Pool ball cut-induced throw and cling/skid/kick experiment

Dave:

Thanks for your lengthy response which I won't quote here.

If the cue tip-CB contact is FRICTIONLESS, the laws of physics demand that the CB will travel in the direction of the contact vector. (This would be the maximum squirt case.) The force on the CB can be resolved in two directions: one force axial through the contact point and one force tangential, but we have defined the tangential force as zero. Therefore there is only one direction the CB could go in a frictionless case, and that is along the contact vector.

I have to stop here and ask, "do you disagree?" (Please specifically address this question.)

Therefore the fact that the CB does not travel in this direction, and travels closer to (but not co-linear with) the cue direction is due to cue tip-CB friction, whether or not there is slippage during contact.
 
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Shaft said:
If the cue tip-CB contact was FRICTIONLESS, the laws of physics demand that the CB would travel in the direction of the contact vector. (This would be maximum squirt.)
Do you disagree? (Please specifically address this question.)
Click to expand...
Agreed, in theory. However, in real life, a frictionless tip would result in a miscue, which almost always involves multiple hits, so the CB won't usually head in this theoretical direction.

Shaft said:
The fact that the CB does not travel in this direction, and closer to but not co-linear with the cue direction is due to cue tip-CB friction, whether or not there is slippage.
Click to expand...
Agreed.

However, everything else I wrote in the previous post still applies.

Regards,
Dave
 
Shaft said:
If the cue tip-CB contact is FRICTIONLESS, the laws of physics demand that the CB will travel in the direction of the contact vector. (This would be the maximum squirt case.) The force on the CB can be resolved in two directions: one force axial through the contact point and one force tangential, but we have defined the tangential force as zero. Therefore there is only one direction the CB could go in a frictionless case, and that is along the contact vector.
Click to expand...

This question has bothered me, as well.

Of course, the notion of 'frictionless' raises all kinds of questions... But I certainly get the point of this question.

dr_dave said:
Agreed, in theory. However, in real life, a frictionless tip would result in a miscue, which almost always involves multiple hits, so the CB won't usually head in this theoretical direction.
Click to expand...

What if the 'shaft' were perfectly rigid? (impossible, of course, but in keeping with a thought experiment involving 'frictionless' contacts...) Why would it miscue? And, if not, then aren't we back to Shaft's point about the motion of the CB being along the contact vector?

Then, the rest of Shaft's argument would follow, no? This is a bothersome question, at least to me.
 
swest said:
... Why would it miscue? ...
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A miscue happens when the tip slips on the ball. Friction is required to prevent that. Chalk increases the friction.

In general, if there is no friction between two colliding bodies, the only force between them is perpendicular to the contact point/patch (by the definition of frictionless).

There is essentially no slipping between tip and ball during a normal off-center shot. Chalk prevents slipping.
 
swest said:
This question has bothered me, as well.

Of course, the notion of 'frictionless' raises all kinds of questions... But I certainly get the point of this question.



What if the 'shaft' were perfectly rigid? (impossible, of course, but in keeping with a thought experiment involving 'frictionless' contacts...) Why would it miscue? And, if not, then aren't we back to Shaft's point about the motion of the CB being along the contact vector?

Then, the rest of Shaft's argument would follow, no? This is a bothersome question, at least to me.
Click to expand...

My idea here would be a CB firmly affixed to a fiberglass shaft (using a CB as a tip, if you will), with it and the real CB slicked with silicone. That probably will miscue, but not double hit.
 
dr_dave said:
I have not tested this thoroughly; but in my experience, a well-chalked tip still grabs the CB well, even when it is slick and shiny.
Click to expand...

Dr. Dave,

Would you care to do an experiment on this? I'd love to see the results of that. And to take it a step further, an experiment comparing different brands of chalk would be great. And if you did do that, let me know so that I could send you a couple of test cubes. As you probably know, the results of such a test would be very relevant to the age old "does chalk make a difference" debate.

And thanks for your efforts. I can only begin to imagine studying the vast amount of info that you have provided to the pool community.

EDIT: I see you already addressed this in the thread. Nevermind.

Fatz
 
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swest said:
What if the 'shaft' were perfectly rigid? (impossible, of course, but in keeping with a thought experiment involving 'frictionless' contacts...) Why would it miscue?
Click to expand...
If there were no friction (or not enough friction) between the tip and CB, there would be no force (or not enough force) to prevent sliding of the tip along the ball, even with a perfectly rigid shaft. A miscue is a result of the tip sliding on the CB instead of grabbing.


swest said:
And, if not, then aren't we back to Shaft's point about the motion of the CB being along the contact vector?

Then, the rest of Shaft's argument would follow, no? This is a bothersome question, at least to me.
Click to expand...
As Bob pointed out, with no friction between the tip and ball, the only force possible will be along the normal vector, perpendicular to both surfaces at the point of contact.

Catch you later,
Dave
 
Bob Jewett said:
A miscue happens when the tip slips on the ball. Friction is required to prevent that. Chalk increases the friction.

In general, if there is no friction between two colliding bodies, the only force between them is perpendicular to the contact point/patch (by the definition of frictionless).

There is essentially no slipping between tip and ball during a normal off-center shot. Chalk prevents slipping.
Click to expand...
Well stated summary!

Regards,
Dave
 
Pre-Flag Master said:
Dr. Dave,

Would you care to do an experiment on this? I'd love to see the results of that. And to take it a step further, an experiment comparing different brands of chalk would be great. And if you did do that, let me know so that I could send you a couple of test cubes. As you probably know, the results of such a test would be very relevant to the age old "does chalk make a difference" debate.

And thanks for your efforts. I can only begin to imagine studying the vast amount of info that you have provided to the pool community.

EDIT: I see you already addressed this in the thread. Nevermind.

Fatz
Click to expand...
To me, the following are the most interesting questions concerning chalk type:

Does it coat and stick to the tip more easily and better?

Does it stick to the CB more easily and increase the likelihood of cling (excessive throw)?

How much cling (increase in throw) occurs when a chalk smudge appears at the CB-OB contact point?

Does it allow for larger tip offsets from center before getting a miscue, allowing one to impart more spin?

To me, the last question would be the most interesting to test. When I can find some time, I'll get some Blue Diamond and Kamui chalk to compare to the Master chalk I have. They seem to be the brands most talked about.

Catch you later,
Dave
 
dr_dave said:
To me, the following are the most interesting questions concerning chalk type:

Does it coat and stick to the tip more easily and better?

Does it stick to the CB more easily and increase the likelihood of cling (excessive throw)?

How much cling (increase in throw) occurs when a chalk smudge appears at the CB-OB contact point?

Does it allow for larger tip offsets from center before getting a miscue, allowing one to impart more spin?

To me, the last question would be the most interesting to test. When I can find some time, I'll get some Blue Diamond and Kamui chalk to compare to the Master chalk I have. They seem to be the brands most talked about.

Catch you later,
Dave
Click to expand...

You say this, but after reading your BD article many years ago, I went to a dime radius and just couldn't get used to it :(

While I agree that has a larger miscue radius than nickel radius, it just wasn't worth the other issue it was causing me. I think the same goes for a $30 cube of chalk. That price isn't worth a slightly larger miscue radius.

Now, if it didn't get on the balls and stayed on the tip, that would be worth something to me. That more important IMO.

An ideal chalk that can reduce throw (via clean balls) is worth way more to me than a slightly increased miscue limit.

From what I hear, kamui chalk is the opposite if this, in that it sticks like glue to the CB.

Edit: please for the love of god get pre flag masters to test as well. That's a myth that needs to be dispelled...
 
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jtaylor996 said:
after reading your BD article many years ago, I went to a dime radius and just couldn't get used to it :(

While I agree that has a larger miscue radius than nickel radius, it just wasn't worth the other issue it was causing me.
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To which article are you referring? They are all listed and linked here:

Dr. Dave's BD articles

There is really not much difference between a dime and nickel radius, and the miscue limit for both should be very close. What issue was the dime radius causing you?

jtaylor996 said:
I think the same goes for a $30 cube of chalk. That price isn't worth a slightly larger miscue radius.
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I agree with you there. I just ordered a collection of chalks, and I was shocked by the Kamui sticker price. If it isn't a lot better than the other chalks, I'll be pissed.


jtaylor996 said:
Now, if it didn't get on the balls and stayed on the tip, that would be worth something to me. That more important IMO.
Click to expand...
I'm not sure this will be easy to characterize or measure, but I'll think about it.

jtaylor996 said:
An ideal chalk that can reduce throw (via clean balls) is worth way more to me than a slightly increased miscue limit.

From what I hear, kamui chalk is the opposite if this, in that it sticks like glue to the CB.
Click to expand...
Agreed. If a chalk sticks to the CB a lot more and increases the frequency of cling (excessive throw) significantly, that would be a bad thing.


jtaylor996 said:
Edit: please for the love of god get pre flag masters to test as well. That's a myth that needs to be dispelled...
Click to expand...
I think I might have some pre-flag cubes. I'll give it a try. What are the claims concerning pre-flag vs. post-flag?

Thanks for your input,
Dave
 
jtaylor996 said:
I think I've heard everything from curing cancer to it making a great eye liner. :rolleyes:
Click to expand...
The cancer part might be tough to test, and I'm not willing to try the eye liner thing, but I'll test it for the miscue limit.:grin-square:

Catch you later,
Dave
 
3kushn said:
Lou You are correct with the name. You may also be correct with your suspicion that there's some wax in the Aramith product. I know you try to play on/with clean equipment, but I still contend your study needs more work, making sure the cleanliness of the cloth is consistent comparing both products. Two new cloths would be best. This would help confirm that something isn't Wearing ONTO the balls. Micro Scratches.

Looking at the Novus website it states: 4.Reapply NOVUS No. 1 regularly to maintain the antistatic, smudge and scratch resistant properties. How does it maintain scratch resistant properties? Could it be a harder surface treatment than say Carnauba? The "Clean and Shine" product is a cleaner only and I'd say is not helpful by itself.

Not trying to argue here. I'm been looking into this for years, even made my own cleaner. Worked well but a pain in the butt and couldn't find an adequate suspension system. Novus 1 may contain a higher quality abrasive giving even a better surface finish than Aramith. May have to try it too.

Check out 3M Finesses-It. My belief is there's no wax. MSDS sheets never tell the story.

Gotta Verhoeven warm and ready over here. Just so you know. ;)
Click to expand...


I have no idea how it does what it does, but I'd say the balls shine up as well as with the Aramith product. And what I really like is that the balls don't smudge up as much with Novus. I think part of it is that the Aramith product has a much higher degree of viscosity.

A heated Verhoeven... what's that? (J/K.) It's just that I hardly ever get the chance to play 3C any more. Maybe a couple of times a year when I'm in SoCal.

Lou Figueroa
 
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