Long stroke vs. short stroke?

[JoeW]

Thanks Bob, I always like to learn something new. Apparently all the twisting and contortions such as those recommended by Colin Colenso in this video http://www.youtube.com/watch?v=xW1tsONEI_U
are not about using muscles to to power the cue stick through the cue ball but are about using these muscles to increase the acceleration of the cue stick, correct?

Given your comments, throwing the cue stick at the same speed would yield the same amount of energy transfer as when a hand is in contact with the same stick at the same speed?

Apparently the observation that some big guys have a harder break (as evidenced by ball scatter) is a function of their ability to generate more acceleration of the stick than smaller guys. I realize there are some smaller guys who have a powerful break.

On the other hand, positive reasonably tight contact with the stick until contact with the cue ball would allow the player more time to continuously accelerate the cue stick wouldn't it? And by extension, a longer bridge (distance from bridge hand to cue ball) would also allow for more time to accelerate the cue – correct?

Is it known whether more acceleration is generated early in the swing versus later in the swing?

All things being equal, a heavier cue stick would have more inertia and thus lead to a more powerful break, wouldn't it? I suppose there is a trade off with regard to the muscles' ability to generate acceleration and the weight of the cue but it does seem that much heavier cues could be used -- why not?

BTW, given your comments I suspect the differences I observed had more to do with the differences in the resistance of wood versus phenolic balls. In general, You can force the nail through wood resting on concrete, you can only hit a "hard" cue ball when there is much less resistance on the horizontal axis..

 

[Scott Lee]

Okay Joe...how are you gonna measure "reasonably tight contact"? That's about as ambiguous as anything else.

Scott Lee
http://poolknowledge.com

positive reasonably tight contact
.

 

[dr_dave]

I'm not Bob, but we usually agree on most (if not all) things.

Thanks Bob, I always like to learn something new. Apparently all the twisting and contortions such as those recommended by Colin Colenso in this video http://www.youtube.com/watch?v=xW1tsONEI_U
are not about using muscles to to power the cue stick through the cue ball but are about using these muscles to increase the acceleration of the cue stick, correct?

Yes.

Given your comments, throwing the cue stick at the same speed would yield the same amount of energy transfer as when a hand is in contact with the same stick at the same speed?

Yes (maybe not the exact same theoretically, but certainly the "same" practically).

Apparently the observation that some big guys have a harder break (as evidenced by ball scatter) is a function of their ability to generate more acceleration of the stick than smaller guys.

Yes.

I realize there are some smaller guys who have a powerful break.

Power comes more with proper break technique than it does with muscle.

On the other hand, positive reasonably tight contact with the stick until contact with the cue ball would allow the player more time to continuously accelerate the cue stick wouldn't it?

Acceleration comes with forward pushing force, not grip tightness. Not much grip tightness is required to generate typical forward pushing forces.

a longer bridge (distance from bridge hand to cue ball) would also allow for more time to accelerate the cue – correct?

... most definitely!

All things being equal, a heavier cue stick would have more inertia and thus lead to a more powerful break, wouldn't it?

No. The optimal break cue weight will be very different from one person to the next.

I suppose there is a trade off with regard to the muscles' ability to generate acceleration and the weight of the cue but it does seem that much heavier cues could be used -- why not?

See the information and resources on the optimal break cue weight resource page.

Regards,
Dave

 

[dr_dave]

Sean,

I have also experienced this issue with the cue testing machine I used for squirt experiments many years ago. We had to take a lot of care to design the "grip" to be flexible (like the flesh in a human hand) and to slow the momentum of the mechanism after the hit. If you mechanically clamp down on the cue with a mechanism, the mechanism effectively becomes part of the cue, and the momentum of the mechanism prevents the cue from slowing as much as it would with a human grip (with flexible flesh) and a human stroke (which doesn't add as much momentum after the hit as a mechanism with a more-rigid grip would). With larger tip offsets, a non-human mechanism with a "death grip" easily causes double hits resulting in miscues.

Fortunately, with a typical human grip and stroke, even though the tip can come close to hitting the CB a second time, this does not happen, even close to the miscue limit. For more info and experimental results, see the following article:

"Coriolis was brilliant ... but he didn't have a high-speed camera - Part IV: maximum cue tip offset" (BD, October, 2005)​

However, I could imagine this happening under certain conditions. For example, if a person had a very bony hand with very little flesh between the bones and the cue, and the person used a "death grip," the effect could occur (especially if the person was also wearing Earl-type arm weights). The effect would also be more likely to occur with a very non-whippy and low-squirt (AKA LD) shaft (e.g., a carbon fiber shaft) that flexes back quickly after hitting and bouncing away from the CB with an off-center hit.

Sean,

Another factor with non-human mechanisms (and maybe with a really tight and stiff "death grip") is that the effective mass of the cue is increased if there is a rigid connection between the cue and whatever is holding the cue.

FYI, I just added some analysis to one of my technical proof documents that looks at the effect of cue weight. Check out the plots on the last two page here:

TP A.30 - The effects of cue tip offset on cue ball speed and spin​

The conclusion of the analysis is:

With heavier cues (or effectively heavier cues), double hits, pushes, and/or miscues are likely at larger tip offsets.

Enjoy,
Dave

 

[JoeW]

Did not realize there were so many people on now. Made this edit that was probably missed

BTW, given your comments I suspect the differences I observed had more to do with the differences in the resistance of wood versus phenolic balls. In general, You can force the nail through wood resting on concrete, you can only hit a "hard" cue ball when there is much less resistance on the horizontal axis..

--------------------------------------------------------------------------------

 

[JoeW]

Oh yeah, read the optimal break cue weight -- thanks for all the answers. Learned some new things today.

 

[Sloppy Pockets]

Given your comments, throwing the cue stick at the same speed would yield the same amount of energy transfer as when a hand is in contact with the same stick at the same speed?

In my own impromptu experiments at the table, this is exactly what I have seen. And I am a compact 275 pounds and have pretty good size guns - lot more mass than Earl and all his weights combined. This discovery made me accept that the cue itself is what is doing 99% of the work.

Apparently the observation that some big guys have a harder break (as evidenced by ball scatter) is a function of their ability to generate more acceleration of the stick than smaller guys.

This is very obvious when looking at power hitters in baseball. Some big guys can generate a lot of bat speed even without perfect technique. Guys like Ken Griffey Jr. had some size, but mostly achieved great results by smooth and continuous application of force throughout the swing. It's all in the timing of the action.

On the other hand, positive reasonably tight contact with the stick until contact with the cue ball would allow the player more time to continuously accelerate the cue stick wouldn't it? And by extension, a longer bridge (distance from bridge hand to cue ball) would also allow for more time to accelerate the cue – correct?

Is it known whether more acceleration is generated early in the swing versus later in the swing?

You only need enough firm contact to be able to accelerate the cue to max velocity and have it not slip in your cue hand. That has been shown by many here to be accomplished with a loose cradle grip.

Yes, a longer bridge could possibly lead top greater acceleration, but a lot is dependent on your particular body: arm mass (heavier arm needs more force to accelerate it), muscle composition (fast-twitch/slow-twitch muscle ratio), ligament and tendon length and attachment, limb length, etc. A long bridge with a long back swing could lead to a slower final velocity instead of faster.

Acceleration should be constant throughout the stroke if the applied force is constant. For example, look at a rocket sitting on the launch pad right at ignition. You might not realize it just looking at it sitting there, but it is actually accelerating, albeit very imperceptibly. Since F=ma, and the force (thrust) is constant, mass of rocket is constant, therefore, acceleration is constant.

The difference with a human is that we can't apply the same amount of force throughout the entire stroke. The legs and truck are very powerful compared to the arms, which are much more powerful than the wrists and they more powerful than the fingers. Engaging the lower body first (think Van Boening or Stalev) gets a head start on acceleration through impeccable timing and the proper use of large muscle mass to get the cue accelerating early on. Just like cracking a whip or throwing a power punch, the action begins at the base and proceeds in a wave-like motion throughout the body that ends in the hands. This is why I believe you are getting the best results by tightening the grip, but only at the very end of the stroke. By doing this, you are adding that last bit of possible acceleration to the cue. Again, it's all in the timing of the motion.

All things being equal, a heavier cue stick would have more inertia and thus lead to a more powerful break, wouldn't it? I suppose there is a trade off with regard to the muscles' ability to generate acceleration and the weight of the cue but it does seem that much heavier cues could be used -- why not?

There are some new designs I've seen that are heavier but balanced in a way that is supposedly easier to accelerate. I asked about them at one point on AZB but got no response. Bottom line is if you can break faster with a heavy cue than with a lighter use, you should feel free to use one.