(This link will jump you into the section where Willie demonstrates his closed loop bridge.) (YouTube)
I don't agree with Willie's stroke style (i.e. from the shoulder as shown in the video), but I've found his closed bridge to be extremely stable and rock steady. The only change I make, is not to let the flesh of my fingers "drag" on the shaft like he shows in the video. A little corn starch applied in there on the contacts points where the cue contacts my fingers fixes that nicely.
Another closed bridge that seems to work well -- albeit it would make you think it's completely against what's traditionally taught -- is the closed bridge that Earl Strickland uses. Basically, it's a traditional closed loop bridge (like taught in Mosconi's little red book), but Earl hooks his index finger on the OUTSIDE of his thumb, not on top of or on the inside of the thumb. Earl basically uses the top surface of his thumb as a "channel" to ride the cue shaft on top of; the middle finger provides the "left wall" and the index finger provides the "right wall" to guide the cue and keep it on track.
I also agree with the synopsis about a variation of the open bridge where the thumb, instead of sticking up in the air at a 45-degree angle (of course clamped against the index finger), the thumb is instead folded over onto the index finger. The cue travels between the knuckle of the index finger and the knuckle of the thumb, keeping the skin taught and preventing the flesh from moving to and fro. This gives added stability. Shane Van Boening uses this variation of the open bridge all the time, as do most Filipino pros.
from sfleinen:
The overlapping index finger closed bridge [with the index finger wrapping around the cue and firmly pressing on top of the middle finger] is extremely stable, since one of the legs of the tripod (the ring finger) is the foundation that the cue rests on, with the index finger keeping the cue down on top of it. It's basically a self-locking bridge. (This is as opposed to the traditional closed loop bridge, which consists of a "two-piece" construction -- the three-finger tripod / heel of the hand foundation is one piece, and the index finger loop / thumb is another piece; the player has to make sure that both "pieces" are pressed/locked together to keep it stable.) The overlapping index finger bridge also forms a "V"-bridge internally, albeit this "V"-bridge is laying on its side, with the open aperture of the "V" facing the player. The traditional looped index finger closed bridge tends to more or less form a circular orifice, or else a "shelf" (on the thumb) that the cue rests on.
The only caveat with the overlapping index finger closed bridge is that it almost "requires" a shaft with a pro taper. A standard slope-tapered shaft will "jam" inside the aperture created by the index finger on top of the ring finger, unless the player compensates by slightly releasing the pressure [applied by the index finger on top of the ring finger] in direct correlation with the increasing diameter of the shaft as it passes through that aperture.
Open vs closed
Is a closed bridge better than an open bridge?
An argument can be made that an open bridge is better for most players and most shots. It doesn't look as fancy as the wide variety of closed bridges people use, but an open bridge offers many advantages. It:
Now, some people don't like the cue leaving their bridge hand, which can occur with an open bridge on firm follow shots and power shots with English; but as long as there is no risk of hitting nearby obstacle balls (in which case, a closed bridge might be advisable), this is not really an issue since the CB is already gone before the shaft moves in the bridge. Some people also tend to lift the tip during the stroke, especially with shots requiring more power, and premature lift can result in miscuing over the top of the CB, but this is a stroke issue (e.g., grip tightening and/or elbow dropping), not a bridge issue. For them, the closed bridge could help; although, eliminating the grip or stroke flaws might be a better alternative. Otherwise, whether the bridge is closed or open really has no effect on the CB, except for the fact that the increased friction associated with a closed bridge could reduce power and control a small amount. Some rail bridges, especially when cue-ing low close to a cushion, do require a closed bridge. Now, psychologically, there could be many more advantages to a closed bridge. The human mind is a powerful thing.
from sfleinen AZB post:
While the "index finger looping over and contacting the thumb" seems to be the "classic" picture folks get in their minds when they picture the closed bridge, there are others -- and ones which are now more popular than that style, due to being more conducive to stability and accuracy.
The mislabeled "Filipino bridge" -- where the index finger presses down upon the top of the middle finger -- is almost a de-facto "must know" in the higher echelon of play. This type of bridge creates a "V"-channel inside that the cue shaft is guided on, which is much more accurate than the meaty loop offered by the classic "index finger looped over the shaft and touching the thumb" style. However, there's a trick to orienting that internal "V"-channel vertically so that it offers the same side-to-side stability that an open bridge offers:
http://forums.azbilliards.com/showth...39#post3119239
And, one of the most unique closed bridges occurs when you take either of the above two types -- the "looped index finger" and/or the "index finger pressing down upon the middle finger" bridges -- and you fold the top half (last two joints) of the middle finger under the hand. In other words, only the upper segment of the middle finger is visible and supporting the cue shaft; the rest of that middle finger is folded under.
Willie Hoppe demonstrates:
http://youtube.com/watch?v=sc4iaJWu8Ak#t=2m38s
What this does is to offer even more stability, and, in the case of the index-pressing-down-upon-the-middle finger bridge type, a naturally vertical "V"-channel without lifting the palm of the hand in the air nor any need for "scrunching." I use this for power draw shots, because folding that middle finger under the hand lowers the bridge close to the table surface, and because of its stability, you can really crank on the draw shots with little fear of miscuing, because the apex of the "V"-channel itself is resting on the table surface.
Length
Is a longer bridge better?
TP A.10 (Download) shows how when you increase bridge length, the cue ball contact point error can increase. This can create unwanted side spin, which can result in unwanted squirt (cue ball deflection), swerve (cue ball curve), and throw.
Bridge length can also affect how you apply side spin and compensate for squirt. For more information, see "Aiming": aim compensation for squirt, swerve, and throw.
A longer bridge length can help create more power with less jerkiness; but with more length you will get less tip-placement accuracy. Every individual will have an optimal length where these trade-offs are balanced.
More information about bridge length effects can be found in "Fundamentals - Part IV: bridge length" (Download) (BD, December, 2008). Here is a concise summary of conclusions from the article:
Disadvantages of a longer bridge:
Advantages of a longer bridge:
Does bridge length and tightness have any effect on CB deflection?
No, per the info here: See Squirt(bridge length effects on squirt (CB deflection))
See these two videos:
YouTube: Grip and Bridge Technique and Advice
YouTube: Pool and Billiards Grip and Bridge Technique and Advice Part II
You guys did miss presentation of the most popular closed bridge, which is the Filipino-style, index-finger-pressing-down-upon-middle-finger closed bridge, with the thumb pressing against the side of the middle finger (it's basically "along for the ride" -- most of the clamping work is done by the index finger upon the middle finger). You'll notice most of the pros have now adopted this style closed bridge, with the "pure loop" style closed bridge (as taught in Mosconi's little red book) being quite rarely seen in pros these days.
Another closed bridge that is extremely stable is the Willie Hoppe style closed bridge, as shown here:
http://youtube.com/watch?v=sc4iaJWu8Ak#t=155s
(This link will jump you into the section where Willie demonstrates his closed loop bridge.) (YouTube)
I don't agree with Willie's stroke style (i.e. from the shoulder as shown in the video), but I've found his closed bridge to be extremely stable and rock steady. The only change I make, is not to let the flesh of my fingers "drag" on the shaft like he shows in the video. A little corn starch applied in there on the contacts points where the cue contacts my fingers fixes that nicely.
Another closed bridge that seems to work well -- albeit it would make you think it's completely against what's traditionally taught -- is the closed bridge that Earl Strickland uses. Basically, it's a traditional closed loop bridge (like taught in Mosconi's little red book), but Earl hooks his index finger on the OUTSIDE of his thumb, not on top of or on the inside of the thumb. Earl basically uses the top surface of his thumb as a "channel" to ride the cue shaft on top of; the middle finger provides the "left wall" and the index finger provides the "right wall" to guide the cue and keep it on track.
I also agree with the synopsis about a variation of the open bridge where the thumb, instead of sticking up in the air at a 45-degree angle (of course clamped against the index finger), the thumb is instead folded over onto the index finger. The cue travels between the knuckle of the index finger and the knuckle of the thumb, keeping the skin taught and preventing the flesh from moving to and fro. This gives added stability. Shane Van Boening uses this variation of the open bridge all the time, as do most Filipino pros.
from sfleinen:
The overlapping index finger closed bridge [with the index finger wrapping around the cue and firmly pressing on top of the middle finger] is extremely stable, since one of the legs of the tripod (the ring finger) is the foundation that the cue rests on, with the index finger keeping the cue down on top of it. It's basically a self-locking bridge. (This is as opposed to the traditional closed loop bridge, which consists of a "two-piece" construction -- the three-finger tripod / heel of the hand foundation is one piece, and the index finger loop / thumb is another piece; the player has to make sure that both "pieces" are pressed/locked together to keep it stable.) The overlapping index finger bridge also forms a "V"-bridge internally, albeit this "V"-bridge is laying on its side, with the open aperture of the "V" facing the player. The traditional looped index finger closed bridge tends to more or less form a circular orifice, or else a "shelf" (on the thumb) that the cue rests on.
The only caveat with the overlapping index finger closed bridge is that it almost "requires" a shaft with a pro taper. A standard slope-tapered shaft will "jam" inside the aperture created by the index finger on top of the ring finger, unless the player compensates by slightly releasing the pressure [applied by the index finger on top of the ring finger] in direct correlation with the increasing diameter of the shaft as it passes through that aperture.
Open vs closed
Is a closed bridge better than an open bridge?
An argument can be made that an open bridge is better for most players and most shots. It doesn't look as fancy as the wide variety of closed bridges people use, but an open bridge offers many advantages. It:
- is very easy to learn (even for beginners).
- provides un-obscured view of the stick (especially with a low stance), for aiming and establishing the stroking direction.
- is very stable, even at fairly large heights (with the heel of the hand on the table and the hand cupped).
- keeps the stick centered and unrestricted in the V-shape through the entire stroke, even with significant shaft taper (this is not the case with all closed bridges).
- offers the least and most consistent resistance to cue movement, especially with hot, humid, and/or dirty conditions.
- offers a greater range of bridge heights. It can be easily flattened to a low cue position, and can be raised higher when bridging over a ball or shooting jacked-up shots.
- makes it easier to reach extended shots, as an option to using a mechanical bridge.
Now, some people don't like the cue leaving their bridge hand, which can occur with an open bridge on firm follow shots and power shots with English; but as long as there is no risk of hitting nearby obstacle balls (in which case, a closed bridge might be advisable), this is not really an issue since the CB is already gone before the shaft moves in the bridge. Some people also tend to lift the tip during the stroke, especially with shots requiring more power, and premature lift can result in miscuing over the top of the CB, but this is a stroke issue (e.g., grip tightening and/or elbow dropping), not a bridge issue. For them, the closed bridge could help; although, eliminating the grip or stroke flaws might be a better alternative. Otherwise, whether the bridge is closed or open really has no effect on the CB, except for the fact that the increased friction associated with a closed bridge could reduce power and control a small amount. Some rail bridges, especially when cue-ing low close to a cushion, do require a closed bridge. Now, psychologically, there could be many more advantages to a closed bridge. The human mind is a powerful thing.
from sfleinen AZB post:
While the "index finger looping over and contacting the thumb" seems to be the "classic" picture folks get in their minds when they picture the closed bridge, there are others -- and ones which are now more popular than that style, due to being more conducive to stability and accuracy.
The mislabeled "Filipino bridge" -- where the index finger presses down upon the top of the middle finger -- is almost a de-facto "must know" in the higher echelon of play. This type of bridge creates a "V"-channel inside that the cue shaft is guided on, which is much more accurate than the meaty loop offered by the classic "index finger looped over the shaft and touching the thumb" style. However, there's a trick to orienting that internal "V"-channel vertically so that it offers the same side-to-side stability that an open bridge offers:
http://forums.azbilliards.com/showth...39#post3119239
And, one of the most unique closed bridges occurs when you take either of the above two types -- the "looped index finger" and/or the "index finger pressing down upon the middle finger" bridges -- and you fold the top half (last two joints) of the middle finger under the hand. In other words, only the upper segment of the middle finger is visible and supporting the cue shaft; the rest of that middle finger is folded under.
Willie Hoppe demonstrates:
http://youtube.com/watch?v=sc4iaJWu8Ak#t=2m38s
What this does is to offer even more stability, and, in the case of the index-pressing-down-upon-the-middle finger bridge type, a naturally vertical "V"-channel without lifting the palm of the hand in the air nor any need for "scrunching." I use this for power draw shots, because folding that middle finger under the hand lowers the bridge close to the table surface, and because of its stability, you can really crank on the draw shots with little fear of miscuing, because the apex of the "V"-channel itself is resting on the table surface.
Length
Is a longer bridge better?
TP A.10 (Download) shows how when you increase bridge length, the cue ball contact point error can increase. This can create unwanted side spin, which can result in unwanted squirt (cue ball deflection), swerve (cue ball curve), and throw.
Bridge length can also affect how you apply side spin and compensate for squirt. For more information, see "Aiming": aim compensation for squirt, swerve, and throw.
A longer bridge length can help create more power with less jerkiness; but with more length you will get less tip-placement accuracy. Every individual will have an optimal length where these trade-offs are balanced.
More information about bridge length effects can be found in "Fundamentals - Part IV: bridge length" (Download) (BD, December, 2008). Here is a concise summary of conclusions from the article:
Disadvantages of a longer bridge:
- Stroking errors result in larger tip position errors.
- If the length is not needed for power, the longer stroke might allow more room for error to be introduced during the stroke (i.e., a shorter, more compact stroke might be more accurate).
- If a player has a long bridge but is not using the full length on the back stroke, the bridge length (and associated tip position error) is larger than it needs to be. However, if the extra length is helping with sighting and aiming, it might be justified.
- A small change in bridge position creates a larger change in cue tip position. If the bridge hand shifts accidentally or deforms during the stroke, or if the cue shifts slightly within the bridge, larger errors will result.
- For soft touch shots, a shorter bridge and stroke is usually more effective.
Advantages of a longer bridge:
- A longer bridge can help improve visual sighting.
- Smoother acceleration is possible, especially when using more power. Not as much force will be required over the longer distance to achieve a desired cue speed. The stroke will tend to be jerkier and usually more susceptible to errors with a shorter bridge, requiring larger forces over the shorter distance to achieve the desire cue speed.
- A person with large and/or inflexible hands might need to elevate the back of the cue more with a shorter bridge, and cue elevation can reduce accuracy by creating more swerve when side spin is used (intentionally or not). Using a longer bridge can help some people keep their cue more level, especially with draw shots.
- A longer bridge might better match the natural pivot length for your cue (especially low-squirt cues). This can help reduce CB direction errors when unintentional side spin is applied (e.g., due to stroke swoop). It can also be important if using the back-hand english (BHE) method to compensate for squirt when applying side spin intentionally.
- A longer bridge and stroke might help some people gauge the speed of the shot better; although, this might not apply for soft touch shots (see above).
- Some people just feel more natural and comfortable with a longer bridge and stroke, and shortening it will feel too uncomfortable (even after practice), and their overall performance will not be better with a change. Like many things in pool, personal preference and comfort is often an important factor.
Does bridge length and tightness have any effect on CB deflection?
No, per the info here: See Squirt(bridge length effects on squirt (CB deflection))
See these two videos:
YouTube: Grip and Bridge Technique and Advice
YouTube: Pool and Billiards Grip and Bridge Technique and Advice Part II
For more info, visit billiards.colostate.edu
Carom Shots
See: 30-degree and 90-degree Rules for Cue Ball Control in Pool and Billiards
... how to predict cue ball motion to prevent scratches, aim break out shots, aim caroms, play position, and get through traffic.
... how to predict cue ball motion to prevent scratches, aim break out shots, aim caroms, play position, and get through traffic.
For more info, visit billiards.colostate.edu
Cue
Pool Cue Information
... how to select, characterize, maintain, and use different types of pool cues.
(external web-link) for more information:
see Disc II of the Video Encyclopedia of Pool Shots
Balance point
What is the "balance point" of a cue, and does it affect shot performance?
A cue's balance point is its center of gravity, which is the point at which you can balance the cue (e.g., if you support it on a finger). Obviously, the balance point needs to be in front of the grip hand; otherwise, the front of the cue would lift up off an open bridge. Other than that, the balance point is mostly unimportant (except for personal preference based on "feel"). The balance point certainly does not impact shot effectiveness, even for follow shots with an open bridge. The CB is long gone before the bridge even feels the effect of the tip-CB collision, as demonstrated in part 2 of the following video:
NV B.96 - Grip and bridge technique and advice (part 1)(YouTube)
NV B.96 - Grip and bridge technique and advice (part 2)(YouTube)
Now, a shaft that is heavy on the front end (moving the balance point forward) will affect cue ball deflection, which does affect shots with side spin. For more info, see the squirt end mass resource page.
Cleaning
How do you clean and maintain a cue?
Wiping with a damp rag and rubbing dry with a dry rag usually does the trick fairly well, especially if done regularly. Mr. Clean (or generic brand) Magic Eraser (dry or slightly damp) also does a very good job.
from JoeW:
I have been cleaning cues for many years and have tried many systems because I like a clean stick. About one year ago someone mentioned trying Mr. Clean's Magic Eraser. You can buy these in most any grocery store. I have found there is nothing better to return a cue stick to a like new condition.
Dampen the sponge like Magic Eraser and wipe down the cue including the ferrule. Wipe the excess moisture (there should be very little) and the grime off the cue with a cotton towel.
You can use a dollar bill to burnish the stick if you want to be like the old time pool players.
The best way to slick the cue that I have found is to use an old piece of leather. Could be a piece cut from a belt, the tongue of a shoe or whatever. Soft natural leather is all that is needed.
Wind the leather around the cue and move it as fast as you can up and down the first 18 inches or so. This will heat up and seal the cue. It is almost ready to use.
Wet the edge of the cue tip liberally with saliva and then burnish this with a dollar bill or the back of a piece of emery cloth (that is what I use). This will make the tip look nice but more importantly it will help to harden it and it will be less likely to mushroom.
from Majic:
I smooth the shaft after using the magic eraser and burnish it. I also use a dry film lubricant afterwards and this helps seal as well as provide a slick surface. Some people I know use Rain-X. RZ-50 made by Dupont is a clear product just to mention a couple. If you decide to experiment with other products just be certain is doesn't dry with a white film.
From eb_in_nc:
There's a product on the market called Q-Wiz. It's a double sided pad, the one side for roughing, the other for polishing. It is a high tech micro abrasive that won't burn through the finish and reduce the diameter of the cue. I've been using it for one year and love how it works. It's also washable and reusable.
Dent removal
How do you repair a dent in a wood shaft?
If the dent really is a "dent" (where the wood fibers have been compressed) and not a "gouge" (where wood has been removed), try putting a drop of water on the dent (e.g., with a cue tip) and let it sit and dry over night. This usually helps swell the fibers back up, restoring the shaft close to the pre-dent condition. If it doesn't work completely the first time, try again. If the dent pops out too much, lightly sand with very-fine-grit sand paper.
Elevation effects
What effects does cue elevation have on a shot, and how should I change my technique when jacking up the cue?
When you "jack up" your cue, by raising the butt (back) end, several bad things can happen, including:
Items 1 and 2 above are often due to one's vision center not being aligned properly when elevated. This is a very common problem. One approach to solving this problem is aiming the shot in a level-cue position and then elevate the cue from this aim (like a lot of people do when aiming jump shots). You can also glance down at the cue in the elevated position to make sure your vision center is over the cue.
Some of the technique advice normally suggested for jump shots also applies to other elevated-cue shots. For example, your stance and grip can be much more comfortable if you bend your bridge arm and choke up on the cue, allowing you to get closer to the cue and CB, also enabling a more comfortable and consistent stroke. It also helps to make sure you have pressure on your bridge hand and keep it as still as possible.
When jacking up the cue, one must be aware of the effects on effective tip offset (and the amount of spin imparted). Some people have trouble perceiving this effect. The following diagram from "Draw Shot Physics - Part IV: cue elevation effects" (Download) (BD, July, 2009) illustrates the concept.
... how to select, characterize, maintain, and use different types of pool cues.
(external web-link) for more information:
see Disc II of the Video Encyclopedia of Pool Shots
Balance point
What is the "balance point" of a cue, and does it affect shot performance?
A cue's balance point is its center of gravity, which is the point at which you can balance the cue (e.g., if you support it on a finger). Obviously, the balance point needs to be in front of the grip hand; otherwise, the front of the cue would lift up off an open bridge. Other than that, the balance point is mostly unimportant (except for personal preference based on "feel"). The balance point certainly does not impact shot effectiveness, even for follow shots with an open bridge. The CB is long gone before the bridge even feels the effect of the tip-CB collision, as demonstrated in part 2 of the following video:
NV B.96 - Grip and bridge technique and advice (part 1)(YouTube)
NV B.96 - Grip and bridge technique and advice (part 2)(YouTube)
Now, a shaft that is heavy on the front end (moving the balance point forward) will affect cue ball deflection, which does affect shots with side spin. For more info, see the squirt end mass resource page.
Cleaning
How do you clean and maintain a cue?
Wiping with a damp rag and rubbing dry with a dry rag usually does the trick fairly well, especially if done regularly. Mr. Clean (or generic brand) Magic Eraser (dry or slightly damp) also does a very good job.
from JoeW:
I have been cleaning cues for many years and have tried many systems because I like a clean stick. About one year ago someone mentioned trying Mr. Clean's Magic Eraser. You can buy these in most any grocery store. I have found there is nothing better to return a cue stick to a like new condition.
Dampen the sponge like Magic Eraser and wipe down the cue including the ferrule. Wipe the excess moisture (there should be very little) and the grime off the cue with a cotton towel.
You can use a dollar bill to burnish the stick if you want to be like the old time pool players.
The best way to slick the cue that I have found is to use an old piece of leather. Could be a piece cut from a belt, the tongue of a shoe or whatever. Soft natural leather is all that is needed.
Wind the leather around the cue and move it as fast as you can up and down the first 18 inches or so. This will heat up and seal the cue. It is almost ready to use.
Wet the edge of the cue tip liberally with saliva and then burnish this with a dollar bill or the back of a piece of emery cloth (that is what I use). This will make the tip look nice but more importantly it will help to harden it and it will be less likely to mushroom.
from Majic:
I smooth the shaft after using the magic eraser and burnish it. I also use a dry film lubricant afterwards and this helps seal as well as provide a slick surface. Some people I know use Rain-X. RZ-50 made by Dupont is a clear product just to mention a couple. If you decide to experiment with other products just be certain is doesn't dry with a white film.
From eb_in_nc:
There's a product on the market called Q-Wiz. It's a double sided pad, the one side for roughing, the other for polishing. It is a high tech micro abrasive that won't burn through the finish and reduce the diameter of the cue. I've been using it for one year and love how it works. It's also washable and reusable.
Dent removal
How do you repair a dent in a wood shaft?
If the dent really is a "dent" (where the wood fibers have been compressed) and not a "gouge" (where wood has been removed), try putting a drop of water on the dent (e.g., with a cue tip) and let it sit and dry over night. This usually helps swell the fibers back up, restoring the shaft close to the pre-dent condition. If it doesn't work completely the first time, try again. If the dent pops out too much, lightly sand with very-fine-grit sand paper.
Elevation effects
What effects does cue elevation have on a shot, and how should I change my technique when jacking up the cue?
When you "jack up" your cue, by raising the butt (back) end, several bad things can happen, including:
- If you don’t hit exactly on the center line of the CB (either intentional or not), the CB will swerve and go off line more (see HSV B.10 (YouTube). Some people have more success getting a center-ball hit on an elevated-cue shot by focusing on the CB (instead of the OB, as normal) during the final stroke.
- It can be more difficult to visually align the cue with the desired aiming line of the shot.
- More elevation causes the CB to hop; and with more speed, the CB will hop over a longer distance and possibly hit the OB while still bouncing. If the CB hits the OB while airborne, the cut angle will be changed and you might miss the shot (see jump shot over cut).
- The more you elevate the cue with draw shots, the less spin the CB will have when it gets to the OB, for a given tip offset and cue speed (for more info, see "Draw Shot Physics - Part IV: cue elevation effects" (Download) - BD, July, 2009). However, elevation does help create "quicker" draw (for more info, see "Draw Shot Physics - Part III: spin ratio" (Download) - BD, June, 2009 and "Draw Shot Physics - Part IV: cue elevation effects" (Download) - BD, July, 2009).
Items 1 and 2 above are often due to one's vision center not being aligned properly when elevated. This is a very common problem. One approach to solving this problem is aiming the shot in a level-cue position and then elevate the cue from this aim (like a lot of people do when aiming jump shots). You can also glance down at the cue in the elevated position to make sure your vision center is over the cue.
Some of the technique advice normally suggested for jump shots also applies to other elevated-cue shots. For example, your stance and grip can be much more comfortable if you bend your bridge arm and choke up on the cue, allowing you to get closer to the cue and CB, also enabling a more comfortable and consistent stroke. It also helps to make sure you have pressure on your bridge hand and keep it as still as possible.
When jacking up the cue, one must be aware of the effects on effective tip offset (and the amount of spin imparted). Some people have trouble perceiving this effect. The following diagram from "Draw Shot Physics - Part IV: cue elevation effects" (Download) (BD, July, 2009) illustrates the concept.
Is it possible to have the cue perfectly level at a pool table (i.e., is it possible to not have the cue elevated)?
No. Because the cue must clear over the rails, the cue must be elevated some on practically all pool shots. Here's an illustration from Patrick Johnson (from AZB post (external forum-link)) that illustrates why:
No. Because the cue must clear over the rails, the cue must be elevated some on practically all pool shots. Here's an illustration from Patrick Johnson (from AZB post (external forum-link)) that illustrates why:
The cue must be elevated some to clear the rail cushion and hit the ball low enough to prevent a miscue. The cue must be elevated even more when the CB is farther from the cushion (and a fatter part of the cue is over the rail) and/or when a below-center hit is used. For example, see: TP A.3 - Minimum cue elevation required for a head-spot-to-foot-spot center-ball-hit shot. (Download)
"Feel," "hit," "feedback," and "playability"
What do "feel," "hit," "feedback," and "playability" really mean in relation to a cue, and do they affect a shot?
These are qualitative phrases used to describe the force and shock (impulse) a player feels and the vibration and sound a player hears during and after (but mostly after) the cue tip hits the cue ball.
The "feel" and "sound" of a hit are affected by shot speed and how far the tip hits off center. They are also affected by:
- tip type, hardness, and efficiency
- ferrule type and material
- shaft material, design, size, and taper
- joint material, design, and construction
- butt material, design, and construction (including the wrap and end bumper)
- shaft straightness
- tip quality and shape
- tip diameter and shaft taper, especially if a closed bridge is used
- cue weight, balance, and mass distribution
- the amount of end-mass, which determines the amount of squirt (CB deflection)
The shock and vibration is felt and the sound is heard after the CB is already gone, so they have no direct effect on the outcome of a shot; although, some people claim the "feel" is important to getting good "feedback" on the shot (indicating if the CB was struck well with the appropriate speed), but not all players place importance on this. To many, what the CB does is "feedback" enough.
A cue's flex or vibration can't have much to do with the physics between the tip and CB during the extremely brief (approximately 0.001 second) impact time. Most of the flex and vibration occurs well after the CB is gone. For example, see:
HSV A.76a - close-up of tip during off-center hit (YouTube)
The vibration affects the "feel" of the cue, but it doesn't have much (if any) effect on the physics between the tip and CB.
Regardless of the physics, there are many "qualitative intangibles" ("feel," "hit," "sound," "feedback," "aesthetics," etc.) that might be psychologically important to a player even if the characteristics might not have any direct effect on the outcome of a shot.
Ferrule
What is the purpose for the ferrule?
The main purpose for the ferrule is to protect the wood on the end of the shaft. A ferule does allow one to change the tip without damaging the shaft wood, and it might help distribute the impact forces to the shaft during tip impact. The ferrule also affects the look, feel ("hit"), and sound of the cue. A smaller and lighter ferrule results in less squirt (since the ferrule material is typically heavier than wood).
from RRfireblade:
Purpose for a ferrule:
* "Intended" to protect end grain.
* Better base for adhering tip.
* Allows for better facing of surface during a re-tipping, plus no wood removal to shorten shaft length over time.
* Protects shaft from poor chalking technique.
* Acts as a buffer to help retain shaft diameter during 'maintenance'.
* Style and appearance. Same as any other ring work.
* Tradition.
* Really nothing to be gained by not having one. (end mass can be equaled or even reduced with the right ferrule material)
from Cornerman (concerning why a ferrule is used):
Tradition. It's a good bet that a ferrule pre-dates the tip. Chalk pre-dates the tip which means shafts were subject to split ends and needed protection or repair. With a tip and pad, no ferrule is needed IMO.
from ShootingArts:
... there are almost endless materials to make ferrules out of including the pool balls themselves. Ferrules can be lighter than the wood, heavier than the wood, stronger than the wood, weaker than the wood, stiffer than the wood, more flexible than the wood, on and on. In addition the adhesive use to hold the ferrule on may offset the tiny difference in weight savings of some ferrules.
The ferrule was developed long before we had the quality adhesives that we have now. The pads we use now serve the same purpose the ferule once did, to keep the wood from splintering. Note that ivory ferules normally have a pad installed to prevent them from splintering.
Ferrules are decorative, they may help us aim by giving us an easier to see point to focus on, and they can be chosen to serve a purpose, mostly giving a softer hit. A hard ferrule stiffens the hit compared to a soft ferule but I'm pretty skeptical of a hard ferule and 29" of wood giving an detectably stiffer hit than 30" of the same wood. What the hard ferrule may do is change the sound of the hit a little.
Jump cue
What is different about a jump cue?
Jump cues are shorter and lighter, with a hard tip (e.g., phenolic). All of these features make it easier to get more rebound height off the table slate with a legal hit.
Laminated shafts
Why are some shafts (e.g., some LD shafts) laminated, consisting of layers or radial segments glued together?
Laminated shafts can have better strength and consistency with lower-quality cuts of wood. They can also have better dimensional stability, being less prone to warp over time. Also, shafts of the same brand and model will tend to be more consistent because there is less chance for wood grain variance, as compared to a solid piece of wood.
Low squirt (low deflection or LD) shafts
Can a low-deflection (LD) shaft help my game?
An LD shaft has less "endmass" than a regular shaft. As a result, it creates less cue ball squirt. I prefer the phrase "low squirt" to "low deflection" or "LD" (for more info, see "Squirt section").
"Squirt - Part V: low-squirt cues" (Download) (BD, December, 2007) summarizes the results of a poll concerning whether or not a low-squirt shaft helps and who it helps. I present and discuss the results in the article. I also present a logical analysis with a graphical interpretation to try to explain how a low-squirt shaft can help. The assumptions of the analysis are similar to what Shepard describes in an example in his Everything you Always Wanted to Know About Cue Ball Squirt, but Were Afraid to Ask article (Download).
BTW, here's the last line of the article: my answer to the question of whether a low-squirt shaft can help is: yes, especially if you believe it can help you. The mind is a powerful thing. I use a low-squirt cue and I think I play better with it; therefore, I probably do. I wrote this because the analysis shows only a small expected increase in accuracy with a low-squirt cue for a player with decent squirt knowledge/intuition. Although, a novice player who knows nothing about squirt and how to compensate for it can definitely benefit (a small amount) from a low-squirt shaft, especially when they use english (intentionally or not). The CB will go closer to where they are aiming. That's usually a good thing. Now, if the tip is aligned center-ball to begin with and the unintentional english is applied with a "swoop" (non straight) stroke, whichever cue has a natural pivot length (or effective pivot length) best matched to the player's bridge length will be the best at reducing the effects of squirt (or the net result of squirt, swerve, and throw).
Advantages
Here is a summary of possible advantages of low-squirt shafts:
- The CB will come off the cue tip closer to the aiming line when using side spin. Therefore, not as much aim adjustment or compensation is required when using side spin. For people who aren't good at compensating for squirt, this can be very helpful.
- A player might be more consistent with shots with side spin since the possible range of squirt is smaller than with regular shafts. Basically, if there is less squirt then less aiming adjustment is required. For more info, see "Squirt - Part V: low-squirt cues" (Download) (BD, December, 2007).
- Back-hand and/or front-hand english (BHE and FHE) aim-and-pivot aim compensation methods might be more suited to a player's natural bridge length with a low-squirt shaft.
- It can be possible to get slightly more spin on the CB with a low-squirt shaft, but this effect is very small.
- Many low-squirt shafts are constructed as a radial laminate (long wedge-shaped sections glued together and then turned down on a lathe), so they are more likely to hold their straightness over time (i.e., they are less likely to warp). If the wood laminates are chosen carefully (e.g., with a certain grain orientations), this might help improve strength. Also, this could help with consistency from one shaft to another of the same model. Some people think the radial consistency also helps create a more consistent "hit," regardless of the orientation (twist angle) of the cue, but this effect is questionable. Some people think radial consistency also helps create more consistent squirt, but that effect is also questionable (see "Squirt - Part VII: cue test machine results" (Download) - BD, February, 2008).
Disadvantages
Low-squirt shafts might not be good for everybody. Here are what I consider some disadvantages of low-squirt shafts:
- A "low-squirt" cue can be expensive.
- If somebody is used to compensating aim with a higher-squirt cue, it might be difficult to adjust to the lower-squirt cue.
- Some people might not like the "feel" or "hit" or "sound" or "look" of a low-squirt shaft.
- Some people might not like the small shaft diameter or taper of some low-squirt shafts, especially if a closed bridge is used.
- A low-squirt shaft might not be as mechanically sound over long-term use (i.e., the shaft end is not as strong and tough).
- If someone hits lots of low-speed side spin shots, and he or she is used to a higher squirt helping to cancel some or all of the swerve, then he or she might have trouble adjusting to a low-squirt shaft (where more swerve compensation would be required for these shots).
- Low-squirt shafts have long "natural pivot lengths," which might not be appropriate for either BHE or FHE on certain shots. Therefore, there is no simple aim-and-pivot squirt-compensation method ... a "combination" of BHE and FHE will be required. For more info, see back-hand and front-hand English under English section.
- If you have a short bridge length, a low squirt cue could result in more directional error (as compared to a regular squirt cue with a shorter pivot length) due to any unintentional pivot during your stroke.
- If you are used to a low-squirt cue, and you find yourself in a place without your cue, where only regular-squirt cues are available, you might not play very well (until you can adjust).
- A low-squirt cue will not make it easier to compensate for swerve and throw. To aim shots with side spin, many factors need to be taken into consideration. For more info, see aim compensation for squirt, swerve, and throw under English section.
from Patrick Johnson:
Each increment of tip offset equals more squirt with a high squirt shaft than the same increment with a low squirt shaft - so the same tip placement error has greater effect with a high-squirt shaft.
The effect of tip placement errors is higher or lower for two shafts in the same ratio as the squirt produced by the two shafts. If a shaft produces 1/3 more squirt, then tip placement errors have 1/3 more effect.
What is the difference between a low-deflection shaft and a low-squirt shaft?
Nothing. They are the same. A low-squirt shaft creates less ("low") cue-ball squirt but actually results in large ("high") cue deflection (because the end of the shaft is lighter and usually more flexible ... so it deflects away from the CB more with an off-center hit). So a "low"-deflection shaft actually has "high" deflection!!!
This is why I and others prefer the term: "low-squirt shaft" because it results in less CB squirt. A "low"-deflection shaft has low CB deflection, but high cue deflection. Also, what the shaft is doing (deflecting) is not important. What the CB is doing is what counts. The CB squirts less with a low-squirt shaft.
Getting more spin
Does a low-squirt shaft allow me to put more spin on the cue ball?
The short answer is: No.
Here's a longer answer:
Per "Squirt - Part II: experimental results" (Download) (BD, September, 2007), a common low-squirt shaft has a squirt angle of about 1.8 degrees at close to maximum tip offset, as compared to 2.5 degrees for a typical regular-squirt cue. So a low-squirt shaft offers only about 30% less squirt than a typical regular-squirt cue.
Per TP B.7 (Download), if you calculate the effective offsets using the squirt angles above, the percentage change in effective tip offset and the resulting spin is 2-3%, so a low-squirt shaft does not give you much gain in spin-generating capability.
Now, when comparing cues and/or tips, it is important that the actual tip offset is the same for both. If the tip size and shape are different, and one uses "tips of English" as a measure, perceived tip offset can be very different than actual offset, resulting in significant differences in the amount of spin. See the "tips" of English resource page for more illustrations and explanations.
Also, with draw shots, if someone is accustomed to a larger shaft that is close to touching the cloth at CB address, and they place a smaller diameter shaft in that same apparent position (close to the cloth), the effective tip contact point offset on the ball will be lower.
For more info on LD shaft spin effects, see:
- maximum side spin(under English)
- miscue limit(under squirt)
Can one cue stick produce more spin than another? No.
The force of a stick's momentum and the force produced by its squirt are combined into a single "force vector" that points through the CB in the direction the CB will travel. So when a stick is pivoted at its Squirt Pivot Point to hit the CB at a given spot, it produces the same "force vector" as any other stick doing the same thing, no matter what its angle of approach (the same as a theoretical unpivoted "no-squirt" cue).
The CB can't tell which direction a stick is pointed - it can only "feel" the direction and magnitude of this "force vector". And since every stick produces the same "force vector", every stick "feels" the same to the CB and the CB reacts the same way to each.
Masse cue
What is different about a masse cue?
Masse cues are typically shorter, heavier, and stiffer, and typically have a larger shaft diameter and tip. The shorter length is to improve handling and reduce overhead clearance problems. The extra strength and stiffness are for durability and better action. The extra weight can also help you get more action with less effort.
Natural pivot length
How do I determine the natural pivot length for my shaft, and why should I?
"Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007) explains and illustrates back-hand English (BHE), front-hand english (FHE), a cue's natural pivot length, and advice for selecting a break cue. Here's a procedure recommended by Colin Colenso for measuring natural pivot length:
Place OB about 6 inches from a corner pocket. Align CB in a straight line with this about 5-6 feet away. Align to pot straight, pivot and hit the shot near maximum speed to ensure insignificant swerve. Adjust bridge length until you consistently have the CB hitting pretty much at the original aim.
It's pretty obvious when you're hitting this shot within 1/10th inch of center which allows you to narrow down the intrinsic pivot point to less than an inch. The CB would spin on the spot if the OB was hit about 1/20th inch off center. This is plenty of accuracy over 5-6 feet. Pretty much as accurate as one could hope to aim the initial pot.
A demonstration can be found in this clip from Disc II of The Video Encyclopedia of Pool Shots: (external web-link)
YouTube video link: Back Hand English for Deflection
"Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007) also presents a simple procedure for measuring the natural pivot length for a cue; although, throw is more of a factor in these measurements. The procedure in the article yields more of an "effective pivot length," which compensates for both squirt and throw.
TP B.1 (Download) uses physics and math to predict the natural pivot length for a cue from squirt angle measurements. Here are some of the conclusions supported by the analysis:
- Squirt angle varies nearly linearly with tip offset, and tip offset varies nearly linearly with cue pivot angle. This is what makes the BHE and FHE methods effective, provided swerve and throw are also taken into consideration.
- A cue's natural pivot length does vary a little with both tip offset and tip shape (radius), so when comparing different cues with experimental measurements, it is important to use the same tip shape and the same amount of tip offset (English) for each cue.
- Cue pivot lengths reported by Platinum Billiards seem to be a little low. They report a range from 8 inches (for a "high-squirt" cue) to 14 inches (for a "low-squirt" cue). Although, numbers from Colin's procedure seem to back up this lower range.
- Expected cue pivot lengths reported in Ron Shepard's 2001 paper "Everything you Always Wanted to Know About Cue Ball Squirt, but Were Afraid to Ask" (Download) appear to be much too large. He reports a range from 10 inches (for a "high-squirt" cue) to 50 inches (for a "low-squirt" cue).
For more information about squirt (AKA "cue ball deflection") and how it is related to the natural pivot length of a cue, see the squirt (cue ball deflection) resource section.
from Patrick Johnson:
The traditional "aim-and-pivot" squirt test keeps the balls at the same distance and pivots the shaft to different angles by shifting the bridge hand (pivot point) back and forth until the shot is made.
This Simple Squirt Test keeps the shaft aimed at the same two points on the CB and OB while changing the distance between the balls until the shot is made. Changing the distance between the balls while aiming at the same points on them changes the angle of the cue in (hopefully) a more controlled way that can be more accurately measured.
Is there a pivot point for a cue that will compensate for throw and/or swerve in addition to squirt?
Unfortunately, the amount of throw varies with cut angle, shot speed, type of English, amount of topspin or bottom-spin, and ball conditions. Also, swerve depends on shot speed, shot distance, cue elevation, amount and type of side spin/roll, and ball/cloth conditions. Therefore, it is difficult to predict a required cue pivot point to compensate for anything more than squirt. Maybe this could be done for medium speed shots, at medium distances, with a medium amount of side spin (with a consistent amount of draw or follow); but otherwise, aim-and-pivot aim compensation alone is not adequate to account for all of the subtleties associated with squirt, swerve, and throw. Having said all of that, aim-and-pivot methods (e.g., BHE and/or FHE) can still be very helpful to many players on many shots.
How much deflection does a cue of given pivot length produce?
from Patrick Johnson:
Knowing your cue's Pivot Length is the basis for a simple method of visualizing squirt correction that can reduce the guesswork.
Pivot Length is the distance from your cue's tip to its Pivot Point, the place to pivot your cue to apply squirt-correcting backhand English. This is because (here's the useful part ->) Pivot Length is the distance the CB travels to be off target by exactly the same distance as your Tip Offset from the CB's center.
That means you should aim your shot one Tip Offset to the side of your target for each Pivot Length between the CB and the OB (minus something for swerve).
Here's a drawing with some detail about how to do that. For illustration it assumes a Pivot Length of exactly 12.5 inches (1 diamond on a 9-foot table), which is probably not an uncommon "high squirt" Pivot Length. Of course, each cue's Pivot Length can be different.
What is different about a masse cue?
Masse cues are typically shorter, heavier, and stiffer, and typically have a larger shaft diameter and tip. The shorter length is to improve handling and reduce overhead clearance problems. The extra strength and stiffness are for durability and better action. The extra weight can also help you get more action with less effort.
Natural pivot length
How do I determine the natural pivot length for my shaft, and why should I?
"Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007) explains and illustrates back-hand English (BHE), front-hand english (FHE), a cue's natural pivot length, and advice for selecting a break cue. Here's a procedure recommended by Colin Colenso for measuring natural pivot length:
Place OB about 6 inches from a corner pocket. Align CB in a straight line with this about 5-6 feet away. Align to pot straight, pivot and hit the shot near maximum speed to ensure insignificant swerve. Adjust bridge length until you consistently have the CB hitting pretty much at the original aim.
It's pretty obvious when you're hitting this shot within 1/10th inch of center which allows you to narrow down the intrinsic pivot point to less than an inch. The CB would spin on the spot if the OB was hit about 1/20th inch off center. This is plenty of accuracy over 5-6 feet. Pretty much as accurate as one could hope to aim the initial pot.
A demonstration can be found in this clip from Disc II of The Video Encyclopedia of Pool Shots: (external web-link)
YouTube video link: Back Hand English for Deflection
"Squirt - Part IV: BHE, FHE, and pivot-length calibration" (Download) (BD, November, 2007) also presents a simple procedure for measuring the natural pivot length for a cue; although, throw is more of a factor in these measurements. The procedure in the article yields more of an "effective pivot length," which compensates for both squirt and throw.
TP B.1 (Download) uses physics and math to predict the natural pivot length for a cue from squirt angle measurements. Here are some of the conclusions supported by the analysis:
- Squirt angle varies nearly linearly with tip offset, and tip offset varies nearly linearly with cue pivot angle. This is what makes the BHE and FHE methods effective, provided swerve and throw are also taken into consideration.
- A cue's natural pivot length does vary a little with both tip offset and tip shape (radius), so when comparing different cues with experimental measurements, it is important to use the same tip shape and the same amount of tip offset (English) for each cue.
- Cue pivot lengths reported by Platinum Billiards seem to be a little low. They report a range from 8 inches (for a "high-squirt" cue) to 14 inches (for a "low-squirt" cue). Although, numbers from Colin's procedure seem to back up this lower range.
- Expected cue pivot lengths reported in Ron Shepard's 2001 paper "Everything you Always Wanted to Know About Cue Ball Squirt, but Were Afraid to Ask" (Download) appear to be much too large. He reports a range from 10 inches (for a "high-squirt" cue) to 50 inches (for a "low-squirt" cue).
For more information about squirt (AKA "cue ball deflection") and how it is related to the natural pivot length of a cue, see the squirt (cue ball deflection) resource section.
from Patrick Johnson:
The traditional "aim-and-pivot" squirt test keeps the balls at the same distance and pivots the shaft to different angles by shifting the bridge hand (pivot point) back and forth until the shot is made.
This Simple Squirt Test keeps the shaft aimed at the same two points on the CB and OB while changing the distance between the balls until the shot is made. Changing the distance between the balls while aiming at the same points on them changes the angle of the cue in (hopefully) a more controlled way that can be more accurately measured.
Is there a pivot point for a cue that will compensate for throw and/or swerve in addition to squirt?
Unfortunately, the amount of throw varies with cut angle, shot speed, type of English, amount of topspin or bottom-spin, and ball conditions. Also, swerve depends on shot speed, shot distance, cue elevation, amount and type of side spin/roll, and ball/cloth conditions. Therefore, it is difficult to predict a required cue pivot point to compensate for anything more than squirt. Maybe this could be done for medium speed shots, at medium distances, with a medium amount of side spin (with a consistent amount of draw or follow); but otherwise, aim-and-pivot aim compensation alone is not adequate to account for all of the subtleties associated with squirt, swerve, and throw. Having said all of that, aim-and-pivot methods (e.g., BHE and/or FHE) can still be very helpful to many players on many shots.
How much deflection does a cue of given pivot length produce?
from Patrick Johnson:
Knowing your cue's Pivot Length is the basis for a simple method of visualizing squirt correction that can reduce the guesswork.
Pivot Length is the distance from your cue's tip to its Pivot Point, the place to pivot your cue to apply squirt-correcting backhand English. This is because (here's the useful part ->) Pivot Length is the distance the CB travels to be off target by exactly the same distance as your Tip Offset from the CB's center.
That means you should aim your shot one Tip Offset to the side of your target for each Pivot Length between the CB and the OB (minus something for swerve).
Here's a drawing with some detail about how to do that. For illustration it assumes a Pivot Length of exactly 12.5 inches (1 diamond on a 9-foot table), which is probably not an uncommon "high squirt" Pivot Length. Of course, each cue's Pivot Length can be different.
Click to enlarge
"Squirt," "deflection," "stiffness"
How is cue deflection related to ball squirt?
These terms can be confusing and misleading. Here's my summary:
"low-deflection" (LD) shaft
= "low-cue-ball-deflection" shaft =
= "low-squirt" shaft
= "low end-mass" shaft
= usually flexible (AKA "whippy", compliant, not stiff, "like a wet noodle") shaft end
An LD shaft, due to its smaller end mass, is usually whippy close to the tip. This causes the shaft to bend or flex (i.e., "deflect") a lot during an off-center hit, and the low end mass results in less squirt (cue ball "deflection").
I also prefer the term "squirt" over "cue ball deflection." I certainly prefer "low-squirt" over "low-deflection" (because of the ambiguous meaning of "deflection"). I also prefer "small" instead of "low" because that can also be ambiguous. Although, it's not easy to change the terminology people use when it is so ingrained. As long as people are clear, it really doesn't matter. When I hear "low deflection cue," I just assume the implication is "small squirt shaft."
Types and tapers
What is different about the different types of cues and shaft tapers?
From Wikipedia's pool shaft page: (external web-link)
Shafts are made with various tapers, the two most common being the pro taper and the European taper. The pro taper has the same diameter from the tip to 30–35 cm (12-14 inches) toward the joint, at which point it begins to widen. The European taper widens continually and smoothly from the ferrule toward the joint. Despite their names, the continually sloping European taper is found in most North American bar and house cues, and not all professional players prefer a straight pro taper on their custom, two-piece models.
From Snapshot9:
Cues can up to a 14 mm tip, and lots of Break/Jump cues, or Break cues, or Jump cues have a 14 mm tip because a bigger tip is better for Breaking and/or Jumping. Break cues commonly have a Conical taper (also called European) for added stiffness.
A Break/Jump cue is one that is used for Breaking and Jumping with part of butt coming off so that the shorter Jump portion can be used. Jump cues/portions are commonly
40" long, the minimum length they can be.
Leather tips are better for control, but Phenolic tips, which are harder, are better for power and/or lift when jumping. I have a J&J Break/Jump cue with a phenolic ferrule/tip combination that I like a lot, and they can be bought for $60/65 dollars. I used to believe in separate Break cue and jump cue, but the J&J Break/jump changed my mind about that, and a Break/jump combo takes up less space in your case. Phenolic tips do some getting used to though, and almost require a center ball hit.
A standard taper started out 8-10"
A pro taper started out 10-13", now is 13-15"
An European taper is like a long cone shape, with no part of the shaft being the same diameter at any 2 points. (constantly tapers down to the tip).
There is also a straight taper, which a lot of Snooker cues have.
Vibration
How much and in what manner does a cue deform and vibrate during and after a shot?
Here are some excellent super-slow motion videos illustrating cue vibration effects with side spin shots:
Russian experience with high-speed video of pool cues (external web-link)
And here are some with follow and draw shots:
Russian experience with high-speed video of pool cues - part 2 (external web-link)
HSV B.9 - Cue deflection and vibration (YouTube)
Here's an excellent article from DBKcues presenting technical results of some experiments on this topic:
Investigation in Some Wave Properties of a Billiards Cue (external web-link)
Some additional examples of accelerometer measurements can be found here:
TP A.9 - Cue accelerometer measurements (Download)
The amplitudes, frequencies, mode shapes, and duration of cue vibration are big factors in determining the "hit" or "feel" of a cue.
Weight
What is the best weight for a cue?
For you main playing cue, use whatever weight feels most comfortable. A heavier cue might be easier for some to keep on line during the stroke, but this is a very individual thing.
Now, for a break cue, the optimal weight for maximum cue ball (CB) speed will depend on your arm anatomy (the size and weights of the different parts of your arm) and muscle physiology (e.g., fast-twitch vs. slow-twitch muscle fiber dominance). The only way to find out the optimal weight for sure is to experiment. Cue weight isn't a question of just physics. Physiology also comes into play. Some people have more fast-twitch muscle fibers than others. Because of this, cue weight selection can be a very personal thing.
Cue and tip efficiency also affect maximum break speed. Phenolic tips can be 10-15% more efficient than typical leather tips. That basically results in 3-4% more cue ball speed (for a given cue weight and speed), which basically results in the object balls traveling 10-15% farther, slightly increasing the likelihood of pocketing a ball.
Other than tip efficiency, what determines CB speed is the cue's momentum at impact, and CB speed is what we are striving for (in addition to accuracy) with a break. Cue momentum is the product of cue mass and cue speed. For a given cue speed, if the cue has more mass, the CB will go faster; and for a given cue weight, if the cue has more speed, the CB will go faster. Both factors (cue speed and cue weight) are important. Some people can generate more momentum with a lighter cue, and some can generate more with a heavier cue.
Here are some examples to further explain the momentum effect. If a person is using a cue of mass (m) can generate a certain speed (v), the speed of the cue ball is directly related to cue momentum (mv). If the same person uses a cue 10% lighter (.9m), he or she would probably be able to generate more cue speed, let's say 5% more speed (1.05v). In this case, the cue momentum (.9m * 1.05v = .945mv) would be about 5% less than with the original cue. If the same person used a cue 10% heavier (1.10m), and generated 5% less speed (0.95v) as a result, the cue momentum (1.10m * 0.95v = 1.045mv) would be about 5% more than with the original cue. In this case, the slightly heavier cue would be better. If, on the other hand, the additional weight resulted in a greater loss in speed, let's say 15% (0.85v), the cue momentum (1.10m * 0.85v = .935mv) would be about 7% less than with the original cue. In this case the original (lighter) cue would be better.
A good analogy to pool break cue weight selection is baseball bat weight selection. A lighter bat can be swung faster, but a heavier bat has more mass. Some players can generate more bat momentum and ball speed (and distance) with a heavier bat (e.g., Babe Ruth), and some do better with a much lighter bat (e.g., Barry Bonds). An excellent web page dealing with baseball bat weight effects can be found here: Bat Weight, Swing Speed and Ball Velocity. (external web-link)
Notice the ball speed vs. bat weight graphs about 3/4 down on the web page. They are very flat at the optimal weight, implying bat weight doesn't really make that much difference in the range of typical values. This effect should be similar with break cues. If you are in your preferred weight range, an ounce more or less shouldn't make much difference.
One final note concerning cue weight: There is a limit to how light a cue can be before double hits become a problem, especially with large tip offset shots (e.g., maximum sidespin or draw). If the cue is too light, it will stay in contact with or catch up to the CB after the first hit. For sidespin shots, the result will be similar to that of a miscue (i.e., excessive squirt). For more info, see TP A.30 (Download) and "Coriolis was brilliant ... but he didn't have a high-speed camera - Part IV: maximum cue tip offset" (Download) (BD, October, 2005).
From pooltchr:
1. I believe the best weight for any player is the weight that feels most comfortable for all types of shots.
2. I believe that different weights can produce slightly different results, but those differences are so slight that most good players can adapt their stroke to get the desired results regardless of the chosen weight.
3. While a long draw shot does require more speed than a shorter one (adjusting speed and or spin is the only way to control draw)we still don't need to use maximum (break) speed even for maximum draw. For that reason, I think any good player can get the required speed with any weight cue. Those same players would be able to adjust their stroke to compensate for the weight differences in various cues.
4. Since over the course of a game, a player will need to vary speed and spin from shot to shot, the most comfortable weight to the individual player makes the most sense to me. It's easier to make slight adjustments to speed and spin with a well balanced comfortable cue. You can establish a centergistic or reference point for a stroke speed follow shot, then work from there to know what is needed when you need to do something else with the cue ball.
How is cue deflection related to ball squirt?
These terms can be confusing and misleading. Here's my summary:
"low-deflection" (LD) shaft
= "low-cue-ball-deflection" shaft =
= "low-squirt" shaft
= "low end-mass" shaft
= usually flexible (AKA "whippy", compliant, not stiff, "like a wet noodle") shaft end
An LD shaft, due to its smaller end mass, is usually whippy close to the tip. This causes the shaft to bend or flex (i.e., "deflect") a lot during an off-center hit, and the low end mass results in less squirt (cue ball "deflection").
I also prefer the term "squirt" over "cue ball deflection." I certainly prefer "low-squirt" over "low-deflection" (because of the ambiguous meaning of "deflection"). I also prefer "small" instead of "low" because that can also be ambiguous. Although, it's not easy to change the terminology people use when it is so ingrained. As long as people are clear, it really doesn't matter. When I hear "low deflection cue," I just assume the implication is "small squirt shaft."
Types and tapers
What is different about the different types of cues and shaft tapers?
From Wikipedia's pool shaft page: (external web-link)
Shafts are made with various tapers, the two most common being the pro taper and the European taper. The pro taper has the same diameter from the tip to 30–35 cm (12-14 inches) toward the joint, at which point it begins to widen. The European taper widens continually and smoothly from the ferrule toward the joint. Despite their names, the continually sloping European taper is found in most North American bar and house cues, and not all professional players prefer a straight pro taper on their custom, two-piece models.
From Snapshot9:
Cues can up to a 14 mm tip, and lots of Break/Jump cues, or Break cues, or Jump cues have a 14 mm tip because a bigger tip is better for Breaking and/or Jumping. Break cues commonly have a Conical taper (also called European) for added stiffness.
A Break/Jump cue is one that is used for Breaking and Jumping with part of butt coming off so that the shorter Jump portion can be used. Jump cues/portions are commonly
40" long, the minimum length they can be.
Leather tips are better for control, but Phenolic tips, which are harder, are better for power and/or lift when jumping. I have a J&J Break/Jump cue with a phenolic ferrule/tip combination that I like a lot, and they can be bought for $60/65 dollars. I used to believe in separate Break cue and jump cue, but the J&J Break/jump changed my mind about that, and a Break/jump combo takes up less space in your case. Phenolic tips do some getting used to though, and almost require a center ball hit.
A standard taper started out 8-10"
A pro taper started out 10-13", now is 13-15"
An European taper is like a long cone shape, with no part of the shaft being the same diameter at any 2 points. (constantly tapers down to the tip).
There is also a straight taper, which a lot of Snooker cues have.
Vibration
How much and in what manner does a cue deform and vibrate during and after a shot?
Here are some excellent super-slow motion videos illustrating cue vibration effects with side spin shots:
Russian experience with high-speed video of pool cues (external web-link)
And here are some with follow and draw shots:
Russian experience with high-speed video of pool cues - part 2 (external web-link)
HSV B.9 - Cue deflection and vibration (YouTube)
Here's an excellent article from DBKcues presenting technical results of some experiments on this topic:
Investigation in Some Wave Properties of a Billiards Cue (external web-link)
Some additional examples of accelerometer measurements can be found here:
TP A.9 - Cue accelerometer measurements (Download)
The amplitudes, frequencies, mode shapes, and duration of cue vibration are big factors in determining the "hit" or "feel" of a cue.
Weight
What is the best weight for a cue?
For you main playing cue, use whatever weight feels most comfortable. A heavier cue might be easier for some to keep on line during the stroke, but this is a very individual thing.
Now, for a break cue, the optimal weight for maximum cue ball (CB) speed will depend on your arm anatomy (the size and weights of the different parts of your arm) and muscle physiology (e.g., fast-twitch vs. slow-twitch muscle fiber dominance). The only way to find out the optimal weight for sure is to experiment. Cue weight isn't a question of just physics. Physiology also comes into play. Some people have more fast-twitch muscle fibers than others. Because of this, cue weight selection can be a very personal thing.
Cue and tip efficiency also affect maximum break speed. Phenolic tips can be 10-15% more efficient than typical leather tips. That basically results in 3-4% more cue ball speed (for a given cue weight and speed), which basically results in the object balls traveling 10-15% farther, slightly increasing the likelihood of pocketing a ball.
Other than tip efficiency, what determines CB speed is the cue's momentum at impact, and CB speed is what we are striving for (in addition to accuracy) with a break. Cue momentum is the product of cue mass and cue speed. For a given cue speed, if the cue has more mass, the CB will go faster; and for a given cue weight, if the cue has more speed, the CB will go faster. Both factors (cue speed and cue weight) are important. Some people can generate more momentum with a lighter cue, and some can generate more with a heavier cue.
Here are some examples to further explain the momentum effect. If a person is using a cue of mass (m) can generate a certain speed (v), the speed of the cue ball is directly related to cue momentum (mv). If the same person uses a cue 10% lighter (.9m), he or she would probably be able to generate more cue speed, let's say 5% more speed (1.05v). In this case, the cue momentum (.9m * 1.05v = .945mv) would be about 5% less than with the original cue. If the same person used a cue 10% heavier (1.10m), and generated 5% less speed (0.95v) as a result, the cue momentum (1.10m * 0.95v = 1.045mv) would be about 5% more than with the original cue. In this case, the slightly heavier cue would be better. If, on the other hand, the additional weight resulted in a greater loss in speed, let's say 15% (0.85v), the cue momentum (1.10m * 0.85v = .935mv) would be about 7% less than with the original cue. In this case the original (lighter) cue would be better.
A good analogy to pool break cue weight selection is baseball bat weight selection. A lighter bat can be swung faster, but a heavier bat has more mass. Some players can generate more bat momentum and ball speed (and distance) with a heavier bat (e.g., Babe Ruth), and some do better with a much lighter bat (e.g., Barry Bonds). An excellent web page dealing with baseball bat weight effects can be found here: Bat Weight, Swing Speed and Ball Velocity. (external web-link)
Notice the ball speed vs. bat weight graphs about 3/4 down on the web page. They are very flat at the optimal weight, implying bat weight doesn't really make that much difference in the range of typical values. This effect should be similar with break cues. If you are in your preferred weight range, an ounce more or less shouldn't make much difference.
One final note concerning cue weight: There is a limit to how light a cue can be before double hits become a problem, especially with large tip offset shots (e.g., maximum sidespin or draw). If the cue is too light, it will stay in contact with or catch up to the CB after the first hit. For sidespin shots, the result will be similar to that of a miscue (i.e., excessive squirt). For more info, see TP A.30 (Download) and "Coriolis was brilliant ... but he didn't have a high-speed camera - Part IV: maximum cue tip offset" (Download) (BD, October, 2005).
From pooltchr:
1. I believe the best weight for any player is the weight that feels most comfortable for all types of shots.
2. I believe that different weights can produce slightly different results, but those differences are so slight that most good players can adapt their stroke to get the desired results regardless of the chosen weight.
3. While a long draw shot does require more speed than a shorter one (adjusting speed and or spin is the only way to control draw)we still don't need to use maximum (break) speed even for maximum draw. For that reason, I think any good player can get the required speed with any weight cue. Those same players would be able to adjust their stroke to compensate for the weight differences in various cues.
4. Since over the course of a game, a player will need to vary speed and spin from shot to shot, the most comfortable weight to the individual player makes the most sense to me. It's easier to make slight adjustments to speed and spin with a well balanced comfortable cue. You can establish a centergistic or reference point for a stroke speed follow shot, then work from there to know what is needed when you need to do something else with the cue ball.
For more info, visit billiards.colostate.edu
Cue Ball Control
Position (Cue Ball) Control in Pool and Billiards
... how to control cue ball motion and play for position at the pool table.
(external web-links) for more information:
see Chapter 5 in The Illustrated Principles of Pool and Billiards,
Disc I and Disc II of the Video Encyclopedia of Pool Shots (VEPS) , and
Disc I and Disc II of the Video Encyclopedia of Pool Practice (VEPP)
45-degree rule for center-table position and routes
What is the 45-degree rule, and how is it used to position the CB at or through the center of the table?
It states that if the CB rolls into the short rail at close to a 45-degree angle, it will head off two rails fairly close to the center of the table. For more info, see the following demonstration from Disc II of the Video Encyclopedia of Pool Shots (VEPS) (external web-link):
YouTube video: 45-degree rule for center-of-table position routes in pool and billiards, from VEPS II (NV B.74)
See "VEPS GEMS - Part III: English and Position Control" (Download) (BD, March, 2010) for more information.
Here's a good drill from Disc II of the Video Encyclopedia of Pool Practice (VEPP) (external web-link) for practicing getting to the center of the table off pocket hangers:
YouTube video: Pool drill for practicing getting center-of-table position off hangers, from VEPP II (NV C.7)
See “VEPP – Part V: Hanger Table-Center Drills,” (Download) (BD, August, 2012) for more information.
Drills for practicing cue ball control and position play
What are some useful drills for getting better at cue ball control and position play?
The following drills are excellent for learning and improving cue ball control and position play: (See drills resource page.
Leaving an angle on a shot and coming into the line of a shot
How do I do this?
See the following demonstration from Disc II of the Video Encyclopedia of Pool Shots: (external web-link)
YouTube video: Leaving an angle and coming into the line of a shot in pool, from VEPS II (NV B.73)
Sometimes, it is important to play for a precise point or line, rather to a general area. Here's an example from Disc III of the Video Encyclopedia of Pool Shots: (external web-link)
YouTube video: Playing for exact position instead of to an area in pool and billiards, from VEPS III (NV B.77)
Nearly straight-in shots
How can I get position on the next shot if the current shot is nearly straight in?
See: NV B.30 - Cue ball position control with nearly straight-in shots.(YouTube)
Rail cut-shot 60-degree rule
How can I predict final cue ball direction for rail cut shots?
For rolling-cue-ball rail cut shots, you can use the 30-degree rule, as illustrated in the diagram below. The peace sign can be used to visualize the expected angle off the OB if the rail were not there, and the mirror of this angle gives you the final cue ball direction. An interesting fact is that the sum of the angle of the initial CB line relative to the rail and the mirror angle relative to the rail normal always adds to 60 degrees (see the quote from mohrt below). This is because 90 - 30 = 60.
... how to control cue ball motion and play for position at the pool table.
(external web-links) for more information:
see Chapter 5 in The Illustrated Principles of Pool and Billiards,
Disc I and Disc II of the Video Encyclopedia of Pool Shots (VEPS) , and
Disc I and Disc II of the Video Encyclopedia of Pool Practice (VEPP)
45-degree rule for center-table position and routes
What is the 45-degree rule, and how is it used to position the CB at or through the center of the table?
It states that if the CB rolls into the short rail at close to a 45-degree angle, it will head off two rails fairly close to the center of the table. For more info, see the following demonstration from Disc II of the Video Encyclopedia of Pool Shots (VEPS) (external web-link):
YouTube video: 45-degree rule for center-of-table position routes in pool and billiards, from VEPS II (NV B.74)
See "VEPS GEMS - Part III: English and Position Control" (Download) (BD, March, 2010) for more information.
Here's a good drill from Disc II of the Video Encyclopedia of Pool Practice (VEPP) (external web-link) for practicing getting to the center of the table off pocket hangers:
YouTube video: Pool drill for practicing getting center-of-table position off hangers, from VEPP II (NV C.7)
See “VEPP – Part V: Hanger Table-Center Drills,” (Download) (BD, August, 2012) for more information.
Drills for practicing cue ball control and position play
What are some useful drills for getting better at cue ball control and position play?
The following drills are excellent for learning and improving cue ball control and position play: (See drills resource page.
- Billiard University (BU) playing-ability exams
- line-of-balls drill
- "playing the ghost" rating drills
- position control drills
- target practice drills
- 3-ball drill
- wagon wheel drills
Leaving an angle on a shot and coming into the line of a shot
How do I do this?
See the following demonstration from Disc II of the Video Encyclopedia of Pool Shots: (external web-link)
YouTube video: Leaving an angle and coming into the line of a shot in pool, from VEPS II (NV B.73)
Sometimes, it is important to play for a precise point or line, rather to a general area. Here's an example from Disc III of the Video Encyclopedia of Pool Shots: (external web-link)
YouTube video: Playing for exact position instead of to an area in pool and billiards, from VEPS III (NV B.77)
Nearly straight-in shots
How can I get position on the next shot if the current shot is nearly straight in?
See: NV B.30 - Cue ball position control with nearly straight-in shots.(YouTube)
Rail cut-shot 60-degree rule
How can I predict final cue ball direction for rail cut shots?
For rolling-cue-ball rail cut shots, you can use the 30-degree rule, as illustrated in the diagram below. The peace sign can be used to visualize the expected angle off the OB if the rail were not there, and the mirror of this angle gives you the final cue ball direction. An interesting fact is that the sum of the angle of the initial CB line relative to the rail and the mirror angle relative to the rail normal always adds to 60 degrees (see the quote from mohrt below). This is because 90 - 30 = 60.
English can be used to alter the path. Also, using stun or draw or less than full forward roll can also be used to alter the path.
from mohrt:
from mohrt:
If you come into the rail at 30 degrees, the path will be 30 degrees out. If you come in at 15 degrees, it will be 45 degrees out. If you come in at 25 degrees, it will be 35 degrees out. Notice it always adds up to 60 degrees.
Scratch avoidance
How do I avoid a scratch in different situations?
See the following video demonstrations: (YouTube and internal)
Speed effects
What effect does shot speed have on the 90-degree and 30-degree rules?
Shot speed has no effect on the 90-degree rule. With a stun shot, the CB heads straight down the tangent line, regardless of speed.
With follow and draw shots, the CB persists along the tangent line longer before curving to the final direction, as demonstrated in this video:
YouTube link
For more information, including the effects of cue elevation, see: HSV B.23 - cue ball path speed, spin, and cue elevation effects. (YouTube)
For more information, see "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (June, 2005).
For more information, see "Draw Shot Primer - Part I: physics" (Download) (January, 2006).
The condition of the cloth also has an effect. With a slicker cloth, the CB persists along the tangent line longer before curving to the final direction.
Useful reference lines
How can I know where the cue ball will go on every type of shot?
See: (YouTube Videos)
YouTube video: Using the 30 and 90 degree rules to break out clusters in pool, from VEPS I (NV B.68)
For more info, see:
Where the CB goes for different types of shots
Where will the cue ball go after it hits an object ball?
For a stun shot, most people know the right answer: in the tangent line direction, perpendicular to the OB direction. This is the 90-degree rule (see "The 90° rule: Part I - the basics" - (Download) BD, January, 2004). If you want a more precise answer that accounts for various effects (e.g., friction and English), see the following instructional articles: (Downloads)
"90° and 30° Rule Follow-up - Part II: speed effects" (BD, March, 2005).
"90° and 30° Rule Follow-up - Part III: inelasticity and friction effects" (BD, April, 2005).
"90° and 30° Rule Follow-up - Part IV: english effects" (BD, May, 2005).
"90° and 30° Rule Follow-up - Part V: the final chapter" (BD, June, 2005).
FYI, here is a convenient one-page summary of the 90-degree rule. (Download)
For a rolling CB, the cue ball changes direction by about 30 degrees for a wide range of cut shots (1/4 to 3/4 ball hit). This is the 30 degree rule (see "The 30° rule: Part I - the basics" - (Download) BD, April, 2004). If you want to be more precise, the angle is a little more (about 34 degrees) closer to a 1/2-ball hit and a little less (about 27 degrees) closer to a 1/4-ball or 3/4-ball hit. If you want to know how to account for speed effects, see "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (BD, June, 2005). If you want an easy way to use your hand to accurately visualize the cue ball direction, use the Dr. Dave peace-sign technique. FYI, here is a convenient one-page summary of the 30-degree rule. (Download)
For a draw shot with good draw action, and for cut angles smaller than about 40 degrees (i.e., ball-hit fraction greater than about 3/8), the trisect system is your answer (see "Draw Shot Primer - Part III: using the trisect system" - (Download) BD, March, 2006). You can use a modified version of the Dr. Dave peace-sign technique to predict the cue ball direction (see the article (Download), NV B.43 (YouTube), and NV B.67 (YouTube) for illustrations and examples).
For shots "in between" all of these different cases, the cue ball will go somewhere in between the indicated directions. The only way to get a feel for how much "in between" the cue ball will go is to practice ... a lot!
For more info, see Disc I and Disc II of the Video Encyclopedia of Pool Shots (external web-links) and: (YouTube Videos)
For roll shots, there are good approximations for the CB deflection angles.
For a fairly full hit, with a ball-hit-fraction greater than 3/4, the CB will deflect about 3-times the cut angle.
For a fairly thin hit, with a ball-hit-fraction less than 1/4, the CB will deflect about 70% of the angle between the aiming line and the tangent line.
See "Rolling Cue Ball Deflection Angle Approximations" (Download) (BD, November, 2011) for illustrations, examples, and more information.
There are similar rules for draw shots. For more information, see "Draw Shot Cue Ball Directions" (Download) (BD, December, 2011).
As with the 30 degree rule and trisect system, the full-hit and thin-hit rules apply to the final direction of the CB. The actual final path of the CB is shifted down the tangent line with higher speed.
Video demonstrations of these types of shots can be found in Disc I of the Video Encyclopedia of Pool Shots. (external web-link)
from Jal (from AZB post (external forum-link), which contains additional information):
When the balls are close enough to each other and/or you're hitting hard enough such that the cue ball doesn't lose any significant backspin on the way to the object ball (or gain more topspin), there is a method of determining the cue ball's direction once it reaches natural roll after the collision. I call it the Bottom-Center-Arrow method, or B-C-A for short, in that it's easy to remember.
Imagine a circle centered on the ghost ball with the bottom of the circle running through the center of the cue ball. This circle represents the face of the cue ball from the shooter's perspective. To determine the CB's roll direction after the collision for any vertical offset (no side spin applied), draw a line from the center of the real cue ball parallel to the line of centers between the ghost ball and the object ball. This will intersect the tangent line at 90 degrees, call it point A. Thus, we have a triangle with the CB at vertex B (bottom of the circle), the ghost ball at C (center of the circle) and point A from which we'll draw an arrow such that it intersects the vertical axis of the large circle. This yields the CB's direction once roll sets in, given that vertical tip offset on the face of cue ball. Here's a diagram:
Scratch avoidance
How do I avoid a scratch in different situations?
See the following video demonstrations: (YouTube and internal)
- NV 3.7 - Using the 90° rule to check for and prevent a scratch
- NV B.25 - Using draw and side spin to beat a scratch in a side pocket, with Tom Ross
- NV B.31 - Using inside English and follow to beat a scratch and get down-table position
- NV B.46 - Cue ball path scratch avoid, cluster break-out, and billiard (carom) examples
- HSV B.12 - Beating a scratch by bouncing the cue ball off the rear rim of a pocket
Speed effects
What effect does shot speed have on the 90-degree and 30-degree rules?
Shot speed has no effect on the 90-degree rule. With a stun shot, the CB heads straight down the tangent line, regardless of speed.
With follow and draw shots, the CB persists along the tangent line longer before curving to the final direction, as demonstrated in this video:
YouTube link
For more information, including the effects of cue elevation, see: HSV B.23 - cue ball path speed, spin, and cue elevation effects. (YouTube)
For more information, see "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (June, 2005).
For more information, see "Draw Shot Primer - Part I: physics" (Download) (January, 2006).
The condition of the cloth also has an effect. With a slicker cloth, the CB persists along the tangent line longer before curving to the final direction.
Useful reference lines
How can I know where the cue ball will go on every type of shot?
See: (YouTube Videos)
- NV B.43 - Cue ball position control stun, roll, and draw reference lines
- NV B.44 - Dr. Dave 30-degree-rule peace-sign hand calibration
- NV B.45 - Cue ball path speed effects
- NV B.46 - Cue ball path scratch avoid, cluster break-out, and billiard (carom) examples
- NV B.60 - Mike Page's Cue Ball Control (part 1)
- NV B.60 - Mike Page's Cue Ball Control (part 2)
- NV B.66 - The 30-degree rule, from VEPS I
- NV B.67 - The trisect system for draw shots, from VEPS I
YouTube video: Using the 30 and 90 degree rules to break out clusters in pool, from VEPS I (NV B.68)
For more info, see:
- "Fundamentals - Part V: CB position control" (Download) (BD, January, 2009)
- "Fundamentals - Part VI: CB control examples" (Download) (BD, February, 2009)
Where the CB goes for different types of shots
Where will the cue ball go after it hits an object ball?
For a stun shot, most people know the right answer: in the tangent line direction, perpendicular to the OB direction. This is the 90-degree rule (see "The 90° rule: Part I - the basics" - (Download) BD, January, 2004). If you want a more precise answer that accounts for various effects (e.g., friction and English), see the following instructional articles: (Downloads)
"90° and 30° Rule Follow-up - Part II: speed effects" (BD, March, 2005).
"90° and 30° Rule Follow-up - Part III: inelasticity and friction effects" (BD, April, 2005).
"90° and 30° Rule Follow-up - Part IV: english effects" (BD, May, 2005).
"90° and 30° Rule Follow-up - Part V: the final chapter" (BD, June, 2005).
FYI, here is a convenient one-page summary of the 90-degree rule. (Download)
For a rolling CB, the cue ball changes direction by about 30 degrees for a wide range of cut shots (1/4 to 3/4 ball hit). This is the 30 degree rule (see "The 30° rule: Part I - the basics" - (Download) BD, April, 2004). If you want to be more precise, the angle is a little more (about 34 degrees) closer to a 1/2-ball hit and a little less (about 27 degrees) closer to a 1/4-ball or 3/4-ball hit. If you want to know how to account for speed effects, see "90° and 30° Rule Follow-up - Part V: the final chapter" (Download) (BD, June, 2005). If you want an easy way to use your hand to accurately visualize the cue ball direction, use the Dr. Dave peace-sign technique. FYI, here is a convenient one-page summary of the 30-degree rule. (Download)
For a draw shot with good draw action, and for cut angles smaller than about 40 degrees (i.e., ball-hit fraction greater than about 3/8), the trisect system is your answer (see "Draw Shot Primer - Part III: using the trisect system" - (Download) BD, March, 2006). You can use a modified version of the Dr. Dave peace-sign technique to predict the cue ball direction (see the article (Download), NV B.43 (YouTube), and NV B.67 (YouTube) for illustrations and examples).
For shots "in between" all of these different cases, the cue ball will go somewhere in between the indicated directions. The only way to get a feel for how much "in between" the cue ball will go is to practice ... a lot!
For more info, see Disc I and Disc II of the Video Encyclopedia of Pool Shots (external web-links) and: (YouTube Videos)
- NV D.11 - Cue Ball Control Target Pool Drill - from Vol-II of the Billiard University instructional DVD series
- NV C.5 - Wagon wheel cue ball control drill, from VEPP II
- NV B.73 - Leaving an angle and coming into the line of a shot, from VEPS II
- NV B.74 - Center-of-table position and routes, with the 45-degree rule, from VEPS II
- NV B.75 - 30-degree-rule natural-angle examples, from VEPS III
- NV B.43 - Cue ball position control stun, roll, and draw reference lines
- NV B.44 - Dr. Dave 30-degree-rule peace-sign hand calibration
- NV B.45 - Cue ball path speed effects
- NV B.46 - Cue ball path scratch avoid, cluster break-out, and billiard (carom) example
- NV B.60 - Mike Page's Cue Ball Control (part 1)
- NV B.60 - Mike Page's Cue Ball Control (part 2)
- NV B.66 - The 30-degree rule, from VEPS I
- NV B.67 - The trisect system for draw shots, from VEPS I
- NV B.68 - Tweener cluster breaks, from VEPS I
- "Fundamentals - Part V: CB position control" (Download) (BD, January, 2009).
- "Fundamentals - Part VI: CB control examples" (Download) (BD, February, 2009).
- the 60-degree rule for rail cut shots(under cue ball(position) section).
- Ralph Eckert's lessons on natural-roll position-play reference lines (YouTube Videos) (part 1, part 2, part 3)
For roll shots, there are good approximations for the CB deflection angles.
For a fairly full hit, with a ball-hit-fraction greater than 3/4, the CB will deflect about 3-times the cut angle.
For a fairly thin hit, with a ball-hit-fraction less than 1/4, the CB will deflect about 70% of the angle between the aiming line and the tangent line.
See "Rolling Cue Ball Deflection Angle Approximations" (Download) (BD, November, 2011) for illustrations, examples, and more information.
There are similar rules for draw shots. For more information, see "Draw Shot Cue Ball Directions" (Download) (BD, December, 2011).
As with the 30 degree rule and trisect system, the full-hit and thin-hit rules apply to the final direction of the CB. The actual final path of the CB is shifted down the tangent line with higher speed.
Video demonstrations of these types of shots can be found in Disc I of the Video Encyclopedia of Pool Shots. (external web-link)
from Jal (from AZB post (external forum-link), which contains additional information):
When the balls are close enough to each other and/or you're hitting hard enough such that the cue ball doesn't lose any significant backspin on the way to the object ball (or gain more topspin), there is a method of determining the cue ball's direction once it reaches natural roll after the collision. I call it the Bottom-Center-Arrow method, or B-C-A for short, in that it's easy to remember.
Imagine a circle centered on the ghost ball with the bottom of the circle running through the center of the cue ball. This circle represents the face of the cue ball from the shooter's perspective. To determine the CB's roll direction after the collision for any vertical offset (no side spin applied), draw a line from the center of the real cue ball parallel to the line of centers between the ghost ball and the object ball. This will intersect the tangent line at 90 degrees, call it point A. Thus, we have a triangle with the CB at vertex B (bottom of the circle), the ghost ball at C (center of the circle) and point A from which we'll draw an arrow such that it intersects the vertical axis of the large circle. This yields the CB's direction once roll sets in, given that vertical tip offset on the face of cue ball. Here's a diagram:
... friction, among other things, has an effect on this idealized geometry.
For more info, visit billiards.colostate.edu
Cue Tip
Billiards and Pool Cue Tip
... properties and physical characteristics of different types of pool cue tips.
Contact time
How long is the tip in contact with the cue ball?
Clips HSV A.77-A.81 and A.147-A.151 (external web-link) show close-ups of cue tip impact for various hardness tips and various speeds. Here are some conclusions:
Some people think that what they do with their grip hand or follow through can change the tip contact time, but this is not the case (i.e., it is not possible to get a significant effect). Also, some people think a softer tip, which has a slightly longer contact time, can create more CB "reaction." This is not the case. The peak force isn't as large with a longer contact time (i.e., the force is spread out over a longer time). Therefore, the "hit" might "feel" slightly different to the player. However, the momentum effects (cue and ball speed changes) will still be the same, assuming the tips being compared have the same efficiency. Another thing that might be different is that a shorter contact time is usually associated with a harder tip, and a harder tip might have better efficiency, so the CB might have slightly more speed and spin with a harder tip for a given cue mass and speed. For more info and resources on these topics, see:
tip hardness effects(cue tip section)
cue tip efficiency(cue tip section)
cue "hit," "feel" and "playability(cue section)
effects of light vs. tight grip(grip section)
stroke acceleration(stroke section)
follow through(stroke section)
from Patrick Johnson:
Longer contact time might increase spin a tiny amount (because the tip rotates a tiny bit farther from center during contact), but not enough to matter - probably not even a noticeable amount.
But longer contact time cannot decrease squirt. In fact, if it increases spin a tiny amount, it also increases squirt a tiny amount.
The bottom line is that increased contact time, even if we could somehow change our stroke to make it happen (which we can't), wouldn't make any significant difference anyway.
Deformation and mushrooming
How much does the tip deform during contact with the cue ball?
Here's an image from some high-speed video filmed by a group from Austria:
... properties and physical characteristics of different types of pool cue tips.
Contact time
How long is the tip in contact with the cue ball?
Clips HSV A.77-A.81 and A.147-A.151 (external web-link) show close-ups of cue tip impact for various hardness tips and various speeds. Here are some conclusions:
- most contact times (i.e., for most tips and most speeds) are very close to a thousandth of a second (0.001 sec).
- a soft tip at slow speed has a longer contact time (about 0.002 sec), but still extremely small.
- a very hard tip (phenolic) at fast speed has a shorter contact time (about 0.0005 sec).
- the contact time decreases slightly for faster speeds, but not by much.
- chalk does not stay on hard tips very well at impact (see the blue clouds that separate from the tips in the videos).
Some people think that what they do with their grip hand or follow through can change the tip contact time, but this is not the case (i.e., it is not possible to get a significant effect). Also, some people think a softer tip, which has a slightly longer contact time, can create more CB "reaction." This is not the case. The peak force isn't as large with a longer contact time (i.e., the force is spread out over a longer time). Therefore, the "hit" might "feel" slightly different to the player. However, the momentum effects (cue and ball speed changes) will still be the same, assuming the tips being compared have the same efficiency. Another thing that might be different is that a shorter contact time is usually associated with a harder tip, and a harder tip might have better efficiency, so the CB might have slightly more speed and spin with a harder tip for a given cue mass and speed. For more info and resources on these topics, see:
tip hardness effects(cue tip section)
cue tip efficiency(cue tip section)
cue "hit," "feel" and "playability(cue section)
effects of light vs. tight grip(grip section)
stroke acceleration(stroke section)
follow through(stroke section)
from Patrick Johnson:
Longer contact time might increase spin a tiny amount (because the tip rotates a tiny bit farther from center during contact), but not enough to matter - probably not even a noticeable amount.
But longer contact time cannot decrease squirt. In fact, if it increases spin a tiny amount, it also increases squirt a tiny amount.
The bottom line is that increased contact time, even if we could somehow change our stroke to make it happen (which we can't), wouldn't make any significant difference anyway.
Deformation and mushrooming
How much does the tip deform during contact with the cue ball?
Here's an image from some high-speed video filmed by a group from Austria:
The full video clip can be viewed at HSV A.76 (YouTube) (it is the third clip in the sequence). The video was shot at 2000 frames per sec with a high-resolution color camera. Here's an isolated clip of the close-up of the tip contact:
I've collected a sequence of images from the video clip and have made them available in MS Word (Download) and PDF (Download) formats. The MS Word file is large (1.7 MB), but it is very useful. If you page down through the file to load all of the images, you can then use the scroll bar to simulate a flip-book animation. The faster you scroll, the faster the simulated "video" plays. The images are 1/2000 second (0.0005 or 5 ten-thousandths of a second) apart.
Here are some observations, insights, and questions from the collection of stills:
- The tip is probably relatively soft based on the contact time and amount of deformation. Contact lasts about 4 frames (over frames 3-6), which corresponds to about two thousandths (0.002) of a second.
- The cue tip seems to stay in contact with the ball as the ball starts to rotate, which might contribute to the amount of cue stick deflection.
- The cue tip had an excessive amount of chalk on it (as evidenced by the pre-impact chalk trail through the air and by the huge chalk cloud after impact).
Here's another excellent video showing the tip dynamics during contact:
YouTube video
Is it important to remove the mushroomed edges of a tip?
If your tip is properly shaped tip and you are hitting the cue ball within the non-miscue zone, the extreme edge of the tip doesn't come into play (e.g., see the diagrams in "Draw Shot Primer - Part VII: tips of English" (Download) - BD, July, 2006).
However, removing the mushroomed edges does:
Efficiency
What affects how well a tip delivers speed to the cue ball?
A hard tip will create slightly more CB speed for a given cue speed. For more info, see:
YouTube video
from Mike Page:
Given that the speed of sound in maple is 4100 m/s, I'm wondering if break cue manufacturers are barking up the wrong tree going to harder and harder tips.
Presumably the motivation for going to hard tips--phenolic or whatever--is a belief that they are more efficient in the way you describe above.
An unintended consequence, though, of these hard tips may be that because the contact time is shorter, there may not be enough time for the ball to "see" the full mass of the stick.
4100 meters/sec is 4 meters per millisecond. A round trip for the compression wave is about 3 meters (two stick lengths). So it takes about three quarters of a millisecond for the cue ball to even have a chance of knowing about the back of the stick.
My guess is the contact time for break tips is in that range.
Why not try an efficient soft tip? Maybe get the contact time up to 1.2 ms or more?
dr_dave's reply:
The harder tips are more efficient (see HSV B.42 - tip and cue efficiency, with Bob Jewett). (YouTube)
My best measurements for phenolic tip contact time gave values close to 1/2 ms, but I didn't test at break speed. For more info, see: Cue Tip Contact Time(cue tip section)
Excellent points and questions. Anecdotally, it seems like the phenolic tips still provide an advantage over softer tips, which currently all seem to be less efficient.
Force
How much force is generated between the tip and the cue ball during a break shot, and what would it take to generate a "ton" of force at the tip?
To keep things simple, let's use a cue weight of 18 oz and assume a perfect tip with a center-ball hit. For this case, TP A.30 (Download) predicts that the outgoing CB speed is about 3/2 (1.5) the incoming cue speed. Let's also assume that the average force during tip contact is about half the peak force. And let's assume the tip is in contact with the ball for 0.001 sec, which is typical.
For any CB speed (vb), given the CB mass (mb), the momentum delivered to the CB is:
mom = mb * vb
For a given duration of contact (dt), this momentum must equal the impulse delivered from the cue:
imp = 1/2 * Fmax * dt
So to find the peak force for a given CB speed:
Fmax = 2*mb*vb/dt
And for a given peak force, the CB speed is:
vb = Fmax*dt/2 / mb
And the cue stick speed required to create this is about:
vs = 2/3 vb = Fmax*dt / 3*mb
For a 20mph break, with a 6oz pool ball, the Fmax equation gives a peak force of:
Fmax = 683 pounds
To achieve a 1 ton (2000 pound) peak force, the vs equation gives a required cue speed of:
vs = 39mph
Hardness effects
Does the tip hardness affect how much English can be applied, or the amount of squirt that results?
Here are some relevant factors:
On a different note, a hard tip will create slightly more CB speed for a given cue speed (see tip efficiency). Some people also prefer a hard tip because they "feel" the force of the shot better (a softer tip dampens the impact a little).
There are many factors related to tip hardness that could influence squirt, including: tip density/weight, tip efficiency, contact time, and effective end mass. "Return of the squirt robot" (Download) (BD, August, 2008) documents an experiment related to the effects of tip hardness on squirt. A softer tip did seem to create slightly more squirt, but the experiment was not very well controlled (see the article (Download) for more info). In general, if the contact time is longer (as is the case with a softer tip), the effective end mass and resulting squirt should be larger (see the rubber-super-ball-tip report (external web-link) as an example). Another set of more careful experiments documented in the Cue and Tip Testing for Cue Ball Deflection (Squirt) video (YouTube) and “Cue Tip Squirt Testing” (Download) (BD, June, 2014). seem to imply that tip type, hardness, and height have very little effect on shaft squirt. Among the wide range of tips tested in the video (YouTube), the harder tips did result in slightly more squirt. This makes sense because the harder tips are denser and heavier, creating more "endmass." The shorter contact time seems to be less of a factor than the added weight.
Another factor involved with a softer tip is that it might better absorb glue and adhere to the ferrule more strongly and making it less likely to come off with lots of use and/or abuse.
from Mike Page:
Here's one more. Even if soft and hard tips held chalk exactly the same, it's possible the soft tip might reduce the chance of miscue. For instance, suppose a miscue occurs when less than 50% of the contact patch has chalk. If the bald regions are small, then this standard may be violated more frequently for a hard tip with its small contact patch.
from Bob Jewett:
One issue is which harness of tip will allow the farther-from-center hit. Some believe that a soft tip takes chalk better so it can hit the ball farther from center.
There is a counter theory, and that is because a softer tip will have a longer contact time than a hard tip. During contact, the tip rides around the side of the ball some, so the final eccentricity as the tip leaves the ball is larger than when the tip first hits the ball. A softer tip, with the longer contact time will be farther off center at the end than a harder tip with the same starting offset. If both tips can only hold to a certain point of offset, and you start your shot so the miscue point is barely reached at the end of contact, the average offset will be larger for the harder tip. This means that the harder tip can create more spin for a given ball speed.
Which dominates? Holding chalk better or starting farther off-center? I don't know of any experiment that has tested this.
Hardness comparison chart
How hard are some tip brands relative to others?
Here is a very thorough chart of tip types and hardnesses for a wide assortment of brands (Download) (from jschelin99 on AZB (external forum-link))
Here is a summary of some durometer hardness test results from FLYINGSNAIL on AZB.(external forum-link)
SAMSARA JUMP - 86.0
BLACK DIAMOND - 81.0
SUPERPRO - 81.0
WB USA - 77.0
BLUE ELF - 76.0
LePRO - 74.5
TALISMAN - (M) 70.5
TAD - (M) 75.0
TRIANGLE - 73.5
"Blue milk duds" - 73.0-74.0
KAMUI - (H. BROWN) 73.5; (M. BROWN) 71.0; (S. BROWN) 62.5; (H. BLACK) 73.5; (M. BLACK) 72.5; (S. BLACK) 62.0
MORRI - (1ST GEN. WITH "S" ONLY) 62.0; (2ND GEN. SOFT) 71.0; (OLD MEDIUM) 77.0; (M III) 75.0
TRIUMPH - 70.0
BLACK KING - (S) 65.5 (M) 67.5 (H) 70.5
TIGER SNIPER - 67.0
BAMMA - 66.0
OLD ELK MASTER ORIGINAL - 65.0
and here's a buying guide (with some useful info) available from PoolDawg (external web-link), including a large set of hardness data for most-commonly-used tips.
How to replace a cue tip
How do you replace the tip on a cue?
The following videos demonstrate the process and tools needs to replace a cue tip:
cue tip replacement (Seyberts) (YouTube)
replacing a cue tip (Home Billiards) (YouTube)
Recommended brands
What brands of tip are commonly recommended?
Morri, Sniper, Triangle, and Kamui.
Size and shape
Does the tip and shaft size and shape make a difference?
For applying english, a smaller-diameter and rounder tip (approximately dime radius) is generally recommended. Here are some possible reasons:
Here's an expanded diagram from "Squirt - Part VI: tip shape" (Download) (BD, January, 2008) that illustrates tip shape effects:
Here are some observations, insights, and questions from the collection of stills:
- The tip is probably relatively soft based on the contact time and amount of deformation. Contact lasts about 4 frames (over frames 3-6), which corresponds to about two thousandths (0.002) of a second.
- The cue tip seems to stay in contact with the ball as the ball starts to rotate, which might contribute to the amount of cue stick deflection.
- The cue tip had an excessive amount of chalk on it (as evidenced by the pre-impact chalk trail through the air and by the huge chalk cloud after impact).
Here's another excellent video showing the tip dynamics during contact:
YouTube video
Is it important to remove the mushroomed edges of a tip?
If your tip is properly shaped tip and you are hitting the cue ball within the non-miscue zone, the extreme edge of the tip doesn't come into play (e.g., see the diagrams in "Draw Shot Primer - Part VII: tips of English" (Download) - BD, July, 2006).
However, removing the mushroomed edges does:
- make the tip look prettier, and it might be less visually distracting to some.
- feel better if you happen to pull the tip back through your bridge during your stroke (which isn't recommended).
Efficiency
What affects how well a tip delivers speed to the cue ball?
A hard tip will create slightly more CB speed for a given cue speed. For more info, see:
YouTube video
from Mike Page:
Given that the speed of sound in maple is 4100 m/s, I'm wondering if break cue manufacturers are barking up the wrong tree going to harder and harder tips.
Presumably the motivation for going to hard tips--phenolic or whatever--is a belief that they are more efficient in the way you describe above.
An unintended consequence, though, of these hard tips may be that because the contact time is shorter, there may not be enough time for the ball to "see" the full mass of the stick.
4100 meters/sec is 4 meters per millisecond. A round trip for the compression wave is about 3 meters (two stick lengths). So it takes about three quarters of a millisecond for the cue ball to even have a chance of knowing about the back of the stick.
My guess is the contact time for break tips is in that range.
Why not try an efficient soft tip? Maybe get the contact time up to 1.2 ms or more?
dr_dave's reply:
The harder tips are more efficient (see HSV B.42 - tip and cue efficiency, with Bob Jewett). (YouTube)
My best measurements for phenolic tip contact time gave values close to 1/2 ms, but I didn't test at break speed. For more info, see: Cue Tip Contact Time(cue tip section)
Excellent points and questions. Anecdotally, it seems like the phenolic tips still provide an advantage over softer tips, which currently all seem to be less efficient.
Force
How much force is generated between the tip and the cue ball during a break shot, and what would it take to generate a "ton" of force at the tip?
To keep things simple, let's use a cue weight of 18 oz and assume a perfect tip with a center-ball hit. For this case, TP A.30 (Download) predicts that the outgoing CB speed is about 3/2 (1.5) the incoming cue speed. Let's also assume that the average force during tip contact is about half the peak force. And let's assume the tip is in contact with the ball for 0.001 sec, which is typical.
For any CB speed (vb), given the CB mass (mb), the momentum delivered to the CB is:
mom = mb * vb
For a given duration of contact (dt), this momentum must equal the impulse delivered from the cue:
imp = 1/2 * Fmax * dt
So to find the peak force for a given CB speed:
Fmax = 2*mb*vb/dt
And for a given peak force, the CB speed is:
vb = Fmax*dt/2 / mb
And the cue stick speed required to create this is about:
vs = 2/3 vb = Fmax*dt / 3*mb
For a 20mph break, with a 6oz pool ball, the Fmax equation gives a peak force of:
Fmax = 683 pounds
To achieve a 1 ton (2000 pound) peak force, the vs equation gives a required cue speed of:
vs = 39mph
Hardness effects
Does the tip hardness affect how much English can be applied, or the amount of squirt that results?
Here are some relevant factors:
- A hard tip holds its shape better over time, in general.
- Tip hardness (within the typical range) should not have a significant or direct effect on the amount of English that can be applied.
- The amount of English is limited by the tip offset that creates a miscue.
- A tip not "treated" (e.g., scuffed) properly, will not hold chalk very well, and miscues will be more likely at smaller tip offsets. A harder tip might require more attention in this regard.
- Soft tips seem to hold chalk better than hard tips, in general.
- A soft tip will give the cue a softer "feel" (less impact in grip hand) and have a different sound than a hard tip. Some people prefer some sounds and "feels" more than others.
On a different note, a hard tip will create slightly more CB speed for a given cue speed (see tip efficiency). Some people also prefer a hard tip because they "feel" the force of the shot better (a softer tip dampens the impact a little).
There are many factors related to tip hardness that could influence squirt, including: tip density/weight, tip efficiency, contact time, and effective end mass. "Return of the squirt robot" (Download) (BD, August, 2008) documents an experiment related to the effects of tip hardness on squirt. A softer tip did seem to create slightly more squirt, but the experiment was not very well controlled (see the article (Download) for more info). In general, if the contact time is longer (as is the case with a softer tip), the effective end mass and resulting squirt should be larger (see the rubber-super-ball-tip report (external web-link) as an example). Another set of more careful experiments documented in the Cue and Tip Testing for Cue Ball Deflection (Squirt) video (YouTube) and “Cue Tip Squirt Testing” (Download) (BD, June, 2014). seem to imply that tip type, hardness, and height have very little effect on shaft squirt. Among the wide range of tips tested in the video (YouTube), the harder tips did result in slightly more squirt. This makes sense because the harder tips are denser and heavier, creating more "endmass." The shorter contact time seems to be less of a factor than the added weight.
Another factor involved with a softer tip is that it might better absorb glue and adhere to the ferrule more strongly and making it less likely to come off with lots of use and/or abuse.
from Mike Page:
Here's one more. Even if soft and hard tips held chalk exactly the same, it's possible the soft tip might reduce the chance of miscue. For instance, suppose a miscue occurs when less than 50% of the contact patch has chalk. If the bald regions are small, then this standard may be violated more frequently for a hard tip with its small contact patch.
from Bob Jewett:
One issue is which harness of tip will allow the farther-from-center hit. Some believe that a soft tip takes chalk better so it can hit the ball farther from center.
There is a counter theory, and that is because a softer tip will have a longer contact time than a hard tip. During contact, the tip rides around the side of the ball some, so the final eccentricity as the tip leaves the ball is larger than when the tip first hits the ball. A softer tip, with the longer contact time will be farther off center at the end than a harder tip with the same starting offset. If both tips can only hold to a certain point of offset, and you start your shot so the miscue point is barely reached at the end of contact, the average offset will be larger for the harder tip. This means that the harder tip can create more spin for a given ball speed.
Which dominates? Holding chalk better or starting farther off-center? I don't know of any experiment that has tested this.
Hardness comparison chart
How hard are some tip brands relative to others?
Here is a very thorough chart of tip types and hardnesses for a wide assortment of brands (Download) (from jschelin99 on AZB (external forum-link))
Here is a summary of some durometer hardness test results from FLYINGSNAIL on AZB.(external forum-link)
SAMSARA JUMP - 86.0
BLACK DIAMOND - 81.0
SUPERPRO - 81.0
WB USA - 77.0
BLUE ELF - 76.0
LePRO - 74.5
TALISMAN - (M) 70.5
TAD - (M) 75.0
TRIANGLE - 73.5
"Blue milk duds" - 73.0-74.0
KAMUI - (H. BROWN) 73.5; (M. BROWN) 71.0; (S. BROWN) 62.5; (H. BLACK) 73.5; (M. BLACK) 72.5; (S. BLACK) 62.0
MORRI - (1ST GEN. WITH "S" ONLY) 62.0; (2ND GEN. SOFT) 71.0; (OLD MEDIUM) 77.0; (M III) 75.0
TRIUMPH - 70.0
BLACK KING - (S) 65.5 (M) 67.5 (H) 70.5
TIGER SNIPER - 67.0
BAMMA - 66.0
OLD ELK MASTER ORIGINAL - 65.0
and here's a buying guide (with some useful info) available from PoolDawg (external web-link), including a large set of hardness data for most-commonly-used tips.
How to replace a cue tip
How do you replace the tip on a cue?
The following videos demonstrate the process and tools needs to replace a cue tip:
cue tip replacement (Seyberts) (YouTube)
replacing a cue tip (Home Billiards) (YouTube)
Recommended brands
What brands of tip are commonly recommended?
Morri, Sniper, Triangle, and Kamui.
Size and shape
Does the tip and shaft size and shape make a difference?
For applying english, a smaller-diameter and rounder tip (approximately dime radius) is generally recommended. Here are some possible reasons:
- The smaller, rounder shape allows for a more uniform contact area as the tip offset is increased. If you have The Illustrated Principles of Pool and Billiards (external web-link), this is illustrated in Figure 2.2 on pg. 18. This could help make miscues less likely at large tip offsets.
- A smaller tip and shaft will have less endmass and squirt. There are possible advantages and disadvantages with a lower-squirt shaft.
- A smaller tip might make it easier for some people to visualize and pinpoint the desired tip contact point on the cue ball.
- With large tip-offset draw shots, you get more table clearance (see "Draw Shot Primer - Part VII: tips of english" (Download) - BD, July, 2006 for illustrations) with a smaller and rounder tip.
- For shots with English, the impact is more centralized to the core of the cue for a smaller, rounder tip. This might result in a better "feel" for some people with firm shots.
Here's an expanded diagram from "Squirt - Part VI: tip shape" (Download) (BD, January, 2008) that illustrates tip shape effects:
Another concern related to shaft diameter is bridge comfort. With a closed bridge, some shaft sizes and tapers will be more comfortable than others to different individuals. This is less of a concern with an open bridge.
The shaft size and tip shape can also influence how some people apply English if they use "tips" of English and/or an aim-and-pivot squirt compensation system (e.g., BHE). This might make some people think they are getting more or less English with different size and shape tips. For more info, see "Squirt - Part VI: tip shape" (Download) (BD, January, 2008).
Tip shape can also affect the results of squirt-testing machines that position the shaft and CB the same with each test. If the tip shape is different from one shaft to the next, the effective tip offset will be different, creating a slightly different amount of squirt, with everything else being equal. This could have an adverse effect on squirt-testing results. In comparing shafts, identical tips should be used. Each shaft should be tested with the same tip size, shape, height, hardness, and weight.
from Patrick Johnson (from AZB post): (external web-link)
The shaft size and tip shape can also influence how some people apply English if they use "tips" of English and/or an aim-and-pivot squirt compensation system (e.g., BHE). This might make some people think they are getting more or less English with different size and shape tips. For more info, see "Squirt - Part VI: tip shape" (Download) (BD, January, 2008).
Tip shape can also affect the results of squirt-testing machines that position the shaft and CB the same with each test. If the tip shape is different from one shaft to the next, the effective tip offset will be different, creating a slightly different amount of squirt, with everything else being equal. This could have an adverse effect on squirt-testing results. In comparing shafts, identical tips should be used. Each shaft should be tested with the same tip size, shape, height, hardness, and weight.
from Patrick Johnson (from AZB post): (external web-link)
(The diagram above) shows four tips touching the cue ball at 30 degrees offset from center (about halfway from center to edge), which is about where the miscue limit is no matter what the size or shape of your tip.
There are two shaft diameters shown: top = 12.75 mm; bottom = 10 mm.
There are two tip shapes shown: left = nickel radius; right = dime radius.
As you can see, the larger diameter shaft (at top) contacts the cue ball farther from its edge at the miscue limit, and there's room at the edge of the tip to spare with either tip shape. This is because a 60-degree arc (30 degrees in each direction) on a nickel or dime radius is smaller than 12.75 mm wide.
The smaller diameter shaft (at bottom) still has a small amount of room at the edge of the tip with the dime shape, but is right on the edge with the nickel shape. This is because a 60-degree arc (30 degrees in each direction) on a nickel radius is just about 10 mm wide and on a dime radius it's just a little less than 10 mm wide.
Conclusions:
- Nickel or dime radius only makes a difference on very small diameter tips.
- On very small tips it's better to have a dime radius than a nickel radius.
There are two shaft diameters shown: top = 12.75 mm; bottom = 10 mm.
There are two tip shapes shown: left = nickel radius; right = dime radius.
As you can see, the larger diameter shaft (at top) contacts the cue ball farther from its edge at the miscue limit, and there's room at the edge of the tip to spare with either tip shape. This is because a 60-degree arc (30 degrees in each direction) on a nickel or dime radius is smaller than 12.75 mm wide.
The smaller diameter shaft (at bottom) still has a small amount of room at the edge of the tip with the dime shape, but is right on the edge with the nickel shape. This is because a 60-degree arc (30 degrees in each direction) on a nickel radius is just about 10 mm wide and on a dime radius it's just a little less than 10 mm wide.
Conclusions:
- Nickel or dime radius only makes a difference on very small diameter tips.
- On very small tips it's better to have a dime radius than a nickel radius.
For more info, visit billiards.colostate.edu
Cut Shot
Cut Shot in Pool and Billiards
... various effects, measures, and techniques related to a pool cut shot.
(external web-links) For more information:
see Chapter 3 in The Illustrated Principles of Pool and Billiards
and Disc I of the Video Encyclopedia of Pool Shots
Back cut
What is a back cut and why is it tougher than a regular cut?
A back cut is a cut shot where the cue ball is shot well away from the target pocket (e.g., when the cue ball is much closer to the target pocket rail than the object ball). These shots can be more difficult than cut shots looking toward a pocket because the required cut angle can appear larger than it actually is, because you are looking away from the pocket. As a result, most people tend to over cut back cuts (i.e., they are hit too thin). For more info, see shot #6 in VEPS-I (external web-link). Also, with back cuts, because you are looking away from the pocket and the near rail adjacent to the pocket, the visual cues for the pocket location are not as clear as with non-back-cuts (where you are looking toward both rails adjacent to the pocket, helping to provide better visualization of the pocket location).
A back cut up to (and even more than) 90 degrees is possible with the help of outside English (OE) . Diagram 2 in "Throw - Part VI: inside/outside English" (Download) (BD, January, 2007) shows how much OE is necessary for "gearing" OE (resulting in no throw). For a 90-degree cut, 80% English is "gearing," so to throw the ball in the SIT direction with a very thin cut, you need more than 80% English. For more info, see:
HSV B.33 - Outside English gearing, and cut and spin-induced throw (YouTube)
NV B.86 - Cut-induced throw (CIT) and spin-induced throw (SIT), from VEPS IV (YouTube)
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
from Patrick Johnson:
When we shoot back cuts we're looking away from some important visual cues, namely the pocket and the rails that point to it. We learned to use these cues to help us see the OB-to-pocket line and find the contact point/cut angle without all the walking around (the usual reason for innovation). But we learned them subliminally, so we don't notice that we're using them and don't know what's wrong when they're gone.
Once we do know what's wrong, the simple solution is obvious: revert to walking around and sighting the OB-to-pocket line as we did before learning to use the visual cues (or resort to the stick-pivot method or any other "mechanical" method to get a fix on the contact point/cut angle).
AIMING TIP:
The main difference between back cuts and other cuts is that there's no nearby rail behind the OB to show you the direction to the pocket. So a useful trick for aiming back cuts is to "replace" the rail by imagining one right behind the OB pointing to the pocket. Sounds a little nutty, but this often helps to see where to hit the OB. It even helps on non-back cuts where the OB is farther from the rail (this is why OBs in the middle of the table can be harder to aim).
The rail behind the OB is an important visual "cue" - I find OBs on or near the rail much easier to aim.
Ball-hit fraction vs. cut angle
How is cut angle related to ball-hit fraction?
Illustrations, equations, plots, and numbers on this topic are available here:
TP A.23 - Ball-hit fraction vs. cut angle (Download)
Here's a useful illustration from “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011) defining the standard ball-hit fractions:
... various effects, measures, and techniques related to a pool cut shot.
(external web-links) For more information:
see Chapter 3 in The Illustrated Principles of Pool and Billiards
and Disc I of the Video Encyclopedia of Pool Shots
Back cut
What is a back cut and why is it tougher than a regular cut?
A back cut is a cut shot where the cue ball is shot well away from the target pocket (e.g., when the cue ball is much closer to the target pocket rail than the object ball). These shots can be more difficult than cut shots looking toward a pocket because the required cut angle can appear larger than it actually is, because you are looking away from the pocket. As a result, most people tend to over cut back cuts (i.e., they are hit too thin). For more info, see shot #6 in VEPS-I (external web-link). Also, with back cuts, because you are looking away from the pocket and the near rail adjacent to the pocket, the visual cues for the pocket location are not as clear as with non-back-cuts (where you are looking toward both rails adjacent to the pocket, helping to provide better visualization of the pocket location).
A back cut up to (and even more than) 90 degrees is possible with the help of outside English (OE) . Diagram 2 in "Throw - Part VI: inside/outside English" (Download) (BD, January, 2007) shows how much OE is necessary for "gearing" OE (resulting in no throw). For a 90-degree cut, 80% English is "gearing," so to throw the ball in the SIT direction with a very thin cut, you need more than 80% English. For more info, see:
HSV B.33 - Outside English gearing, and cut and spin-induced throw (YouTube)
NV B.86 - Cut-induced throw (CIT) and spin-induced throw (SIT), from VEPS IV (YouTube)
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
from Patrick Johnson:
When we shoot back cuts we're looking away from some important visual cues, namely the pocket and the rails that point to it. We learned to use these cues to help us see the OB-to-pocket line and find the contact point/cut angle without all the walking around (the usual reason for innovation). But we learned them subliminally, so we don't notice that we're using them and don't know what's wrong when they're gone.
Once we do know what's wrong, the simple solution is obvious: revert to walking around and sighting the OB-to-pocket line as we did before learning to use the visual cues (or resort to the stick-pivot method or any other "mechanical" method to get a fix on the contact point/cut angle).
AIMING TIP:
The main difference between back cuts and other cuts is that there's no nearby rail behind the OB to show you the direction to the pocket. So a useful trick for aiming back cuts is to "replace" the rail by imagining one right behind the OB pointing to the pocket. Sounds a little nutty, but this often helps to see where to hit the OB. It even helps on non-back cuts where the OB is farther from the rail (this is why OBs in the middle of the table can be harder to aim).
The rail behind the OB is an important visual "cue" - I find OBs on or near the rail much easier to aim.
Ball-hit fraction vs. cut angle
How is cut angle related to ball-hit fraction?
Illustrations, equations, plots, and numbers on this topic are available here:
TP A.23 - Ball-hit fraction vs. cut angle (Download)
Here's a useful illustration from “Aim, Align, Sight - Part I: Introduction and Ghost Ball Systems” (Download) (BD, June, 2011) defining the standard ball-hit fractions:
from Bob_Jewett (from AZB post (external forum-link)):
Here is a plot of the cut angle you get versus the fullness of hit. For example, a fullness of 0.5 -- an exact half-ball hit -- gives a cut angle of 30 degrees. (This ignores throw which can be several degrees depending on speed, spin, cut angle and ball conditions, but that is mostly a separate issue.) A couple of other fullness to note are 3/4 full which gives an angle slightly under 15 degrees and 1/4 full which produces about a 48-degree cut.
Here is a plot of the cut angle you get versus the fullness of hit. For example, a fullness of 0.5 -- an exact half-ball hit -- gives a cut angle of 30 degrees. (This ignores throw which can be several degrees depending on speed, spin, cut angle and ball conditions, but that is mostly a separate issue.) A couple of other fullness to note are 3/4 full which gives an angle slightly under 15 degrees and 1/4 full which produces about a 48-degree cut.
Estimating cut angle
How can you estimate the cut angle for a shot?
On Disc I of the Video Encyclopedia of Pool Shots(external web-link), we show how to use your hand to recognize 1/4-ball, 1/2-ball, and 3/4-ball hits. We also show how to calibrate your hand so you can judge these shots (and the corresponding cut angles) fairly accurately. Knowing these three angles well can help you estimate the angle required for any shot. The cut angles for various ball-hit fractions can be found at the end of TP A.23 (Download).
A simple way to visualize and estimate cut angles is to imagine an analog clock face (or use one on your wrist). If noon (12) is straight (0 degrees), 11 and 1 are at 30 degrees (1/2-ball hit), 10 and 2 are at 60 degrees (about an 1/8-ball hit), and each minute is 6 degrees. For example, halfway between 12 and 1 ( at 2 1/2 minutes) is 15 degrees (about a 3/4-ball hit), and halfway between 1 and 2 is 45 degrees (about a 1/4-ball hit).
Below is a template posted by oldschool1478 (in AZB post (external forum-link)) that can be useful to estimate cut angles and required aim points when practicing. Here's a printable PDF version (Download). If the center of the cutout is placed over the necessary ghost-ball position with the arrow pointed back to the cue ball, sighting to the pocket gives the necessary cut angle, clock position, ghost-ball overlap, and aim point (center of small circle) relative to the object ball. For example, the required aim for a 30 degree cut (assuming no throw) is through the edge of the object ball. The dashed ghost-balls in the small illustrations are useful to get a sense for the amount of ball overlap required on a particular shot.
How can you estimate the cut angle for a shot?
On Disc I of the Video Encyclopedia of Pool Shots(external web-link), we show how to use your hand to recognize 1/4-ball, 1/2-ball, and 3/4-ball hits. We also show how to calibrate your hand so you can judge these shots (and the corresponding cut angles) fairly accurately. Knowing these three angles well can help you estimate the angle required for any shot. The cut angles for various ball-hit fractions can be found at the end of TP A.23 (Download).
A simple way to visualize and estimate cut angles is to imagine an analog clock face (or use one on your wrist). If noon (12) is straight (0 degrees), 11 and 1 are at 30 degrees (1/2-ball hit), 10 and 2 are at 60 degrees (about an 1/8-ball hit), and each minute is 6 degrees. For example, halfway between 12 and 1 ( at 2 1/2 minutes) is 15 degrees (about a 3/4-ball hit), and halfway between 1 and 2 is 45 degrees (about a 1/4-ball hit).
Below is a template posted by oldschool1478 (in AZB post (external forum-link)) that can be useful to estimate cut angles and required aim points when practicing. Here's a printable PDF version (Download). If the center of the cutout is placed over the necessary ghost-ball position with the arrow pointed back to the cue ball, sighting to the pocket gives the necessary cut angle, clock position, ghost-ball overlap, and aim point (center of small circle) relative to the object ball. For example, the required aim for a 30 degree cut (assuming no throw) is through the edge of the object ball. The dashed ghost-balls in the small illustrations are useful to get a sense for the amount of ball overlap required on a particular shot.
from Bob Jewett:
The tip of the cue is at the center of the ghost ball. The distance X is the base of an isosceles triangle. If X is measured in quarter inches, it gives the angle, pretty nearly.
The tip of the cue is at the center of the ghost ball. The distance X is the base of an isosceles triangle. If X is measured in quarter inches, it gives the angle, pretty nearly.
Here are x (in) x (in/4) actual angle and error:
1 4 3.82 0.18
2 8 7.65 0.35
3 12 11.48 0.52
4 16 15.32 0.68
5 20 19.19 0.81
6 24 23.07 0.93
7 28 26.99 1.01
8 32 30.93 1.07
9 36 34.92 1.08
10 40 38.94 1.06
11 44 43.02 0.98
12 48 47.16 0.84
13 52 51.36 0.64
14 56 55.64 0.36
15 60 60.00 0.00
16 64 64.46 -0.46
17 68 69.04 -1.04
18 72 73.74 -1.74
19 76 78.59 -2.59
from Dead Crab:
I have a way of estimating cut angles to within a degree. It works for me. Estimating to within 5 degrees would be a cinch.
1. Place a small piece of tape (blue painter's tape is good) on your cue shaft 15" from the tip.
2. Place tip of cue on the CB-OB line so that the 15" mark on the cue is over the top of the CB (obviously, not touching it).
3. Leaving the tip stationary, swing the butt of the cue so that the alignment of the cue long axis is parallel to the line of the OB-intended pocket.
4. Estimate the distance (in inches) from the tape mark on the cue to the CB-OB line (i.e. drop a perpendicular to the CB-OB line from the mark on the cue. Multiply this distance by 4. That is your cut angle, in degrees.
With a little practice, the difference between 3.5" and 4" is obvious, and clearly distinguishes a 14 degree from a 16 degree cut angle. For longer shots, you can use the cue joint rather than the 15" mark, and multiply by 2 instead of 4 to get the cut angle.
From a practical viewpoint, it is important to note that the tip of the cue need not be at the GB center. Since the GB center may be 7' away, a more practical approach is to place the 15" mark on your cue over the CB, with the tip on the estimated CB-GB line (as discussed, for long shots the CB-OB line is often adequate for longer shots). Then pivot the cue around the tip until it lies parallel to the OB-pocket line. Estimate the base of the triangle in inches, multiply by 4, and you are done. For really close shots the method can be used by extending the estimated CB-OB line "behind" the CB. This saves a lot of reaching. For intermediate and long shots, the 30" point of the cue is often easiest to use (just 1" above joint), and then the multiplier is 2 instead of 4.
If you know the cut angle, you know where to aim from the CB center. 1 mm per degree up to 30 degrees and above that, 0.8 mm/degree off ball edge over 30 degrees covers it pretty well. Ball landmarks come in handy. A visible gap becomes apparent between cloth and ball at about 10 mm off center (napped), 7-8 mm worsted. A 20 degree cut can be aimed at 7:30 or 4:30 on the clock face, a 25 degree shot at 8:00 or 4:00. A 23 degree cut is 2 mm shy of a 25 and 3 mm more than a 20.
"impossible" cut shots
Is it possible to make a shot with an effective cut angle greater than 90 degrees?
Yes. Here are several examples:
1 4 3.82 0.18
2 8 7.65 0.35
3 12 11.48 0.52
4 16 15.32 0.68
5 20 19.19 0.81
6 24 23.07 0.93
7 28 26.99 1.01
8 32 30.93 1.07
9 36 34.92 1.08
10 40 38.94 1.06
11 44 43.02 0.98
12 48 47.16 0.84
13 52 51.36 0.64
14 56 55.64 0.36
15 60 60.00 0.00
16 64 64.46 -0.46
17 68 69.04 -1.04
18 72 73.74 -1.74
19 76 78.59 -2.59
from Dead Crab:
I have a way of estimating cut angles to within a degree. It works for me. Estimating to within 5 degrees would be a cinch.
1. Place a small piece of tape (blue painter's tape is good) on your cue shaft 15" from the tip.
2. Place tip of cue on the CB-OB line so that the 15" mark on the cue is over the top of the CB (obviously, not touching it).
3. Leaving the tip stationary, swing the butt of the cue so that the alignment of the cue long axis is parallel to the line of the OB-intended pocket.
4. Estimate the distance (in inches) from the tape mark on the cue to the CB-OB line (i.e. drop a perpendicular to the CB-OB line from the mark on the cue. Multiply this distance by 4. That is your cut angle, in degrees.
With a little practice, the difference between 3.5" and 4" is obvious, and clearly distinguishes a 14 degree from a 16 degree cut angle. For longer shots, you can use the cue joint rather than the 15" mark, and multiply by 2 instead of 4 to get the cut angle.
From a practical viewpoint, it is important to note that the tip of the cue need not be at the GB center. Since the GB center may be 7' away, a more practical approach is to place the 15" mark on your cue over the CB, with the tip on the estimated CB-GB line (as discussed, for long shots the CB-OB line is often adequate for longer shots). Then pivot the cue around the tip until it lies parallel to the OB-pocket line. Estimate the base of the triangle in inches, multiply by 4, and you are done. For really close shots the method can be used by extending the estimated CB-OB line "behind" the CB. This saves a lot of reaching. For intermediate and long shots, the 30" point of the cue is often easiest to use (just 1" above joint), and then the multiplier is 2 instead of 4.
If you know the cut angle, you know where to aim from the CB center. 1 mm per degree up to 30 degrees and above that, 0.8 mm/degree off ball edge over 30 degrees covers it pretty well. Ball landmarks come in handy. A visible gap becomes apparent between cloth and ball at about 10 mm off center (napped), 7-8 mm worsted. A 20 degree cut can be aimed at 7:30 or 4:30 on the clock face, a 25 degree shot at 8:00 or 4:00. A 23 degree cut is 2 mm shy of a 25 and 3 mm more than a 20.
"impossible" cut shots
Is it possible to make a shot with an effective cut angle greater than 90 degrees?
Yes. Here are several examples:
See also:
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
Impossible cuts can also be made by jumping or hopping the CB so it hits the OB while airborne. More info and video demonstrations of this can be found here:
jump shot over cut effects(see jump shots section)
Margin for error
How does the difficulty of a shot vary with cut angle?
The following analysis (which includes several useful graphs) shows how the margin for error varies with both shot distance and cut angle:
TP 3.4 - Margin of error based on distance and cut angle (Download)
Also, the effective size of the pocket varies with angle and speed. For more info, see: pocket "size" and "center"(see pockets section)
from Bob_Jewett:
An article that discusses how the angle increases the difficulty of a shot (which is to say, decreases the allowed error), is at: http://www.sfbilliards.com/articles/1994.pdf (April) (Download)
The article includes a simple graphical way to see how much the cut angle increases the difficulty over a straight-in shot of the same length.
Over-cutting
Why do people over-cut cut shots (i.e., hit OB ball too thin)?
Sometimes the aim is just off. When using english (especially outside english), swerve and/or throw might be the culprit. For more info, see:
aim compensation for squirt, swerve, and throw(see aiming section)
On firm follow shots and/or jump shots, sometimes the OB is over-cut because the CB is airborne when it hits the OB. For more info, see:
jump shot overcut effect(see jump shots section)
follow shot ball-hop effects(see follow section)
from Bob Jewett:
There is some throw on all shots. That is, the surface of the cue ball is somewhat sticky, and as it passes across the surface of the object ball, it will pull the object ball off the ideal path, which is the line through the centers of the two balls at the instant of contact.
If the cue ball is moving faster, there is not as much friction. This is contrary to the simple explanation of friction which says that the coefficient of friction does not change with the force of the contact. The reduction seems to be over a factor of two as you crank the speed up
If you have stun on the cue ball (no follow or draw), the throw you see on a cut shot is maximized for that speed because all the rubbing is to the side. As you add draw or follow, the effective friction is reduced because part of the rubbing is up or down, and that doesn't contribute to the throw.
Most players have no idea that this stuff is going on, and to some extent it is better for them not to know. They learn subconsciously to make corrections for it, and if they start thinking about it during shots, their brain will get in the way of their arm.
There are fairly simple demonstrations for this. It is discussed on Dr. Dave's web site (external web-link) and in Bob Jewett's May '06 BD article (Download).
The cue ball also jumps on hard shots as mentioned above, but this causes thinner cuts mostly for short distances to the object ball or excess stick elevation.
Speed and travel distances for the CB and OB
How do CB and OB speeds and travel distances vary with cut angle?
See "Fundamentals - Part VII: speed control" (Download) (BD, March, 2009). It includes distance graphs for both stun and rolling CB shots.
For more information, see the ball speed and travel distance section.
Undercutting
Why do some people undercut some cut shots (i.e., hit OB ball too full)?
Some people have trouble visualizing the required ghost-ball center for a cut shot, and get influenced too much by the ball contact point. For more info and illustrations, see "Fundamentals - Part II: aiming" (Download) (BD, October, 2008).
Sometimes, cut-induced throw (CIT) is the cause; and when english (especially inside english), swerve and/or throw might be the culprit. For more info, see:
aim compensation for squirt, swerve, and throw(see aiming section)
One way to compensate for undercutting the ball is to use outside English, but this isn't the best approach for all people. For more info, see: English section
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
Impossible cuts can also be made by jumping or hopping the CB so it hits the OB while airborne. More info and video demonstrations of this can be found here:
jump shot over cut effects(see jump shots section)
Margin for error
How does the difficulty of a shot vary with cut angle?
The following analysis (which includes several useful graphs) shows how the margin for error varies with both shot distance and cut angle:
TP 3.4 - Margin of error based on distance and cut angle (Download)
Also, the effective size of the pocket varies with angle and speed. For more info, see: pocket "size" and "center"(see pockets section)
from Bob_Jewett:
An article that discusses how the angle increases the difficulty of a shot (which is to say, decreases the allowed error), is at: http://www.sfbilliards.com/articles/1994.pdf (April) (Download)
The article includes a simple graphical way to see how much the cut angle increases the difficulty over a straight-in shot of the same length.
Over-cutting
Why do people over-cut cut shots (i.e., hit OB ball too thin)?
Sometimes the aim is just off. When using english (especially outside english), swerve and/or throw might be the culprit. For more info, see:
aim compensation for squirt, swerve, and throw(see aiming section)
On firm follow shots and/or jump shots, sometimes the OB is over-cut because the CB is airborne when it hits the OB. For more info, see:
jump shot overcut effect(see jump shots section)
follow shot ball-hop effects(see follow section)
from Bob Jewett:
There is some throw on all shots. That is, the surface of the cue ball is somewhat sticky, and as it passes across the surface of the object ball, it will pull the object ball off the ideal path, which is the line through the centers of the two balls at the instant of contact.
If the cue ball is moving faster, there is not as much friction. This is contrary to the simple explanation of friction which says that the coefficient of friction does not change with the force of the contact. The reduction seems to be over a factor of two as you crank the speed up
If you have stun on the cue ball (no follow or draw), the throw you see on a cut shot is maximized for that speed because all the rubbing is to the side. As you add draw or follow, the effective friction is reduced because part of the rubbing is up or down, and that doesn't contribute to the throw.
Most players have no idea that this stuff is going on, and to some extent it is better for them not to know. They learn subconsciously to make corrections for it, and if they start thinking about it during shots, their brain will get in the way of their arm.
There are fairly simple demonstrations for this. It is discussed on Dr. Dave's web site (external web-link) and in Bob Jewett's May '06 BD article (Download).
The cue ball also jumps on hard shots as mentioned above, but this causes thinner cuts mostly for short distances to the object ball or excess stick elevation.
Speed and travel distances for the CB and OB
How do CB and OB speeds and travel distances vary with cut angle?
See "Fundamentals - Part VII: speed control" (Download) (BD, March, 2009). It includes distance graphs for both stun and rolling CB shots.
For more information, see the ball speed and travel distance section.
Undercutting
Why do some people undercut some cut shots (i.e., hit OB ball too full)?
Some people have trouble visualizing the required ghost-ball center for a cut shot, and get influenced too much by the ball contact point. For more info and illustrations, see "Fundamentals - Part II: aiming" (Download) (BD, October, 2008).
Sometimes, cut-induced throw (CIT) is the cause; and when english (especially inside english), swerve and/or throw might be the culprit. For more info, see:
aim compensation for squirt, swerve, and throw(see aiming section)
One way to compensate for undercutting the ball is to use outside English, but this isn't the best approach for all people. For more info, see: English section
For more info, visit billiards.colostate.edu
