Deflection, Endmass and Shaft Design

[Fred Agnir]

fuck Ron Shepard and fuck Bob Jewett both on their obsession with deflection. They're both PH.D's that can't play a lick and as FL always used to say...that stands for post hole diggers!

First of all, if FL is your source, then you can be sure it ain't true. Bob Jewett not only won the Collegiate championship, but also has run over a hundred in straight pool. Ron Shepard is a very good player, certainly above average. I'd put him up against 90% of the players I've met on these forums (over a hundred?).

Fred

 

[Fred Agnir]

It appears that the article is drawing an effective parallel between mass and inertial resistance to force...is this done so the reader may quantify additional values at some later date using this "mass" as a component for some kind of thrust calc that may actually define the curve of the resistance of different shafts?
What seems to be the prevailing

I think you're thinking too hard. The definition for "effective endmass" is simply the mass of the equation that pertains to collisions. Whether you use conservation of energy or momentum or both, by using the known inputs (mass of cueball, initial velocity of cue and initial velocity of cueball) and outputs (final velocity of cueball) and solving for "mass" of the cuestick, you will get the mass that is involved in the collision. That is, "the effective endmass." Regardless of stiffness and how it contributed, the result in question is still effective endmass and how it relates/contributes to the collision. How stiffness is related may be a different question altogether. I suspect it may be more correct to ask how the stiffness relates to the effective endmass in the collision.

One simple theory is that the effective endmass is related to the speed of the transverse wave. If the transverse wave is roughly 3" per microsecond, and the tip/ball contact time is .001-.002 seconds, then the "effective endmass" would be confined to the first 3-6" of the shaft. Add weight to that first 3-6" and that weight would be part of the effect. That's one theory.

Fred

 

[Fred Agnir]

Agreed...but don't worry with the math just yet...make sure the methods are good...re-read the quote from the article. "...it is the resistance to sideways motion...This effective mass..." Would I be correct in saying that the author paraphrased the term "effective mass" for clarity, NOT as a definition to derive a unit of measure (such as grams, oz, etc.) from which a calculation of the resistance could be derived. Then, it appears he goes right ahead with calculations from a paraphrased term. In my estimation, the actual mass or weight (we'll assume planet earth at sea level) of the tip simply cannot be used to accurately measure (or even estimate) the resistance of a complex structure to bending, impulse or otherwise, particularly when the fulcrum (the bridge) of the structure (from which one might derive a moment-type calculation) is constantly changing.

I would be interested to hear your opinion when you have time to review the article...thanks.

Take the word "deflection" out of the discussion. It's a bogus word that might be misleading you, especially if you are an engineer. It's not deflection that's being discussed, so any quantifyable resistance that you might be discussing is moot. Fulcrum length and resistance to bending forces are not what is being discussed in the squirt white paper.

The paper's discussion is a simple collision exercise at it's simplest. Keep that in mind when reading it, and I think it makes sense to engineering types.

Fred

 

[Jon]

How about we keep it simple.
The lighter the front of your shaft is, the less it will deflect.

Or the closer the "flex-point" is to the tip, the less deflection. (Which is my understanding.)

Jon

 

[bruin70]

,,,,,,,,,,,,,,,
The lighter the front of your shaft is, the less it will deflect.

Jon

i don't think that's necessarily right. aluminum is light but i don't think there's any give there.

 

[frankncali]

Both Shepard and Jewett can play and both have good pool knowledge.

I dont understand some peoples unwillingness to except technological advances in Cue making. To ignore it make no sense. Theres not 1 other sport that the players just say "no thanks I stick with this".

In golf Tiger and V-Jay might not understand the mechanics but they use the
advances. Gold has came a long long way over the years. No one uses the older stuff. Never seen a Pro t it up with some of the old Wilson balls.
Tell the Pros that should not use Balattas or another new ball advancement.

Theres no reason for everyone to run out and but a anti deflection shaft but
if it helps then why worry about the ones that do use them. If the old ones
are better then you hold an advantage.

Theres something to the end mass causing deflection theory because its easily proven. Some cuemakers even place a lighter wood in for the tendon giving it a little less mass.

I agree with Fred that its best to keep in mind that its a simple test and that
many more varibles and testing angles could be performed. However as Tate
said .. try a little extra weight on the end and watch .

I am glad all of these scientific guys exist and like taking looks at advancing the sport. That just leaving the playing to everyone else.

 

[TheBook]

Post hole diggers?

I thought PhD stood for Pool Hustling Degree.

 

[sjm]

I dont understand some peoples unwillingness to except technological advances in Cue making. To ignore it make no sense. Theres not 1 other sport that the players just say "no thanks I stick with this".

In golf Tiger and V-Jay might not understand the mechanics but they use the
advances. Gold has came a long long way over the years. No one uses the older stuff. Never seen a Pro t it up with some of the old Wilson balls.
Tell the Pros that should not use Balattas or another new ball advancement.

If the old ones
are better then you hold an advantage.

Comparing pool to golf in this regard is absurd. The results of golf club technology advances are easily measured by machinery, are published and made public, and are patently visible when the game of golf is watched up close.

No top pro would play with a golf club made thirty years ago, yet there is an almost endless supply of cues that are thirty years old that play just about perfect by the standards of today. That's because technological innnovations in cuemaking have been minimal in recent years, and not many believe that the cues of today are superior to those of yesteryear. Countless top players are happy to use a cue that's more than a few years old.

The Predator shaft is different, and I agree that those considering a cue purchase might want to "test drive" one with a Predator. If it helps, consider it. But t's not a superior product, just a different one.

 

[drivermaker]

Bob Jewett not only won the Collegiate championship, but also has run over a hundred in straight pool. Ron Shepard is a very good player, certainly above average.
Fred

Well Fred, I think we have some of those "big fish" stories coming out again.
Jewett NEVER ran over a hundred, and there are others besides FL that can attest to his abilities, or I should say his inabilities at the table. Jewett also once personally said what his high run was on here, and it wasn't 100.

As far as Ron Shepard goes....a "very good player" and "certainly above average" are so far from each other in meaning that it's like light years away.

Here's the facts and truth to that statement...Ron Shepard is NOT a "very good player". However, I will concede that he's "above average". BTW, I don't know what you consider the average player to be in skill level, but in golf the average handicap is 19. That means a score of about 95 or 96.
What would you say makes up an "average player" in pool?

 

[TheBook]

Do you think that pro give a hoot about technology. They will play with anything that will sponsor them. Why else would a pro use a Cue Tech cue? Another way to look at it is maybe the Cue Tech is the most technically advanced cue and the rest of us like playing with old technology.

 

[Black-Balled]

I think.........

 

[Billy_Bob]

1. Problem, when you use english and aim at the far center diamond, the cue ball does not hit the far center diamond, but will hit one or two inches off the mark. (using cue ball only, no object ball)

2. By placing your bridge hand about 9 inches back from the tip, aiming at the far center diamond with a center hit, then pivoting your back hand slightly to apply english, the cue ball will probably hit closer to the far center diamond (when not using a low deflection shaft like Predator). Where you place your hand to get no deflection or squirt is called the pivot point. Experiment by moving your hand closer to the tip or further away.

3. On page 10 of the Shepard squirt paper is the section called "Squirt Measurements". This details how to test for cue ball deflection.

4. Platinum Billiards lists "pivot points" for various cues, however some disagree as to the accuracy of these pivot points. For example they list a Predator 314 as having a pivot point of 11.9 inches back from the tip. I have a Predator 314 shaft and it seems to me that the pivot point is back near the butt of my cue. In general the more mass, the closer to the tip the pivot point will be, the less mass, the further back the pivot point will be.
https://www.platinumbilliards.com/rating_deflect.php

5. I have read that tip radius (nickel, dime, etc.) might have an effect on squirt. I have not seen the results of any testing for this anywhere.

6. See the following patent, part of which *includes* the hole in the end of the shaft/ferrule.
http://patft.uspto.gov/netacgi/nph-...,725,437.WKU.&OS=PN/5,725,437&RS=PN/5,725,437

7. Search google.com groups (Usenet) group rec.sport.billiard for deflection...
http://groups.google.ca/groups?hl=en&lr=&q=deflection&btnG=Search&meta=group=rec.sport.billiard

8. High speed videos of squirt...
http://www.engr.colostate.edu/~dga/pool/high_speed_videos/HSV4-4.htm
http://www.engr.colostate.edu/~dga/pool/high_speed_videos/HSV4-5.htm

9. So far as I am concerned, I just want the cue ball to go where I am aiming when using english. I can do this by placing my bridge hand on my regular cue about 10 inches back and moving my backhand to move the tip for english, then the cue ball will hit the far center diamond the same as a center hit. Or I can do this with my Predator 314 by moving my front hand left/right.

The bottom line is that I have a method of aiming when using english which sends the cue ball to the same spot as a center hit. Players who have been playing for years have learned to compensate for this or do not use english on long shots. Some of these players also have difficulty adjusting to a low deflection shaft.

 

[HittMan]

at issue

im not sure if you just have a prob. with the article or just the debate?

but ive always hated it when people try to take out the human error. i dont think it matters as much as people think, of course for some its good to make a big stink out of it cause theyr trying to make a profit from it.

do you think if you had more accurate equiptment it would make you a champ?

i always laughed about one guys test machine that supposedly measured deflction, but he was really measuring throw but most people dont know the difference, they just watched and took his unscientific word for it?

ive been wanting to do some experiments but have not had time to make the test pieces.

what do you think would happen with a 20mm, 25mm shaft with a 13mm ferrule? more or less deflection? do you think at some rediculous size there will be no deflection? what about some super stiff material for the ferrule end of the shaft?

hhhhhmmmmmm......

My problem is with understanding...I agree there are plenty of places to look at for error but the idea is presented, strictly speaking, that less deflection will make you a better player. A whole lot of my friends and potential customers are quite interested in becoming better players and have money to spend to achieve that end. I began this query trying to become simply literate concerning the article and was, frankly, somewhat surprised to finally read the cornerstone article.

I agree that several of these "experiments" prove little. I don't know at this point whether I consider another experiment worth looking at or not. I think I don't understand...but it may just be snake oil. If all I need to do is drill a hole in the end of my shafts to help my customers be better players, then so be it...but don't expect me to do this blindly,

Interestingly, your understanding is like mine before I began digging...that is a stiffer shaft would deflect the cue ball less...however the arguement is the a less stiff shaft will deflect the cue ball less. To me, this is a contradiction to what I have found at the table...thus my questioning. I may be confusing deflection with predictability...if so, I'll take predictability.

 

[gulfportdoc]

They're both PH.D's that can't play a lick

Well I don't know about Ron, but Jewett plays pretty strong-- and at all games. He's also a certified master BCA instructor.

Doc

 

[HittMan]

Good. I hope you're not as ignorant about squirt as most cuemakers are. To demonstrate the extremes, just tape a AA battery on end of a house cue about an inch from the end and shoot some simple inside english shots. You'll soon see it's effect in action. You'l be lucky to hit the right rail much less the pocket.

Chris

That may be true,,,I can easily do this and will get back to you. But I have to say that I don't think it would be easy to hit the sames rails on the same shot if you were to tape a brick on the butt end of the cue either...I am just not sure what that proves...are you? I think we are looking at something out of the bounds of reasonable possibility for most players...don't you? Seriously...I'm curious about this.

 

[HittMan]

humor is good

Then go to the sources directly on RSB. Ron Shepard and Bob Jewett are available to you 24/7 over there and will answer all questions. They revel in these kinds of discussions and everyone's dicks will get harder than diamonds if you start a thread on it over there.

AZ members consist of players who have either learned to live with it or don't give a rat's ass one way or another.
It's just not that big a deal if you know how to play.

If you're concerned about the deflection issue for your customers, then get Predator blanks for everyone and just do what you have to do to fit their cues. Anyone that is so freaked out about deflection will eventually get a Predator anyway, so you might as well put the money in YOUR pocket. So, my final words on the subject are....fuck Ron Shepard and fuck Bob Jewett both on their obsession with deflection. They're both PH.D's that can't play a lick and as FL always used to say...that stands for post hole diggers!

This may be the funniest reply I have ever read...anywhere...period. Seriously man, you're killin' me. Where is this RSB? I gotta get me some of this madness. Do you promise they'll be as fun as you?

 

[HittMan]

i would say NOT. my guess is that with more whip in a shaft(i guess at this point i'm straying from the "endmass" concept), the more leeway for inconsistancy. the 3 cushion players play with stiff tapers, thus less flex, thus less room for inconsistancy, as the shaft will always play the same. but, i have to assume that player mechanics makes up the greatest reason for performance, so i don't indulge in all that "predator" stuff unless it would make me feel good.

most shafts have a good and bad side, especially if they have a pro taper and if cuemakers don't give you the very best of the very best shaftwoods. i notice some of the very picky players turn their cue to the spot they want before shooting......it makes a difference to them. for me it's all about feel....if it feels good, i play better. predator "feels" fake to me.

I agree completely...my experience matches yours. But consider...are you thinking that a unique, individual shaft (the same shaft) will not play consistently day in and day out? I think it will...yes it may have a good side and a bad side but it will play the same tomorrow...won't it?
This really got started for me when a customer came in with a predator shaft to have the ferrule replaced...I was quite surprised to find the end hollow. I would not consider doing this unless I am pretty darn sure it would help. I actually think Predator has a problem with the center of those shafts and I wonder if this isn't simply a justification...and I don't really like the hit much either...but that's personal.

 

[drivermaker]

This may be the funniest reply I have ever read...anywhere...period. Seriously man, you're killin' me. Where is this RSB? I gotta get me some of this madness. Do you promise they'll be as fun as you?

They'll be even more fun...more than a barrel full of MONKEYS, as JAM might say.
Something already tells me you know exactly where it is and have been a regular over there that's now looking to create a firestorm here with a deflection debate. However, just do a search in Google under groups for rec.sportbilliard, or is it rec.sportbilliards....does anyone know?
I think you'll be a real Hit, Man, on that site. It's just what they need to bring it back to life.

 

[HittMan]

While of occasonal academic interest, ultimately the deflection topic is a lot of bull. Even those inexplicably, and almost comically, obsessed with the subject readily concede that squirt, swerve and deflection are ultimately inseparable in the study of how the cue ball is delivered for given strokes. Yet, far too often, it is the very people who concede this point that attempt to consider the deflection topic in a vacuum.

Want to master deflection, swerve, and squirt? Go practice. If you think you can only do so using a Predator shaft, then you are victim of a growing myth poupularized not only by those at Predator but by many others who'd rather sell you a $200 shaft rather than a $100 shaft. The Predator is different, not better. If you like paying a premium price for a product that simply doesn't qualify as premium, a Predator shaft is a wise choice.

Let's face it, the top players master the variables of squirt, swerve and deflection for given strokes and speed through pracitce, repetition and experience, not through the application of science.

ok...this is what I think I am learning, as well. I was thinking that there was more agreement on this topic but I am learning that this is not the case. In fact, I am learning that it may be possible that a few vociferous advocates, motivated by money or a sense of superiority may have influenced a large numbers of people who don't know any better. I really don't want to speak further on this til I find the source and get more/better information.

 

[drivermaker]

Well I don't know about Ron, but Jewett plays pretty strong-- and at all games. He's also a certified master BCA instructor.

Doc

Does being a certified master BCA instructor automatically mean that you can play? You also forgot to mention that he writes a monthly science article for Billiards Digest...let's give credit where credit is due.