Predicting cue ball direction (using elevated cue)

[jondrums]

On occasion I have found it really useful to elevate the butt of my cue and slightly jump the cue ball, so that when it comes off the object ball it jumps into a pack of balls. Can anyone help with some rule of thumb guide for how to predict the cue ball direction if it makes contact with the object ball while airborne? It doesn't seem to go along the tangent line at all - quite a bit less than 90 degrees I think.
jon

 

[cuetable]

On occasion I have found it really useful to elevate the butt of my cue and slightly jump the cue ball, so that when it comes off the object ball it jumps into a pack of balls. Can anyone help with some rule of thumb guide for how to predict the cue ball direction if it makes contact with the object ball while airborne? It doesn't seem to go along the tangent line at all - quite a bit less than 90 degrees I think.
jon

You have asked some interesting questions! I never thought of them... And I couldn't find it in my Koehler book

While I don't have any answers, I have more questions to add :

1, Is the cue ball still on the cloth when it makes the first contact to the object ball when it has been striked by an elevated cue?

2, Will this result in a very slight over cut?

3, Will the energy from the collision effect the carom angle greatly?

4, Why does the cue ball jump after a forced follow? after a 9-ball break?

Thank you

 

[3andstop]

I use this type shot now and again. Mostly from behind the rack while shooting into a corner pocket when my angle is slighter than I would like to get into the stack.

It would be great to have some safety valve ball nearby but unless its a low glancing angle down into the pack (which seems to send the cue ball in a path along the line of entry, what I've found is that the cue ball pretty much plops down in the middle and the ball spread around it.

 

[9ballrun]

quote"4, Why does the cue ball jump after a forced follow? after a 9-ball break?"

On a break shot when you hit it hard the cue ball is hoping across the table so if the ball is jumping up after hitting the rack try hitting it either a little harder or softer so that it contacts the rack at a different time in it approach. I saw an interesting thing done one time where a guy lined up a bunch of dimes from the cue ball to the rack to show this and then filmed it in slow motion. It was really cool. I hope that makes sense. As far as the force follow shot the cue ball is actully trying to climb up the object ball from the spin that you put on it.

 

[juggler314]

On occasion I have found it really useful to elevate the butt of my cue and slightly jump the cue ball, so that when it comes off the object ball it jumps into a pack of balls. Can anyone help with some rule of thumb guide for how to predict the cue ball direction if it makes contact with the object ball while airborne? It doesn't seem to go along the tangent line at all - quite a bit less than 90 degrees I think.
jon

I don't think you'll be able to get any basic rules of thumb on this, the ball is actually coming off at a tangent line, just not the one you are thinking off. If you take some video and see where the cue actually contacts the object ball, *that* tangent line will be used. The higher up on the object ball you jump into the more the observed tangent line will differ from the tangent line it would with no jump. In order to be able to accuarately predict what will happen you'll first need to be able to very accurately hit a particular height on the object ball (say always contacting it 1/4" off the bed of the table), then if you can do that, you could probably do some quick math to find out how the angles change.

I've used that shot on occassion - mostly as a lark - to break apart a cluster - but in general I am usually just trying to land it in the middle of the rack, not a particular spot.

 

[juggler314]

1, Is the cue ball still on the cloth when it makes the first contact to the object ball when it has been striked by an elevated cue?

If the cue is still on the cloth when it contacts the first ball, it wont jump high enough to clear other balls and land in the middle of a cluster. When jumping into a cluster you are really taking the forward energy of the cue ball, and changing it's direction, thus when you clip an object ball, the cue will not be moving forward so fast, but it will gain some height. If you contact both the object ball and the table bed simultaneously it will only jump as high as it was jumping before the contact - which is probably not very much.

2, Will this result in a very slight over cut?

Yes - on the same logic as my earlier post. If you hit a ball in the air, the tangent line will shift over based on the actual contact point. This means if you aim it like you aren't jumping you will either over or under cut the ball (depending on whether you are cutting or reverse cutting the ball). If you find the actual contact point, then draw that tangent line in mid-air. Then take the reflection of that line onto the table bed, it will show the tangent to the actual path of the object ball.

3, Will the energy from the collision effect the carom angle greatly?

I don't think the carom angle will be different, except that as above, your actual tangent will not be what you think it is based on a 2D surface. The carom angle will hold true for the cue ball moving in 3D space above the table.

4, Why does the cue ball jump after a forced follow? after a 9-ball break?

This was answered already.

 

[mikepage]

quote"4, Why does the cue ball jump after a forced follow? after a 9-ball break?"

On a break shot when you hit it hard the cue ball is hoping across the table so if the ball is jumping up after hitting the rack try hitting it either a little harder or softer so that it contacts the rack at a different time in it approach. I saw an interesting thing done one time where a guy lined up a bunch of dimes from the cue ball to the rack to show this and then filmed it in slow motion.

If you've never done this, try putting a coin right in front of the cueball and executing a normal shot--say a spot shot. It's amazing what you have to do to get the cueball to NOT jump over the coin.

As far as the force follow shot the cue ball is actully trying to climb up the object ball from the spin that you put on it.

Though this happens sometimes (the vertical equivalent of skid), I kinda think the most likely culprit when the CB jumps up on a force follow shot is the CB being airborne at contact.

 

[Bob Jewett]

On occasion I have found it really useful to elevate the butt of my cue and slightly jump the cue ball, so that when it comes off the object ball it jumps into a pack of balls. Can anyone help with some rule of thumb guide for how to predict the cue ball direction if it makes contact with the object ball while airborne? It doesn't seem to go along the tangent line at all - quite a bit less than 90 degrees I think.
jon

There is no rule of thumb unless you control how high on the object ball you hit. Practice the shot with different fullnesses, separations, speeds and elevations. The other problem is that the object ball will be over cut if the cue ball is in the air, as mentioned before. Learning how much also requires practice. Byrne has a chapter in his "Advanced Technique" book on jump shots.

 

[nick serdula]

The master told me once.

Anyone bouncing into the pack can't play. It isn't a good way to go at all acording to he who shall remain nameless. Pool is about consistancy. That bouncing thing on a very criticalshot just is a bad way to go.
This is according to the master! I am just repeating here.
Free stuff from me! I wish you good luck.
Nick

 

[Bob Jewett]

Anyone bouncing into the pack can't play. ... This is according to the master! ...

Some of us don't play as well as The Master. I recall being impressed by the way Joe Balsis could jump into the rack when he had gotten too straight on a shot. Of course that was back when the cloth may have made it easier to jump.

 

[bustinbob_99]

Straight pool is all about control. Controlling the rack in the bottom half of the table. Controlling the cue for positioning various break shots. The stun shot plus or minus with high or low is about as much variation that I would be comfortable with in a run. Unless you're a rabbit, stay on the cloth.

 

[rikdee]

Jumping balls in the context of this thread is legitimate technique. Remember, we're not talking about radically bounding cueballs but instead controlled jumps, sometimes rising but an inch or two above the table bed. Not only can small clusters be separated but slightly jumping the CB on a short, straight in ball can cause the object ball itself to bouce sometimes just enough to clear the edge of an obstucting (third) ball. Additionally, jumping the CB will at times enable you to fly the CB over a ball or balls that would otherwise prevent the CB from getting to the most desired area of the table (jumping obstructing balls).

_Rick

 

[jondrums]

Thanks for all the replies

Thanks for all the replies - good discussion!
I get out of shape enough that this shot does come up for me.

EDIT - I figured something out just a minute ago -

I think I have a good way to visualize the cue ball path after an airborne collision. I will work on it and post an descriptive image.

Jon

 

[jondrums]

I did some calculations in excel. I know most of you couldn't care less about this physics stuff, but I couldn't let it rest. Here is a plot for those of you that might be interested.

The deviation from the standard 90deg tangent line is dependant on both cut angle and CB height off the table at the moment of contact. The effect is most pronounced on smaller cut angles, and of course when the cue ball is higher off the table at contact.

One thing to note, is that for larger cut angles (>15deg) and only a moderate jump action, the deviation from 90deg tangent path is quite small.
Jon

 

[Bob Jewett]

I did some calculations in excel. I know most of you couldn't care less about this physics stuff, but I couldn't let it rest. Here is a plot for those of you that might be interested....

Have you included the fact that the object ball cut angle is increased on jump shots? This would reduce the "difference from 90" by a little.

 

[jondrums]

no, that plot is for "resultant" cut angle. In other words, I assumed that the shooter already compensated by aiming to undercut just right.
my next task is to figure out how much the ball is overcut based on height of cue ball. I've noticed that this is considerably tougher to figure out!

I've also noticed that this is not strictly a straight pool topic, but it doesn't seem like anyone in the main forum cares about technical stuff anymore, so unless anyone objects, I'd like to keep the discussion here.
Jon

 

[jondrums]

Here's a plot showing the amount of overcut when the cue ball is not on the table at contact.

I failed trying to do the calculation, then realized that I could use a solid modeling tool to do the simulation for me.That's also where the visual graphical aid below comes from.

Since most people don't have an intuitive feel for small angles, here is a handy reference:

A ball placed on the foot spot is allowed +/- 2 degrees of error from the center of the pocket, and will still go in on a table with 5" pockets. So anything over 2-3 degrees overcut is probably enough to cause a behind the rack break shot to miss.

 

[Patrick Johnson]

Here's a plot showing the amount of overcut when the cue ball is not on the table at contact.

Seems to me that a jumped CB on a cut shot shifts some of the transferred spin to being around the horizontal axis, creating more "throw". Would this be enough to significantly decrease the effective overcut? I assume, since the technique is used to create overcut, that it doesn't entirely counteract it.

pj
chgo

 

[nick serdula]

Joe knew the master

Some of us don't play as well as The Master. I recall being impressed by the way Joe Balsis could jump into the rack when he had gotten too straight on a shot. Of course that was back when the cloth may have made it easier to jump.

True story,
Joe,Babe and Erving would not play him for money ever neither would Willie. I know becuase my dad offered to back them and they declined. Decades later when I came to know him and we became friends he told me how he knew them and was unbeatable before he was 16 and that a mob boss used to take all bets on him when he was only 14. That was how they knew him they were all freinds as kids and he was the origional killer.
At 16 he had enough sense to lie about his age,join the army and was a fighter pilot. That was how he got away from the mob. After he got out of the army and moved to the deep south. He didn't touch a pool stick for over 20 years. He started playing again and figured all the people that used to back him were dead or would never hear about him.
He respected Willie the most.
He never cared how many he could run and he never pracited after he developed his stroke. He just did what he needed to collect. Back before this computer age he was the origional trap waiting to happen.
He told me he was working for $.25 a week . After he was tought how to play and still only 14 his boss put him in a $100.00 game. He said it scared the $hit out of him and he didn't miss a ball for 100 points. The old man rembered the boss just laughing at his pool playing friend and handing him the winnings saying ,"Here kid this is for you". He said his hands shook all the way home. When he got home he just gave his money to his mother.
He still rembered how much that man loved him as a son and told him to look him up after the war. He said that scared him even more.
I should write a book.
Nick