How does shaft diameter at and near ferrule affect deflection?

S

Shooter1

AzB Silver Member
Silver Member
If you had to identical pro taper wood shafts from the same manufacturer and one was say, 12.5mm od at the ferrule and the other 12.9mm od, and the thicker one would be a bit thicker up the balance of the shaft to the joint, which one would deflect more?
My logic tells me the 12.5mm would deflect more as the diameter is smaller, (a bit less end mass) and the end of the cue would move off center more after cue ball contact? Consequently, the 12.9mm shaft would deflect less because it is a bit more rigid there causing the cueball to squirt off line more.

I have a couple shafts I'm thinking about reducing the od on and would like some thoughts on the above forst.

Thanks.
 
Shooter1 said:
If you had to identical pro taper wood shafts from the same manufacturer and one was say, 12.5mm od at the ferrule and the other 12.9mm od, and the thicker one would be a bit thicker up the balance of the shaft to the joint, which one would deflect more?
My logic tells me the 12.5mm would deflect more as the diameter is smaller, (a bit less end mass) and the end of the cue would move off center more after cue ball contact? Consequently, the 12.9mm shaft would deflect less because it is a bit more rigid there causing the cueball to squirt off line more.

I have a couple shafts I'm thinking about reducing the od on and would like some thoughts on the above forst.

Thanks.
Click to expand...
I think you have that backwards, What you want is for the ball to deflect less so less end mass is less deflection.
 
Once could, in principle, take some space-age material and make a cue that is 1" in diameter at the tip, but weigh no more than a Z3 at the tip. In principle, these 2 cues would have the same deflection::

That is:: The diameter of the shaft and tip is not part of the deflection equation--except as they add mass to the tip-end of the cue.
 
Shooter1 said:
If you had to identical pro taper wood shafts from the same manufacturer and one was say, 12.5mm od at the ferrule and the other 12.9mm od, and the thicker one would be a bit thicker up the balance of the shaft to the joint, which one would deflect more?
My logic tells me the 12.5mm would deflect more as the diameter is smaller, (a bit less end mass) and the end of the cue would move off center more after cue ball contact? Consequently, the 12.9mm shaft would deflect less because it is a bit more rigid there causing the cueball to squirt off line more.

I have a couple shafts I'm thinking about reducing the od on and would like some thoughts on the above forst.

Thanks.
Click to expand...
A wider tip would mean more end mass, which would mean more CB deflection (squirt). It might also mean more stiffness, but that has little or no visible effect on squirt (according to Dr. Dave).

This is already being discussed in another current thread: https://forums.azbilliards.com/threads/pool-cue-stiffness.550763/

pj
chgo
 
Shooter1 said:
If you had to identical pro taper wood shafts from the same manufacturer and one was say, 12.5mm od at the ferrule and the other 12.9mm od, and the thicker one would be a bit thicker up the balance of the shaft to the joint, which one would deflect more?
My logic tells me the 12.5mm would deflect more as the diameter is smaller, (a bit less end mass) and the end of the cue would move off center more after cue ball contact? Consequently, the 12.9mm shaft would deflect less because it is a bit more rigid there causing the cueball to squirt off line more.

I have a couple shafts I'm thinking about reducing the od on and would like some thoughts on the above forst.

Thanks.
Click to expand...

Reducing the shaft diameter definitely reduces CB deflection. For more info, see:
Enjoy!
 
Shooter1 said:
If you had to identical pro taper wood shafts from the same manufacturer and one was say, 12.5mm od at the ferrule and the other 12.9mm od, and the thicker one would be a bit thicker up the balance of the shaft to the joint, which one would deflect more?
My logic tells me the 12.5mm would deflect more as the diameter is smaller, (a bit less end mass) and the end of the cue would move off center more after cue ball contact? Consequently, the 12.9mm shaft would deflect less because it is a bit more rigid there causing the cueball to squirt off line more.

I have a couple shafts I'm thinking about reducing the od on and would like some thoughts on the above forst.

Thanks.
Click to expand...
On rereading that, you did have it right, just that people don't usually refer to the cue when they talk about deflection, But your logic was correct.
 
dendweller said:
On rereading that, you did have it right, just that people don't usually refer to the cue when they talk about deflection, But your logic was correct.
Click to expand...
Ahhhh someone with good reading comprehension. I thought the same thing. He's referring to the cuetip....not the cueball/
 
Thanks for the replies and confirmation that my logic is correct. Dr. Dave's link, was a good read (and his vids are good as well) .
 
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