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Squirt. End Mass and Cue Flexibility.
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LAMas
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Squirt. End Mass and Cue Flexibility. - 01-23-2016, 12:33 AM

For all these years, It has been held here that only end mass determines squirt and when I proffered that I thought that the flexing or bending of the shaft is also an important component, I and others were dismissed. One need not be a scientist to have good intuition and conscious reasoning, but here one is dissed unless he has a pedigree above that of a pool player.

I just found this old paper from 2006 that I had not been pointed to before here on AZ Billiards Forum since I joined 2003. I wonder but will not ask why?


Cue and ball deflection (or “squirt”) in billiards
Rod cross
Physics Department of Sydney, Sydney NSW 2006, Australia

VII Conclusion

....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...

Acknowledgements
This article was inspired by previous theoretical efforts by Ray Higley and by Professors David Alciatore and Ron Shepard, concerning the origin of squirt in billiards,

http://www.physics.usyd.edu.au/~cros....%20squirt.pdf

This scientist could also be wrong even with an overhead camera and accelerometers etc,.

Be well


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Bob Jewett
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01-23-2016, 01:10 AM

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Originally Posted by LAMas View Post
For all these years, It has been held here that only end mass determines squirt ...
I have held in the past that stiffness can affect squirt. It clearly will determine how much of the front of the stick will be included in the effective end mass. Whether there is a significant variation among maple shafts made by more or less standard methods including coring is a good question. What is clear is that weight near the front of the cue can have a large effect as shown by a lot of low-squirt designs (and Mike Page's vise-grips experiment).

Cross in his paper also says that the elasticity of the tip is important to squirt but that seems not to show up in the typical range of leather tips. Further, phenolic tips, which I would describe as inelastic for Cross' use, seem to have the same squirt characteristics, more or less, as leather tips.


Bob Jewett
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01-23-2016, 01:18 AM

Quote:
Originally Posted by Bob Jewett View Post
I have held in the past that stiffness can affect squirt. It clearly will determine how much of the front of the stick will be included in the effective end mass. Whether there is a significant variation among maple shafts made by more or less standard methods including coring is a good question. What is clear is that weight near the front of the cue can have a large effect as shown by a lot of low-squirt designs (and Mike Page's vise-grips experiment).
Apples and oranges?
What if the vise grip was attached to a noodle?
In the "past" you were intuitive as are many pool players that are not scientists.

Be well


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01-23-2016, 01:23 AM

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Originally Posted by LAMas View Post
... In the "past" you were intuitive as are many pool players that are not scientists. ..
A rather strange remark. What did you mean by it?


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01-23-2016, 01:30 AM

I haven't read all the stuff on Dr. Dave's site about squirt, but I think he also says that shaft flexibility has *some* effect. I don't know how much effect. It does seem to me like it must play at least some role.

I guess the main argument against it is that the time it takes the compression wave, or is it the "transverse" wave? IDK...some wave..lol. Anyway the time it takes that wave to move down the shaft and cause the shaft to bend, the cue ball is already long gone.

This makes a lot of sense. I think there might be some high speed video to support this as well.

Good question though.

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01-23-2016, 01:42 AM

Quote:
Originally Posted by Bob Jewett View Post
A rather strange remark. What did you mean by it?
"I have held in the past that stiffness can affect squirt...."
Bob Jewett

Was that intuition or an empirical deduction?

Be well


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01-23-2016, 01:51 AM

Quote:
Originally Posted by KMRUNOUT View Post
I haven't read all the stuff on Dr. Dave's site about squirt, but I think he also says that shaft flexibility has *some* effect. I don't know how much effect. It does seem to me like it must play at least some role.

I guess the main argument against it is that the time it takes the compression wave, or is it the "transverse" wave? IDK...some wave..lol. Anyway the time it takes that wave to move down the shaft and cause the shaft to bend, the cue ball is already long gone.

This makes a lot of sense. I think there might be some high speed video to support this as well.

Good question though.

KMRUNOUT
I think that compression effects a transverse wave which implies that depending on the frequency, the CB could feel a few compressive forces during contact according to the article.

Be well


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Interesting Paper
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Interesting Paper - 01-23-2016, 03:44 AM

Lamas,
Interesting Paper but its 5am so I read some scanned some and went to the conclusion. There was a statement in this paper that I use that applies to aiming I found interesting verifying a theory of mine but again its 5am.

I would have thought that shaft flexibility would have been included a long time ago in this theory but apparently it hasn't been after all the cue ball does have a weight and that weight would cause resistance to the stroke, none of which I could measure however I have seen a local painter here who also is a pool player who took a shaft and made it very whippy on home lathe and seems to play very well with it.

I would guess that further conversation concerning squirt will now cover shaft stiffness and butt flexibility as part of the equation and it rightfully should if it can be determined that there is a point that is physically attainable in a practical sense that those parameters can be obtained and used within the confines of a cue stick that can be used for normal play. The first question here being is the data from the Meucci test that seems to come up from time to time about butt flexibility and what was actually found out and it seems that there was some shaft and butt combinations that produced a lot less squirt than expected. I think I read some cautions about the efficacy of that testing as well due to the way things were setup for testing so we have more variables. Nice Post. I am not someone who understands anything really about Physics but I have worked with squirt and squirt variables enough to it can be understood enough by laymen such as myself to be able to put it into a plan where shots work out as planned but you have to adhere to one thing. You have to stroke as chosen in the planning phase. Nice one, Kudos.

What happened to PJ's thread on Swoop Stroke?

Robin

Quote:
Originally Posted by LAMas View Post
For all these years, It has been held here that only end mass determines squirt and when I proffered that I thought that the flexing or bending of the shaft is also an important component, I and others were dismissed. One need not be a scientist to have good intuition and conscious reasoning, but here one is dissed unless he has a pedigree above that of a pool player.

I just found this old paper from 2006 that I had not been pointed to before here on AZ Billiards Forum since I joined 2003. I wonder but will not ask why?


Cue and ball deflection (or “squirt”) in billiards
Rod cross
Physics Department of Sydney, Sydney NSW 2006, Australia

VII Conclusion

....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...

Acknowledgements
This article was inspired by previous theoretical efforts by Ray Higley and by Professors David Alciatore and Ron Shepard, concerning the origin of squirt in billiards,

http://www.physics.usyd.edu.au/~cros....%20squirt.pdf

This scientist could also be wrong even with an overhead camera and accelerometers etc,.

Be well


"Let your "Stick" do the talking!"

336Robin
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The Target Ball Concept-Aiming,
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Robbing the Bank Shot!-Pass Over Banking
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01-23-2016, 08:00 AM

Quote:
Originally Posted by KMRUNOUT View Post
I haven't read all the stuff on Dr. Dave's site about squirt, but I think he also says that shaft flexibility has *some* effect. I don't know how much effect. It does seem to me like it must play at least some role.
First of all, it is important to distinguish between a cue's stiffness in the axial or longitudinal direction and stiffness in the sideways or transverse direction.

For a cue to be able to hit a CB effectively, it must have significant stiffness in the hitting direction (i.e., it must have a large axial of longitudinal stiffness). That's why any theoretical discussion like "What if the cue were a noodle?" is just downright silly (unless the "noodle" is fat and dry, and is able to resist buckling and fracture during a hit ).

The sideways or transverse stiffness of the cue is much less than the axial or longitudinal stiffness (i.e., the cue is very flexible in response to sideways deflection; and these sideways deflections are very small anyway during an off-center hit, due to the incredibly brief tip contact time). However, transverse stiffness does affect the effective endmass of a shaft and amount of resulting CB deflection (squirt). A complete and detailed explanation of this, supported by numerous resources can be found here:

cue endmass and stiffness effects

Concerning the effects of tip elasticity; theoretically, one would think this would have a large effect on tip contact time and resulting squirt; but in reality, with real tips on real cues, the difference in squirt over a wide range of tip types and hardnesses is miniscule (i.e., of no practical significance). For proof, see cue tip hardness effects and the following video:

NV D.15 - Cue and Tip Testing for Cue Ball Deflection (Squirt)

Enjoy,
Dave

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01-23-2016, 08:28 AM

I remember when Bob Meucci came out with the '79 brochure. It had references to deflection and everyone looked at each other and said "WTF is deflection?" Cues in those days were mostly steel-jointed, ivory-ferruled telephone poles. Bob's cues felt like a 58" buggy whip but whatta' ya' know, they freakin' played awesome. At almost any big tourn. for 25yrs. almost all the top players played with one. Trendsetting cues for sure.
  
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Absolutely!
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Absolutely! - 01-23-2016, 08:37 AM

Quote:
Originally Posted by garczar View Post
I remember when Bob Meucci came out with the '79 brochure. It had references to deflection and everyone looked at each other and said "WTF is deflection?" Cues in those days were mostly steel-jointed, ivory-ferruled telephone poles. Bob's cues felt like a 58" buggy whip but whatta' ya' know, they freakin' played awesome. At almost any big tourn. for 25yrs. almost all the top players played with one. Trendsetting cues for sure.
Absolutely, the only thing I am unsure of is the size of the ferrule. I guess I like the idea of the smaller ferrule. His designs went way into the demographic of the Amateur Pool Player. Great marketing techniques.


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01-23-2016, 08:49 AM

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Originally Posted by LAMas View Post
"I have held in the past that stiffness can affect squirt...."
Bob Jewett

Was that intuition or an empirical deduction?

Be well
It was rough analysis based on transverse wave propagation. Stiffness affects the effective "impedance" of the interaction.

But I think a good scientist (or anyone who tries to understand how things work) relies on intuition to find promising directions. The important part comes after the direction is decided -- the analysis and objective testing of the idea begins.


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01-23-2016, 09:02 AM

Quote:
Originally Posted by garczar View Post
I remember when Bob Meucci came out with the '79 brochure. It had references to deflection and everyone looked at each other and said "WTF is deflection?" Cues in those days were mostly steel-jointed, ivory-ferruled telephone poles. Bob's cues felt like a 58" buggy whip but whatta' ya' know, they freakin' played awesome. At almost any big tourn. for 25yrs. almost all the top players played with one. Trendsetting cues for sure.
-------------

I never did like the whippy shafts, though. I was playing with a European/ conical tapered house cue that I had made into a Sneaky back then. I'm playing with a conical taper OB Pro now but with an 11.75 mm tip vs a nearly 13 mm tip back then.

Low front end mass & flex do not need to be mutually exclusive. There does NOT have to be only one contributing factor or parameter that contributes to reducing squirt.

Bob Meucci now has what he calls his Power Piston Butts.

In golf there is shaft flex that most are familiar with but then there is what Dr. Dave mentioned which in golf shafts is referred to as torque. When graphite shaft manufacture came along & given the extensive research & development for golf because of the huge monetary incentive it opened up a whole new area of shaft fitting for individual golf swings. It allowed different shaft 'flexes' to be matched up with different degrees of torque.

Bobby Jones hated his hickory shafted 7 iron. When technology allowed for testing an intact golf club & his set was tested all of his hickory shafted irons were very close but the 7 iron was way off & very different.

If the monetary incentive ever came along, I would not doubt that there would be synthetic material pool cue shafts being manufactured & used.

Best Wishes 2 You & All.

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01-23-2016, 09:14 AM

I haven't gotten all the way through it, but I did notice:

Quote:
"The ball therefore rotates about two different axes simultaneously."
Which would appear to violate Euler's rotation theorem which states that "any displacement of a rigid body such that a point on the rigid body remains fixed, is equivalent to a single rotation about some axis that runs through the fixed point.".

One could argue that the point is semantic, but I wouldn't expect such a fundamental mistake in a peer reviewed article.

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What about Top Right or Left?
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What about Top Right or Left? - 01-23-2016, 09:22 AM

Im not qualified to talk about such but what about off center hits, high or low? Do they not spin sideways while rotating end over end to some degree?


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