new video and analysis dealing with throw and small-gap combinations

dr_dave

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Check out the following new video dealing with small-gap combos, where cut-induced throw is very important. Physics effects are covered first, and then practical game-situation examples are demonstrated.

NV J.1 - Small-Gap-Combination Throw Effects and Game-Situation Examples

And for the math/physics nerds out there, check out the following analysis proving a gap of 3/8" (9.5 mm) produces interesting results (as shown in the video). I know some of you might know about this effect already; but for those who don't, it might be quite interesting and surprising.

TP B.21 - Small-gap-combination throw effects

Even if you aren't a math/physics nerd, you still might be interested in looking as some of the plots and bold-text conclusions in the analysis document.

Enjoy,
Dave
 

BRussell

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Thanks for doing this. I feel there's too much attention to frozen combinations, probably because they're easy to show off, but small gaps are so much more common.

I've also tried to do a little testing like you've done here, and my sense is that 1. almost-frozen tiny gaps act just like frozen balls, and 2. it's really hard to cut a combination when they're pretty close, probably because there's some throw cancelling out the cut, like you showed here.
 

dr_dave

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Thanks for doing this. I feel there's too much attention to frozen combinations, probably because they're easy to show off, but small gaps are so much more common.

I've also tried to do a little testing like you've done here, and my sense is that 1. almost-frozen tiny gaps act just like frozen balls, and 2. it's really hard to cut a combination when they're pretty close, probably because there's some throw cancelling out the cut, like you showed here.
Thank you for the comments. My sense (and results) are the same as your sense.

Regards,
Dave
 

Bob Jewett

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Some additional points about small-gap (and even 2-ball gap) combinations, see the first article in this group: http://www.sfbilliards.com/articles/2001.pdf

With the zero-throw gap at about 10mm, a convenient way to judge the gap is the tip of the pool cue. Usually players know how many mm that is even if they aren't familiar with mm/cm otherwise. If your tip is just a little to big to fit, the gap is close to 10 mm. My little finger is real close to the right size.

I suppose you need to check the local rules to see what's allowed if you actually start to measure things.
 

dr_dave

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Some additional points about small-gap (and even 2-ball gap) combinations, see the first article in this group: http://www.sfbilliards.com/articles/2001.pdf
Thanks for the link. Good article (as always).

With the zero-throw gap at about 10mm, a convenient way to judge the gap is the tip of the pool cue. Usually players know how many mm that is even if they aren't familiar with mm/cm otherwise. If your tip is just a little to big to fit, the gap is close to 10 mm. My little finger is real close to the right size.
Great ideas! Thanks.


I suppose you need to check the local rules to see what's allowed if you actually start to measure things.
If somebody tells me I cannot use my hands to visualize or measure stuff at the table, I'm gonna tell them "go to hell" (or worse). I'm Italian and like to use my hands when I talk and when I "measure" a shot (e.g., with the 30 degree rule peace sign, or with visualizing a contact-point mirror shift with the shallow-angle kicking system, or with measuring off a certain distance on my cue for finding an aim point on the rail using an equal-distance mirror system, etc. Are you saying some people would consider this stuff "illegal?").

Regards,
Dave
 

Bob Jewett

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... If somebody tells me I cannot use my hands to visualize or measure stuff at the table, I'm gonna tell them "go to hell" (or worse). I'm Italian and like to use my hands when I talk and when I "measure" a shot (e.g., with the 30 degree rule peace sign, or with visualizing a contact-point mirror shift with the shallow-angle kicking system, or with measuring off a certain distance on my cue for finding an aim point on the rail using an equal-distance mirror system, etc. Are you saying some people would consider this stuff "illegal?").

Regards,
Dave
If you haven't run into those people in league already, you must have a pretty mellow bunch there. I've had one player -- a pro player whose name many would recognize -- say that the mark I used to put on my ferrule to keep the cue orientation the same on all shots was an aiming device and therefor my cue was illegal. And then there are the players who will call a foul on you if you set your cue stick on the table while you tie your shoelaces.

But here is the relevant section from the BCAPL rules:

f. You may use your cue, held in your hand or not, to help align a shot. You may use your cue and hands to measure angles and distances for bank shots and kick shots. No other cues, bridges or equipment may be used. (AR p. 79).

g. You may only use your vision to judge whether the cue ball or an object ball would fit through a gap, or to judge what ball the cue ball would contact first. You may not use any ball, cue, rack, chalk cube, or any other equipment or other part of your body as a width-measuring device. (AR p. 79).
Penalty for (f-g): Foul immediately upon the violation, regardless of whether a shot is executed.​

There doesn't appear to be an exception in (g) for those players of the Italian persuasion. No gap measuring allowed.
 

Neil

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Dr. Dave, have you got your right and lefts mixed up, or am I missing something there?
 

dr_dave

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... here is the relevant section from the BCAPL rules:

f. You may use your cue, held in your hand or not, to help align a shot. You may use your cue and hands to measure angles and distances for bank shots and kick shots. No other cues, bridges or equipment may be used. (AR p. 79).

g. You may only use your vision to judge whether the cue ball or an object ball would fit through a gap, or to judge what ball the cue ball would contact first. You may not use any ball, cue, rack, chalk cube, or any other equipment or other part of your body as a width-measuring device. (AR p. 79).
Penalty for (f-g): Foul immediately upon the violation, regardless of whether a shot is executed.​

There doesn't appear to be an exception in (g) for those players of the Italian persuasion. No gap measuring allowed.
To me, the "spirit" of rule "g" is to disallow measuring of a gap through which another ball might pass through. I think it could be argued that it doesnot apply to measuring distances or gap sizes in all other situations. But maybe that's just the Italian in me holding out hope.

Catch you later,
Dave

PS: If I had any say in a rules revision, I would eliminate all restrictions like these and let a player use their cue or any part of their body to visualize or measure whatever they want (shot line, cut angle, kick/bank angle, mirror distance, ball pass-through gap, gap for combo throw check, etc.), as long as they don't mark the cloth or rails (e.g., with a chalk smudge or cube of chalk). I would also not require that they keep the cue in at least one hand at all times. IMO, simpler and less-restrictive rules are better rules.
 

Bob Jewett

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... PS: If I had any say in a rules revision, I would eliminate all restrictions like these and let a player use their cue or any part of their body to visualize or measure whatever they want (shot line, cut angle, kick/bank angle, mirror distance, ball pass-through gap, gap for combo throw check, etc.), as long as they don't mark the cloth or rails (e.g., with a chalk smudge or cube of chalk). I would also not require that they keep the cue in at least one hand at all times. IMO, simpler and less-restrictive rules are better rules.
I agree with this. The removal of this restriction might even lead to some innovative techniques. In the end, the player still has to make the shot. The possible techniques do not make the game unfair.
 

dr_dave

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Dr. Dave, have you got your right and lefts mixed up, or am I missing something there?
Whenever I say "right" or "left" in the video, it is always from the shooter's perspective. So if I say I'm throwing a ball to the right and I am facing the camera, the throw is to the viewer's left. I guess I should always be more clear about this sort of thing (e.g., by saying "to the my right" of "to the shooter's right" or "to the left on the screen"), but that gets a little old after a while.

Regardless, if there is a specific spot in the video where you think I say something wrong, please let me know where to find it so I can check it out.

Thanks,
Dave
 

dr_dave

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PS: If I had any say in a rules revision, I would eliminate all restrictions like these and let a player use their cue or any part of their body to visualize or measure whatever they want (shot line, cut angle, kick/bank angle, mirror distance, ball pass-through gap, gap for combo throw check, etc.), as long as they don't mark the cloth or rails (e.g., with a chalk smudge or cube of chalk). I would also not require that they keep the cue in at least one hand at all times. IMO, simpler and less-restrictive rules are better rules.
I agree with this. The removal of this restriction might even lead to some innovative techniques. In the end, the player still has to make the shot. The possible techniques do not make the game unfair.
I like the way you think ... and I agree.

Regards,
Dave
 

Neil

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Whenever I say "right" or "left" in the video, it is always from the shooter's perspective. So if I say I'm throwing a ball to the right and I am facing the camera, the throw is to the viewer's left. I guess I should always be more clear about this sort of thing (e.g., by saying "to the my right" of "to the shooter's right" or "to the left on the screen"), but that gets a little old after a while.

Regardless, if there is a specific spot in the video where you think I say something wrong, please let me know where to find it so I can check it out.

Thanks,
Dave

I did miss something. At 43 sec, you said it can be thrown to the left by hitting the 8 to the left. I missheard it and thought you said on the left instead of to the left.
 

Black-Balled

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I hate to be the one...but I don't think Italian is acceptable justification.

Haha...I look fwd to studying the vids. In addition to being side pocket dumb, I am also combo handicapped as well...too.
 

dr_dave

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In addition to being side pocket dumb, I am also combo handicapped as well...too.
I am often shocked by how poorly people (even pros at times) aim small-gap-combos due to an insufficient understanding of basic throw concepts. I hope this new video helps you and others do better in this regard.

Catch you later,
Dave
 

longhorns2

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isn't this related to the fact that you don't see much throw until ~25 degree cut angles?

btw your past stuff on throw really helped my game. i try to explain it to people and even really good players don't really believe/understand it. but i still think they eventually learn how to visualize it
 

dr_dave

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isn't this related to the fact that you don't see much throw until ~25 degree cut angles?
Cut-induced throw (CIT) increases fairly linearly between 0 and about 30 degrees (see the plots in "Throw - Part II: results" - BD, September, 2006). It is maximum close to 30 degrees, but it is about half maximum at 15 degrees.

btw your past stuff on throw really helped my game. i try to explain it to people and even really good players don't really believe/understand it. but i still think they eventually learn how to visualize it
I'm glad to hear it. FYI, if you want to suggest a good learning resource for throw, here's a good place to start:

throw tutorial

Regards,
Dave
 

Dan White

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Great stuff, Dave! It is one thing to "kinda sorta" know how to hit a close combination, but I had no idea there was a sweet spot where you could hit the shot almost anywhere (up to half ball or so) and still have the combo go straight.

Along the lines of your last graph in the second link, have you considered what the upper and lower bounds are for the 3/8" gap shot where you can still expect to pocket the ball straight in? I know it depends on shot length and pocket opening, but let's say I estimate a 1/4 inch gap. Can I figure it will still be straight with maybe a little throw, and vice versa for a shot that is closer to 1/2 inch?
 

Shotcy

AzB Silver Member
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Really helpful. I've always known about the frozen ball thing but you do a great job at breaking down the small gap scenario. Playing a lot of straight pool lately, looking forward to using this knowledge.

Hey Dr.Dave, how do you find the Revo shaft? Also what is your preference or favorite shaft and why? If ya don't mind me asking.
 
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