# LD vs regular shafts

#### hang-the-9

##### AzB Silver Member
Silver Member
Squirt happens because the CB rotates while in contact with the tip, pushing the shaft to one side and the CB the other way. So I'm thinking without CB rotation there's no squirt - but I can't think of a way to test it.

pj
chgo

I am not sure if the issue is rotation but more so the fact that if you hit the side of a round object you can't help but apply side force to it as you go through it vs just spin. The cueball does curve with spin, but that is a smaller affect than what happens when you push it to the side.

When you hit a flat surface, you also apply some side force from center, but if that center is fixed in place, would the force on one side of the surface cause it to move to the opposite side? Or just go straight anyway?

Let's say the round object could not spin, nor the flat object. But they can be moved side to side without issue. Would a square cueball have some deflection?

#### hang-the-9

##### AzB Silver Member
Silver Member
This seems impossible. If you strike a square block left of center it will have to rotate clockwise around its center of mass, which means it will be pushed aside, unless there is an equal force applied to the same face but right of center, canceling the rotation with an equal but counter-clockwise force. Then the block would move straight in the same direction of each colliding force.

Yes to my mind having this object seems impossible to do in reality but I wonder if a simulation can do this math. It's not hard to image an object not being able to move around the axis but being able to slide side to side. Say a block on an ice sheet, for some reason you could not rotate the cube, but you can push it around the ice. It's just hard to imagine HOW this object would exist in our world and what can cause it not to spin but yet move in any other direction. For it not to spin, you need to hold it steady at the center, but in reality anything that can do that, at least in my mind, would cause a change in how it can move left/right/up/down. As a pure thought experiment though, I can imagine such an object. I mean the force is still applied more to one side than the other, so in physics opposite reaction would mean the force has to go the other way, which would cause the spin to happen. But if the spin is blocked, the force goes where? For it to go straight would seem a bit odd to me, and yet for it to go to the side, would be equally strange to imagine. In the real world, any force that would prevent spin would prevent it from moving at all, since you have friction blocking the spin and also movement through say a metal rod connected to something. So you need to have some imaginary reality where spin can be blocked through some totally internal force to the cube, yet without large mass since that large mass would cause the block not to side to the side but stick in place.

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#### Patrick Johnson

##### Fish of the Day
Silver Member
I am not sure if the issue is rotation
It is what causes squirt in pool - that's well known.

...but more so the fact that if you hit the side of a round object you can't help but apply side force to it as you go through it
I don't think this is true unless your stick is pushed sideways so it "pushes back" (actually, the ball does all the pushing).

pj
chgo

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
I am not sure if the issue is rotation but more so the fact that if you hit the side of a round object you can't help but apply side force to it as you go through it vs just spin. The cueball does curve with spin, but that is a smaller affect than what happens when you push it to the side.

When you hit a flat surface, you also apply some side force from center, but if that center is fixed in place, would the force on one side of the surface cause it to move to the opposite side? Or just go straight anyway?

Let's say the round object could not spin, nor the flat object. But they can be moved side to side without issue. Would a square cueball have some deflection?

I do believe a square cb would be pushed aside from a glancing blow unless another force was acting on it also. Try pushing a box, off center, across a table. It has no choice but to move diagonally away from your pushing hand.

#### hang-the-9

##### AzB Silver Member
Silver Member
I do believe a square cb would be pushed aside from a glancing blow unless another force was acting on it also. Try pushing a box, off center, across a table. It has no choice but to move diagonally away from your pushing hand.

Ah, but if the box is off center, your force is going to the side of it, not straight, which is similar to the round side of the cueball. I mean something like your cell phone, place it on the desk with long side facing you and even with your chest and push on one side. It will rotate. Now imagine that it can't rotate, but has the same mass and friction on the table. Where will it go? Human logic tells you forward since you are pushing forward and it can't rotate so it goes forward. But Physics Logic would say that you are pushing on the side, so the force is greater on one side than the other so it should move to the side (equal and opposite), even though you are pushing a flat object forward, which your brain states should go forward.

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#### dr_dave

##### Instructional Author
Gold Member
Silver Member
I am not sure if the issue is rotation but more so the fact that if you hit the side of a round object you can't help but apply side force to it as you go through it vs just spin. The cueball does curve with spin, but that is a smaller affect than what happens when you push it to the side.

When you hit a flat surface, you also apply some side force from center, but if that center is fixed in place, would the force on one side of the surface cause it to move to the opposite side? Or just go straight anyway?

Let's say the round object could not spin, nor the flat object. But they can be moved side to side without issue. Would a square cueball have some deflection?
If you or others want to know what causes squirt (CB deflection), see the explanations and illustrations here:

What causes squirt?

And for the geeks out there with strong math and physics backgrounds, here's the technical analysis:

TP A.31 – The physics of squirt

Enjoy,
Dave

#### mikemosconi

##### AzB Silver Member
Silver Member
IN my mind, the one of the worst things you can do to yourself as a beginner is to worry about deflection, squirt, curve, swerve, etc. The game is hard enough to master and worrying about that stuff will mess you up beyond belief. Just pick one cue that is comfortable for you- any cue, any weight, any kind of shaft, etc. and if it FEELS good in your hands, never put it down for another and your game will progress as it naturally should without impairment. Think of it this way- the greatest player ever used a cue made by hand over 50 years ago and NOBODY today can beat him at his game - so that is ALL the proof you need my friend- the rest of this marketing BS will set back your \$\$ and your game if you keep it in your head. Guaranteed!

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
IN my mind, the one of the worst things you can do to yourself as a beginner is to worry about deflection, squirt, curve, swerve, etc. The game is hard enough to master and worrying about that stuff will mess you up beyond belief. Just pick one cue that is comfortable for you- any cue, any weight, any kind of shaft, etc. and if it FEELS good in your hands, never put it down for another and your game will progress as it naturally should without impairment. Think of it this way- the greatest player ever used a cue made by hand over 50 years ago and NOBODY today can beat him at his game - so that is ALL the proof you need my friend- the rest of this marketing BS will set back your \$\$ and your game if you keep it in your head. Guaranteed!

You are right. All a player needs to know is how to use your cue to make it all it work for you. Some of the best players in the world could probably not explain squirt, swerve, deflection, etc... because they don't care. They know it happens and they know how to deal with it. But some players want to know the details of why things happen, and this is fine too as long as it doesn't hamper improvement.

#### Patrick Johnson

##### Fish of the Day
Silver Member
...if the box is off center, your force is going to the side of it, not straight
Even in this imaginary universe where the square box doesn't rotate, I don't think it would work like that. I think no matter how far from center you hit the imaginary box it (and your stick) would act like you hit it dead center.

I don't think there's a pre-existing sideways force; I think the sideways force is created by the interaction of the tip and ball during contact. Your thought experiment eliminates the very part of that interaction that creates the sideways force.

pj
chgo

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
For many, understanding pool physics effects and principles actually speeds improvement. For more info on this topic, see:

physics “understanding” sometimes provides useful insight

knowledge can be useful, but you still need skill

Regards,
Dave

I believe this. I'd say for most it does. Knowledge is power. But some people spend more time talking about the finer details than actually learning to play, and, though they understand everything, they never develop the skills they desire.

#### hang-the-9

##### AzB Silver Member
Silver Member
IN my mind, the one of the worst things you can do to yourself as a beginner is to worry about deflection, squirt, curve, swerve, etc. The game is hard enough to master and worrying about that stuff will mess you up beyond belief. Just pick one cue that is comfortable for you- any cue, any weight, any kind of shaft, etc. and if it FEELS good in your hands, never put it down for another and your game will progress as it naturally should without impairment. Think of it this way- the greatest player ever used a cue made by hand over 50 years ago and NOBODY today can beat him at his game - so that is ALL the proof you need my friend- the rest of this marketing BS will set back your \$\$ and your game if you keep it in your head. Guaranteed!

I don't agree with this, without knowing why things happen you can't really learn how to work with it except by trial and error, and if something different comes up you have no way to compensate or learn something new except again by trial and error over a long period of time.

You know how to hit shot A, but then you have shot B. If you have no idea how you made shot A how will you know how to aim at shot B without starting from the beginning again. Lets say you know that to make the car go you stuck this bent metal thing in a hole in the car and there is some liquid that comes out. Then you go to another pump that is diesel and you say "hm.. metal bent thing, liquid, this makes my car go", and now you have an issue because you did not learn what gas is or different types of engines but only knew the end result of using gas.

You really need to know the how and they why of something to get proficient at it. And I think even if you don't apply what you know, say reading about stars but not becoming an astronomer, it will help you in any sort of situation. Knowing more is pretty much always better than knowing less outside of relying on just dumb luck. For example you may not know that a plant is poison, so you eat it, and you get some random immunity to a disease because that plant did not kill you for some reason. A person with knowledge would say "that is a dangerous plant and I am not going to touch it", so they avoid it and did not get that same immunity. That is an example of ignorance over knowledge through sheer luck. But there are way way way more cases where you want to know something rather than not.

There is actually an interesting SciFi short story about a future where people forgot how to do math in their heads, they just used computers and calculators for so long the knowledge of HOW those devices worked was lost. Then some guy basically reverse engineered them and became some oddity that the military wanted to use. They used the "it's better to just do it instead of learn how to do it" idea and lost a whole facet of knowledge.

If all you can say about playing pool is "I hit the ball here for this shot" but can't say why that works for you, that is a big loss since you will never be able to teach.

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#### dr_dave

##### Instructional Author
Gold Member
Silver Member
For many, understanding pool physics effects and principles actually speeds improvement. For more info on this topic, see:

physics “understanding” sometimes provides useful insight

knowledge can be useful, but you still need skill
I believe this. I'd say for most it does. Knowledge is power. But some people spend more time talking about the finer details than actually learning to play, and, though they understand everything, they never develop the skills they desire.
Yep. In pool, knowledge is useless without skill. But sometimes knowledge can help you build skill faster.

Regards,
Dave

#### Patrick Johnson

##### Fish of the Day
Silver Member
...some people spend more time talking about the finer details than actually learning to play, and, though they understand everything, they never develop the skills they desire.
Maybe I don't get out enough, but I've never met anybody like you describe. Everybody I know with an interest in pool's finer details is an avid player who plays better because of what they know.

This sounds to me like the myth about "too much knowledge causing analysis paralysis".

pj
chgo

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
Maybe I don't get out enough, but I've never met anybody like you describe. Everybody I know with an interest in pool's finer details is an avid player who plays better because of what they know.

This sounds to me like the myth about "too much knowledge causing analysis paralysis".

pj
chgo

You're right....maybe you don't get out enough. Lol. But I don't believe too much knowledge leads to analysis paralysis. For most people it leads to good and decisive decision making.

Anyway, these types of players I mentioned exist everywhere. They have a wealth of knowledge because they read everything they can about pool, and they keep themselves informed on all the top pros, can tell you exactly which pro uses which cue, who lost to whom and by how much or for whatever amount of cash. They have a mind full of stats and pool knowledge, hours upon hours of it. But for whatever reason they just don't invest hours upon hours on developing their skills in order to become a solid player. They know how to play, but lack of table time has their knowledge ranked way above their skill level.

And I am in no way saying players shouldn't read and learn everything they can about pool. I'm just saying acquired knowledge has to be balanced out with developing skills. Above all, skill matters most, imo. Solid skills beats a lot of players, and then mix in some useful knowledge, well....that's a combination that beats most players.

The key is to learn the things that you can use to become a better player, not to try to learn every little thing there is to know. Knowing that the cb squirts when using side spin, and knowing how to deal with it using your cue, is useful information. Knowing what causes the cb to squirt isn't as important. Millions of people drive their cars very well, despite the fact that they have no knowledge about the motor, transmission, or brake system. They know how to work the pedals, the gear shift and the steering wheel, and that's all they need to know to be good at it.

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#### KMRUNOUT

##### AzB Silver Member
Silver Member
Squirt happens because the CB rotates while in contact with the tip, pushing the shaft to one side and the CB the other way. So I'm thinking without CB rotation there's no squirt - but I can't think of a way to test it.

pj
chgo

I believe the squirt is introduced when an impact occurs at a point to the left or right of the center of mass of the object being struck. The component vectors yield a transverse component. I think a square block will also deflect, unless it is somehow prevented from moving or rotating, at which point I think we’ve parted ways with any issue involved in pool physics.

KMRUNOUT

Sent from my iPhone using AzBilliards Forums

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
I believe the squirt is introduced when an impact occurs at a point to the left or right of the center of mass of the object being struck. The component vectors yield a transverse component. I think a square block will also deflect, unless it is somehow prevented from moving or rotating, at which point I think we’ve parted ways with any issue involved in pool physics.

KMRUNOUT

Sent from my iPhone using AzBilliards Forums

That's it, the same as any two objects colliding off center (not head-on), be it people bumping into people or cars crashing into each other, or pool balls. The lighter object will always be pushed aside. If the cue shaft had zero flexibility the cb would react to the full weight of the cue stick, which is more than 3 times the weight of the cb. Only because of the friction at impact (chalk) the cb would be forced somewhat in the direction of the stroke, but deflected a few degrees offline. With no chalk or no tip the cb would be deflected closer along the line from point of contact through its center of mass - maximum deflection.

By increasing shaft flexibility and decreasing shaft end mass, the weight of the cb has more influence during impact. The cb can now push the shaft aside and move closer along the line of the stroke. That's the beauty of LD shafts -- due to light end mass and shaft flexibility, the cb pushes the shaft aside so that the entire weight of the cue stick isn't acting on the cb to push it aside. More shaft deflection equals less cb deflection.

I know Dr Dave will point out that end mass is all that matters, but if you could use a robot shooter with no lateral give in the bridge piece or grip arm/piece, and test a cue that has a super light shaft end mass but zero flexibility, then the cb would react to the full weight of the cue stick and deflect out of its way, because the cue stick path would remain fixed. Fortunately we humans have some give in our bridge hand, so there is always some deflected lateral movement of the shaft when the tip strikes the cb. But a more flexible shaft ensures more shaft deflection, which is a good thing, if you like LD shafts.

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#### Patrick Johnson

##### Fish of the Day
Silver Member
That's it, the same as any two objects colliding off center (not head-on), be it people bumping into people or cars crashing into each other, or pool balls. The lighter object will always be pushed aside. If the cue shaft had zero flexibility the cb would react to the full weight of the cue stick, which is more than 3 times the weight of the cb. Only because of the friction at impact (chalk) the cb would be forced somewhat in the direction of the stroke, but deflected a few degrees offline. With no chalk or no tip the cb would be deflected closer along the line from point of contact through its center of mass - maximum deflection.

By increasing shaft flexibility and decreasing shaft end mass, the weight of the cb has more influence during impact. The cb can now push the shaft aside and move closer along the line of the stroke. That's the beauty of LD shafts -- due to light end mass and shaft flexibility, the cb pushes the shaft aside so that the entire weight of the cue stick isn't acting on the cb to push it aside. More shaft deflection equals less cb deflection.

I know Dr Dave will point out that end mass is all that matters, but if you could use a robot shooter with no lateral give in the bridge piece or grip arm/piece, and test a cue that has a super light shaft end mass but zero flexibility, then the cb would react to the full weight of the cue stick and deflect out of its way, because the cue stick path would remain fixed. Fortunately we humans have some give in our bridge hand, so there is always some deflected lateral movement of the shaft when the tip strikes the cb. But a more flexible shaft ensures more shaft deflection, which is a good thing, if you like LD shafts.
If I read you correctly, you believe (like KMRUNOUT) that with no tip/ball slippage and no CB rotation there would be no squirt?

pj
chgo

#### BC21

##### https://www.playpoolbetter.com
Gold Member
Silver Member
If I read you correctly, you believe (like KMRUNOUT) that with no tip/ball slippage and no CB rotation there would be no squirt?

pj
chgo

No.... I think there would be deflection/squirt. I was agreeing with KMRUNOUT that imagining a scenario where the cb (or any object for that matter) is unable to move or rotate around its center of mass when struck off center has no reality in pool physics, or any physics in general.

#### Patrick Johnson

##### Fish of the Day
Silver Member
If I read you correctly, you believe (like KMRUNOUT) that with no tip/ball slippage and no CB rotation there would be no squirt?

No.... I think there would be deflection/squirt. I was agreeing with KMRUNOUT that imagining a scenario where the cb (or any object for that matter) is unable to move or rotate around its center of mass when struck off center has no reality in pool physics, or any physics in general.
How about if there was no rotation but 100% tip/ball slippage - like, say, an unchalked tip with grease on it? Would there be squirt then? Or would it be a "carom" like two silicone coated balls colliding off center?

pj
chgo