"If you hit a CB with a butt heavy cue and a balanced cue with the exact same stroke (assuming both cues weigh the same) in the exact same spot, the CB will react the exact same way."
why/why not?
thanks-
why/why not?
thanks-
is this true? (balance point question)
- Thread starter evergruven
- Start date
Yes. Why not? The CB “feels” only the force of the stroke (weight x speed). How would balance be “felt”?
ASS - angle, spot & speed - the only things that matter to the CB.
pj
chgo
PS. Unless the balance difference changes the weight (mass) in the first 6-8” near the tip - then squirt would change for side spin shots.
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depends on the spot
If you hit the cue ball dead center directly inline with the stroke, not just on the centerline, it doesn't matter. This spot will be slightly higher than dead center due to hitting down a little on the cue ball but since we are talking theory anyway dead center is close enough.
Now, what if we don't hit the cue ball dead center? The bridge and the grip are both elastic and as results with robots have proven, the cue stick held in an elastic grip gives a different result than one held in a rigid grip.
Once we realize that a cue stick doesn't stay perfectly inline when it hits a cue ball away from the center, then it is easy to understand that the inertia of the stick does matter. The sideways inertia of the stick varies with the balance point among other factors. We aren't really concerned with the other factors for this question and they are many and variable. How stiff is the stick for example? The difference between these new carbon fiber shafts and an old moochie soft maple shaft might be quite significant but because of too many variables it is more practical to test these things than to try to computer model or calculate them.
The short version is that the balance point affects the movement of both cue stick and cue ball. Enough to make you miss or make many shots? Probably not, more a matter of feel. Moving the balance point has more impact on feel than actual play.
Hu
If you hit the cue ball dead center directly inline with the stroke, not just on the centerline, it doesn't matter. This spot will be slightly higher than dead center due to hitting down a little on the cue ball but since we are talking theory anyway dead center is close enough.
Now, what if we don't hit the cue ball dead center? The bridge and the grip are both elastic and as results with robots have proven, the cue stick held in an elastic grip gives a different result than one held in a rigid grip.
Once we realize that a cue stick doesn't stay perfectly inline when it hits a cue ball away from the center, then it is easy to understand that the inertia of the stick does matter. The sideways inertia of the stick varies with the balance point among other factors. We aren't really concerned with the other factors for this question and they are many and variable. How stiff is the stick for example? The difference between these new carbon fiber shafts and an old moochie soft maple shaft might be quite significant but because of too many variables it is more practical to test these things than to try to computer model or calculate them.
The short version is that the balance point affects the movement of both cue stick and cue ball. Enough to make you miss or make many shots? Probably not, more a matter of feel. Moving the balance point has more impact on feel than actual play.
Hu
Yes, assuming the tip and shaft end mass is the same for both cues.
... because the CB doesn't know the difference.
However, cue balance could affect CB deflection and your stroke per the info here:
cue balance point effects
Regards,
Dave
To be clear, you're talking about the difference between a human grip and a non-human grip. The difference can't be produced by a human gripping tighter or looser.
Matter to what? Not to the CB.
Maybe, but like differences in stiffness, it doesn't affect the CB.
I'm not aware of any tests that support this.
pj
chgo
If your looking for scientific reason: look to posters above.
If just a pool players opinion:
I have more than one cue that weighs within .01 ounces of each other. However, one has a balance point of 18 from bumper and the other has a balance point of 23 from the bumper.
Both cues are same length etc..etc..
Differences to me:
The front heavy cue helps me stay online better with open bridge shots. Especially when I use open bridge and need to put some power in it.
The back heavy cue ....to me...is better for masse type shots but it seems I dont shoot as straight with it in normal play.
Both cues are made of identical wood, ferrule, tip....etc...etc...
Just my .02
Rake
It depends on the color of the cue.
No significant difference but you also need to assume the same the same kind of construction in the two cues. Let's assume the cues have identical shafts.
If the butt-heavy cue got that way by the clumsy installation of a makeshift weight bolt that has a little bit of slide during the shot, and the other cue is nice and solid, the two cues will play differently. But that has nothing to do with the centers of gravity of the cues.
The main difference for me is that a strangely balanced cue just feels weird and my timing seems to be off when I try to use it. That will certainly give the impression of hitting the ball differently.
What sort of difference would you imagine could be there? More cue ball speed for a given stick speed? More spin for a given eccentricity of hit? Ability to hit farther from center? Beyond those it's hard for me to think of what might change.
As for why the balance point is unimportant, the basic reason is that the cue tip is in contact with the ball for a longer time than it takes the compression wave of the tip/ball hit to reach the end of the back end of the cue stick and return. We could think about a very long cue -- thirty or fourty feet -- for which the compression wave, which travels at the speed of sound in the cue stick material, has not had time to travel to the butt of the cue and return before the cue ball leaves the tip. In that case all of the mass of the cue behind a certain point will not participate in the collision. If you move mass from the front of such a weird stick to the back, the stick will play as if it is lighter.
How much of that strange stick will be effective? If the speed of sound in the stick is 4000 meters per second (typical for hardwood), and the tip/ball contact is 1 thousandth of a second (pretty typical) then the compression wave travels 4 meters. But the wave has to make a round trip during the millisecond for the tip/ball to "see" the mass back in the cue -- the presence of the weight in back can only be "communicated" to the tip by a reflected wave coming back. So, for the assumptions made, only the mass in the first two meters or 78 inches of stick affects the shot.
This leads to an interesting question about carbon fiber shafts: If the speed of sound is higher in them than in wood, can they be more efficient at transferring energy into the cue ball? In general when you are looking at energy transfer situations as described above, you would like to see a time of contact that allows multiple round trips of the compression wave. In a normal cue stick, there is only time enough for slightly over one round trip. In general, that condition leads to some deficit of energy transfer. With either a shorter cue or a higher speed of sound, the number of round trips for the compression wave is increased, which theoretically will give a better energy transfer. I suspect that carbon fiber has a higher speed of sound than wood but it likely depends on the exact construction of the cue.
Also, above at the start I said "no significant difference" because there will be a slight difference when you move the mass back, theoretically. In effect you are making the stick longer by a little and tending very slightly towards the 40-foot-long cue. How much change? A rear-weighted cue is probably only two inches different on balance point compared to a "normal" cue. I think that will make only small difference in energy transfer efficiency. The usual efficiency is somewhere around 80%, and I doubt the moving the balance like that is going to make even a 1% difference.
Wow. That's quite a variation. Is that just from the position of a weight bolt?
No weight bolts in either.
One has a lot of extra weight added to nose, ebony, metal joints, big pin, inserts...etc
The other is drilled out from rear almost to A joint with weight add with lead tape to add weight back to specific areas to keep balance point where I want it.
Both my cues have duck tape all over them. Yeah, people fight over me as soon as I pull my cues out.
Lol
Rake
tests
pj,
You have been involved in discussions concerning early robots on this forum. The fact that you can't evaluate the information from the tests doesn't mean you aren't aware of a test.
With a rigid cue shaft mount to the robot the wonder shafts and standard shafts resulted in pretty much the same cue ball action and path. Adding bubble wrap to mimic a human grip resulted in considerably different results.
I have seen the claims about only the few inches behind the tip mattering, 4-7 inches. If that were true you could put a ten inch stub in a huge mechanical fixture and get the same result as a full shaft and cue in a player's hands. That isn't going to happen as that early testing demonstrated.
It wouldn't be hard to pick up a like new or in excellent shape large linear bearing on ebay along with an electric solenoid for consistency. A little wiring and a switch or button and that would be all the equipment needed other than a little machine work to adapt a pin to the front of the bearing. Probably all for under five hundred dollars, maybe a lot under.
I am not curious myself. I have used cues from 12 ounces to over two pounds, forward weighted, back weighted, balanced under my hand. I have hit with various low deflection cues including the revo. I don't have the 12 ounce snooker cue now but I doubt any of them surpass it significantly in lowering deflection and many won't match it. It was low deflection long before low deflection was cool. Attracted too much attention hauling a snake coffin around so I got the moochie. I did win a handful of local pool tournaments with the snooker cue.
Hu
pj,
You have been involved in discussions concerning early robots on this forum. The fact that you can't evaluate the information from the tests doesn't mean you aren't aware of a test.
With a rigid cue shaft mount to the robot the wonder shafts and standard shafts resulted in pretty much the same cue ball action and path. Adding bubble wrap to mimic a human grip resulted in considerably different results.
I have seen the claims about only the few inches behind the tip mattering, 4-7 inches. If that were true you could put a ten inch stub in a huge mechanical fixture and get the same result as a full shaft and cue in a player's hands. That isn't going to happen as that early testing demonstrated.
It wouldn't be hard to pick up a like new or in excellent shape large linear bearing on ebay along with an electric solenoid for consistency. A little wiring and a switch or button and that would be all the equipment needed other than a little machine work to adapt a pin to the front of the bearing. Probably all for under five hundred dollars, maybe a lot under.
I am not curious myself. I have used cues from 12 ounces to over two pounds, forward weighted, back weighted, balanced under my hand. I have hit with various low deflection cues including the revo. I don't have the 12 ounce snooker cue now but I doubt any of them surpass it significantly in lowering deflection and many won't match it. It was low deflection long before low deflection was cool. Attracted too much attention hauling a snake coffin around so I got the moochie. I did win a handful of local pool tournaments with the snooker cue.
Hu
Since I had a PM about this....
The speed of sound in wood is complicated. There are actually three different speeds -- along the grain (as in a shaft), around the rings, and perpendicular to the rings. I think there is around a 4:1 variation in the different directions.
I imagine that there is some variation depending on how the wood is grown and dried. The two common woods for cue shafts -- maple and ash -- are typically listed with only a single number for speed of sound with the grain and perhaps numbers for one or two other directions. Ash is slightly faster than maple in the lists I've seen.
The best sources of info I've found on this is from musicians who seem to be even more interested in how woods "ring" than pool players are.
hi bob, when I initially posted, I was wondering about cue ball travel (and then, object ball travel), maybe lagging with two of the same cues with different balance points as a test, etc.
you mentioned energy transfer..in my mind anyway, I'm seeing better/more energy transfer from a more forward-weighted cue; although, that weight wouldn't necessarily be found in the shaft, right?
so if the weight's not in the shaft, there is a difference, but per physics, not enough to make a significant difference in cue performance, if I'm understanding.
if not, feel free to correct
thanks all for the replies!
Dont forget about wearing the correct socks for the shot before you. :thumbup:
thanks for the explanation bob