Making a 45 degree cut with Tops, Bottoms and Center ball hits

[recoveryjones]

Set up a 45 degree cut as illustrated on the Wei table.45 degrees is measured with your cue stick by placing it over the side pocket to a corner pocket.

START(
%Ai5J5%Pg9V9

)END

Now(experiment) cut that shot in with tops,bottoms and a center ball with a half ball (aiming) hit(slow to medium pace) and check out the results.A half ball hit is aiming the center of the cue ball to the outside edge of the object ball.If you do this experiment you will find that the object ball is potted with tops and bottoms, however, it will not be potted with center ball using a half ball hit.To pot it with center ball you will need to cut it more using a 1/4 ball hit.A 1/4 ball hit is aiming the center of the cue ball at 1/4 of the object ball located between the center of the object ball and outside edge.

The reason(I think) this happens is because the center ball hit comes in sliding rather than rolling and actually pushes the object ball forward a slight tad before the cut takes effect.Experiment with simuliar 40-45 degree cuts using tops,bottoms and stun and check the results.I was very pleased when I discovered this info.Let me know how this experiment works for you.
RJ

ps. I'm no teacher so only experimentation will show if this works for you as it does for me.

 

[GStrong]

That is not a 45 degree cut... if the ob was on the rail it would be 45. Like this:

START(
%Ag8D3%BN6^6%EO7]6%FK9]4%HJ4^8%KK6^3%MN5[9%OM5^3%P\7O4%Wr7D2
%X[4[0%Yf2F3%Z]4N4
)END

And there is no way you can make that with a half ball hit. For me, it is a 1/4 ball hit.

 

[lewdo26]

An article Bob's written for the latest BD reveals the results of his experiments with CIT and different hits along the vertical axis (much like yours).

Seems like a new theory on that is emerging, and maybe one day it'll be in introductory books like other CIT situations, and save folks like me a lot of trial and error.

Tell you the truth, I didn't understand Bob Jewett's explanation for why a deadball grabs more, so hopefully he'll chime in.

 

[Colin Colenso]

Basically, the faster the surfaces are moving in relation to each other, the less friction contributes to Contact Induced Throw. One shock result of this for many is that stun with IE on a half ball cut, throws less than center ball stun.

Here is a video of some tests I conducted on this:
http://www.youtube.com/watch?v=D-xtzn4vbiQ

 

[recoveryjones]

That is not a 45 degree cut... if the ob was on the rail it would be 45. Like this:

START(
%Ag8D3%BN6^6%EO7]6%FK9]4%HJ4^8%KK6^3%MN5[9%OM5^3%P\7O4%Wr7D2
%X[4[0%Yf2F3%Z]4N4
)END

And there is no way you can make that with a half ball hit. For me, it is a 1/4 ball hit.

Thanks, I changed the illustration using a protractor and even it might not be accurate.

The main point I'm trying to make is that certain pots will go in with tops and bottoms (with a half ball hit) and others using center ball will not. I got this info via Bert Kinister from one of his DVD's.
RJ

 

[mnShooter]

I completely understand the physics behind this. It has to do with the different coefficients of static and kinetic friction. Basically when two objects are sliding there is less friction than when they are at rest. Think of locking up your tires on an icy road or peeling out in the rain.

So from this can you draw the conclusion that a straight in shot will go in a tiny bit more often with a stop shot then it will with draw or follow?

 

[mikepage]

I completely understand the physics behind this. It has to do with the different coefficients of static and kinetic friction. Basically when two objects are sliding there is less friction than when they are at rest. Think of locking up your tires on an icy road or peeling out in the rain.

So from this can you draw the conclusion that a straight in shot will go in a tiny bit more often with a stop shot then it will with draw or follow?

No, your physics is wrong here.

And your last conclusion is wrong.

This is *all* kinetic friction.

To understand why there is more throw for the centerball (stun) shot than the others the first thing a person has to do is get rid of the word "grab" when describing throw. The mental model of one ball grabbing the other and throwing it off course is wrong, and the inability of that model to explain the results you see is one reason why it's not only wrong but leads to practical wrong conclusions.

Here's the deal. Unless you're talking about unusual things like "cling" or a ball "skidding" on you, the friction between the balls is all kinetic friction. It's the result of the surfaces of two balls rubbing across one another. Unless there's a smudge of chalk at the contact region, they are never temporarily connected for any of your shots.

So why does the stun shot throw more?

Imagine you're standing on an ice rink holding a broom, and you want to move toward a wall. The only way you can move is by swiping the broom across the ice. Let's say one good swipe moves you two feet. So if you swiped the broom straight away from the wall, you'd move two feet closer to the wall. If instead you swiped the broom parallel to the wall, you would move two feet sideways and none at all closer to the wall. If you swiped at an angle away from the wall, you'd move something between none and two feet toward the wall, depending on the angle.

For your shots, there is but one swipe of the balls, and the outcome depends on the direction of the swipe. For a stun shot, where the cueball is sliding into the object ball, the entire swipe is sideways and the entire swipe contributes to throw. When there is topspin or bottom spin on the cueball, the direction of the swipe is part sideways and part up or down. But it's still only one single swipe. So if any of the swipe is directed up or down, that's less of the swipe that can be directed sideways. So throw is maximized for a stun shot, and there is less throw when the cueball has either topspin or bottom spin.

This is why the "gear" effect or the "grab" idea you read about in books to explain throw is nonsense. (The gear idea leads to other wrong conclusions as well).

So cinching a straight or nearly straight in shot with stop/stun is the wrong thing to do. Small amounts of unintentional sidespin will be most damaging under these circumstances. Hitting these with a wee bit of draw or a wee bit of follow really helps because it gets rid of most of the unintentional throw problem.

mike page
fargo

 

[TSW]

Good post, Mike. Why is the gear theory so pervasive if its conclusions are wrong?

 

[mikepage]

Good post, Mike. Why is the gear theory so pervasive if its conclusions are wrong?

IMO, the gear theory of throw is to pool what the Iraq/911 connection is to international relations.

Both "feel" right when we first hear them, and then we hold onto them with a death grip no matter how many facts try to pry them loose.....

In other words, I don't know... except that perhaps it's the easiest visual model that leads the the existence of throw, even though it doesn't get anything else right about it.

mike page
fargo

 

[recoveryjones]

No, your physics is wrong here.

And your last conclusion is wrong.

This is *all* kinetic friction.

To understand why there is more throw for the centerball (stun) shot than the others the first thing a person has to do is get rid of the word "grab" when describing throw. The mental model of one ball grabbing the other and throwing it off course is wrong, and the inability of that model to explain the results you see is one reason why it's not only wrong but leads to practical wrong conclusions.

Here's the deal. Unless you're talking about unusual things like "cling" or a ball "skidding" on you, the friction between the balls is all kinetic friction. It's the result of the surfaces of two balls rubbing across one another. Unless there's a smudge of chalk at the contact region, they are never temporarily connected for any of your shots.

So why does the stun shot throw more?

Imagine you're standing on an ice rink holding a broom, and you want to move toward a wall. The only way you can move is by swiping the broom across the ice. Let's say one good swipe moves you two feet. So if you swiped the broom straight away from the wall, you'd move two feet closer to the wall. If instead you swiped the broom parallel to the wall, you would move two feet sideways and none at all closer to the wall. If you swiped at an angle away from the wall, you'd move something between none and two feet toward the wall, depending on the angle.

For your shots, there is but one swipe of the balls, and the outcome depends on the direction of the swipe. For a stun shot, where the cueball is sliding into the object ball, the entire swipe is sideways and the entire swipe contributes to throw. When there is topspin or bottom spin on the cueball, the direction of the swipe is part sideways and part up or down. But it's still only one single swipe. So if any of the swipe is directed up or down, that's less of the swipe that can be directed sideways. So throw is maximized for a stun shot, and there is less throw when the cueball has either topspin or bottom spin.

This is why the "gear" effect or the "grab" idea you read about in books to explain throw is nonsense. (The gear idea leads to other wrong conclusions as well).

So cinching a straight or nearly straight in shot with stop/stun is the wrong thing to do. Small amounts of unintentional sidespin will be most damaging under these circumstances. Hitting these with a wee bit of draw or a wee bit of follow really helps because it gets rid of most of the unintentional throw problem.

mike page
fargo

Excellent Post and very much appreciated.
RJ

 

[lewdo26]

No, your physics is wrong here.

And your last conclusion is wrong.

This is *all* kinetic friction.

To understand why there is more throw for the centerball (stun) shot than the others the first thing a person has to do is get rid of the word "grab" when describing throw. The mental model of one ball grabbing the other and throwing it off course is wrong, and the inability of that model to explain the results you see is one reason why it's not only wrong but leads to practical wrong conclusions.

Here's the deal. Unless you're talking about unusual things like "cling" or a ball "skidding" on you, the friction between the balls is all kinetic friction. It's the result of the surfaces of two balls rubbing across one another. Unless there's a smudge of chalk at the contact region, they are never temporarily connected for any of your shots.

So why does the stun shot throw more?

Imagine you're standing on an ice rink holding a broom, and you want to move toward a wall. The only way you can move is by swiping the broom across the ice. Let's say one good swipe moves you two feet. So if you swiped the broom straight away from the wall, you'd move two feet closer to the wall. If instead you swiped the broom parallel to the wall, you would move two feet sideways and none at all closer to the wall. If you swiped at an angle away from the wall, you'd move something between none and two feet toward the wall, depending on the angle.

For your shots, there is but one swipe of the balls, and the outcome depends on the direction of the swipe. For a stun shot, where the cueball is sliding into the object ball, the entire swipe is sideways and the entire swipe contributes to throw. When there is topspin or bottom spin on the cueball, the direction of the swipe is part sideways and part up or down. But it's still only one single swipe. So if any of the swipe is directed up or down, that's less of the swipe that can be directed sideways. So throw is maximized for a stun shot, and there is less throw when the cueball has either topspin or bottom spin.

This is why the "gear" effect or the "grab" idea you read about in books to explain throw is nonsense. (The gear idea leads to other wrong conclusions as well).

So cinching a straight or nearly straight in shot with stop/stun is the wrong thing to do. Small amounts of unintentional sidespin will be most damaging under these circumstances. Hitting these with a wee bit of draw or a wee bit of follow really helps because it gets rid of most of the unintentional throw problem.

mike page
fargo

Thanks a lot, Mike. I do understand it now. I still don't know how I'd apply that knowledge to game situations but I'm sure it'll become clear.

 

[mnShooter]

Ok so it's the direction of the swipe that causes more friction. I see. I thought my thinking was wrong on the kinetic vs static friction but couldn't figure out why.

 

[lewdo26]

Basically, the faster the surfaces are moving in relation to each other, the less friction contributes to Contact Induced Throw. One shock result of this for many is that stun with IE on a half ball cut, throws less than center ball stun.

Here is a video of some tests I conducted on this:
http://www.youtube.com/watch?v=D-xtzn4vbiQ

Colin, what is the explanation why OE throws more than IE (if it does)?

 

[mikepage]

Colin, what is the explanation why OE throws more than IE (if it does)?

I'm not Colin, but...

Imagine you're hitting a half-ball cut shot with no english. Our experience is that when you hit the shot harder, there is less throw. This means the coefficient of kinetic friction gets smaller when the two surfaces rub past one another at higher speeds.

Inside english is a way to get the surfaces to rub together at a higher speed (and thus produce less throw) without hitting the shot harder.

mike page
fargo

 

[Colin Colenso]

I'm not Colin, but...

Imagine you're hitting a half-ball cut shot with no english. Our experience is that when you hit the shot harder, there is less throw. This means the coefficient of kinetic friction gets smaller when the two surfaces rub past one another at higher speeds.

Inside english is a way to get the surfaces to rub together at a higher speed (and thus produce less throw) without hitting the shot harder.

mike page
fargo

Sorry Lewdo for not seeing your question and responding...

Thanks to Mike for the response. I think he's spot on.

Colin

 

[Tennesseejoe]

Thanks to all for the posts---This was really great.

 

[Jal]

Colin, what is the explanation why OE throws more than IE (if it does)?

It has to be said that general statements about inside and outside english are usually wrong, in that they apply to certain shots and not to others. Sometimes outside throws more than inside, sometimes it doesn't. The reason is that there are two things that govern the amount of sideways throw: the magnitude of the friction and its direction. Both are affected by cut angle and how much draw or follow is present.

Where outside does cause more throw, it's as Mike Page explained, because of a reduction in surface speed. But if the surface speed is reduced enough, the cueball ends up rolling across the object ball, just like on the surface of the table, and throw is reduced. This happens when a touch of outside is used with stun shots at moderate cut angles, up to around half-ball hits. At larger cut angles, using a little bit of outside on a stun shot increases throw because of the surface speed thing. But using still more will reduce it where it causes the ball to end up rolling.

There are other circumstances where outside reduces throw, such as when draw or follow is present. But this also depends on cut angle. It does this by changing the direction of the friction.

The good thing about throw is that it's typically small, less than a degree, and our guestimations are usually good enough. When in doubt, just roll the cueball.

Jim

 

[lewdo26]

The good thing about throw is that it's typically small, less than a degree, and our guestimations are usually good enough. When in doubt, just roll the cueball.

Jim

First of all, I'd like to thank Mike, Colin and Jal for taking the time to explain all these questions. Greatly appreciated.

So far, I've understood that spin (vertical or sidespin) reduces throw in relation to stun shots due to increased surface speed (and therefore less friction).

Cool, now the other question I have is the following: I got a cut to the left (I'm deliberately not specifying the cut angle) and I use, say, low outside... the OB throws an X amount of degrees to the left.

Now, I'm shooting exactly the same shot, with the same amount of spin, but low inside instead. Does the object ball throw exactly the same amount of degrees to the right?

Thanks again.

 

[mikepage]

First of all, I'd like to thank Mike, Colin and Jal for taking the time to explain all these questions. Greatly appreciated.

So far, I've understood that spin (vertical or sidespin) reduces throw in relation to stun shots due to increased surface speed (and therefore less friction).

No. The "surface speed" thing is a secondary effect. Forget that for a minute. Think of the rubbing as providing a certain amount of force to the object ball. The presence of topspin or bottomspin changes the *direction* of that force, making some of it push up or down on the object ball. That means there's less to push sideways and cause throw.

Cool, now the other question I have is the following: I got a cut to the left (I'm deliberately not specifying the cut angle) and I use, say, low outside... the OB throws an X amount of degrees to the left.

Now, I'm shooting exactly the same shot, with the same amount of spin, but low inside instead. Does the object ball throw exactly the same amount of degrees to the right?

Thanks again.

No. With inside english, you are guaranteed to throw the object ball to the right--because that is definitely the direction of the rubbing. Things are more complicated with outside english. As Jim pointed out, with a small amount of outside english, you'll throw the ball to the right, and with a large amount of outside english, you'll throw the ball to the left. "Large" and "small" here depend on the cut angle. With outside english, the rubbing could be in either direction because the relative surface speed due to the english is opposite to the relative surface speed due to the cut, and it is the *net* relative surface speed that matters.

mike page
fargo

 

[Colin Colenso]

It has to be said that general statements about inside and outside english are usually wrong, in that they apply to certain shots and not to others. Sometimes outside throws more than inside, sometimes it doesn't. The reason is that there are two things that govern the amount of sideways throw: the magnitude of the friction and its direction. Both are affected by cut angle and how much draw or follow is present.

Where outside does cause more throw, it's as Mike Page explained, because of a reduction in surface speed. But if the surface speed is reduced enough, the cueball ends up rolling across the object ball, just like on the surface of the table, and throw is reduced. This happens when a touch of outside is used with stun shots at moderate cut angles, up to around half-ball hits. At larger cut angles, using a little bit of outside on a stun shot increases throw because of the surface speed thing. But using still more will reduce it where it causes the ball to end up rolling.

There are other circumstances where outside reduces throw, such as when draw or follow is present. But this also depends on cut angle. It does this by changing the direction of the friction.

The good thing about throw is that it's typically small, less than a degree, and our guestimations are usually good enough. When in doubt, just roll the cueball.

Jim

Hi Jim,
Very interesting points.
I'll have to try some shots out and see if I can verify / quantify.

btw. In my tests (my balls may be a bit dirty, and hitting out of a dimple on a heavy nap cloth may exaggerate throw), but the variation on a half ball hit between slow stun and a lot of OE was over 6 degrees or 13 inches over 7 feet. So hitting the same contact point, with the wrong spin can cause a player to miss by half a diamond either side for long shots if they align for natural roll angle.

Colin