Kamui chalk and deflection

Larry,

I think the only way that works is that they are talking about the NET effect. With better grip on the ball one can get more spin to speed ratio & the increase in that ratio will bring the ball back quicker than a lesser spin to speed ratio. That diagram is misleading IMO, unless there is some new physics of which I am not aware.

Regards & Best Wishes,
Rick

The diagram and the wording in their ad is ample proof for no one to believe any of their hype. They obviously don't have a clue.:shakehead:

Yep, love the chalk but gotta call BS on that one, especially based on personal experience...
Scott

Rod Cross, a physics professor from the University Of Sydney, did a pretty thorough study of these phenomena back in 2008:


http://www.physics.usyd.edu.au/~cross/PUBLICATIONS/39. squirt.pdf


Regarding the effect of sliding friction on squirt, he found the following to be true:

As expected, the unchalked tip has a lower coefficient of friction than the chalked tip, resulting in a generally lower ball spin and a generally larger squirt angle. At small impact parameters, where the cue approaches the ball surface almost at right angles, even the unchalked tip grips the ball. The resulting squirt angle and ball spin are the same, regardless of whether the tip is chalked or not. Surprisingly, there is not a large difference between a chalked tip impacting directly on the smooth ball or on emery paper [during one set of trials he used 800 grit sandpaper taped to the CB as well as using a chalked tip] taped to the ball. The implication is that the squirt angle and the ball spin are almost the same, regardless of the coefficient of sliding friction, provided only that the tip grips the ball during the collision.

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You'll have to read the article yourself to see if you agree with his experimental methods, but he seems to agree with previous researchers on the role of both static and sliding friction in reducing squirt.

He found that the chalked tip grips the ball at impact and does not slip at all during the entire contact time at smaller tip offsets (below 30º angle of incidence), but that the tip starts to slip beyond 30º, increasing the contact time substantially.

At angles of incidence exceeding about 30°, the tip gripped the glass at the beginning of the collision, but then slid on the glass when F/N increased to about 0.7. The sliding stage extended the impact duration to 12 ms.

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IMO it is possible that a chalk with a higher coefficient of friction (as Kamui claims to have) might allow larger offsets without slippage, thereby reducing the amount of squirt induced. I'm not saying this is actually happening, just that it seems theoretically possible to me.

Interestingly, he seems to feel that there may be other forces at play in causing squirt aside from tip end-mass:

The experimental data shows that elasticity of the cue tip plays a dominant role in the collision process and suggests that cues with thin shafts might generate lower squirt angles as a result of their greater flexibility rather than their lower mass. Further theoretical and experimental work will be needed to determine why some cues generate lower squirt angles than others.

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And, as always in science, more work needs to done.

bbb said:

from what i gather from their website they claim kamui chalk will decrease deflection.
what do you think
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No proof. I think they should either prove this claim or drop it from the marketing. And the diagram is especially misleading. It indicates the using kamui chalk leads to zero deflection.

Also I think that it would be fairly easy to build a jig to test this.

Like the chalk because of the smooth feel- that s it.
That marketing is a huge factor...ok- everyone understands it. But to make such a statement makes me just shakin my head.

i m also very sure, that chalk has very little to nothing to do with deflection.

So...

We all seem to agree for the most part, that as far as we know, the effect of chalk has 'nothing' to do with the actual amount of CB squirt/deflection.

I say that it might affect the overall net effect if it allows for an increased spin to speed ratio for a given force so that the swerve can bring the ball back more for that given force of shot.

Sloppy Pockets posts a study that is interesting although perhaps inconclusive.

As Fran Crimi has pointed out several times, there are things in the cue sports that we simply do not have a complete understanding & that science may one day shed some new light.

Therefore I think we should keep an open mind, as we always should.

That being said if Kamui is going to make such a claim then they should give the scientific support for it as John Barton said.

I do like their Super Soft tip though & Ingo likes the chalk for reasons other than squirt reduction.

I got it!!!

I know exactly what they mean. They are comparing a good shot with a miscue (caused by slippage). This is a illogical comparison and nonsense.

This is the only way I see they can have any accuracy of the diagram.

Although it may not be true directly, but slippage depends on the cue ball mass to effective endmass ration and friction. If you are able to increase friction, then you can decrease the mass of the shaft near the tip, which would decrease squirt.
Now cue makers have to design new lighter shafts and you will have to buy one to stay on top

bbb said:

from what i gather from their website they claim kamui chalk will decrease deflection.
what do you think
View attachment 286354

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I'm calling bull shit on another kamui sales promotion...... they obviously think that all pool players are stupid.... that is how they sell all their overpriced hyped up crap

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