Shaft Stiffness and efficiency.

Consider 2 cue balls rolling down table at 1 foot per second. The first CB (left) has natural roll while the second CB (right) has side spin equal to its rolling velocity::

spinningcb.JPG


The point of contact with the table of each CB moved down table at 1 foot per second (equal velocity).

The equator on the first CB is rotating at 1 foot per second. and the pat of rotation is the equator of the rolling ball. The equator is moving at 1 foot per second over the cloth.

The path of rotation of the second CB is displaced from the equator (due to the side spin) but the part of rotation remains 1 foot per second over the cloth. The equator in this case is now rolling at 1.414 feet per second. Thus the second CB has more angular momentum and thus more energy even while traveling at the same velocity (1 foot per second).

The friction of the cloth on the table saps energy from the CBs at equal point-of-contact speeds equally. But the second CB has more energy and thus rolls farther.
 
Bob Jewett said:
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.
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You misrepresent what I said:: I illustrated what I meant in the previous thread post.
 
The original question was: will cue shaft stiffness affect CB speed- it will not to any degree that would matter in the outcome of a pool game - CB speed- correct resulting position- has more to do with the skill of the cueist than any other factor given equal playing circumstances.

Choosing a stiffer shaft in hope that it results in less effort to achieve desired results is pure lunacy. Talent and hard work produce correct results - if you have enough talent, put in the hours, compete regularly, you will play at your best whether you choose wood, CF, LD or whatever- as long as one is comfortable with their chosen cue- all the rest is talent and hard work - just like everything else in life.

Marketing hype has sold billions upon billions of dollars in the newest and latest and greatest sports equipment. Would you rather be Mosconi with an older Rambow cue made on a primitive lathe or Joe Blow with a CF everything cue?
 
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Patrick Johnson said:
Aren't we comparing two balls hit on different spots with the same force? How does one have more energy?
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Yes, this was the point Bob Jewett brought up (and my original mistake/miswording) where::

2 CBs hit with the same cue, one center and one offset in any direction, the one hit in the center will have greater energy and velocity.

However, 2 CB rolling at the same linear velocity--the CB with <more> sidespin will roll a greater difference (or slow down less quickly).

And I guess we are more than a little off topic now............
 
justnum said:
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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I like sandwiches.

pj
chgo
 
Patrick Johnson said:
I like sandwiches.

pj
chgo
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Pool needs some standard foods and drink that all pool players can talk about. Talking food and drink culture is a relief and pleasant topic.

Have you tried a chicken adobo hero?

I sell a kimchi pizza.

How about ramen spaghetti?

Simple hotel foods you can eat on the road. Players can trade at night. The food from
their hometowns. If any.
 
MitchAlsup said:
... However, 2 CB rolling at the same linear velocity--the CB with <more> sidespin will roll a greater difference (or slow down less quickly). ...
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I think this isn't true. You can test it by: Set an object ball into rapid spin in place by shooting it into a ball with a max spin stop shot. Tap the spinning ball gently with another ball. Notice how rapidly it slows its linear motion compared to a simply rolling ball. That can be done by timing its movement and noting the length of the path. (Don't hit any cushions during the timing.)
 
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Bob Jewett said:
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.
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That method would work, I agree. I should have been more specific. I’m looking for cb velocity curve, based on cue efficiency.

if there isn’t any data on that, I’d like to know if the relationship of efficiency and cb speed in the 20+ mph range would be predictable from other data.

On a line graph where x (vertical) is observed cb velocity , and y (horiz) is cue efficiency, what would the line do between 90 and 100 efficiency? If the various cues moved at 20 mph/32.18kmh. Is there a point where gains in efficiency would translate to insignificant gains in velocity?

I tried to ask the question in the context of “Maple vs Purple Heart” as I thought there may have been some testing done on that. The whole thing may be a placebo for all I know, which would be a fine reason that manufacturers don’t flaunt the data to sell PH shafts. Joking aside, I’d like to have a goal for a prototype I’m toying with.
 
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
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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Mike is truly dead on……intended or unintended side spin on a cue ball does not attain the same distance as a dead
center hit. In baseball or golf, the ball travels further when it is hit with less spin, assuming launch angle & swing speed
are the same. Center ball in pool, and vertical English, should be a pool player’s bread and butter shots, at least IMO.
 
eyesjr said:
That method would work, I agree. I should have been more specific. I’m looking for cb velocity curve, based on cue efficiency. ...
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So far as I know, no one has ever shown that the efficiency (% of theoretical energy transfer) changes with ball/stick speed. Maybe Predator or someone else with the equipment has tested it. I would guess that the efficiency does not change much.

In one experiment done a long time ago, the measured ball speed was 130% of stick speed rather than the 150% mentioned above for a 3:1 ratio of masses. I think that was measured at only one speed.

If you wanted to measure that yourself, just do the experiment above with different drop heights.
 
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mikemosconi said:
The original question was: will cue shaft stiffness affect CB speed- it will not to any degree that would matter in the outcome of a pool game - CB speed- correct resulting position- has more to do with the skill of the cueist than any other factor given equal playing circumstances.

Choosing a stiffer shaft in hope that it results in less effort to achieve desired results is pure lunacy. Talent and hard work produce correct results - if you have enough talent, put in the hours, compete regularly, you will play at your best whether you choose wood, CF, LD or whatever- as long as one is comfortable with their chosen cue- all the rest is talent and hard work - just like everything else in life.

Marketing hype has sold billions upon billions of dollars in the newest and latest and greatest sports equipment. Would you rather be Mosconi with an older Rambow cue made on a primitive lathe or Joe Blow with a CF everything cue?
Click to expand...

I am not sure it's stiffness that affects the cueball action, but compression of the shaft. Those may be two different things. For example, there are building materials that are stiff in one direction but not the other, and by mixing them we can get a stronger material, like rebar concrete. Concrete has a strong compression strength but not so much laterally, if it's hit head on, it's stiff, but not from the side. Adding metal lacework in the mix makes it stronger overall. A pool cue can be stiff in bending force but can compress along the length and thus absorb more of the hit force to the cueball. That is why IMHO (with me not being an actual engineer or scientist just being curious about things and having a brain) a carbon fiber shaft that has a much smaller compression factor than wood and can put more action on the cueball at the same stroke force.

We are not looking at anything like talent or skill of the user here, we are looking at the pure performance of the materials. It's the same as looking at a low deflection shaft vs a normal one, you need to be a good player to play better with either one, but it's a fact that one of them reacts differently from the other when a ball is struck, and objectively the one that causes less variables in the game is the "better" one. A good race car driver can beat a bad one using a slower car, but there is no arguing that in tests you can see how one car is faster or has more grip, making it "better" or more efficient as the object created for a purpose.
 
hang-the-9 said:
I am not sure it's stiffness that affects the cueball action, but compression of the shaft. Those may be two different things. For example, there are building materials that are stiff in one direction but not the other, and by mixing them we can get a stronger material, like rebar concrete. Concrete has a strong compression strength but not so much laterally, if it's hit head on, it's stiff, but not from the side. Adding metal lacework in the mix makes it stronger overall. A pool cue can be stiff in bending force but can compress along the length and thus absorb more of the hit force to the cueball. That is why IMHO (with me not being an actual engineer or scientist just being curious about things and having a brain) a carbon fiber shaft that has a much smaller compression factor than wood and can put more action on the cueball at the same stroke force.

We are not looking at anything like talent or skill of the user here, we are looking at the pure performance of the materials. It's the same as looking at a low deflection shaft vs a normal one, you need to be a good player to play better with either one, but it's a fact that one of them reacts differently from the other when a ball is struck, and objectively the one that causes less variables in the game is the "better" one. A good race car driver can beat a bad one using a slower car, but there is no arguing that in tests you can see how one car is faster or has more grip, making it "better" or more efficient as the object created for a purpose.
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I agree with you - my contention has always been that too many people look for equipment fixes and are not willing to improve their fundamentals via hard work. Golf is an even better example of this . Some people here would be happier if the cue could be pre programmed for them - is that next?

For anyone to worry about CB speed control coming from a shaft change just seems ludicrous to me - yes I am old school😁😁
 
mikemosconi said:
I agree with you - my contention has always been that too many people look for equipment fixes and are not willing to improve their fundamentals via hard work. Golf is an even better example of this . Some people here would be happier if the cue could be pre programmed for them - is that next?

For anyone to worry about CB speed control coming from a shaft change just seems ludicrous to me - yes I am old school😁😁
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Your right mike, there are no quick fixes. The more you use the same cue. the more, you will understand some of the aspects of this thread. Alot of this stuff you can't really feel, as it happens too quick. But you can definitely see it happen. Unfortunately the hype of the latest great shaft. Always seams to out way the need too, actually put the endless hours of hard work in.
 
Can someone explain how the shaft, 'stiffness/efficiency/math/physics' calculation helped me make this Force-Follow shot?

 
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