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

dr_dave

Instructional Author
Gold Member
Silver Member
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.
I was also shocked by the precision over such a large angle range, both with the analysis plot and the results at the table (in the video).

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?
Thank you for asking this. It encouraged me to add a new page to the analysis file. Gaps between 1/4" and 1/2" give good results over 15-20 degrees. 3/8" has superior accuracy, but 1/4" offers a wider range of angles with decent accuracy with faster-speed shots. Check out the plots on the new last page.

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
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.
I'm glad to hear people like the new video. Straight pool players definitely have the most to benefit from this info; although, small-gap combos also come up fairly often in bar-box 8-ball.

Hey Dr.Dave, how do you find the Revo shaft?
I like it. It is smooth (and should stay that way for a long time), it stays clean (and is very easy to clean with a damp towel when it does get dirty), it should be warp free, it is difficult to ding or scratch, and it looks cool. Its CB deflection is also similar to the Z2 (which I used for many years), so I didn't have to adjust how I aim sidespin shots.

Also what is your preference or favorite shaft and why? If ya don't mind me asking.
I like small diameter and low deflection. Nothing else really matters to me. The reasons I like LD are here:

advantages of LD shafts

I also prefer a harder tip, per the info here:

tip hardness effects

I don't care about the "feel" of the hit or "feedback," per the info here:

cue "feel," "hit," "feedback," and "playability"

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
I was also shocked by the precision over such a large angle range, both with the analysis plot and the results at the table (in the video).

Thank you for asking this. It encouraged me to add a new page to the analysis file. Gaps between 1/4" and 1/2" give good results over 15-20 degrees. 3/8" has superior accuracy, but 1/4" offers a wider range of angles with decent accuracy with faster-speed shots. Check out the plots on the new last page.
It is important to point out that all of the results will vary slightly based on ball conditions. I used what are considered typical values for friction in my analysis, but the amount of throw with vary from one ball set to the next (see the ball cleaning and surface condition effects resource page).

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
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?
Thank you for asking this. It encouraged me to add a new page to the analysis file. Gaps between 1/4" and 1/2" give good results over 15-20 degrees. 3/8" has superior accuracy, but 1/4" offers a wider range of angles with decent accuracy with faster-speed shots. Check out the plots on the new last page.
FYI, to those interested, I just posted another new version of TP B.21, so now there is an additional "last page" showing how things change (or don't change) with ball conditions.

Also, with encouragement and help from Bob Jewett, I added an analytical derivation for the optimal gap size. It is in fact 3/8" (9.5 mm). That's on the bottom of the 2nd page of the new version of the document.

I hope the math and physics nerds out there like it (I do),
Dave
 

Dan White

AzB Silver Member
Silver Member
I was also shocked by the precision over such a large angle range, both with the analysis plot and the results at the table (in the video).

Thank you for asking this. It encouraged me to add a new page to the analysis file. Gaps between 1/4" and 1/2" give good results over 15-20 degrees. 3/8" has superior accuracy, but 1/4" offers a wider range of angles with decent accuracy with faster-speed shots. Check out the plots on the new last page.

Regards,
Dave

Those last few additions are very helpful. Here's what I think I can remember long term from all of this. Correct me if I'm wrong.

For cases where the combination balls are lined up to center pocket:

If the gap is about the diameter of my cue tip (1/2 inch) then I can slop it in up to about a 3/4 ball hit whether I hit it soft or hard. This means I can cut to the left or right depending on where I need the cue ball to go and still pocket the ob!

If the gap is about half the diamater of my cue tip (1/4 inch) then I can shoot up to a half ball hit at pocket speed, or 3/4 ball hit if I shoot hard.

If the gap is about 3/4 the diameter of my cue tip (3/8 inch), the ob will go straight up to a half ball hit at pocket speed. At fast speed, I can only go up to about a 3/4 ball hit and expect the ob to still go straight.

Hit a few practice shots to test table conditions.

So the common thing about all gaps from half the tip diameter up to the tip diameter (easy to compare) is that as long as you shoot less than a 3/4 ball hit at any speed, the ball should go in.
 

dr_dave

Instructional Author
Gold Member
Silver Member
Those last few additions are very helpful. Here's what I think I can remember long term from all of this. Correct me if I'm wrong.

For cases where the combination balls are lined up to center pocket:

If the gap is about the diameter of my cue tip (1/2 inch) then I can slop it in up to about a 3/4 ball hit whether I hit it soft or hard. This means I can cut to the left or right depending on where I need the cue ball to go and still pocket the ob!

If the gap is about half the diamater of my cue tip (1/4 inch) then I can shoot up to a half ball hit at pocket speed, or 3/4 ball hit if I shoot hard.

If the gap is about 3/4 the diameter of my cue tip (3/8 inch), the ob will go straight up to a half ball hit at pocket speed. At fast speed, I can only go up to about a 3/4 ball hit and expect the ob to still go straight.

Hit a few practice shots to test table conditions.

So the common thing about all gaps from half the tip diameter up to the tip diameter (easy to compare) is that as long as you shoot less than a 3/4 ball hit at any speed, the ball should go in.
Those are good approximate rules of thumb. Also, instead of "shoot less than a 3/4 ball hit," I would say "hit fuller than a 3/4 ball hit."

Good job,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
Those last few additions are very helpful. Here's what I think I can remember long term from all of this. Correct me if I'm wrong.

For cases where the combination balls are lined up to center pocket:

If the gap is about the diameter of my cue tip (1/2 inch) then I can slop it in up to about a 3/4 ball hit whether I hit it soft or hard. This means I can cut to the left or right depending on where I need the cue ball to go and still pocket the ob!

If the gap is about half the diamater of my cue tip (1/4 inch) then I can shoot up to a half ball hit at pocket speed, or 3/4 ball hit if I shoot hard.

If the gap is about 3/4 the diameter of my cue tip (3/8 inch), the ob will go straight up to a half ball hit at pocket speed. At fast speed, I can only go up to about a 3/4 ball hit and expect the ob to still go straight.

Hit a few practice shots to test table conditions.

So the common thing about all gaps from half the tip diameter up to the tip diameter (easy to compare) is that as long as you shoot less than a 3/4 ball hit at any speed, the ball should go in.
FYI, I just added the following to TP B.21:

Here's a good overall simplified "rule of thumb:" If a small-gap combo is wired to the center of a pocket, with a gap size between 1/4" (6 mm, about 1/2 the width of a typical shaft) and 1/2" (13 mm, about the width of a typical shaft), anything fuller than a 3/4-ball hit (14.5 degrees) between the 1st and 2nd ball will result in pocketing the 2nd ball (at any speed).

Thank you again,
Dave
 
Last edited:

Dan White

AzB Silver Member
Silver Member
FYI, I just added the following to TP B.21:

Here's a good overall simplified "rule of thumb:" If a small-gap combo is wired to the center of a pocket, with a gap size between 1/4" (6 mm, about 1/2 the width of a typical shaft) and 1/2" (13 mm, about the width of a typical shaft), anything fuller than a 3/4-ball hit (14.5 degrees) between the 1st and 2nd ball will result in pocketing the 2nd ball (at any speed).

Thank you again,
Dave

Nice! I couldn't have said it better myself.
 

dr_dave

Instructional Author
Gold Member
Silver Member
Has anybody tried out the magical 3/8" (1/3 ball radius) combo gap size at a table yet? If so, did you get results similar to that demonstrated in the video?

I also posted this on Facebook, and I have been shocked by how little response it got. I personally think this is one of the most dramatic physics-related effects I've ever seen on a pool table.

Regards,
Dave


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
 

dr_dave

Instructional Author
Gold Member
Silver Member
Has anybody tried out the magical 3/8" (1/3 ball radius) combo gap size at a table yet? If so, did you get results similar to that demonstrated in the video?

I also posted this on Facebook, and I have been shocked by how little response it got. I personally think this is one of the most dramatic physics-related effects I've ever seen on a pool table.
FYI to those interested, I just created a resource page summarizing all of the interesting and useful conclusions from the physics analysis. Here it is:

small-gap combo resource page

Enjoy,
Dave
 

Jimmorrison

AzB Silver Member
Silver Member
I have not had a chance to try all the shots yet, still making sure the frozen combo stuff sinks in. What a great shot to know. Your original post was very timely for me. I just learned that shot the week before. Shown to me by a guy that has all this stuff memorized. Very useful info. I had just pocketed a ball in the opposite side and gone three rails to break up the frozen balls. Just missed them and rolled by, towards the bottom rail. I was lamenting the missed break out and wondering what to do next. This guy walks up and says, you don’t have to break that up, hit it thick on the right side. Worked like a charm. Way better to shoot for shape on that shot then to roll into them and hope for the best. Once I get it drilled in, I will go on to the next level, with your video. Great info and great presentation, thank you.
 

kaznj

AzB Silver Member
Silver Member
Dr Dave thanks for the great information. Can English on the cue ball be used to hit the first object ball a little fuller and still throw the second object ball?
 

dr_dave

Instructional Author
Gold Member
Silver Member
I have not had a chance to try all the shots yet, still making sure the frozen combo stuff sinks in. What a great shot to know. Your original post was very timely for me. I just learned that shot the week before. Shown to me by a guy that has all this stuff memorized. Very useful info. I had just pocketed a ball in the opposite side and gone three rails to break up the frozen balls. Just missed them and rolled by, towards the bottom rail. I was lamenting the missed break out and wondering what to do next. This guy walks up and says, you don’t have to break that up, hit it thick on the right side. Worked like a charm. Way better to shoot for shape on that shot then to roll into them and hope for the best. Once I get it drilled in, I will go on to the next level, with your video. Great info and great presentation, thank you.
I hope the info, and your practicing, pays off.

Good luck,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dr Dave thanks for the great information.
You're welcome.

Can English on the cue ball be used to hit the first object ball a little fuller and still throw the second object ball?
Yes. Spin transfer also comes into play. I actually filmed a bunch of shots like this, but the video was already long enough, and the sidespin stuff would have added too much confusion to the already fairly-complicated info.

Regards,
Dave
 

Dan White

AzB Silver Member
Silver Member
Has anybody tried out the magical 3/8" (1/3 ball radius) combo gap size at a table yet? If so, did you get results similar to that demonstrated in the video?

I also posted this on Facebook, and I have been shocked by how little response it got. I personally think this is one of the most dramatic physics-related effects I've ever seen on a pool table.

Regards,
Dave

Yes, I played around with it a little bit. Works like a charm and is amazing to see. This knowledge fills a gap for me because whenever I was presented with a close combination I was never sure what the heck was going to happen. The use of the cue shaft is very helpful. You can simply put the tip of the cue on the cloth and slide it up to the two balls so you can compare the gap to the shaft. I'm going to play around with it more to get a better feel for the limits. I'd like to get a feel for how much cut I need in order to pocket a combination that is off just a little, for instance. For someone who plays 14.1, this could be a killer way to open clusters with confidence.

Regarding low feedback, maybe people don't understand it's importance, or could be that some suffer from the "Oh, I already knew that" mentality! lol
 

dr_dave

Instructional Author
Gold Member
Silver Member
Yes, I played around with it a little bit. Works like a charm and is amazing to see.
I was also amazed when I saw the results at the table.

This knowledge fills a gap for me because whenever I was presented with a close combination I was never sure what the heck was going to happen. The use of the cue shaft is very helpful. You can simply put the tip of the cue on the cloth and slide it up to the two balls so you can compare the gap to the shaft. I'm going to play around with it more to get a better feel for the limits. I'd like to get a feel for how much cut I need in order to pocket a combination that is off just a little, for instance. For someone who plays 14.1, this could be a killer way to open clusters with confidence.
Well stated. I agree.

Regarding low feedback, maybe people don't understand it's importance, or could be that some suffer from the "Oh, I already knew that" mentality! lol
I think you're right on both counts.

Best regards,
Dave
 

Dan White

AzB Silver Member
Silver Member
So I spent a few minutes playing around with close gap shots and noticed a couple of situations where this knowledge can be applied.

1. It isn't only for small gap combination shots. If the cue ball is 3/8" from the ob, the same things happen. Let's say the cb/ob are lined up to a side pocket and both balls are at center table. If the gap is 3/8" I can shoot a half ball shot in either direction to move the cue ball where I want it and the ball still goes in. It is easier to make this shot than shooting jacked up straight at the ob. You don't have to worry about a double hit as much.

Of course the balls aren't usually exactly 3/8", so be aware that it will tend to throw a little at closer gaps, and cut a little at wider gaps. Adjust accordingly with speed and/or english.

2. Having knowledge of the 3/8" gap properties makes it easier to predict large gap combinations, at least for me. I had two balls near the long rail about an inch apart and above the side pocket. Normally in 14.1 I'd worry about being able to break them apart as I don't play combinations unless I have to. I knew that a half ball hit would produce an overcut, which is what I needed. It only takes a little practice to get a feel for how much cut you get for up to an inch gap. Hit softly and pocketed the ball.

Another situation: Had a combination in the pack about an inch gap. It was aimed at the left point of the corner pocket. I predicted it would throw to center right pocket with slow speed. I hit a carom combination which moved every ball in the pack, and pocketed the ob right where I thought. I never would have attempted this shot before Great new weapon!!!

Close gap shots sound rare and therefore not so useful, but this knowledge allows you to predict larger gap behavior with more confidence.

Maybe it's just me but I get jazzed when I learn something so useful.

Thanks Dave!
 

dr_dave

Instructional Author
Gold Member
Silver Member
So I spent a few minutes playing around with close gap shots and noticed a couple of situations where this knowledge can be applied.

1. It isn't only for small gap combination shots. If the cue ball is 3/8" from the ob, the same things happen. Let's say the cb/ob are lined up to a side pocket and both balls are at center table. If the gap is 3/8" I can shoot a half ball shot in either direction to move the cue ball where I want it and the ball still goes in. It is easier to make this shot than shooting jacked up straight at the ob. You don't have to worry about a double hit as much.

Of course the balls aren't usually exactly 3/8", so be aware that it will tend to throw a little at closer gaps, and cut a little at wider gaps. Adjust accordingly with speed and/or english.

2. Having knowledge of the 3/8" gap properties makes it easier to predict large gap combinations, at least for me. I had two balls near the long rail about an inch apart and above the side pocket. Normally in 14.1 I'd worry about being able to break them apart as I don't play combinations unless I have to. I knew that a half ball hit would produce an overcut, which is what I needed. It only takes a little practice to get a feel for how much cut you get for up to an inch gap. Hit softly and pocketed the ball.

Another situation: Had a combination in the pack about an inch gap. It was aimed at the left point of the corner pocket. I predicted it would throw to center right pocket with slow speed. I hit a carom combination which moved every ball in the pack, and pocketed the ob right where I thought. I never would have attempted this shot before Great new weapon!!!

Close gap shots sound rare and therefore not so useful, but this knowledge allows you to predict larger gap behavior with more confidence.

Maybe it's just me but I get jazzed when I learn something so useful.

Thanks Dave!
Excellent points Dan. I was also jazzed up by some of useful results of the analysis. Like you, I feel much more confident with all sorts of small-gap shots now (combos or not). BTW, an important difference with cuts vs. combos is you have direct control over the CB's spin. With a small-gap cut, sidespin can be used to change the throw amount and/or direction, and top/bottom spin will reduce the amount of throw (see throw draw/follow effects).

Best regards,
Dave
 
Top