Answers to Frequently Asked Questions (FAQs) About Various Billiards and Pool Topics
Categories
Table
Billiards and Pool Table Information
... what is different from one pool table to the next.
Cloth effects
What affect does the condition of a cloth have on play?
Two physical properties describe the condition of a cloth: sliding friction ("slick" vs. "sticky") and rolling resistance ("slow vs. "fast"). A "slick" cloth has very little sliding friction and allows the CB to retain its spin longer. For example, it is much easier to draw the ball on a "slick" cloth. For more information, see: cloth and cue ball effect under draw in "draw" section.
A "fast" cloth offer very little resistance to rolling, so the balls roll much farther before coming to rest.
Cloth friction has an important effect on draw and follow shots at an angle. With a slick cloth, the CB persists along the tangent line longer before curving to the final direction, as demonstrated with speed changes in this video (a faster shot simulates slicker conditions):
... what is different from one pool table to the next.
Cloth effects
What affect does the condition of a cloth have on play?
Two physical properties describe the condition of a cloth: sliding friction ("slick" vs. "sticky") and rolling resistance ("slow vs. "fast"). A "slick" cloth has very little sliding friction and allows the CB to retain its spin longer. For example, it is much easier to draw the ball on a "slick" cloth. For more information, see: cloth and cue ball effect under draw in "draw" section.
A "fast" cloth offer very little resistance to rolling, so the balls roll much farther before coming to rest.
Cloth friction has an important effect on draw and follow shots at an angle. With a slick cloth, the CB persists along the tangent line longer before curving to the final direction, as demonstrated with speed changes in this video (a faster shot simulates slicker conditions):
In general, a new and clean cloth in a dry climate is usually more "slick" and "faster" than old and dirty cloth in a humid climate. A dirty cloth can also lead to dirtier balls, which can result in more cling. For more info, see "throw" section.
Cloth friction also has an important effect on CB swerve and masse shots. A slick cloth delays the curve, causing the CB to swing out more.
For more info on the effects of humidity, see: humidity effects in this section.
Cloth types
What is pool table cloth made of, and what are the different brands and types?
We don't have a great link for this section. If you know of any links which compare cloths, we appreciate an email: [email protected]
Cushion nose height
Why is the height of the rail cushion nose not at the center of the ball?
"Rail height (nose-line to table-bed) should be 63 ½% (+1 %) or between 62 ½% and 64 ½ % of the diameter of the ball."
If the cushion nose height were at the ball center (0.5D), instead, rebounding balls would slide more and would hop significantly if they come into the cushion with topspin (especially at fast speed).
Another obvious height would be at the "center of percussion" of the ball (0.7D), per TP 4.2 (Download), so the rebounding balls would tend to roll away from the rails more naturally. However, this height would tend to drive a rebounding ball down into the table, which would tend to slow the ball more, accelerate cloth wear (and faster formation of a "rail groove"), and cause the rebounding ball to hop.
The WPA 0.635D offers a good compromise between the 0.5D and 0.7D values. This height was determined empirically to result good rebound performance without too much ball hop or cloth wear.
Drawing lines on the cloth
How can I draw lines on the cloth for lining up practice shots or for marking the rack location?
from Billy_Bob:
I put lines on my table for practice by using a construction chalk line. You pull the line out of the spool, pull the line tight between the two points, then snap it. Then I vacuum up the excess dust. For example I place a line diagonal from corner pocket to corner pocket. Then can practice progressive straight in shots and align the balls exactly straight on the line.
Also I use "tailor's chalk" which you can get at a fabric store or a sewing store. They use this to mark hems on pants legs for how high they should be. It is white and triangular shaped with sharp edges. I use this to mark where the rack goes on the table for quicker racking - commonly done with 14.1 (straight pool). Again this leaves "particles" on the table after marking, so I vacuum after marking the table.
from Deeman (concerning the head string line):
They use a pen with white ink. You can get one at a crafts store. The white pen does seem to be the best choice for permanent lines although i have the standard black ones.
Equipment specifications
Where can I find information on pool equipment specifications like cushion height?
We don't have a great link for this section. If you know of any links which talk about equipment specifications, we appreciate an email: [email protected]
How to clean and maintain
What's the safest and most effective way to clean a table's cloth?
from Fran Crimi:
Two things you don't want to see happen to your cloth regardless of it's type, are stretching and breaking too many fibers which result in fuzziness.
Vacuums with a hard pull will stretch the cloth. Rotating brushes will obviously break more fibers than non-rotating brushes. If I were you, I'd get rid of the rotating brushes and use a fine brush on a vacuum with a light pull. Then move the vacuum in one direction down table...and this has nothing to do with the cloth being directional or non-directional. This is about breaking the least amount of fibers as possible. Don't go back and forth like you're vacuuming your carpet.
When you're done with that, run a slightly damp cloth in one direction down the length of the table, always towards the foot rail, and let it air dry. No blow dryers. Vacuum as infrequently as you can. The more often you do it, the more fibers you'll break. Simonis 860 should not be even slightly fuzzy, unless you're breaking the fibers.
What should I do to keep my table in good condition?
from RSB_FAQ:
1. Keep the table clean - cover it when not in use; don't let food or drink near it; keep junk off the rails. Let everyone know that the table is to be treated with respect and care, then be sure and follow your own advice.
2. Avoid using talc. Also, do not chalk your cue over the table, or place the chalk upside-down [open-side down?] on the rails.
3. Brush your table regularly (after each session is not too often), and clean the rails with a damp cloth.
4. Vacuum the table at least every few weeks with a dust buster type. Avoid using a vacuum cleaner with rotating brushes unless you have worsted wool cloth, like Simonis or Granito. Also, if you have a non-worsted or directional cloth, always brush or vacuum the cloth in the same direction, usually head to foot. Vacuum the table brush itself to remove the chalk dust.
5. At least once a month, use a damp lint free towel to wipe down the cloth. Some prefer instead to mist the cloth with a water and then brush it.
6. Wash the balls regularly, at least with water, or maybe mild soap and water.
7. If you want to practice jump or masse shots, get a little extra square of cloth to put under the cue ball, or you may leave little white marks all over the table.
8. Don't let people sit on the rails - it will cause the cushions to come loose.
Humidity effects
How does an increase in humidity affect how a table plays?
With more humid conditions, the following changes occur:
Lighting
What should I know when selecting and purchasing pool table lighting?
We don't have a great link for this section. If you know of any links which talk about lighting and specifications, we appreciate an email: [email protected]
Pocket sizes
Are there standards for the sizes of the pockets on different tables?
There are standard sizes (and other geometric specs). An illustration of the different parameters can be found in TP 3.5 (Download). However, not all tables are made the same. Rails and pockets can vary significantly from one manufacturer to the next. The side pockets are usually larger than the corner pockets, especially on larger tables; however, on many coin operated "bar boxes," the opposite is often true. Pockets are also sometimes "shimmed" to make the openings smaller to make the table play "tougher."
For more information about pockets, see:
effects and physical characteristics related to pool table pockets in "pockets" section.
"Speed" of the cloth
What is the "speed" of the cloth, and how do you measure it?
Here's a good article from Joe Waldron (external web-link) on this topic.
Related information concerning the effects of cloth "speed" on draw and drag shots can be found in "draw" section.
For more information on the effects of various cloth conditions, see cloth effects in this section.
Standard pool table dimensions and required room sizes
What are the standard pool table sizes and dimensions, and how large of a room is required for each?
Standard size pool tables, along with the playing surface dimensions (measured between the noses of the cushions) are:
12-ft (snooker): 140" (356.9 cm) x 70" (177.8 cm)
10-ft (over sized): 112" (284.5 cm) x 56" (142.2 cm)
9-ft (regulation size table): 100” (254 cm) x 50” (127 cm)
8-ft+ (pro 8): 92” (233.7 cm) x 46" (116.8 cm)
8-ft (typical home table): 88" (223.5 cm) x 44" (111.8 cm)
7-ft+ (large "bar box"): 78-82" (198.1-208.3 cm) x 39-41" (99.1-104.1 cm)
7-ft ("bar box"): 74-78" (188-198.1 cm) x 37-39" (94-99.1 cm)
6-ft ("small bar box"): 70-74" (177.8-188 cm) x 35-37" (88.9-94 cm)
More info can be found here: Wikipedia pool table dimensions resource page (external web-link).
from RSB_FAQ:
The minimum space for a table is the playing area plus the length of a cue (58") plus about 6 inches for the back swing, more for comfort, on each side. This gives the table:
Cloth friction also has an important effect on CB swerve and masse shots. A slick cloth delays the curve, causing the CB to swing out more.
For more info on the effects of humidity, see: humidity effects in this section.
Cloth types
What is pool table cloth made of, and what are the different brands and types?
We don't have a great link for this section. If you know of any links which compare cloths, we appreciate an email: [email protected]
Cushion nose height
Why is the height of the rail cushion nose not at the center of the ball?
"Rail height (nose-line to table-bed) should be 63 ½% (+1 %) or between 62 ½% and 64 ½ % of the diameter of the ball."
If the cushion nose height were at the ball center (0.5D), instead, rebounding balls would slide more and would hop significantly if they come into the cushion with topspin (especially at fast speed).
Another obvious height would be at the "center of percussion" of the ball (0.7D), per TP 4.2 (Download), so the rebounding balls would tend to roll away from the rails more naturally. However, this height would tend to drive a rebounding ball down into the table, which would tend to slow the ball more, accelerate cloth wear (and faster formation of a "rail groove"), and cause the rebounding ball to hop.
The WPA 0.635D offers a good compromise between the 0.5D and 0.7D values. This height was determined empirically to result good rebound performance without too much ball hop or cloth wear.
Drawing lines on the cloth
How can I draw lines on the cloth for lining up practice shots or for marking the rack location?
from Billy_Bob:
I put lines on my table for practice by using a construction chalk line. You pull the line out of the spool, pull the line tight between the two points, then snap it. Then I vacuum up the excess dust. For example I place a line diagonal from corner pocket to corner pocket. Then can practice progressive straight in shots and align the balls exactly straight on the line.
Also I use "tailor's chalk" which you can get at a fabric store or a sewing store. They use this to mark hems on pants legs for how high they should be. It is white and triangular shaped with sharp edges. I use this to mark where the rack goes on the table for quicker racking - commonly done with 14.1 (straight pool). Again this leaves "particles" on the table after marking, so I vacuum after marking the table.
from Deeman (concerning the head string line):
They use a pen with white ink. You can get one at a crafts store. The white pen does seem to be the best choice for permanent lines although i have the standard black ones.
Equipment specifications
Where can I find information on pool equipment specifications like cushion height?
We don't have a great link for this section. If you know of any links which talk about equipment specifications, we appreciate an email: [email protected]
How to clean and maintain
What's the safest and most effective way to clean a table's cloth?
from Fran Crimi:
Two things you don't want to see happen to your cloth regardless of it's type, are stretching and breaking too many fibers which result in fuzziness.
Vacuums with a hard pull will stretch the cloth. Rotating brushes will obviously break more fibers than non-rotating brushes. If I were you, I'd get rid of the rotating brushes and use a fine brush on a vacuum with a light pull. Then move the vacuum in one direction down table...and this has nothing to do with the cloth being directional or non-directional. This is about breaking the least amount of fibers as possible. Don't go back and forth like you're vacuuming your carpet.
When you're done with that, run a slightly damp cloth in one direction down the length of the table, always towards the foot rail, and let it air dry. No blow dryers. Vacuum as infrequently as you can. The more often you do it, the more fibers you'll break. Simonis 860 should not be even slightly fuzzy, unless you're breaking the fibers.
What should I do to keep my table in good condition?
from RSB_FAQ:
1. Keep the table clean - cover it when not in use; don't let food or drink near it; keep junk off the rails. Let everyone know that the table is to be treated with respect and care, then be sure and follow your own advice.
2. Avoid using talc. Also, do not chalk your cue over the table, or place the chalk upside-down [open-side down?] on the rails.
3. Brush your table regularly (after each session is not too often), and clean the rails with a damp cloth.
4. Vacuum the table at least every few weeks with a dust buster type. Avoid using a vacuum cleaner with rotating brushes unless you have worsted wool cloth, like Simonis or Granito. Also, if you have a non-worsted or directional cloth, always brush or vacuum the cloth in the same direction, usually head to foot. Vacuum the table brush itself to remove the chalk dust.
5. At least once a month, use a damp lint free towel to wipe down the cloth. Some prefer instead to mist the cloth with a water and then brush it.
6. Wash the balls regularly, at least with water, or maybe mild soap and water.
7. If you want to practice jump or masse shots, get a little extra square of cloth to put under the cue ball, or you may leave little white marks all over the table.
8. Don't let people sit on the rails - it will cause the cushions to come loose.
Humidity effects
How does an increase in humidity affect how a table plays?
With more humid conditions, the following changes occur:
- The cloth plays slower (because of increased rolling resistance) .
- English "takes" more on the rails (i.e., the ball "bites" more due to increased friction).
- Draw shots are more difficult due to increased "drag" (due to the cloth playing "stickier" with increased sliding friction).
- Banks go "shorter" (due to more friction and CB hop).
- The CB hops off the rails more (and this delays post rebound curve, making the effective bank angle even shorter).
- The pockets play "tighter" because rebound is "shorter" (and rail-induced spin "takes" more) off the pocket walls.
- The balls can throw more, and there can be more cling/skid (because the balls tend to get more dirty and hold chalk residue more).
- Swerve happens sooner so squerve (the combined effects of squirt and swerve) will be less.
Lighting
What should I know when selecting and purchasing pool table lighting?
We don't have a great link for this section. If you know of any links which talk about lighting and specifications, we appreciate an email: [email protected]
Pocket sizes
Are there standards for the sizes of the pockets on different tables?
There are standard sizes (and other geometric specs). An illustration of the different parameters can be found in TP 3.5 (Download). However, not all tables are made the same. Rails and pockets can vary significantly from one manufacturer to the next. The side pockets are usually larger than the corner pockets, especially on larger tables; however, on many coin operated "bar boxes," the opposite is often true. Pockets are also sometimes "shimmed" to make the openings smaller to make the table play "tougher."
For more information about pockets, see:
effects and physical characteristics related to pool table pockets in "pockets" section.
"Speed" of the cloth
What is the "speed" of the cloth, and how do you measure it?
Here's a good article from Joe Waldron (external web-link) on this topic.
Related information concerning the effects of cloth "speed" on draw and drag shots can be found in "draw" section.
For more information on the effects of various cloth conditions, see cloth effects in this section.
Standard pool table dimensions and required room sizes
What are the standard pool table sizes and dimensions, and how large of a room is required for each?
Standard size pool tables, along with the playing surface dimensions (measured between the noses of the cushions) are:
12-ft (snooker): 140" (356.9 cm) x 70" (177.8 cm)
10-ft (over sized): 112" (284.5 cm) x 56" (142.2 cm)
9-ft (regulation size table): 100” (254 cm) x 50” (127 cm)
8-ft+ (pro 8): 92” (233.7 cm) x 46" (116.8 cm)
8-ft (typical home table): 88" (223.5 cm) x 44" (111.8 cm)
7-ft+ (large "bar box"): 78-82" (198.1-208.3 cm) x 39-41" (99.1-104.1 cm)
7-ft ("bar box"): 74-78" (188-198.1 cm) x 37-39" (94-99.1 cm)
6-ft ("small bar box"): 70-74" (177.8-188 cm) x 35-37" (88.9-94 cm)
More info can be found here: Wikipedia pool table dimensions resource page (external web-link).
from RSB_FAQ:
The minimum space for a table is the playing area plus the length of a cue (58") plus about 6 inches for the back swing, more for comfort, on each side. This gives the table:
"Seven foot" tables vary in size. Work down from the 8' dimensions. "8+" is an "over sized" 8-foot table.
If your room does not meet these minimum size requirements, many billiard retailers will suggest that you can still put a table in, and use short cues (52", or 48"). Many people have found they are unhappy having to resort to shorter cues, and should have either gotten a smaller table, or no table at all. Others, of course, take the opposite view -- they are delighted to have any table.
In the end, only you will know whether you are happy with the room dimensions and need for short cues. Before you spend money for a table that will cause you to smash the walls in frustration, try this:
(1) Find an indulgent pool hall when it's not busy.
(2) Measure your space (at home) carefully, including the distance from the table to all walls that require a special cue
(3) Go to the pool hall with a piece or pieces of plywood or some such, and a short cue, and set up the "walls" to replicate where the walls would be in your house. Play for several hours, using the short cue when needed.
Between two tables you can do with about the length of a cue, the limit is caused not by the cue, but by the player being able to go into his stance between the tables. Deluxe rooms really need more room on all sides to let possible passers-by move without bumping into the players.
from realkingcobra (on AZB): (external forum-link)
A 4 1/2 x 9 ft pool table gets it's measurements from finish of rail to finish of rail.
4 1/2 feet = 54"
9 ft = 108"
Take the playing surface of a 9 ft pool table, it's 50" x 100" now add in the 2" of cloth on the cushions on the side rails to the playing surface, what you come up with is 2" of cushion/cloth on the left side rail, plus 2" of cloth/cushion on the right side rail, plus the 50" of the playing surface from side to side. Now, add that together and you have 2"+2"+50" = 54" which equals 4 1/2 feet.
Now, if you double that measurement you'd be adding up 4 side rails at 2" each...remember you're DOUBLING the width, so that means instead of adding just 2 rails, you'd be adding up the width of 4 rails, at 2" each, plus you'd be doubling the width of the table side to side being 50" twice, so that's 100"...now add up....2"+2"+2"+2"+50"+50"= 108" which equals 9 feet even, EXCEPT....we all know all pool tables only have 2 end rails and NOT 4, so in order to keep the playing surface twice as long as it is wide...you have to subtract 2 of them 4 rails as ghost rails....meaning they're not really there on the pool table, so if you take and subtract the 4" of ghost rails from the 9 ft...108" that leaves you with 104", now subtract the 4" of cloth/cushions that ARE on the table, and you end up with 100"....so that's how you get a 50" x 100" playing surface out of a 4 1/2 x 9 pool table.
Table difficulty factor (TDF)
How can you determine how difficult a table plays, and how to I use this information to adjust scores from player rating systems?
The Table Difficulty Factor (TDF) system (Download) provides a very easy system to measure how "tough" a table plays. It is based on table size and the three corner-pocket measurements illustrated below. Four factors are used to account for table size, pocket size, pocket wall angle, and pocket shelf depth. Each factor is a number less than, equal to, or greater than 1, where 1 indicates average or standard. By multiplying the four factors, you get the TDF which is a good measure of table “toughness.” If TDF=1, the table has an average level of difficulty; if TDF>1, the table plays more difficult than average; and if TDF<1, the table plays easier than average.
If your room does not meet these minimum size requirements, many billiard retailers will suggest that you can still put a table in, and use short cues (52", or 48"). Many people have found they are unhappy having to resort to shorter cues, and should have either gotten a smaller table, or no table at all. Others, of course, take the opposite view -- they are delighted to have any table.
In the end, only you will know whether you are happy with the room dimensions and need for short cues. Before you spend money for a table that will cause you to smash the walls in frustration, try this:
(1) Find an indulgent pool hall when it's not busy.
(2) Measure your space (at home) carefully, including the distance from the table to all walls that require a special cue
(3) Go to the pool hall with a piece or pieces of plywood or some such, and a short cue, and set up the "walls" to replicate where the walls would be in your house. Play for several hours, using the short cue when needed.
Between two tables you can do with about the length of a cue, the limit is caused not by the cue, but by the player being able to go into his stance between the tables. Deluxe rooms really need more room on all sides to let possible passers-by move without bumping into the players.
from realkingcobra (on AZB): (external forum-link)
A 4 1/2 x 9 ft pool table gets it's measurements from finish of rail to finish of rail.
4 1/2 feet = 54"
9 ft = 108"
Take the playing surface of a 9 ft pool table, it's 50" x 100" now add in the 2" of cloth on the cushions on the side rails to the playing surface, what you come up with is 2" of cushion/cloth on the left side rail, plus 2" of cloth/cushion on the right side rail, plus the 50" of the playing surface from side to side. Now, add that together and you have 2"+2"+50" = 54" which equals 4 1/2 feet.
Now, if you double that measurement you'd be adding up 4 side rails at 2" each...remember you're DOUBLING the width, so that means instead of adding just 2 rails, you'd be adding up the width of 4 rails, at 2" each, plus you'd be doubling the width of the table side to side being 50" twice, so that's 100"...now add up....2"+2"+2"+2"+50"+50"= 108" which equals 9 feet even, EXCEPT....we all know all pool tables only have 2 end rails and NOT 4, so in order to keep the playing surface twice as long as it is wide...you have to subtract 2 of them 4 rails as ghost rails....meaning they're not really there on the pool table, so if you take and subtract the 4" of ghost rails from the 9 ft...108" that leaves you with 104", now subtract the 4" of cloth/cushions that ARE on the table, and you end up with 100"....so that's how you get a 50" x 100" playing surface out of a 4 1/2 x 9 pool table.
Table difficulty factor (TDF)
How can you determine how difficult a table plays, and how to I use this information to adjust scores from player rating systems?
The Table Difficulty Factor (TDF) system (Download) provides a very easy system to measure how "tough" a table plays. It is based on table size and the three corner-pocket measurements illustrated below. Four factors are used to account for table size, pocket size, pocket wall angle, and pocket shelf depth. Each factor is a number less than, equal to, or greater than 1, where 1 indicates average or standard. By multiplying the four factors, you get the TDF which is a good measure of table “toughness.” If TDF=1, the table has an average level of difficulty; if TDF>1, the table plays more difficult than average; and if TDF<1, the table plays easier than average.
See the Table Difficulty Factor (TDF) document (Download) to see how the following four factors are assigned:
TSF: table size factor
PSF: pocket size factor
PAF: pocket angle factor
PLF: pocket shelf factor
The total Table Difficulty Factor (TDF) is calculated by multiplying the four factors:
TDF = TSF x PSF x PAF x PLF
The TDF can be used to adjust numbers from any scoring or rating system(in "rating" section) like the Billiard University Exams, “playing the ghost” drills, Hopkins Q Skills drill, or the Fargo rating drill or handicapping system(all in "rating" section). An effective score, taking table difficulty into consideration, can be calculated with:
(effective score) = (raw score) x TDF
See the TDF document (Download) for details and examples. And for more information, see: “Billiard University (BU) - Part IV: Table Difficulty” (Download) (BD, November, 2013).
from realkingcobra in AZB post: (external forum-link)
Facings play a major role in rejecting balls from pockets as do cushions. Take the Olhausen tables for example. The cushions are very...very soft, the facings are 1/8" and very soft. What happens on an Olhausen table is that when you're attempting to pocket a ball in the corner pocket coming down the rails, you're shooting the ball right into the outer have of the pocket facing with no rail wood support behind the cushion. When you do this, what happens is that when the ball being pocketed hits the facing, instead of deflecting to-wards the back of the pocket, it compresses the facing and cushion kind of like creating a flat spot at the end of the cushion, which in turn kicks the ball across the pocket to the opposite facing and back out again, and you don't even have to shoot the shot hard to get this "rejection" to happen. So, now comes in the role of the facings. If the soft 1/8" facings are replaced with harder 3/16" neoprene facings, these facings don't compress nearly as much when you shoot a ball into them, so the balls that would normally reject....go in because they deflect off the facings deeper into the back of the pocket.
from Sloppy Pockets in AZB post (external forum-link), concerning how to properly measure the pocket mouth and throat dimensions (at the intersections of the yellow lines, not at the labeled red dimensions):
TSF: table size factor
PSF: pocket size factor
PAF: pocket angle factor
PLF: pocket shelf factor
The total Table Difficulty Factor (TDF) is calculated by multiplying the four factors:
TDF = TSF x PSF x PAF x PLF
The TDF can be used to adjust numbers from any scoring or rating system(in "rating" section) like the Billiard University Exams, “playing the ghost” drills, Hopkins Q Skills drill, or the Fargo rating drill or handicapping system(all in "rating" section). An effective score, taking table difficulty into consideration, can be calculated with:
(effective score) = (raw score) x TDF
See the TDF document (Download) for details and examples. And for more information, see: “Billiard University (BU) - Part IV: Table Difficulty” (Download) (BD, November, 2013).
from realkingcobra in AZB post: (external forum-link)
Facings play a major role in rejecting balls from pockets as do cushions. Take the Olhausen tables for example. The cushions are very...very soft, the facings are 1/8" and very soft. What happens on an Olhausen table is that when you're attempting to pocket a ball in the corner pocket coming down the rails, you're shooting the ball right into the outer have of the pocket facing with no rail wood support behind the cushion. When you do this, what happens is that when the ball being pocketed hits the facing, instead of deflecting to-wards the back of the pocket, it compresses the facing and cushion kind of like creating a flat spot at the end of the cushion, which in turn kicks the ball across the pocket to the opposite facing and back out again, and you don't even have to shoot the shot hard to get this "rejection" to happen. So, now comes in the role of the facings. If the soft 1/8" facings are replaced with harder 3/16" neoprene facings, these facings don't compress nearly as much when you shoot a ball into them, so the balls that would normally reject....go in because they deflect off the facings deeper into the back of the pocket.
from Sloppy Pockets in AZB post (external forum-link), concerning how to properly measure the pocket mouth and throat dimensions (at the intersections of the yellow lines, not at the labeled red dimensions):
from iusedtoberich AZB post: (external forum-link)
Perhaps something like laying post it notes stuck on the cushion can extend the lines of the cushion to a real intersection point, that can then be measured to and from.
Terminology
What are all of the terms used to describe different features on a pool table?
from Bob_Jewett:
Perhaps something like laying post it notes stuck on the cushion can extend the lines of the cushion to a real intersection point, that can then be measured to and from.
Terminology
What are all of the terms used to describe different features on a pool table?
from Bob_Jewett:
For more info, visit billiards.colostate.edu
Throw
Throw in Pool and Billiards
... how to judge and compensate for object ball throw in pool shots with and without English.
(external links) for more information:
see Sections 4.04, 7.03, and 7.04 in The Illustrated Principles of Pool and Billiards
and Disc IV of the Video Encyclopedia of Pool Shots
Answers to questions about CIT, SIT, and OE
How do you know which way the object ball will throw for different types of shots?
Throw direction depends on the direction of the relative motion of the surface of the cue ball in contact with the object ball. This direction is affected by both cut angle and spin. "Throw - Part VI: inside/outside english" (Download) (BD, January, 2007) and "Throw - Part VII: CIT/SIT combo" (Download) (BD, February, 2007) illustrate the different possibilities quite well. Here's a good video demonstration and explanation of both cut-induced throw (CIT) and spin-induced throw (SIT):
... how to judge and compensate for object ball throw in pool shots with and without English.
(external links) for more information:
see Sections 4.04, 7.03, and 7.04 in The Illustrated Principles of Pool and Billiards
and Disc IV of the Video Encyclopedia of Pool Shots
Answers to questions about CIT, SIT, and OE
How do you know which way the object ball will throw for different types of shots?
Throw direction depends on the direction of the relative motion of the surface of the cue ball in contact with the object ball. This direction is affected by both cut angle and spin. "Throw - Part VI: inside/outside english" (Download) (BD, January, 2007) and "Throw - Part VII: CIT/SIT combo" (Download) (BD, February, 2007) illustrate the different possibilities quite well. Here's a good video demonstration and explanation of both cut-induced throw (CIT) and spin-induced throw (SIT):
See also:
Do CIT and SIT add or subtract as independent factors?
Object ball throw depends on cut angle, shot speed, type and amount of English, and the amount of vertical plane spin (draw, follow, stun). The following series of instructional articles elaborate on all of these factors: (Downloads)
"Throw - Part I: introduction" (BD, August, 2006).
"Throw - Part II: results" (BD, September, 2006).
"Throw - Part III: follow and draw effects" (BD, October, 2006).
"Throw - Part IV: spin-induced throw" (BD, November, 2006).
"Throw - Part V: SIT speed effects" (BD, December, 2006).
"Throw - Part VI: inside/outside english" (BD, January, 2007).
"Throw - Part VII: CIT/SIT combo" (BD, February, 2007).
"Throw - Part VIII: spin transfer" (BD, March, 2007).
"Throw - Part IX: spin transfer follow-up" (BD, April, 2007).
"Throw - Part X: the big picture" (BD, May, 2007).
"Throw - Part XI: everything you ever wanted to know about throw" (BD, June, 2007).
"Throw - Part XII: calibration, and hold shots" (BD, July, 2007).
Collision-induced throw (CIT) and spin-induced throw (SIT) are just different names for throw, depending upon the primary cause of the throw, but the effects don't really combine as separate factors.
Outside English (OE) can diminish, eliminate, or even reverse the direction of throw. But at larger cut angles, a small amount of OE can actually increase the amount of throw (e.g., see Diagram 1 in "Throw - Part VII: CIT/SIT combo" (Download) (BD, February, 2007)). Again, the reason has to do with the relative surface speed between the balls. Sliding friction (and therefore throw) is greater at slower relative surface speeds. With larger cut angles, inside English (IE) increases the relative surface speed between the balls and reduces the amount of friction and the amount of throw. For a large cut angle, a small amount of OE can reduce (but not reverse) the surface speed some resulting in more friction and more throw.
With "gearing outside English" (GOE) there is no sideways force whatsoever. That's why there is no throw. The OB heads exactly in the impact-line direction (i.e., in the ghost-ball line-of-centers direction). There can be throw only when there is a sliding force between the CB and OB. With gOE there is no sliding between the balls during contact (see "Throw - Part VI: inside/outside English" - (Download) BD, January, 2007). With less-than-gearing OE, throw is in one direction (the CIT direction); and with more-than-gearing OE, throw is in the other direction (the SIT direction). There either is throw or there is not, and it can be in one direction or the other. GOE completely eliminates throw and cling. It's just tough judging the exact "gearing" amount of OE you need for each cut angle.
"Cling," "skid," and "kick"
What is "cling," "skid" and "kick?"
"Cling" (AKA "skid" or "kick") refers to a "bad hit" resulting from an excessive amount of throw, well beyond what is expected for a given shot. When the CB hits an OB with a cut angle or non-gearing spin, there is friction between the CB and OB at the point of contact that resists the relative motion between the balls. This is what causes throw (CIT or SIT(in "throw" section)), which is normal. A "bad hit" occurs when the amount of friction is greater than normal (e.g., because there is a chalk mark at the point of contact). In this case, the amount of throw (or ball hop and topspin loss in the case of a nearly straight follow shot) is larger than the typical amount.
People sometimes mistake a naturally large amount of throw as cling, especially if they are unaware of how throw varies with the type of shot. Again, cling is an amount of throw much greater than should be expected for a given shot and conditions. People also sometimes think that a "bad hit" results from the CB and OB actually clinging together for a longer time than normal. This is not the case, even though it might seem this way based on the reaction of the balls.
Cling can occur more often with old, beat up (e..g, from phenolic tip damage), scuffed (e.g., from miscues), and dirty balls, where portions of the ball surfaces might create more friction than other portions (especially when the suspect portions collect and hold chalk easily). However, cling also occurs with new, clean, and smooth balls. The primary cause for cling is a chalk mark or smudge (or a significant amount of chalk dust) appearing at the contact point between the CB and OB. Anytime you see chalk smudges on the CB, you should wipe them off (or ask for a referee to wipe them off if you are in the middle of a tournament game). Definitely wipe off he cue ball before each break shot or any time you have ball in hand. We have enough reasons to miss shots as it is without having to worry about excessive and unpredictable throw due to cling caused by chalk smudges.
Some people have suggested that cling can be caused directly by static electricity, but this is highly questionable. Although, a possible explanation is that static (resulting from the balls sliding across the cloth) could indirectly cause cling by somehow allowing chalk dust to collect on and stick to the balls more easily (but this is also questionable). Throw could also be larger (for all shots) if the balls are "cleaned" or polished with a substance that alters the ball surface (e.g., by leaving a residue behind or by chemically etching or altering the surface), creating more friction. Some polishes/waxes or aggressive chemical cleaners (e.g., acetone) could have these effects. Some people have suggested that oils, from human hands, deposited on the balls as they are handled can help minimize the effects of cling . This could be the case, especially if the balls were previously "cleaned." However, an excessive amount of oil could make it easier for chalk smudges to remain on the cue ball, which would result in more frequent cling. It has also been suggested that cling can occur more frequently on cloth that is new, thin, and slick because chalk smudges on the CB might tend to wear off less easily under these conditions (although, this is probably a very small effect). Cling might be more noticeable when playing with new and clean balls (e.g., in televised tournament conditions), where the amount of throw is less than with older and dirtier balls. Because the amount of throw can be less with ideal conditions, when cling does occur it can be strikingly noticeable.
George Onoda wrote an article (see pp. 13-14 here (Download)) illustrating how cling might be more likely with low-inside and high-outside English shots, where a new chalk mark might be more likely to end up at the ball contact point, but cling is probably more random than this suggests (due to previous chalk marks or smudges on the balls that happen to end up at the ball contact point, on any shot).
Throw, including cling, can be avoided by using a "gearing" amount of outside English. For more info, see: using outside English to limit or prevent throw and cling in "English" section.
Cling is often talked about in relation to excessive throw of the OB with a cut shot, but it can also create a lot of trouble for slow-roll follow shots. The CB won't follow the OB near as much as you would expect when there is cling. This video illustrates the effect.
In the snooker world, the term "kick" is sometimes also used to refer to CB hop and its effect on OB motion. The effects of CB hop, along with video demonstrations, can be found on the ball hop in "follow" section.
Here's an example of purposely creating cling (with a chalk smudge) to help create a reverse bank angle:
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
The shot is demonstrated in Shot 731 here:
NV B.92 - "Impossible" cut shots, from VEPS V (YouTube)
Here's a fun proposition shot utilizing chalk-induced cling in a devious manner:
NV B.91 - Frozen-throw-down-rail proposition shot, from VEPS V (YouTube)
Other interesting shots utilizing cling can be found in:
Bob Jewett's April '09 BD article (Download).
If the CB and OB don't stay in contact longer when "cling" occurs, what is it that happens instead?
"Cling" in the context of pool doesn't actually mean the balls stick or "cling" together (although, it can seems like this based on the reaction of the balls when "cling" occurs). It just means there is more friction to resist sliding during contact.
The contact time between the balls, which is extremely small, depends only on how the balls compress (in the perpendicular or normal direction) during contact. The amount of sliding or friction between the balls during contact really doesn't affect the contact time. With a cut angle, the CB tends to slide on the OB during contact. At smaller cut angles, the CB and OB slide at first but then "gear" together during contact. This happens sooner with more friction (e.g., with "cling"), but the contact time doesn't change. At larger cut angles, the CB slides during the entire contact time, even with a more-than normal amount of friction.
What changes with increased friction is the amount of loss of relative sliding speed between the balls. With enough friction, the sliding disappears completely resulting in gearing motion. But again, this all happens during the normal ball compression and restitution.
Draw and follow effects
Do shots with draw and follow throw as much as shots with stun?
Stun shots exhibit the most cut-induced throw (see "Throw - Part II: results" - (Download) BD, September, 2006) and spin-induced throw (see "Throw - Part IV: spin-induced throw" - (Download) BD, November, 2006). Draw and follow shots exhibit less throw (see "Throw - Part III: follow and draw effects" - (Download) BD, October, 2006); and if they have the same amount of bottom or top spin, the amount of throw is the same (and less than the amount of stun throw). See "Throw - Part III: follow and draw effects" (Download) (BD, October, 2006) and Bob Jewett's May '06 article (Download) to see how stun, follow, and draw shot throws compare. Because bottom spin wears off due to "drag" action, many draw shots will have less spin, and more throw, than typical follow shots.
Now, object ball (OB) swerve does have a slight effect on throw with follow and draw, but the effect is very small (see the end of TP A.24 (Download) for example numbers). Strictly, a follow shot will have slight OB swerve in the throw direction, effectively increasing the effective throw a tiny amount; but for all practical purposes, follow and draw shots with equal amounts of spin throw the same amount. Now, if a draw shot has more backspin than a follow shot has topspin, then the draw shot will definitely have less throw than the follow shot. The closer a shot is to stun, the more throw it will have.
Why do stun, follow, and draw shots create radically different amounts of throw at small to medium cut angles and similar (but smaller) amounts of throw at large cut angles?
The reason why top and bottom spin make less difference at larger cut angles is that sliding motion between the CB and OB is mostly horizontal at the larger angles. Imagine a CB spinning in place with topspin in contact with an OB ball. If the CB is in front of the OB (as with a full-ball hit), the CB is rubbing straight down on the OB. Now, with the CB still spinning, move it around the OB (while keeping the spin direction the same) simulating different cut angles. When the CB is on the side of the OB (as with a 90 degree cut), the spin creates no rub at all at the point of contact between the balls. The amount of downward rub changes gradually with the cut angle. It is larger for a small cut angle, and smaller for a large cut angle.
Now, throw is caused by horizontal rubbing motion between the CB and OB. When a stunned CB hits the OB at an angle, the rubbing motion is completely horizontal, creating maximum throw. When there is topspin or bottom spin, the rubbing motion is less horizontal, creating less horizontal throw. However, as described above, this effect is less at larger cut angles. That is why stun, follow, and draw shots create similar amounts of throw at larger cut angles.
Examples
What are some example shots where throw and spin transfer can be used or must be accounted for?
Several examples of throw shots are demonstrated in the following video:
- squirt, swerve, and throw confusion in "squirt" section
- HSV B.18 - spin-induced throw speed and English effects (YouTube)
- HSV B.30 - cut-induced and spin-induced throw and spin transfer (YouTube)
- HSV B.33 - outside English gearing, and cut and spin-induced throw (YouTube)
Do CIT and SIT add or subtract as independent factors?
Object ball throw depends on cut angle, shot speed, type and amount of English, and the amount of vertical plane spin (draw, follow, stun). The following series of instructional articles elaborate on all of these factors: (Downloads)
"Throw - Part I: introduction" (BD, August, 2006).
"Throw - Part II: results" (BD, September, 2006).
"Throw - Part III: follow and draw effects" (BD, October, 2006).
"Throw - Part IV: spin-induced throw" (BD, November, 2006).
"Throw - Part V: SIT speed effects" (BD, December, 2006).
"Throw - Part VI: inside/outside english" (BD, January, 2007).
"Throw - Part VII: CIT/SIT combo" (BD, February, 2007).
"Throw - Part VIII: spin transfer" (BD, March, 2007).
"Throw - Part IX: spin transfer follow-up" (BD, April, 2007).
"Throw - Part X: the big picture" (BD, May, 2007).
"Throw - Part XI: everything you ever wanted to know about throw" (BD, June, 2007).
"Throw - Part XII: calibration, and hold shots" (BD, July, 2007).
Collision-induced throw (CIT) and spin-induced throw (SIT) are just different names for throw, depending upon the primary cause of the throw, but the effects don't really combine as separate factors.
Outside English (OE) can diminish, eliminate, or even reverse the direction of throw. But at larger cut angles, a small amount of OE can actually increase the amount of throw (e.g., see Diagram 1 in "Throw - Part VII: CIT/SIT combo" (Download) (BD, February, 2007)). Again, the reason has to do with the relative surface speed between the balls. Sliding friction (and therefore throw) is greater at slower relative surface speeds. With larger cut angles, inside English (IE) increases the relative surface speed between the balls and reduces the amount of friction and the amount of throw. For a large cut angle, a small amount of OE can reduce (but not reverse) the surface speed some resulting in more friction and more throw.
With "gearing outside English" (GOE) there is no sideways force whatsoever. That's why there is no throw. The OB heads exactly in the impact-line direction (i.e., in the ghost-ball line-of-centers direction). There can be throw only when there is a sliding force between the CB and OB. With gOE there is no sliding between the balls during contact (see "Throw - Part VI: inside/outside English" - (Download) BD, January, 2007). With less-than-gearing OE, throw is in one direction (the CIT direction); and with more-than-gearing OE, throw is in the other direction (the SIT direction). There either is throw or there is not, and it can be in one direction or the other. GOE completely eliminates throw and cling. It's just tough judging the exact "gearing" amount of OE you need for each cut angle.
"Cling," "skid," and "kick"
What is "cling," "skid" and "kick?"
"Cling" (AKA "skid" or "kick") refers to a "bad hit" resulting from an excessive amount of throw, well beyond what is expected for a given shot. When the CB hits an OB with a cut angle or non-gearing spin, there is friction between the CB and OB at the point of contact that resists the relative motion between the balls. This is what causes throw (CIT or SIT(in "throw" section)), which is normal. A "bad hit" occurs when the amount of friction is greater than normal (e.g., because there is a chalk mark at the point of contact). In this case, the amount of throw (or ball hop and topspin loss in the case of a nearly straight follow shot) is larger than the typical amount.
People sometimes mistake a naturally large amount of throw as cling, especially if they are unaware of how throw varies with the type of shot. Again, cling is an amount of throw much greater than should be expected for a given shot and conditions. People also sometimes think that a "bad hit" results from the CB and OB actually clinging together for a longer time than normal. This is not the case, even though it might seem this way based on the reaction of the balls.
Cling can occur more often with old, beat up (e..g, from phenolic tip damage), scuffed (e.g., from miscues), and dirty balls, where portions of the ball surfaces might create more friction than other portions (especially when the suspect portions collect and hold chalk easily). However, cling also occurs with new, clean, and smooth balls. The primary cause for cling is a chalk mark or smudge (or a significant amount of chalk dust) appearing at the contact point between the CB and OB. Anytime you see chalk smudges on the CB, you should wipe them off (or ask for a referee to wipe them off if you are in the middle of a tournament game). Definitely wipe off he cue ball before each break shot or any time you have ball in hand. We have enough reasons to miss shots as it is without having to worry about excessive and unpredictable throw due to cling caused by chalk smudges.
Some people have suggested that cling can be caused directly by static electricity, but this is highly questionable. Although, a possible explanation is that static (resulting from the balls sliding across the cloth) could indirectly cause cling by somehow allowing chalk dust to collect on and stick to the balls more easily (but this is also questionable). Throw could also be larger (for all shots) if the balls are "cleaned" or polished with a substance that alters the ball surface (e.g., by leaving a residue behind or by chemically etching or altering the surface), creating more friction. Some polishes/waxes or aggressive chemical cleaners (e.g., acetone) could have these effects. Some people have suggested that oils, from human hands, deposited on the balls as they are handled can help minimize the effects of cling . This could be the case, especially if the balls were previously "cleaned." However, an excessive amount of oil could make it easier for chalk smudges to remain on the cue ball, which would result in more frequent cling. It has also been suggested that cling can occur more frequently on cloth that is new, thin, and slick because chalk smudges on the CB might tend to wear off less easily under these conditions (although, this is probably a very small effect). Cling might be more noticeable when playing with new and clean balls (e.g., in televised tournament conditions), where the amount of throw is less than with older and dirtier balls. Because the amount of throw can be less with ideal conditions, when cling does occur it can be strikingly noticeable.
George Onoda wrote an article (see pp. 13-14 here (Download)) illustrating how cling might be more likely with low-inside and high-outside English shots, where a new chalk mark might be more likely to end up at the ball contact point, but cling is probably more random than this suggests (due to previous chalk marks or smudges on the balls that happen to end up at the ball contact point, on any shot).
Throw, including cling, can be avoided by using a "gearing" amount of outside English. For more info, see: using outside English to limit or prevent throw and cling in "English" section.
Cling is often talked about in relation to excessive throw of the OB with a cut shot, but it can also create a lot of trouble for slow-roll follow shots. The CB won't follow the OB near as much as you would expect when there is cling. This video illustrates the effect.
In the snooker world, the term "kick" is sometimes also used to refer to CB hop and its effect on OB motion. The effects of CB hop, along with video demonstrations, can be found on the ball hop in "follow" section.
Here's an example of purposely creating cling (with a chalk smudge) to help create a reverse bank angle:
HSV A.142 - Vernon Elliott cross-side bank with chalk on the object ball to increase throw and spin transfer (YouTube)
The shot is demonstrated in Shot 731 here:
NV B.92 - "Impossible" cut shots, from VEPS V (YouTube)
Here's a fun proposition shot utilizing chalk-induced cling in a devious manner:
NV B.91 - Frozen-throw-down-rail proposition shot, from VEPS V (YouTube)
Other interesting shots utilizing cling can be found in:
Bob Jewett's April '09 BD article (Download).
If the CB and OB don't stay in contact longer when "cling" occurs, what is it that happens instead?
"Cling" in the context of pool doesn't actually mean the balls stick or "cling" together (although, it can seems like this based on the reaction of the balls when "cling" occurs). It just means there is more friction to resist sliding during contact.
The contact time between the balls, which is extremely small, depends only on how the balls compress (in the perpendicular or normal direction) during contact. The amount of sliding or friction between the balls during contact really doesn't affect the contact time. With a cut angle, the CB tends to slide on the OB during contact. At smaller cut angles, the CB and OB slide at first but then "gear" together during contact. This happens sooner with more friction (e.g., with "cling"), but the contact time doesn't change. At larger cut angles, the CB slides during the entire contact time, even with a more-than normal amount of friction.
What changes with increased friction is the amount of loss of relative sliding speed between the balls. With enough friction, the sliding disappears completely resulting in gearing motion. But again, this all happens during the normal ball compression and restitution.
Draw and follow effects
Do shots with draw and follow throw as much as shots with stun?
Stun shots exhibit the most cut-induced throw (see "Throw - Part II: results" - (Download) BD, September, 2006) and spin-induced throw (see "Throw - Part IV: spin-induced throw" - (Download) BD, November, 2006). Draw and follow shots exhibit less throw (see "Throw - Part III: follow and draw effects" - (Download) BD, October, 2006); and if they have the same amount of bottom or top spin, the amount of throw is the same (and less than the amount of stun throw). See "Throw - Part III: follow and draw effects" (Download) (BD, October, 2006) and Bob Jewett's May '06 article (Download) to see how stun, follow, and draw shot throws compare. Because bottom spin wears off due to "drag" action, many draw shots will have less spin, and more throw, than typical follow shots.
Now, object ball (OB) swerve does have a slight effect on throw with follow and draw, but the effect is very small (see the end of TP A.24 (Download) for example numbers). Strictly, a follow shot will have slight OB swerve in the throw direction, effectively increasing the effective throw a tiny amount; but for all practical purposes, follow and draw shots with equal amounts of spin throw the same amount. Now, if a draw shot has more backspin than a follow shot has topspin, then the draw shot will definitely have less throw than the follow shot. The closer a shot is to stun, the more throw it will have.
Why do stun, follow, and draw shots create radically different amounts of throw at small to medium cut angles and similar (but smaller) amounts of throw at large cut angles?
The reason why top and bottom spin make less difference at larger cut angles is that sliding motion between the CB and OB is mostly horizontal at the larger angles. Imagine a CB spinning in place with topspin in contact with an OB ball. If the CB is in front of the OB (as with a full-ball hit), the CB is rubbing straight down on the OB. Now, with the CB still spinning, move it around the OB (while keeping the spin direction the same) simulating different cut angles. When the CB is on the side of the OB (as with a 90 degree cut), the spin creates no rub at all at the point of contact between the balls. The amount of downward rub changes gradually with the cut angle. It is larger for a small cut angle, and smaller for a large cut angle.
Now, throw is caused by horizontal rubbing motion between the CB and OB. When a stunned CB hits the OB at an angle, the rubbing motion is completely horizontal, creating maximum throw. When there is topspin or bottom spin, the rubbing motion is less horizontal, creating less horizontal throw. However, as described above, this effect is less at larger cut angles. That is why stun, follow, and draw shots create similar amounts of throw at larger cut angles.
Examples
What are some example shots where throw and spin transfer can be used or must be accounted for?
Several examples of throw shots are demonstrated in the following video:
And here are some more:
"Throw - Part I: introduction" (BD, August, 2006).
"Throw - Part II: results" (BD, September, 2006).
"Throw - Part III: follow and draw effects" (BD, October, 2006).
"Throw - Part IV: spin-induced throw" (BD, November, 2006).
"Throw - Part V: SIT speed effects" (BD, December, 2006).
"Throw - Part VI: inside/outside English" (BD, January, 2007).
"Throw - Part VII: CIT/SIT combo" (BD, February, 2007).
"Throw - Part VIII: spin transfer" (BD, March, 2007).
"Throw - Part IX: spin transfer follow-up" (BD, April, 2007).
"Throw - Part X: the big picture" (BD, May, 2007).
"Throw - Part XI: everything you ever wanted to know about throw" (BD, June, 2007).
"Throw - Part XII: calibration, and hold shots" (BD, July, 2007).
Any time there is throw, there is also spin transfer. Numerous examples of where spin transfer comes into play can be found here: spin transfer examples.
Throw can also be used in "hold" or "kill" shots. Many trick shots also rely on, or are affected by, throw. For examples, see famous trick shots in "trick shots" section.
Frozen balls
Do frozen balls throw more than non-frozen balls?
In the case of combinations, frozen balls will always throw more than non-frozen balls (especially with a larger gap between the OBs) because the 1st OB will pick up some forward roll, which reduces throw. Also, if faster speed is used to help prevent this, throw will be reduced by the speed.
In the case of a cut shot, the OB can be thrown very nearly as much as with a frozen combo, as long as slow speed and stun are used, where throw is maximum. One reason some people might think frozen balls throw more than a stun shot is that frozen balls can be hit softly, easily creating maximum throw. With frozen balls, stun is guaranteed. However with a non-frozen cut shot, where there is distance between the CB and OB, it is very difficult to ensure stun with a soft shot. Therefore, it is rare to get maximum throw with a cut shot. Although, if you do hit a true stun shot at soft speed, the OB will throw very close to the same amount as a frozen ball would.
To answer this question more scientifically, I did a careful experiment to attempt to measure the difference between throw with a frozen-combination and throw with a stunned ball at the same speed.
I used two new and clean Aramith measles balls as OBs, and wiped them after every shot, along with the CB which was another Aramith measles ball. I firmly tapped the two OBs into place (frozen, but not leaning against one another) with one OB on the head spot and the other on the head-rail side of the first with the line of centers along the table center line. I also marked the tapped positions with little white donuts to help further ensure consistent ball placement, shot after shot. I then hit the 1st OB squarely with another CB placed between the balls and the head rail to locate and mark on the far rail the line of centers direction (which was pretty much exactly along the table center line with every shot). I then tapped and marked the CB position about 6 inches on the head-rail side of the near OB along the center-to-edge line of the frozen-ball combo to ensure a consistent cut angle (with a square hit on the 1st ball) very close to 30 degrees. I then hit this shot (after checking that the OB were in fact frozen) about 20 times at as consistent a speed as I could and marked on the far rail where the thrown OB hit (by placing a piece of chalk on the rail with one edge pointing along the line of the thrown OB). I only checked shots where the CB stopped dead and the 2nd OB bounced off the foot rail and came back to within a 1/2-diamond of the head rail to ensure consistent speed. All of the target-speed shots threw the OB very consistently to the same position on the rail.
I then removed the donut for the lead OB, replaced and carefully tilted the lead OB back toward the CB along the CTE line a very small amount and firmly re-tapped the ball into the cloth until the OB sat about 1 mm (a very small gap) away from the 2nd OB. When I was confident with the placement, I put down another donut in the new location and tapped the ball in place even more firmly. I then hit about 20 shots with this new position (resulting in a non-frozen stunned hit of the lead OB into the 2nd), with everything else the same. Again, the direction the ball headed was very consistent for the shots at the target speed.
Here are the results after measuring the distances between the head spot and rail marks carefully and doing the throw angle calculations:
throw angle for frozen balls = 5.16 degrees
throw angle for non-frozen stun shot of same speed and cut angle = 4.95 degrees
Therefore, my experiment suggests frozen balls might throw a very small percentage more (about 4% more) than a stunned ball. However, this difference is not very significant, and could be partly due to experimental error.
During a frozen-ball combo, does the CB still apply force on the 1st OB while it is in contact with the 2nd OB, and wouldn't this decrease the amount of resulting throw since the CB might resist the induced spin in the 1st OB and create a reaction force to oppose the throwing force?
There are delays in the ball interactions due to the time it takes for elastic waves to travel between the contact areas (between the CB and 1st OB, and between the 1st and 2nd OBs), but this happens very quickly. The elastic wave speed in pool balls is probably close to 4000 m/s. From Marlow's experiments, ball contact times are probably close to 0.0003 seconds. During that time, the waves have time to travel back and forth across the 1st OB at least 20 times. From these rough calculations, it is clear that forces developed between the CB and 1st OB can certainly have an effect while the 1st OB is interacting with the 2nd OB.
The CB interaction would tend to slow the induced spin that develops in the 1st OB as it interacts with the 2nd OB. This would tend to increase the relative sliding speed between the OBs, which would reduce the dynamic friction COR (since friction is less at faster sliding speeds with pool balls). This would tend to decrease the amount of throw. However, this must be a small/insignificant effect since the experiment above did not reveal this effect.
"Hold" or "kill" shot to limit cue ball drift
Can throw be used to "kill" cue ball motion on a cut shot?
When the CB is close to the OB, English can most definitely be used to limit how much the CB drifts after the hit. For illustrations and explanations, see "Throw - Part XII: calibration, and hold shots" (Download) (BD, July, 2007). However, at larger cue-ball-to-object-ball distances, a plain stun shot will be the most effective. Swerve and drag control become bigger factors at larger distances (see the article (Download) for more info).TP A.29 (Download) presents a full analysis for those with math and physics backgrounds.
Bob Jewett has a good test to explore the ability to use English to hold the CB. See image below:
- NV 7.5 - Frozen ball throw (YouTube)
- NV 7.6 - Frozen cue ball throw (YouTube)
- NV A.18 - Colin Colenso's throw test video (effects of speed and english) (YouTube)
- NV A.21 - Bank shot using throw and spin transfer (YouTube)
"Throw - Part I: introduction" (BD, August, 2006).
"Throw - Part II: results" (BD, September, 2006).
"Throw - Part III: follow and draw effects" (BD, October, 2006).
"Throw - Part IV: spin-induced throw" (BD, November, 2006).
"Throw - Part V: SIT speed effects" (BD, December, 2006).
"Throw - Part VI: inside/outside English" (BD, January, 2007).
"Throw - Part VII: CIT/SIT combo" (BD, February, 2007).
"Throw - Part VIII: spin transfer" (BD, March, 2007).
"Throw - Part IX: spin transfer follow-up" (BD, April, 2007).
"Throw - Part X: the big picture" (BD, May, 2007).
"Throw - Part XI: everything you ever wanted to know about throw" (BD, June, 2007).
"Throw - Part XII: calibration, and hold shots" (BD, July, 2007).
Any time there is throw, there is also spin transfer. Numerous examples of where spin transfer comes into play can be found here: spin transfer examples.
Throw can also be used in "hold" or "kill" shots. Many trick shots also rely on, or are affected by, throw. For examples, see famous trick shots in "trick shots" section.
Frozen balls
Do frozen balls throw more than non-frozen balls?
In the case of combinations, frozen balls will always throw more than non-frozen balls (especially with a larger gap between the OBs) because the 1st OB will pick up some forward roll, which reduces throw. Also, if faster speed is used to help prevent this, throw will be reduced by the speed.
In the case of a cut shot, the OB can be thrown very nearly as much as with a frozen combo, as long as slow speed and stun are used, where throw is maximum. One reason some people might think frozen balls throw more than a stun shot is that frozen balls can be hit softly, easily creating maximum throw. With frozen balls, stun is guaranteed. However with a non-frozen cut shot, where there is distance between the CB and OB, it is very difficult to ensure stun with a soft shot. Therefore, it is rare to get maximum throw with a cut shot. Although, if you do hit a true stun shot at soft speed, the OB will throw very close to the same amount as a frozen ball would.
To answer this question more scientifically, I did a careful experiment to attempt to measure the difference between throw with a frozen-combination and throw with a stunned ball at the same speed.
I used two new and clean Aramith measles balls as OBs, and wiped them after every shot, along with the CB which was another Aramith measles ball. I firmly tapped the two OBs into place (frozen, but not leaning against one another) with one OB on the head spot and the other on the head-rail side of the first with the line of centers along the table center line. I also marked the tapped positions with little white donuts to help further ensure consistent ball placement, shot after shot. I then hit the 1st OB squarely with another CB placed between the balls and the head rail to locate and mark on the far rail the line of centers direction (which was pretty much exactly along the table center line with every shot). I then tapped and marked the CB position about 6 inches on the head-rail side of the near OB along the center-to-edge line of the frozen-ball combo to ensure a consistent cut angle (with a square hit on the 1st ball) very close to 30 degrees. I then hit this shot (after checking that the OB were in fact frozen) about 20 times at as consistent a speed as I could and marked on the far rail where the thrown OB hit (by placing a piece of chalk on the rail with one edge pointing along the line of the thrown OB). I only checked shots where the CB stopped dead and the 2nd OB bounced off the foot rail and came back to within a 1/2-diamond of the head rail to ensure consistent speed. All of the target-speed shots threw the OB very consistently to the same position on the rail.
I then removed the donut for the lead OB, replaced and carefully tilted the lead OB back toward the CB along the CTE line a very small amount and firmly re-tapped the ball into the cloth until the OB sat about 1 mm (a very small gap) away from the 2nd OB. When I was confident with the placement, I put down another donut in the new location and tapped the ball in place even more firmly. I then hit about 20 shots with this new position (resulting in a non-frozen stunned hit of the lead OB into the 2nd), with everything else the same. Again, the direction the ball headed was very consistent for the shots at the target speed.
Here are the results after measuring the distances between the head spot and rail marks carefully and doing the throw angle calculations:
throw angle for frozen balls = 5.16 degrees
throw angle for non-frozen stun shot of same speed and cut angle = 4.95 degrees
Therefore, my experiment suggests frozen balls might throw a very small percentage more (about 4% more) than a stunned ball. However, this difference is not very significant, and could be partly due to experimental error.
During a frozen-ball combo, does the CB still apply force on the 1st OB while it is in contact with the 2nd OB, and wouldn't this decrease the amount of resulting throw since the CB might resist the induced spin in the 1st OB and create a reaction force to oppose the throwing force?
There are delays in the ball interactions due to the time it takes for elastic waves to travel between the contact areas (between the CB and 1st OB, and between the 1st and 2nd OBs), but this happens very quickly. The elastic wave speed in pool balls is probably close to 4000 m/s. From Marlow's experiments, ball contact times are probably close to 0.0003 seconds. During that time, the waves have time to travel back and forth across the 1st OB at least 20 times. From these rough calculations, it is clear that forces developed between the CB and 1st OB can certainly have an effect while the 1st OB is interacting with the 2nd OB.
The CB interaction would tend to slow the induced spin that develops in the 1st OB as it interacts with the 2nd OB. This would tend to increase the relative sliding speed between the OBs, which would reduce the dynamic friction COR (since friction is less at faster sliding speeds with pool balls). This would tend to decrease the amount of throw. However, this must be a small/insignificant effect since the experiment above did not reveal this effect.
"Hold" or "kill" shot to limit cue ball drift
Can throw be used to "kill" cue ball motion on a cut shot?
When the CB is close to the OB, English can most definitely be used to limit how much the CB drifts after the hit. For illustrations and explanations, see "Throw - Part XII: calibration, and hold shots" (Download) (BD, July, 2007). However, at larger cue-ball-to-object-ball distances, a plain stun shot will be the most effective. Swerve and drag control become bigger factors at larger distances (see the article (Download) for more info).TP A.29 (Download) presents a full analysis for those with math and physics backgrounds.
Bob Jewett has a good test to explore the ability to use English to hold the CB. See image below:
At small distances with slow-speed stun, with about 50% english, the effect of throw is irrefutable and dramatic. In fact, with a small enough cut angle, and the right speed and amount of spin, the CB can actually be made to move in the same direction as the OB (e.g., to the left, with a cut to the left). Examples can be viewed in the following video: (YouTube)
NV B.21 - Straight shot squirt, swerve, and throw
Is inside english a better choice than outside english to limit CB sideways drift on some shots?
See the following two videos that study this effect: (YouTube Videos)
Maximum throw
How can I achieve maximum throw using English?
Maximum spin-induced throw (SIT) occurs with slow speed, stun, and about 50% English. See "Throw - Part V: SIT speed effects" (Download) (BD, December, 2006) for more information. The reason why more spin doesn't give more SIT is: friction is less at faster sliding speeds. With more English, the CB slides along the OB with faster relative speed during contact, producing less throwing force. Per Diagram 1 in the SIT article (Download), below about 25% English, speed has no effect on the amount of SIT! For more information on SIT speed effects, see: HSV B.18 - spin-induced throw speed and English effects.(YouTube)
Maximum collision-induced throw (CIT), with no English, occurs with a slow-speed stun shot at about a 1/2-ball hit. See "Throw - Part II: results" (Download) (BD, September, 2006) for more information. At larger cut angles, again the friction is less due to the faster relative sliding motion between the balls during contact. Per Diagram 1 in the CIT article (Download), for cut angles below about 20 degrees, speed has no effect on the amount of CIT!
Maximum throw, under typical conditions, is about 1 inch per foot of CB travel, which is about 5 degrees.
For examples and demonstrations, see the following video:
NV B.21 - Straight shot squirt, swerve, and throw
Is inside english a better choice than outside english to limit CB sideways drift on some shots?
See the following two videos that study this effect: (YouTube Videos)
- NV B.25 - Using draw and sidespin 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
Maximum throw
How can I achieve maximum throw using English?
Maximum spin-induced throw (SIT) occurs with slow speed, stun, and about 50% English. See "Throw - Part V: SIT speed effects" (Download) (BD, December, 2006) for more information. The reason why more spin doesn't give more SIT is: friction is less at faster sliding speeds. With more English, the CB slides along the OB with faster relative speed during contact, producing less throwing force. Per Diagram 1 in the SIT article (Download), below about 25% English, speed has no effect on the amount of SIT! For more information on SIT speed effects, see: HSV B.18 - spin-induced throw speed and English effects.(YouTube)
Maximum collision-induced throw (CIT), with no English, occurs with a slow-speed stun shot at about a 1/2-ball hit. See "Throw - Part II: results" (Download) (BD, September, 2006) for more information. At larger cut angles, again the friction is less due to the faster relative sliding motion between the balls during contact. Per Diagram 1 in the CIT article (Download), for cut angles below about 20 degrees, speed has no effect on the amount of CIT!
Maximum throw, under typical conditions, is about 1 inch per foot of CB travel, which is about 5 degrees.
For examples and demonstrations, see the following video:
Physics details and results
What are all of the factors that affect how much throw a shot will have?
TP A.14 (Download) contains a thorough analysis, and TP A.28 (Download) contains graphs for all types of shots. Let me warn you ahead of time: TP A.14 is full of lots of complicated math and physics, so you might not want to look at the whole thing, but the results in TP A.28 might still be of interest. If not, or at least look at some of the conclusions summarized below. Plots in TP A.14 compare well to experimental, theoretical, and qualitative results presented by Marlow, Sheppard, Koehler, and Jewett. The analysis and results cover both collision-induced throw (CIT) and spin-induced throw (SIT). The effects of cut angle, speed, and spin are also considered.
The model of friction I use is more complete and accurate than any other I have seen presented before. First, I include the effect of speed on friction, based on experimental data from Marlow. And more importantly, I correct an error that appears in many analyses of collisions with friction (e.g., in Shepard's work). The error involves not taking into account the potential loss of relative sliding motion between the CB and OB during impact. I have accounted for this effect, and it significantly affects the results.
Here are some of the conclusions resulting from the mathematical analysis (which agree with what most people understand about throw effects)
What are all of the factors that affect how much throw a shot will have?
TP A.14 (Download) contains a thorough analysis, and TP A.28 (Download) contains graphs for all types of shots. Let me warn you ahead of time: TP A.14 is full of lots of complicated math and physics, so you might not want to look at the whole thing, but the results in TP A.28 might still be of interest. If not, or at least look at some of the conclusions summarized below. Plots in TP A.14 compare well to experimental, theoretical, and qualitative results presented by Marlow, Sheppard, Koehler, and Jewett. The analysis and results cover both collision-induced throw (CIT) and spin-induced throw (SIT). The effects of cut angle, speed, and spin are also considered.
The model of friction I use is more complete and accurate than any other I have seen presented before. First, I include the effect of speed on friction, based on experimental data from Marlow. And more importantly, I correct an error that appears in many analyses of collisions with friction (e.g., in Shepard's work). The error involves not taking into account the potential loss of relative sliding motion between the CB and OB during impact. I have accounted for this effect, and it significantly affects the results.
Here are some of the conclusions resulting from the mathematical analysis (which agree with what most people understand about throw effects)
- Both CIT and SIT are larger at slower speeds.
- CIT increases with cut angle, but levels off at higher cut angles.
- CIT is larger for stun shots.
- CIT is larger for stun shots close to a 1/2-ball hit (30-degree cut angle), per the plot on page 6.
- SIT is maximum for stun and a medium amount of side spin, per the plot on page 7. "Medium" corresponds to 50% English. Additional side spin does not result in more throw; in fact, the model predicts a loss in throw with excess side spin, because friction is less for higher relative speeds between the balls.
- SIT is larger, and most sensitive to side spin, with stun shots. But SIT is not nearly as sensitive to small amounts of side spin as some people think. The more accurate model of friction affected these results significantly.
- Inside English increases CIT at small cut angles.
- Outside English can create SIT that overcomes CIT.
- Outside English creates maximum SIT at small cut angles.
- "Gearing" outside English results in absolutely no throw.
- The theoretical plot of throw vs. cut angle for stun shots matches up with Bob Jewett's experimental data (Image below) very well (see "Throw - Part II: results" - (Download) BD, September, 2006).
- For a stun shot, the amount of CIT is independent of speed at small cut angles.
- For a stun shot, CIT is largest in the half-ball hit range (30-degree cut angle range).
- For a stun shot, at larger cut angles, CIT is larger for slower speeds.
- For a half-ball hit, throw is greatest for a stun shot with no side spin or with 10% outside English. For 50% outside English with a half-ball hit, there is no throw.
Spin transfer
Can you prove to me that spin can be transferred from the cue ball to an object ball?
For the non-believers out there, I now have several resources available to prove that spin transfer exists. Video below provides a high-speed video demonstration of the effect, the spin transfer is clearly visible:
Can you prove to me that spin can be transferred from the cue ball to an object ball?
For the non-believers out there, I now have several resources available to prove that spin transfer exists. Video below provides a high-speed video demonstration of the effect, the spin transfer is clearly visible:
The video clips were filmed with a special high-speed camera.
The super slow-motion playback helps you visualize effects that cannot be seen with the naked eye or with a standard video camera.
Refer to the book (external web-link) for a description and illustration of the principles involved.
Additional clips not referenced in the book (but referenced in Billiards Digest articles (external web-link)). Complete list of these videos are here (external web-link).
For the physics nerds out there: TP A.27 (Download) provides a mathematical proof. And for people who need to see shot examples, here's one that relies on both throw and spin transfer: YouTube video
With shots like the one in the video above, throw and spin transfer are maximum at slower speeds with about 50% English (half maximum). However, at slow speeds, more of the transferred spin will wear off on the way to the rail, so the optimal speed (for the spin-transfer rebound-angle-change effect) will depend on conditions and the distance to the rail.
And here are some others (also see more posted by others below): (YouTube Videos)
Also, HSV A.143-A.146 (external web-link) illustrate spin transfer and "vertical throw" (ball hop) resulting from follow and draw. Notice how the effects are much greater when chalk is added to the object ball surface. Remember: keep those balls clean. Here is another video, with explanations, on the same topic: (YouTube)
HSV B.46 - CB and OB hop and spin transfer during follow shots
Whenever there is throw (SIT or CIT), there is spin transfer (SIS:spin-induced spin or CIS:cut-induced spin); and the more throw you have, the more spin transfer you have. It is a small amount of spin, but it makes a big difference with bank shots (e.g., with an inside cut, the bank is lengthened; and with an outside cut, the bank is shortened). For more info, see bank and kick effects in "kick shots" section.
For a good example of how throw and spin transfer can affect a bank shot, see "Throw - Part VIII: spin transfer" (Download) (BD, March, 2007) and this YouTube video.
Sometimes the phrase "twist the bank in" is used to describe shots like this, where spin transferred to the object ball is used to alter the bank rebound angle.
Section 40 (Spin Transfer Shots) in Disc IV of the Video Encyclopedia of Pool Shots (external web-links) presents several types of shots (with many examples) where cut-induced spin (CIS) and spin-induced spin (SIS) are important factors.
Many trick shots also rely on, or are affected by, throw and spin transfer. For examples, see famous trick shots in "trick shots" section.
from Patrick Johnson:
In both setups (see below) the OB must have spin to go. However, the setup on the right needs CB spin in order to transfer spin to the OB, but the one on the left can transfer spin to the OB without spinning the CB.
The super slow-motion playback helps you visualize effects that cannot be seen with the naked eye or with a standard video camera.
Refer to the book (external web-link) for a description and illustration of the principles involved.
Additional clips not referenced in the book (but referenced in Billiards Digest articles (external web-link)). Complete list of these videos are here (external web-link).
For the physics nerds out there: TP A.27 (Download) provides a mathematical proof. And for people who need to see shot examples, here's one that relies on both throw and spin transfer: YouTube video
With shots like the one in the video above, throw and spin transfer are maximum at slower speeds with about 50% English (half maximum). However, at slow speeds, more of the transferred spin will wear off on the way to the rail, so the optimal speed (for the spin-transfer rebound-angle-change effect) will depend on conditions and the distance to the rail.
And here are some others (also see more posted by others below): (YouTube Videos)
Also, HSV A.143-A.146 (external web-link) illustrate spin transfer and "vertical throw" (ball hop) resulting from follow and draw. Notice how the effects are much greater when chalk is added to the object ball surface. Remember: keep those balls clean. Here is another video, with explanations, on the same topic: (YouTube)
HSV B.46 - CB and OB hop and spin transfer during follow shots
Whenever there is throw (SIT or CIT), there is spin transfer (SIS:spin-induced spin or CIS:cut-induced spin); and the more throw you have, the more spin transfer you have. It is a small amount of spin, but it makes a big difference with bank shots (e.g., with an inside cut, the bank is lengthened; and with an outside cut, the bank is shortened). For more info, see bank and kick effects in "kick shots" section.
For a good example of how throw and spin transfer can affect a bank shot, see "Throw - Part VIII: spin transfer" (Download) (BD, March, 2007) and this YouTube video.
Sometimes the phrase "twist the bank in" is used to describe shots like this, where spin transferred to the object ball is used to alter the bank rebound angle.
Section 40 (Spin Transfer Shots) in Disc IV of the Video Encyclopedia of Pool Shots (external web-links) presents several types of shots (with many examples) where cut-induced spin (CIS) and spin-induced spin (SIS) are important factors.
Many trick shots also rely on, or are affected by, throw and spin transfer. For examples, see famous trick shots in "trick shots" section.
from Patrick Johnson:
In both setups (see below) the OB must have spin to go. However, the setup on the right needs CB spin in order to transfer spin to the OB, but the one on the left can transfer spin to the OB without spinning the CB.
from JB Cases:
...back in the olden days..., back when balls would actually spot, this here shot (see below) used to come up all the time and we had to know how to make the 8 spin BELOW then nine so that it would be safe. This shot very rarely comes up now.
The cue ball STOPS frozen to the nine or just behind it. The eight goes to the side rail and spins to the left going lower down table than the where the nine is. It was IMPOSSIBLE to hit the 8 ANYWHERE to the right of center or it would make the 9 move as well. So you have hit center ball with low right spin which then transfers left spin to the object ball.
...back in the olden days..., back when balls would actually spot, this here shot (see below) used to come up all the time and we had to know how to make the 8 spin BELOW then nine so that it would be safe. This shot very rarely comes up now.
The cue ball STOPS frozen to the nine or just behind it. The eight goes to the side rail and spins to the left going lower down table than the where the nine is. It was IMPOSSIBLE to hit the 8 ANYWHERE to the right of center or it would make the 9 move as well. So you have hit center ball with low right spin which then transfers left spin to the object ball.
Stop shot with side spin
How do you account for throw with a stop shot with side spin?
To stop the cue ball using side spin, there must be a cut angle. In other words, the cue ball must hit the object ball slightly off center as if you were going to "cheat" the pocket (e.g., see NV 5.7 (YouTube)). If you are aiming the shot straight-on, cue ball deflection (squirt) will automatically create the cut angle. With a cut angle, if there was no side spin the object ball would cheat the pocket and the cue ball would drift along the tangent line. With left side spin, squirt causes the cue ball to deflect to the right, creating a cut angle to the left. However, the object ball would be thrown back to the right (due to the left side spin) towards the center of the pocket. Because the cue ball throws the object ball right, the object ball pushes back on the cue ball to the left, counteracting the expected tangent line motion to the right. Therefore, the cue ball stops in place. "90° and 30° Rule Follow-up - Part IV: English effects" (Download) (BD, May, 2005) doesn't address this issue directly, but the information in the article is relevant.
How do you account for throw with a stop shot with side spin?
To stop the cue ball using side spin, there must be a cut angle. In other words, the cue ball must hit the object ball slightly off center as if you were going to "cheat" the pocket (e.g., see NV 5.7 (YouTube)). If you are aiming the shot straight-on, cue ball deflection (squirt) will automatically create the cut angle. With a cut angle, if there was no side spin the object ball would cheat the pocket and the cue ball would drift along the tangent line. With left side spin, squirt causes the cue ball to deflect to the right, creating a cut angle to the left. However, the object ball would be thrown back to the right (due to the left side spin) towards the center of the pocket. Because the cue ball throws the object ball right, the object ball pushes back on the cue ball to the left, counteracting the expected tangent line motion to the right. Therefore, the cue ball stops in place. "90° and 30° Rule Follow-up - Part IV: English effects" (Download) (BD, May, 2005) doesn't address this issue directly, but the information in the article is relevant.
For more info, visit billiards.colostate.edu
Training Aids
Training Aids in Pool and Billiards
... various resources supporting learning and teaching pool.
Aiming aids
Are laser training aids useful for improving one's aim?
A less expensive (i.e., costs nothing) and maybe even a more effective alternative is to have a helper place a real ball in the desired GB(ghost ball) location (adjusted for throw or not) and pull it away when the person shoots.
Also, striped balls are useful to help the shooter visualize both the "aiming line" (from the CB to the GB center) and the "impact line" between the GB and OB centers.
Instructional diagrams
Do you have blank diagrams I can copy or print to use to diagram shots or drills?
Several blank diagrams are available under "templates" in the instructor and student resources page (external web-link). Players and instructors can use them to diagram shots for practice, instruction, or documentation. There is a full color version (Download), and two different B&W versions (with shading, ink-conserving lines-only version (Download)). They are all drawn to scale based on the BCA specifications, and they contain grid lines to help line things up. The pages print to fill a 8.5" x 11" page suitable for a 3-ring binder, and there are two tables per page with room for annotations. You can print the pages directly from the website; or, if you prefer, you can save the files directly to your own computer (by right-clicking and selecting "Save Target As").
Permission to use Dr. Dave's resources
Can I link to or copy documents on your website?
Instructors, schools, and others are welcome to link to or use any of the material posted at billiards.colostate.edu (external web-link), as long as the materials are not repackaged or used in any for-sale items (e.g., manuals, books, DVDs, etc.), and as long as the source is clearly cited (if not linked directly). Material is posted on the website so people can use it and benefit from it, not to keep it private. However, no part of my book, DVDs, or CD-ROMs (external web-link) be copied or used directly without Dr. Dave's permission.
Spotted ball vs. striped ball
What is better for visualizing ball spin, an Aramith red-spots ball or a striped Elephant Practice ball?
The dotted ball is much better for visualizing spin and English. The striped ball works great when the stripe is lined up so the spin is perpendicular to the stripe. However, when the cue ball hits an object ball or a rail, the spin can be difficult or impossible (if the stripe is lined up with the spin direction) to see. For high-speed-video (external web-link) stuff, I like the striped ball, because I can carefully control situations. But for drills and normal play, where you might want to visualize the cue ball spin during all phases of a shot, the spotted ball is superior. You can see the spin on the ball regardless of its orientation.
... various resources supporting learning and teaching pool.
Aiming aids
Are laser training aids useful for improving one's aim?
A less expensive (i.e., costs nothing) and maybe even a more effective alternative is to have a helper place a real ball in the desired GB(ghost ball) location (adjusted for throw or not) and pull it away when the person shoots.
Also, striped balls are useful to help the shooter visualize both the "aiming line" (from the CB to the GB center) and the "impact line" between the GB and OB centers.
Instructional diagrams
Do you have blank diagrams I can copy or print to use to diagram shots or drills?
Several blank diagrams are available under "templates" in the instructor and student resources page (external web-link). Players and instructors can use them to diagram shots for practice, instruction, or documentation. There is a full color version (Download), and two different B&W versions (with shading, ink-conserving lines-only version (Download)). They are all drawn to scale based on the BCA specifications, and they contain grid lines to help line things up. The pages print to fill a 8.5" x 11" page suitable for a 3-ring binder, and there are two tables per page with room for annotations. You can print the pages directly from the website; or, if you prefer, you can save the files directly to your own computer (by right-clicking and selecting "Save Target As").
Permission to use Dr. Dave's resources
Can I link to or copy documents on your website?
Instructors, schools, and others are welcome to link to or use any of the material posted at billiards.colostate.edu (external web-link), as long as the materials are not repackaged or used in any for-sale items (e.g., manuals, books, DVDs, etc.), and as long as the source is clearly cited (if not linked directly). Material is posted on the website so people can use it and benefit from it, not to keep it private. However, no part of my book, DVDs, or CD-ROMs (external web-link) be copied or used directly without Dr. Dave's permission.
Spotted ball vs. striped ball
What is better for visualizing ball spin, an Aramith red-spots ball or a striped Elephant Practice ball?
The dotted ball is much better for visualizing spin and English. The striped ball works great when the stripe is lined up so the spin is perpendicular to the stripe. However, when the cue ball hits an object ball or a rail, the spin can be difficult or impossible (if the stripe is lined up with the spin direction) to see. For high-speed-video (external web-link) stuff, I like the striped ball, because I can carefully control situations. But for drills and normal play, where you might want to visualize the cue ball spin during all phases of a shot, the spotted ball is superior. You can see the spin on the ball regardless of its orientation.
For more info, visit billiards.colostate.edu
Trick and Proposition Shots
Trick and Proposition Shots in Pool and Billiards
... how to set up and shoot artistic pool trick shots and proposition shots.
(external web-link) for more information:
see Disc V of the Video Encyclopedia of Pool Shots (VEPS)
Coin proposition shots
What are some fun and famous proposition shots using a coin?
Several are describe and illustrated in "Coin Proposition Shots" (Download) (BD, January, 2012). Here is a demonstration of the featured shot in the article, involving knocking a quarter off and away from a ball:
... how to set up and shoot artistic pool trick shots and proposition shots.
(external web-link) for more information:
see Disc V of the Video Encyclopedia of Pool Shots (VEPS)
Coin proposition shots
What are some fun and famous proposition shots using a coin?
Several are describe and illustrated in "Coin Proposition Shots" (Download) (BD, January, 2012). Here is a demonstration of the featured shot in the article, involving knocking a quarter off and away from a ball:
Famous trick shots
What are the ten most famous trick shots of all time?
All ten are listed in "VEPS GEMS - Part XVII: Trick and Proposition Shots" (Download) (BD, May, 2011) and they are described and demonstrated on Disc V of the Video Encyclopedia of Pool Shots (external web-links) (VEPS).
Here's the "Butterfly Shot" and the "Line of Four Balls" shot:
What are the ten most famous trick shots of all time?
All ten are listed in "VEPS GEMS - Part XVII: Trick and Proposition Shots" (Download) (BD, May, 2011) and they are described and demonstrated on Disc V of the Video Encyclopedia of Pool Shots (external web-links) (VEPS).
Here's the "Butterfly Shot" and the "Line of Four Balls" shot:
Others can be found here: shots from pool movies and in the Mike Massey trick shot collection (YouTube) video.
Proposition shots
What are some good proposition shots?
Many are described and demonstrated on on Disc V of the Video Encyclopedia of Pool Shots (external web-links) (VEPS). Here's one involving throw of a frozen ball down a rail (which is described and illustrated in "VEPS GEMS - Part XVII: Trick and Proposition Shots" - (Download) BD, May, 2011). YouTube video
And here are some example "impossible" cut shots: YouTube video
Here's the classic: "Hit the quarter off the object ball more than a certain distance (e.g., off a dollar bill)" proposition shot: YouTube video
For more information and examples, see "Coin Proposition Shots" (Download) (BD, January, 2012).
Other famous proposition shots can be found in the Mike Massey trick shot collection (YouTube) video.
Shots from pool movies
How do find and learn how to make the shots from all of the famous pool movies?
I wrote a series of articles for Billiards Digest (BD) describing the famous pool movies and the shots made famous by them. Here they are: (Downloads)
Proposition shots
What are some good proposition shots?
Many are described and demonstrated on on Disc V of the Video Encyclopedia of Pool Shots (external web-links) (VEPS). Here's one involving throw of a frozen ball down a rail (which is described and illustrated in "VEPS GEMS - Part XVII: Trick and Proposition Shots" - (Download) BD, May, 2011). YouTube video
And here are some example "impossible" cut shots: YouTube video
Here's the classic: "Hit the quarter off the object ball more than a certain distance (e.g., off a dollar bill)" proposition shot: YouTube video
For more information and examples, see "Coin Proposition Shots" (Download) (BD, January, 2012).
Other famous proposition shots can be found in the Mike Massey trick shot collection (YouTube) video.
Shots from pool movies
How do find and learn how to make the shots from all of the famous pool movies?
I wrote a series of articles for Billiards Digest (BD) describing the famous pool movies and the shots made famous by them. Here they are: (Downloads)
- "Billiards on the Big Screen - Pool Hall Junkies" (BD, October, 2004).
- "Billiards on the Big Screen - The Color of Money" (BD, September, 2004).
- "Billiards on the Big Screen - The Hustler" (BD, August, 2004).
For more info, visit billiards.colostate.edu
Videos
Billiards and Pool Videos
... where to find interesting pool videos and instructional videos for learning how to play pool.
Austrian high-speed footage
Where can I find that awesome high-quality, slow-motion video footage from that group in Austria?
Here's a collection of the clips, along with some cool music:
... where to find interesting pool videos and instructional videos for learning how to play pool.
Austrian high-speed footage
Where can I find that awesome high-quality, slow-motion video footage from that group in Austria?
Here's a collection of the clips, along with some cool music:
It shows various super-slow-motion carom, jump, and kick shots filmed at 2000 frames/sec with a very high resolution, full color, high-speed camera. The video also includes infrared footage showing how temperatures change dramatically on the ball and cloth during various types of shots. Here's an isolated clip of the close-up of the cue tip hitting the cue ball:
The video collection was provided by the Billiard SportKlub Union out of Austria (here (external web-link)).
Dr. Dave's video production methods
How does Dr. Dave create and post all of those videos online?
People often ask how I make and post videos on this website, so I thought I would share the procedure with others that might be interested:
1) Shoot raw footage with a mini-DV digital video camera mounted in a 4-way adjustable tripod. For overhead shots, I either have the tripod fully or partially on the table, with the help of bar stools; otherwise, it stands on the floor. I often shoot multiple "takes" of the same shot because of missed shots, narration errors, bad lighting or camera views, etc.
2) Download the video from the camera to my PC through a fire-wire interface, using Pinnacle Studio software. Video requires lots of disk space (about 3-4 MB/sec ... that's megabytes per second!).
3) Use Pinnacle Studio to edit out the bad "takes" and trim the beginning and end of the best take. I also remove pauses and errors made (and later corrected) in the middle of a "take." That's why you sometimes see jumps in the middle of a clip.
4) Use CorelDraw to create table-diagram illustrations. I export images as JPEGs and insert them into the video within Pinnacle Studio.
5) Use Pinnacle Studio to store the edited video clip as a compressed Windows Media Video (WMV) file so it won't take up so much disk space and so it will be easily downloadable via the Internet. An uncompressed AVI video file can take up 50-100 more space than a compressed WMV file! In other words, if I didn't compress the video, it would take 50-100 times longer to download it via your Internet connection. The downside (because there are no "free lunches") is that the video image size and quality is not as good.
6) Use Dreamweaver software to edit the website and add links to the new video clips. Upload selected videos to YouTube and embed these into pages on the website.
7) Use Dreamweaver to upload the new website and video files to the web server so they can be viewed by anyone in the world.
That's it ... difficult to learn at first, but very easy once you have done it for a while. It also helps being at a university where there are people around that know how to do all of this stuff and are willing (and excited) to show you how.
Jacksonville Project and other high-speed video studies
What was the Jacksonville Project?
This was a high-speed video study of pool physics stuff carried out by Bob Jewett, Mike Shamos, and others in Jacksonville, Florida in 1998. Here's a list of the original questions they hoped to answer with the study: on this group (external group-link)
These articles describe the study and the results:
"Uncovering the Cue Mysteries" (Download) by Mike Shamos (Billiards Digest, April, 1999)
"Freeze Frame" (Download) by Bob Jewett (Billiards Digest, April, 1999)
"Don't Grip It and Rip It" (Download) by Bob Jewett (Billiards Digest, June, 1999)
Here's a summary of some of the main results:
and here are some articles and info pages describing some of the results:
Austrian high-speed footage in this section
A group in Russia has also captured some really high-speed footage and done some experiments with a cue-testing machine. For more info, see:
high-speed-video footage (external web-link)
Cue Testing Unit (external web-link)
Reviews of Dr. Dave's DVDs
Information about Dr. Dave's "Illustrated Principles of Pool and Billiards" DVDs can be found here (external web-link).
Also see: reviews of Dr. Dave's book in "book" section.
Also see: reviews and testimonials (external web-link) for the "Video Encyclopedia of Pool Shots" (external web-link) instructional series by Dr. Dave and Tom Ross.
from Billy_Bob:
I finally bought Dr. Dave's DVD and book "The Illustrated Principles of Pool and Billiards".
And WOW! The DVD is fantastic! This should have been the first DVD I bought. I learned many new *basic* things from watching this DVD.
By fantastic, I mean that it is short, to the point, and clearly demonstrates many fundamentals of shots.
-Shots like a ball near the side pocket, how to shoot it so you will not scratch in the side. And why it works. (Why speed is the key.)
-How not to scratch on shots. And why it works.
-How similar shots can radically change where the cue ball will wind up depending on speed of hit. And why it works. (Not what you would obviously think.)
-Why some shots hit hard don't work, but hit softly, they do work - and why.
-Things the other players in the pool hall don't tell you, but seem to know.
The most interesting part is the "And why it works" part. He explains some very basic things which I have not seen/read elsewhere, but which should have been mentioned in any basic book on pool. Everyone keeping this stuff a secret or something?
And these basic things are easy once you see how and why.
Everybody says practice fundamentals, but they don't say what fundamentals are exactly. Now I finally know and have fundamental shots to practice.
I will admit that I had this book/DVD on my wish list for quite some time, but put off buying it. I mistakenly thought it would be quite scientific/technical in nature. I thought it would explain what is going on, but not necessarily improve my game much. I was very wrong. It is simple shot basics explained in simple terms which anyone can easily understand.
I would recommend this DVD and book for everyone. Beginner, advanced, and pro.
"The Illustrated Principles of Pool and Billiards"
(Should be called Fundamentals something or other...)
billiards.colostate.edu (external web-links)
Movies with billiards themes
Where can I find information on billiards movies and the shots in the movies?
The following articles describe the movies and show and explain most of the more interesting shots:
Video Encyclopedia of Pool Shots
What is included on the DVD series: "The Video Encyclopedia of Pool Shots (VEPS)"?
Here's a trailer showing examples shots from all five DVDs: YouTube video
Video excerpts and complete lists of shots for each DVD can be found here:
Video Encyclopedia of Pool Shots (VEPS) (external web-link)
Video online
How can I easily find free online videos of pool and billiards instruction, matches, trick shots, and interviews?
The online video collection resource page (external web-link) has links to many free online videos in all categories.
Dr. Dave's video production methods
How does Dr. Dave create and post all of those videos online?
People often ask how I make and post videos on this website, so I thought I would share the procedure with others that might be interested:
1) Shoot raw footage with a mini-DV digital video camera mounted in a 4-way adjustable tripod. For overhead shots, I either have the tripod fully or partially on the table, with the help of bar stools; otherwise, it stands on the floor. I often shoot multiple "takes" of the same shot because of missed shots, narration errors, bad lighting or camera views, etc.
2) Download the video from the camera to my PC through a fire-wire interface, using Pinnacle Studio software. Video requires lots of disk space (about 3-4 MB/sec ... that's megabytes per second!).
3) Use Pinnacle Studio to edit out the bad "takes" and trim the beginning and end of the best take. I also remove pauses and errors made (and later corrected) in the middle of a "take." That's why you sometimes see jumps in the middle of a clip.
4) Use CorelDraw to create table-diagram illustrations. I export images as JPEGs and insert them into the video within Pinnacle Studio.
5) Use Pinnacle Studio to store the edited video clip as a compressed Windows Media Video (WMV) file so it won't take up so much disk space and so it will be easily downloadable via the Internet. An uncompressed AVI video file can take up 50-100 more space than a compressed WMV file! In other words, if I didn't compress the video, it would take 50-100 times longer to download it via your Internet connection. The downside (because there are no "free lunches") is that the video image size and quality is not as good.
6) Use Dreamweaver software to edit the website and add links to the new video clips. Upload selected videos to YouTube and embed these into pages on the website.
7) Use Dreamweaver to upload the new website and video files to the web server so they can be viewed by anyone in the world.
That's it ... difficult to learn at first, but very easy once you have done it for a while. It also helps being at a university where there are people around that know how to do all of this stuff and are willing (and excited) to show you how.
Jacksonville Project and other high-speed video studies
What was the Jacksonville Project?
This was a high-speed video study of pool physics stuff carried out by Bob Jewett, Mike Shamos, and others in Jacksonville, Florida in 1998. Here's a list of the original questions they hoped to answer with the study: on this group (external group-link)
These articles describe the study and the results:
"Uncovering the Cue Mysteries" (Download) by Mike Shamos (Billiards Digest, April, 1999)
"Freeze Frame" (Download) by Bob Jewett (Billiards Digest, April, 1999)
"Don't Grip It and Rip It" (Download) by Bob Jewett (Billiards Digest, June, 1999)
Here's a summary of some of the main results:
- During impact, the cue tip is in contact with the cue ball only for about 0.001 second (a thousandth of a second). This is the case for most shots, regardless of the speed, english offset, or type of grip and follow-through.
- With an off-center hit, the cue stick deflects away from the cue ball substantially.
- During miscues, the cue stick often hits the cue ball multiple times.
- With a typical stroke, the tip reaches maximum speed (i.e., it is no longer accelerating) just before contact with the ball.
and here are some articles and info pages describing some of the results:
- "Coriolis was brilliant ... but he didn't have a high-speed camera - Part II: high-speed video" (Download) (Dr. Dave, Billiards Digest, August, 2005).
- "Coriolis was brilliant ... but he didn't have a high-speed camera - Part IV: maximum cue tip offset" (Download) (Dr. Dave, Billiards Digest, October, 2005)
- bank and kick effects in "bank and kick shots" section
- break hop and squat in "break" section
- cue tip deformation in "cue tip" section
- cue tip contact time in "cue tip" section
- cue tip hardness effects in "cue tip" section
- draw shot effects in "draw" section
- follow shot ball hop in "follow" section
- grip tightness effects in "grip" section
- jump shots in "jump" section
- miscues in "fouls" section
- over spin in "follow" section
- pocket "size" and "center" info in "pocket" section
- pocket rattle in "pocket" section
- rail and point compression shots in "pocket" section
- rail cut shots in "English" section
- rail dribble shots in "follow" section
- "scoop" shots in "fouls" section
- spin transfer in "throw" section
- squirt, swerve, and throw effects in "aiming" section
- stroke acceleration in "stroke" section
Austrian high-speed footage in this section
A group in Russia has also captured some really high-speed footage and done some experiments with a cue-testing machine. For more info, see:
high-speed-video footage (external web-link)
Cue Testing Unit (external web-link)
Reviews of Dr. Dave's DVDs
Information about Dr. Dave's "Illustrated Principles of Pool and Billiards" DVDs can be found here (external web-link).
Also see: reviews of Dr. Dave's book in "book" section.
Also see: reviews and testimonials (external web-link) for the "Video Encyclopedia of Pool Shots" (external web-link) instructional series by Dr. Dave and Tom Ross.
from Billy_Bob:
I finally bought Dr. Dave's DVD and book "The Illustrated Principles of Pool and Billiards".
And WOW! The DVD is fantastic! This should have been the first DVD I bought. I learned many new *basic* things from watching this DVD.
By fantastic, I mean that it is short, to the point, and clearly demonstrates many fundamentals of shots.
-Shots like a ball near the side pocket, how to shoot it so you will not scratch in the side. And why it works. (Why speed is the key.)
-How not to scratch on shots. And why it works.
-How similar shots can radically change where the cue ball will wind up depending on speed of hit. And why it works. (Not what you would obviously think.)
-Why some shots hit hard don't work, but hit softly, they do work - and why.
-Things the other players in the pool hall don't tell you, but seem to know.
The most interesting part is the "And why it works" part. He explains some very basic things which I have not seen/read elsewhere, but which should have been mentioned in any basic book on pool. Everyone keeping this stuff a secret or something?
And these basic things are easy once you see how and why.
Everybody says practice fundamentals, but they don't say what fundamentals are exactly. Now I finally know and have fundamental shots to practice.
I will admit that I had this book/DVD on my wish list for quite some time, but put off buying it. I mistakenly thought it would be quite scientific/technical in nature. I thought it would explain what is going on, but not necessarily improve my game much. I was very wrong. It is simple shot basics explained in simple terms which anyone can easily understand.
I would recommend this DVD and book for everyone. Beginner, advanced, and pro.
"The Illustrated Principles of Pool and Billiards"
(Should be called Fundamentals something or other...)
billiards.colostate.edu (external web-links)
Movies with billiards themes
Where can I find information on billiards movies and the shots in the movies?
The following articles describe the movies and show and explain most of the more interesting shots:
- "Billiards on the Big Screen - Pool Hall Junkies" (BD, October, 2004).
- "Billiards on the Big Screen - The Color of Money" (BD, September, 2004).
- "Billiards on the Big Screen - The Hustler" (BD, August, 2004).
Video Encyclopedia of Pool Shots
What is included on the DVD series: "The Video Encyclopedia of Pool Shots (VEPS)"?
Here's a trailer showing examples shots from all five DVDs: YouTube video
Video excerpts and complete lists of shots for each DVD can be found here:
Video Encyclopedia of Pool Shots (VEPS) (external web-link)
Video online
How can I easily find free online videos of pool and billiards instruction, matches, trick shots, and interviews?
The online video collection resource page (external web-link) has links to many free online videos in all categories.
For more info, visit billiards.colostate.edu
