Shaft Stiffness and efficiency.

E

eyesjr

AzB Silver Member
Silver Member
I’m looking for any kind of test results etc that would show the relationship between shaft stiffness and overall CB velocity. I’m curious how marginal or significant stiffer woods with more compression strength will perform compared to maple. Anyone?

Even a conical vs pro taper test would be a starting point. What is really like is Purple Heart vs maple, or Lily us vs maple at otherwise equal specifications.
 
Given equal weight cue balls, on the same table, I would think that physics would say that the weight of the the cue stick X the velocity of one's cue stroke would equal the speed of the cue ball. I doubt that the wood composition would matter- equal weight X equal velocity should mean equal speed.
 
Is it just the stiffness and or tip, and or weight in a shaft that determines cue ball and cueball velocity? Could it just be how a shaft and or tip compresses and rebounds from that compression that actually affect cue ball speed?
I would think a carbon fiber shaft could rebound from that compression quicker than wood, as while wood compresses, I would think it's rebound would be dampened somewhat.
Does all this actually matter, as Dr Dave has shown that the length of time a tip contacts a ball is extremely short.
 
mikemosconi said:
Given equal weight cue balls, on the same table, I would think that physics would say that the weight of the the cue stick X the velocity of one's cue stroke would equal the speed of the cue ball. I doubt that the wood composition would matter- equal weight X equal velocity should mean equal speed.
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Absolutely, for shots where the cb is struck in the center there probably isn't a significant difference between shaft types. For spin shots it would be more different, depending on shaft deflection, but it's likely still insignificant.

A hard tip, however, produces a noticeable difference in cb speed when compared to a soft tip.
 
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mikemosconi said:
Given equal weight cue balls, on the same table, I would think that physics would say that the weight of the the cue stick X the velocity of one's cue stroke would equal the speed of the cue ball. I doubt that the wood composition would matter- equal weight X equal velocity should mean equal speed.
Click to expand...

No, there is a loss because we live in the real world.

Your equation is only true-ish (tho very wrong) for elastic collisions. There is some energy lost due to compressibility of materials, bending of shaft (even on center ball hits), coefficient of restitution, sound....

There probably isn't a ton of difference, but maybe someone can talk Dr. Dave into researching it, seems esoteric and inane enough for him, plus he'd be distracted from trying to change rules that aren't broken.
 
I truly doubt that tip hardness rating or hitting a cue off center could possibly change the speed of a cue ball on a flat level table surface to any degree that is noticeable to affect position play. Common sense tells you that speed of stroke will be the largest factor in speed of cue ball - period! Everything else has minimal affect on speed given equal weight cue balls and using the same table - you play with a particular cue - shaft - tip because you like the feel and the response - it has nothing to do with speed of your cue ball - that is determined by your stroke speed - off a rail though - spin can add or detract from CB speed- entirely different story
 
DeeDeeCues said:
No, there is a loss because we live in the real world.

Your equation is only true-ish (tho very wrong) for elastic collisions. There is some energy lost due to compressibility of materials, bending of shaft (even on center ball hits), coefficient of restitution, sound....

There probably isn't a ton of difference, but maybe someone can talk Dr. Dave into researching it, seems esoteric and inane enough for him, plus he'd be distracted from trying to change rules that aren't broken.
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I doubt tools exist that a regular human could use to measure 'the diffrrence'.
 
mikemosconi said:
I truly doubt that tip hardness rating or hitting a cue off center could possibly change the speed of a cue ball on a flat level table surface to any degree that is noticeable to affect position play.
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A CB hit off center (side s[pin) will travel farther than a CB hit in the middle even when the cue stick impacts CB at the same forward velocity. It is called angular momentum.
mikemosconi said:
Common sense tells you that speed of stroke will be the largest factor in speed of cue ball - period!
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You need to consider all of the angles where momentum is conserved (linear is one, angular is another).
 
eyesjr said:
I’m looking for any kind of test results etc that would show the relationship between shaft stiffness and overall CB velocity. I’m curious how marginal or significant stiffer woods with more compression strength will perform compared to maple. Anyone?

Even a conical vs pro taper test would be a starting point. What is really like is Purple Heart vs maple, or Lily us vs maple at otherwise equal specifications.
Click to expand...
Why do you need to know this? Pool is a finesse game. Hitting harder isn't going to help. If anything, I'd say that 99% of players need to work on hitting the ball softer.

Forget all that and just pick up a stick (any stick) and get comfortable with it. No need to worry about maximizing cue ball velocity or anything like that. You're overthinking it bud...
 
I truly doubt that tip hardness rating or hitting a cue off center could possibly change the speed of a cue ball on a flat level table surface to any degree that is noticeable to affect position play. Common sense tells you that speed of stroke will be the largest factor in speed of cue ball - period! Everything else has minimal affect on speed given equal weight cue balls and using the same table - you play with a particular cue - shaft - tip because you like the feel and the response - it has nothing to do with speed of your cue ball - that is determined by your stroke speed - off a rail though - spin can add or detract from CB speed- entirely different story
MitchAlsup said:
A CB hit off center (side s[pin) will travel farther than a CB hit in the middle even when the cue stick impacts CB at the same forward velocity. It is called angular momentum.

You need to consider all of the angles where momentum is conserved (linear is one, angular is another).
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That is a bunch of crap! No way a CB hit off center travels further than a CB hit dead center with ALL other factors being equal / you don’t need to be a physicist to understand this - it is just common sense- angular momentum? Another pool related piece of crap term - has no bearing on CB speed
 
Accuracy would almost be impossible to replicate. Every shaft has a diffirent tip on it. Even from the same batch a tip could be off 1% which would vary the results.

dr.dave has done videos on cb deflection and various shafts. But that info really dosen't matter it all comes down to taste. A person could like the feel of a shaft with less deflection/Stiffness.
 
mikemosconi said:
That is a bunch of crap! No way a CB hit off center travels further than a CB hit dead center with ALL other factors being equal / you don’t need to be a physicist to understand this - it is just common sense- angular momentum? Another pool related piece of crap term - has no bearing on CB speed
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Consider:: If you hit the CB with maximum sidespin and medium speed, after a few inches, the CB is traveling in a straight line while rotating at a 45º angle with respect to the direction of travel. In this orientation the CB ahs SQRT(2) = 1.414× as much angular momentum as a CB would have when hit on the vertical centerline of the shot. Thus, it will travel farther due entirely to angular momentum.
 
MitchAlsup said:
Consider:: If you hit the CB with maximum sidespin and medium speed, after a few inches, the CB is traveling in a straight line while rotating at a 45º angle with respect to the direction of travel. In this orientation the CB ahs SQRT(2) = 1.414× as much angular momentum as a CB would have when hit on the vertical centerline of the shot. Thus, it will travel farther due entirely to angular momentum.
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That is false. Adding sidespin does not increase the forward travel. It can help if you contact cushions but then the side spin is converted into speed. A ball struck off-center has less initial speed than a ball struck in the center.

The analysis of where to hit the cue ball for maximum travel with minimum cue stick speed was analyzed a long time ago by Coriolis and more recently (in English) by Ron Shepard. It turns out that you want to hit the ball at about 61% of its height for maximum distance assuming the cue ball will be rolling before it hits a cushion. That's where you want to hit lag shots. I'm sure that Dr. Dave has the analysis on his site.
 
mikemosconi said:
Given equal weight cue balls, on the same table, I would think that physics would say that the weight of the the cue stick X the velocity of one's cue stroke would equal the speed of the cue ball. I doubt that the wood composition would matter- equal weight X equal velocity should mean equal speed.
Click to expand...
The formula relating ball speed to stick speed and including stick weight is in one of Byrne's books (I think in the chapter on picking a break stick) and also on Dr. Dave's site. It is high school level physics.

If a cue stick weighs six ounces, the speed of the ball will equal the speed of the stick and the stick will stop dead. If the cue stick weighs 18 ounces, the cue ball will go forward at 150% of the speed of the stick and the stick's speed will be reduced to 50% of its initial speed.

Both of those ignore the subject of this thread which is the efficiency of the cue but that is a relatively minor effect. The largest factor in the efficiency of a cue -- how close the ball speed is to the ideal speed mentioned above -- seems to be the tip. That is why break tips are often phenolic. Phenolic loses less energy than leather.

Shafts lose energy as well, but I'm not sure stiffness is directly related. I had an old wood shaft that was measured to be less efficient than a newer one. I think it was just tired from hitting the ball as hard as I could during hours of speed practice.
 
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eyesjr said:
I’m looking for any kind of test results etc that would show the relationship between shaft stiffness and overall CB velocity. I’m curious how marginal or significant stiffer woods with more compression strength will perform compared to maple. Anyone?

Even a conical vs pro taper test would be a starting point. What is really like is Purple Heart vs maple, or Lily us vs maple at otherwise equal specifications.
Click to expand...

The issue with this is that you need a machine/robot to test things with good accuracy vs seat of the pants feel humans generally do, unless it's a pretty noticeable change. For example there are people that feel a CF shaft, no matter the brand or model, does not do anything different than a good wood shaft of similar built, but in my experience they do. Especially the Revo shaft, every Revo I played with and talked to people that use that shaft, we all agree that it gives more action to the cueball at the same force hit vs other shafts. But there are people that say that's not the case. The differences players see likely depend on how the player shoots and aims, in addition to the pure mechanical function of the shaft taking out the humans. Which is another flaw our sport has, no-one has a specific way of measuring cues, shafts, cueballs, tables, that is standard and applied to every product. It's not very hard to build, I mean it's basically just a pendulum that drops the cue down like a stroke and then we measure what the ball does, but past the old Iron Willie that was done and not longer used we have nothing. Everyone states GC bank "truer" than a Diamond, but what exactly does that mean? How was it tested? Same for deflection, Dr Dave does tests and he shows like a 1" deflection using a Revo, when I shot it with my test I show it having almost no deflection. Need a machine, and agreed upon testing that only tests the specific thing without any secondary variables added in.
 
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If you want to test the efficiency of a cue stick, here is a relatively simple experiment:

Find a very hard floor like concrete or maybe you can find a steel I-beam exposed somewhere.

Hold the stick tip down towards the floor at a known distance, like two feet.

Drop the stick straight down. (Don't let it twist as it falls.)

Measure how high it bounces.

The ratio of bounce height to drop height gives you the efficiency of the stick.

Some energy may be lost in the floor if it is not perfectly solid, but this test will still let you compare sticks.

For the measurement, you could video record the tip with a ruler behind the cue.

Predator made a lot of tip/stick efficiency measurements with Iron Willie, their simple pool robot. Willie's action was very repeatable which makes it very easy to compare designs.
 
Stiffness matters on cheap old equipment its gone. Old equipment has so much to give in terms of permanent structural changes that make temporary warping easier.

It is easy to sell looking amateurish when the cue is not stiff, especially on the follow through.

If I try wild form technique on new equipment maple or CF or LD, then everyone can hear or see me trying to cheat during the stroke.

Are you trying to look pro or go fishing?
 
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