englishing cue ball

[naji]

Please report back if and when you do a careful experiment.

Concerning the distance between the CB and OB, that does not need to be factor. It is easy to hit the CB high enough to create immediate roll. For more info, see:

natural roll, maximum offset, and overspin​

In other words, complete follow can be created at any CB-OB distance (assuming you can avoid a double hit).

Regards,
Dave

Thanks again for reply. I agree, i have been stressing good follow through stroke to achieve efficient roll, combined with high speed, throw will be canceled 100%, or to 0.1 degrees (1/16th inch of a ball width over 8 feet roughly)

Dr. Dave, look at the graph of the previous post for stun, top, and draw, you are showing the top and draw at large angle almost approaching or equal to stun at that angle, i am having hard time with it. I think at all angles with right high speed and top or draw throw if any is almost identical at all angles

 

[naji]

I'm certainly not going to argue physics with doctor Dave. However I do feel that a very important aspect is being overlooked. When shooting hard the cueball is bouncing (since the cue is almost never completely level). Therefore it does not strike the object ball at the perceived contact point, but a tiny bit "thinner". If you ever practised jump shots you will know what I mean.

This comes up all the time in straightpool when back cutting the classic top spin breakshot. If you dont aim to undercut this shot (playing with hard speed) you WILL overcut the shot. In my experience this is how I and others at my level typically miss these shots. Since you are hitting the edge of the object ball jumping over the equator means you hit the ball thinner. Look at the ball and be convinced.

You make sense, also could be that the tip strikes a hair left or right which could cause squirt- which is CJ's cause to believe one has to use TOI, which is ok, but also one can over do TOI at high speed.
Other factor, the shooter's stroke at high speed could be consistent of leaning one way or the other.

 

[dr_dave]

Dr. Dave, look at the graph of the previous post for stun, top, and draw, you are showing the top and draw at large angle almost approaching or equal to stun at that angle, i am having hard time with it. I think at all angles with right high speed and top or draw throw if any is almost identical at all angles

I didn't just make up these curves. They come from a careful and complete physics analysis that has been backed up by numerous experiments at the table (by several different people). In other words, the curves represent verifiable facts ... not opinion.

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.

I hope that makes sense,
Dave

 

[naji]

I didn't just make up these curves. They come from a careful and complete physics analysis that has been backed up by numerous experiments at the table (by several different people). In other words, the curves represent verifiable facts ... not opinion.

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.

I hope that makes sense,
Dave

Looked back, did not see what speed was used for that graph, it seems the speed was not defined, i assume you used speed less than what it takes to cancel friction? my findings, at higher speeds (within acceptable pool game speed), with long follow through you will have the top/draw graph almost a straight line up and down roughly at about 0.1 to 0.2 degrees for angles range 0-90.

When i cut an almost 80 degrees shot, if i hit with center hard it tends to throw a bit, if i put top and nice follow through fast, no throw for ob up table shooting down table! my straight in shots with same speed cb scratches often an indication i am hitting with straight stroke

 

[hang-the-9]

I have a question for yall,i read Bob Bynes series of books, and Jack Koehlers book years ago, and it seems like i remember them saying it doesnt matter how far out on the cueball you go left or right ,that you get the same amount of English transfer from the cueball to the object ball. The reason for my question is ,in one pocket you are definitly trying to spin the object balls a lot of times to get the cueball out of the way on double kiss paths. Also i would think that you lose aiming ability and maybe even get more cueball deflection the farther out on the cueball that you go,so if one could stay closer to center ball,within a half tip left or right and get the same amount of English transfer to the object ball it would be better,what say ye smart billiard players. Maybe Bob Jewett will have an interjection for me...

If you hit at the same strength, you will get more spin the further out you get from center.

Try to spin a wheel near the center, it's not as easy to move as if you do it from the outside edge.

 

[dr_dave]

my findings, at higher speeds (within acceptable pool game speed), with long follow through you will have the top/draw graph almost a straight line up and down roughly at about 0.1 to 0.2 degrees for angles range 0-90.

When i cut an almost 80 degrees shot, if i hit with center hard it tends to throw a bit, if i put top and nice follow through fast, no throw for ob up table shooting down table! my straight in shots with same speed cb scratches often an indication i am hitting with straight stroke

The throw values most certainly become less with more speed, but the trends and patterns remain the same. BTW, a good summary of all throw effects can be found here (in items 15 through 36 in the list beneath the embedded videos and illustration):

summary of all throw effects​

Regards,
Dave

 

[dr_dave]

I have a question for yall,i read Bob Bynes series of books, and Jack Koehlers book years ago, and it seems like i remember them saying it doesnt matter how far out on the cueball you go left or right ,that you get the same amount of English transfer from the cueball to the object ball.

If you hit at the same strength, you will get more spin the further out you get from center.

Actually, spin-induced throw (SIT) and spin transfer increase with sidespin only up to a certain point ... about 50% english with a full-ball hit. Additional spin (more than about 50%) actually creates less SIT and spin transfer! For demonstrations and detailed explanations, see:

maximum throw and spin transfer
spin transfer resource page​

Regards,
Dave

 

[hang-the-9]

Actually, spin-induced throw (SIT) and spin transfer increase with sidespin only up to a certain point ... about 50% english with a full-ball hit. Additional spin (more than about 50%) actually creates less SIT and spin transfer! For demonstrations and detailed explanations, see:

maximum throw and spin transfer
spin transfer resource page​

Regards,
Dave

Oh.. I think I did not read the full post, I thought he was talking about how much english was applied to the cueball.

 

[dr_dave]

Oh.. I think I did not read the full post, I thought he was talking about how much english was applied to the cueball.

In that case, I agree with you. The amount of spin on the CB increases the farther you hit from center.

Regards,
Dave

 

[ScottK]

I usually do not disagree with what you say, but on this issue, i respectably disagree,

That's odd. All I've ever seen is you disagreeing with both Dave and Bob. Can you point me in the direction of a post, ever, in which you've simply just agreed with anything anyone has said?

 

[naji]

That's odd. All I've ever seen is you disagreeing with both Dave and Bob. Can you point me in the direction of a post, ever, in which you've simply just agreed with anything anyone has said?

I disagree with what you saying!! LOL just kidding.. Pool is really complicated sport, and only those that reached extremely high level (not playing as much as its theory and mechanics), and dedicated to the sport will be able to question its theory and application.

Thanks for your concern.