Ball Action Question

[ndakotan]

If an object ball is close to another ball that is "almost" blocking the target pocket, can the ob be made easier if the cut is one direction or the other? In other words, can you "push" the ob around the edge of a blocker ball? In this situation, people say "you are on the wrong side of the ball, you can't make that ball from there" because the cut of the cue ball will "push" the ball slightly before it begins to roll on its target line.

If the ball can be pushed slightly to a free lane, then I would assume you would need to hit high on the cb to impart "draw" on the ob to get it back in line.

Does this make sense?

 

[Bob Jewett]

If an object ball is close to another ball that is "almost" blocking the target pocket, can the ob be made easier if the cut is one direction or the other? In other words, can you "push" the ob around the edge of a blocker ball? In this situation, people say "you are on the wrong side of the ball, you can't make that ball from there" because the cut of the cue ball will "push" the ball slightly before it begins to roll on its target line.

If the ball can be pushed slightly to a free lane, then I would assume you would need to hit high on the cb to impart "draw" on the ob to get it back in line.

Does this make sense?

You're asking if the object ball can be made to curve. I've offered $200 for anyone who can show me how to do this. No one has taken me up on the offer. I've tried for a couple of hours to do it, but I clearly didn't try all the possible ways that might conceivably work.

It's possible to make the object ball jump over the obstacle.

 

[Jal]

If an object ball is close to another ball that is "almost" blocking the target pocket, can the ob be made easier if the cut is one direction or the other? In other words, can you "push" the ob around the edge of a blocker ball? In this situation, people say "you are on the wrong side of the ball, you can't make that ball from there" because the cut of the cue ball will "push" the ball slightly before it begins to roll on its target line.

If the ball can be pushed slightly to a free lane, then I would assume you would need to hit high on the cb to impart "draw" on the ob to get it back in line.

Does this make sense?

Yes it does, but the effect is so tiny it really has no practical application. If you're cutting a ball to the left say, using draw to impart topspin on the object ball will cause it to curve to the left. Using follow to impart backspin will cause it to curve to the right. The underlying mechanism has to do with throw, but the change in direction as it curves is only a small fraction of the throw angle. It's so small that irregularities in the cloth could mask it.

More curve can be obtained by getting some elevation on the cueball at impact, augmented with english as needed. Needless to say, this is difficult to control. Simply jumping the object ball with an airborn cueball, without necessarily trying to make it curve, is easier.

Jim

 

[a9ballbr8k]

If its close it would be conceivable that you can use english to throw/spin the ball into the pocket instead of direct pocketing.

 

[Bob Jewett]

If its close it would be conceivable that you can use english to throw/spin the ball into the pocket instead of direct pocketing.

Throw seems to happen along a straight line. That is, while the object ball does not travel along the line joining the centers of the cue ball and object ball at the instant of the collision for a throw shot, it does travel along a straight line, as closely as anyone has been able to measure.

In theory, if the cue ball is rotating about the ball-ball contact point, it could put some masse on the object ball, but no one has ever been able to demonstrate this, so far as I know.

 

[Patrick Johnson]

[Does the object ball's path curve?]

Yes it does, but the effect is so tiny it really has no practical application.

I'd say it's so tiny it can't be measured. In fact, I'd say it's so tiny it doesn't exist.

pj
chgo

 

[jondrums]

Bob-
I know this is a different situation, but I swear I've seen an object ball curve after leaving a frozen carom due to transfered draw or follow from the cue ball. It would seem at first glance that the same could be done using follow or (more likely) draw on a medium angle cut. Of course it would have to be done at medium to high speed to keep the action on the cue ball until contact, and because of this it would take at least a few inches for the slight curve action to take on the OB. Perhaps a little elevation of the cue to help keep max draw on the CB until contact.

My opinion on the original question is that I don't think you can get very much effect in a very short distance. If any effect could be caused I would think it would be most pronounced and medium-high speed shot.

Now, onto more esoteric issues - doesn't the nap directionality of the cloth cause a slow rolling ball to turn "into" the grain. I've found that this can be as much as a half ball on a slow rolled spot shot. Also acording to "banking with the beard" a slow rolled ball with transfered english will turn slightly at the end of its travel. I have never actually experienced this myself.
Jon

 

[Bob Jewett]

Bob-
I know this is a different situation, but I swear I've seen an object ball curve after leaving a frozen carom due to transfered draw or follow from the cue ball. .....

Hi Jon,

Sure, I think that can happen, but it's a much different situation.

If the cue ball contacts a single object ball, it can transfer spin in two different ways. It can do it by normal rubbing across the point of contact. That is the normal way that throw works and it's how follow or draw might get on the first ball in a combination. That first kind of spin can't make the object ball curve because it is either around the vertical axis (side spin) or the horizontal axis perpendicular to the object ball's motion (draw or follow). This first kind of spin cannot be around the axis that is parallel to the ball's motion (masse).

The second kind of spin that can be transferred from the cue ball to the object ball is by rotation of the cue ball around the contact point. Imagine making the cue ball spin in place. Now carefully place a ball on top of the spinning cue ball. That ball will gradually acquire rotation from the cue ball from the twisting of the contact point. This is a very strange kind of spin for normal shots to have, and the amount of transfer appears to depend on the size of the contact patch. It is this "contact patch twisting" spin that no one can demonstrate.

I don't think the worsted cloth used on most tables these days has "nap-induced" curve. If someone can describe a reliable demonstration, I'd like to see one.

 

[Jal]

I'd say it's so tiny it can't be measured. In fact, I'd say it's so tiny it doesn't exist.

pj
chgo

You mean it doesn't exist in principle?

To my understanding, there are at least three mechanisms that could/should cause it to curve. One, draw/follow masse, is tiny. Another, sidespin masse, is teeny tiny. And the magnitude of the last, twist or clutch plate masse, is unknown (to me). These are all for an unelevated cueball.

Draw/follow masse should get as large as about an eighth of a degree (roughly), so it should be measurable with some care. It's also compounded by clutch plate masse, however much that might be.

Jim

 

[jondrums]

I don't think the worsted cloth used on most tables these days has "nap-induced" curve. If someone can describe a reliable demonstration, I'd like to see one.

I was shown a very difficult shot by an old timer in North Carolina pool hall. The challenge is to pocket a spotted ball with cue ball in hand in the kitchen without having the CB contact any rail during the shot . It is possible, but it took me about 15 minutes of trying the first time.

Its mostly a CB placement and speed control issue. But another challenge is that you have to aim for an severe undercut (for a centerball hit) on most tables because of the cloth induced curve. I tried this from both sides of the table to make sure it wasn't table roll. I know for a fact that the cloth was moderately used simonis (don't know which number).

For me this convinced me that a slow rolled ball does curve on worn cloth. At first I was convinced it was due to cue elevation and an inexact estimation of center ball, but the clincher was trying the same exact shot using the head spot!

Can anyone else repeat my findings?

Jon

 

[seymore15074]

It's possible to make the object ball jump over the obstacle.

This is exactly what I'm thinking...even if it is slightly blocking the pocket, this is fairly straight forward. Jack up your cue a little and stroke through it firm (don't blast it off of the table). The key here is not to jack up too high, 30 degrees maybe sounds about right if I remember correctly... It causes the cue ball to jump just slightly and impact the top of the object ball causing it to jump over the obstacle. The closer to straight in you are, the easier this becomes...

 

[Bob Jewett]

... To my understanding, there are at least three mechanisms that could/should cause it to curve. One, draw/follow masse, is tiny. Another, sidespin masse, is teeny tiny. And the magnitude of the last, twist or clutch plate masse, is unknown (to me). These are all for an unelevated cueball.

Draw/follow masse should get as large as about an eighth of a degree (roughly), so it should be measurable with some care. It's also compounded by clutch plate masse, however much that might be.

Jim

I'm not sure I understand the part about draw/follow masse. Is that because of throw, which causes the path of the object ball not to be perpendicular to the axis of the draw/follow that the object ball got from the cue ball?

I don't see a good way to measure a curve that is only an eighth of a degree. This is much less than the angle of throw involved on the shot, and you have to demonstrate that the initial path of the object ball (over a very short distance) is not parallel to the final path.

 

[Ballistic Billiards]

ob spin

I'd be willing to put up some cash on this too.
I want to see 2 or more full rotations of back spin
on an ob resulting from the top spin of the cb.

 

[whitey2]

you may have this backwards

Yes it does, but the effect is so tiny it really has no practical application. If you're cutting a ball to the left say, using draw to impart topspin on the object ball will cause it to curve to the left. Using follow to impart backspin will cause it to curve to the right.

It's been a long, tiring week, so I might be wrong, but
I think you have this backwards.

If you cut a ball to the left, using draw, and the object
ball picks up topspin, I believe the object ball will pull
itself to the RIGHT.

If the bet gets high enough, I may come forth with a
technique to curve an object ball.

 

[Jal]

I'm not sure I understand the part about draw/follow masse. Is that because of throw, which causes the path of the object ball not to be perpendicular to the axis of the draw/follow that the object ball got from the cue ball?

Yes, exactly. Mac (Cushioncrawler) told me about it, and I came up with a formula. Dr. Alciatore also worked it out in his TP A.24 here (both formulas agree):

http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-24.pdf

Have you looked into it further and found that this isn't right?

I don't see a good way to measure a curve that is only an eighth of a degree. This is much less than the angle of throw involved on the shot, and you have to demonstrate that the initial path of the object ball (over a very short distance) is not parallel to the final path.

Perhaps I should have used "detect" instead of "measure". Otherwise you would have to know the throw angle very precisely to separate it out, as you're rightly indicating.

I suppose it could be done with a setup so that the edge of the object ball runs along a laser beam. You should see the beam get interrupted and then re-established by the curved path, I should think? Random buffeting by the cloth could be a problem.

Jim

 

[Jal]

It's been a long, tiring week, so I might be wrong, but
I think you have this backwards.

If you cut a ball to the left, using draw, and the object
ball picks up topspin, I believe the object ball will pull
itself to the RIGHT.

If the bet gets high enough, I may come forth with a
technique to curve an object ball.

I still think it will curve to the left. Throw will cause it to start off to the right of the line of centers between the balls, but the equator of the imparted topspin will be pointing a little to the left of the direction the ob is moving (by the amount of the throw angle), causing it to curve left.

You may want to look at Dr. Alciatore's document linked to above. If you still think this is all wrong, please let us know.

Jim

 

[whitey2]

well...

I need to put some more thought into this in the future.

I had written a somewhat-long post here, but I decided to retract it.

I may even go as far as experimenting with rubber stress balls. I have
one here, I wish I had another.

 

[Jal]

I hope you can somehow manage to get a clear demonstration of it, one way or another. You might become a couple of hundred bucks richer for your troubles!
Jim

 

[CreeDo]

A technique we use at my pool hall is a variation of nap-induced curve. It's called sending the OB into one of the worn gullies in the cloth at a slow speed and letting table roll suck shot into the pocket. We call it 'bullshit' for short. It does work to get a ball into a barely-obstructed pocket. It also allows you to 'cut' a ball into the side when it's 87 degrees from the edge of a side pocket.

Pocket billiards at its finest.