Cue Tip Contact Myth-Busting Truths in Super Slow Motion

Texas3cushion said:
Does all this mean that I can start playing one pocket with my phenolic break tip?

That way I don't have to have more than one cue. Would be pretty convenient.

I could rough up the tip really well and use toam chalk.
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I broke and ran a rack of 8b with my j/b and white diamond tip. Played fine but the sound was a tad brutal. I can draw the ball with the WD just as good as with my Mezz/Ultraskin combo too.
 
dr_dave said:
Yes. If the contact time is longer, the average force during that time will be less.
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Excellent. And thanks for reintroducing me to the term impulse as I forgot about the correct terminology.

dr_dave said:
But if there is more force, than the friction force is also greater by the same proportion, assuming the standard COF model of friction (F = mu x N) is valid for the dynamic event of tip/ball collision. If this is the case, then there should be no difference. The impulse (integral of force over contact time) and momentum change is the same for both tips, so the friction impulse is also the same. If you are curious, the basic math and physics related to this can be found here:
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I don't quite understand, you are saying the impulses are equal (agreed), mention that Fmax can be different for identical impulses (agreed) and then mention that the friction force goes up due to the COF equation. But isn't there a limit at which point slippage occurs?

If Fmax for a hard tip is 100
& Fmax for a soft tip is 80 for instance

Surely the hard tip has a chance of overcoming the friction force before the soft tip for the same mu and N?

dr_dave said:
However, I am not sure the miscue limit is based solely on the effective COF of the chalked tip because for all the chalks I have tested, I was not able to find any differences in miscue limit. Honestly, I was surprised by this because I thought there would be a difference, assuming different chalks would have different COFs. I think the miscue limit is determined more by the complicated dynamics of a tip on a flexible shaft hitting the slanted surface of the CB. When the angle of the ball surface exceeds the angle at the typical miscue limit, I suspect no amount of added friction can prevent a miscue, maybe because the tip is being pushed away from the CB surface, so the friction isn't able to grab the surface.
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Here's an experiment for us all to try (I wish I had access to a table right now) use your break cue (or hardest tip), chalk it well, and hit off the rail shots, increasing in power, and see how many times you can go up and down the table before you miscue.

Do the same with the softest tip you can find.

I assume, by your calculation Dave, you would expect the distance to be about equal at the point of miscue?
 
We've gone so far down this rabbithole that Alice is never coming back. Between Dr.D, Jewett and data from the JacksonvilleProject its pretty clear what does/doesn't happen during the oh-so-short contact time. Apparently its also clear that some still cling to myths/OWT's and base their belief/stance on what they think/feel/sense to be correct even in the face of pretty damn solid science. This happens everywhere not just pool.
 
garczar said:
We've gone so far down this rabbithole that Alice is never coming back. Between Dr.D, Jewett and data from the JacksonvilleProject its pretty clear what does/doesn't happen during the oh-so-short contact time. Apparently its also clear that some still cling to myths/OWT's and base their belief/stance on what they think/feel/sense to be correct even in the face of pretty damn solid science. This happens everywhere not just pool.
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In golf instruction you'll hear "what you feel isn't real". Probably applies here.
 
Back a hunnert years or so ago I played with a guy who liked to come up with weird stuff to gamble on. I played with light brooms, heavy brooms, light mops, heavy mops, other things I don't recall. Tried barstools of the swivel variety, if you aren't careful how you grab them they can clip a finger off! The bar manager made us quit with the stools, we were not only a danger to ourselves but to anyone around us!

Anyway, we started chalking everything! The light mops and brooms worked surprisingly well with a little master chalk on them. The heavy broom worked too. The heavy mop had been sitting in dirty mop water from the biker bar for months and we had to quit with it as half the bar was gagging! I did find that the ticket with that big heavy mophead that probably weighed ten pounds or more was to either wait for it to quit swinging or time the stroke to the swing.

The end finding of all of this bar room experimenting was that anything with a rounded surface that would hold a little chalk could apply spin. Another pleasant finding, I could adapt to almost anything when the cash was on the line!

Hu
 
Gary Jones said:
I don't quite understand, you are saying the impulses are equal (agreed), mention that Fmax can be different for identical impulses (agreed) and then mention that the friction force goes up due to the COF equation. But isn't there a limit at which point slippage occurs?
Click to expand...

Yes. The miscue limit.

Gary Jones said:
If Fmax for a hard tip is 100
& Fmax for a soft tip is 80 for instance

Surely the hard tip has a chance of overcoming the friction force before the soft tip for the same mu and N?
Click to expand...

The miscue limit is the same for all tips and all popular chalk brands over the typical range of playing cue tip hardnesses (assuming the tip holds chalk). I think I cover the reasons fairly well here:



Gary Jones said:
Here's an experiment for us all to try (I wish I had access to a table right now) use your break cue (or hardest tip), chalk it well, and hit off the rail shots, increasing in power, and see how many times you can go up and down the table before you miscue.

Do the same with the softest tip you can find.

I assume, by your calculation Dave, you would expect the distance to be about equal at the point of miscue?
Click to expand...

I just tried my Predator BK Rush break cue with a phenolic tip using Master chalk, and I was able to get maximum sidespin at the normal miscue limit. Honestly, I did not expect this, but thank you for encouraging me to do it. Now, I might trust putting more spin on the ball (e.g., backspin with draw shots) when I use my break cue for controlled baby jumps.
 
ShootingArts said:
Back a hunnert years or so ago I played with a guy who liked to come up with weird stuff to gamble on. I played with light brooms, heavy brooms, light mops, heavy mops, other things I don't recall. Tried barstools of the swivel variety, if you aren't careful how you grab them they can clip a finger off! The bar manager made us quit with the stools, we were not only a danger to ourselves but to anyone around us!

Anyway, we started chalking everything! The light mops and brooms worked surprisingly well with a little master chalk on them. The heavy broom worked too. The heavy mop had been sitting in dirty mop water from the biker bar for months and we had to quit with it as half the bar was gagging! I did find that the ticket with that big heavy mophead that probably weighed ten pounds or more was to either wait for it to quit swinging or time the stroke to the swing.

The end finding of all of this bar room experimenting was that anything with a rounded surface that would hold a little chalk could apply spin. Another pleasant finding, I could adapt to almost anything when the cash was on the line!

Hu
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i bet you mopped that up...😂
 
I am tempted to tweeten' this discussion, leaving the elk outdoors - will heighten moral fiber optics - of cuetip integrity. :whistle:
 
bbb said:
i bet you mopped that up...😂
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That big mop was dripping and slinging water everywhere as we experimented with how to time it! Lucky we were both known in there.

Ever see a fight start in a saloon in an old western and all of a sudden the whole place is brawling? That biker bar is the only place I saw that happen! Two friends started fighting and in a flash the whole damned place was in a knot! I was spending time with the manager so we hummed half of them out the door and locked it behind them and the other half stayed inside awhile. How they were sorted I don't know, I was just the door man.

Hu
 
dr_dave said:
COR has little or nothing to do with contact time or amount of spin imparted. A softer tip does have less hit efficiency (i.e., more cue speed is required to get the same CB speed) and a different feel/sound, but when the CB is hit with a give tip offset, and the CB is given the desired speed, there is not difference is spin between a soft and hard tip. I am working on a resource page that will thoroughly and convincingly answer all the questions and mythical statements that keep re-appearing in this thread and on YouTube and Facebook. I'll post a link when it is available. In the meantime, you and others can find answers here:
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Maybe you’re misunderstanding the premise of the issue. You’re testing to achieve a specific result. You’re not testing to get all results, only the results that please your idea. Everything else is continually dismissed. There’s a 1ms variance, which is an increase of 100% from hard to soft. A difference in CoR which has to produce some sort of an impact. You need to stop being so dismissive of your data.
 
dr_dave said:
Yes. The miscue limit.



The miscue limit is the same for all tips and all popular chalk brands over the typical range of playing cue tip hardnesses (assuming the tip holds chalk). I think I cover the reasons fairly well here:





I just tried my Predator BK Rush break cue with a phenolic tip using Master chalk, and I was able to get maximum sidespin at the normal miscue limit. Honestly, I did not expect this, but thank you for encouraging me to do it. Now, I might trust putting more spin on the ball (e.g., backspin with draw shots) when I use my break cue for controlled baby jumps.
Click to expand...


Thanks for indulging my musings Dave. I'll bow out now convinced that a little knowledge was a dangerous thing and my curiosity has been satiated! I don't promise not to try the experiment myself when I am next at the table but, at least for now, I am convinced!
 
dr_dave said:
However, I am not sure the miscue limit is based solely on the effective coefficient of friction (COF) of the chalked tip because for all the chalks I have tested, I was not able to find any differences in miscue limit. Honestly, I was surprised by this because I thought there would be a difference, assuming different chalks would have different COFs. I think the miscue limit is determined more by the complicated dynamics of a tip on a flexible shaft hitting the slanted surface of the CB. When the angle of the ball surface exceeds the angle at the typical miscue limit, I suspect no amount of added friction can prevent a miscue, maybe because the tip is being pushed away from the CB surface, so the friction isn't able to grab the surface.
Click to expand...

It is also possible that the particles in the chalk that embed into the tip and CB surfaces during impact (effectively locking the two surfaces together) cannot embed or stay embedded in the surfaces when the angle of the surfaces is greater than the angle at the miscue limit.
 
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