Thicker shaft produces more deflection?!

VTEC John

VTEC John

Active member
A friend who follows this forum regularly has just informed me that it is accepted wisdom that a 13 mm shaft will produce more deflection than the 12-plus shafts currently popular. Is this true, what is the explanation for it? Seems to me tha,; all other things being equal, a stronger piece of wood will bend less than a weaker piece.
 
VTEC John said:
A friend who follows this forum regularly has just informed me that it is accepted wisdom that a 13 mm shaft will produce more deflection than the 12-plus shafts currently popular. Is this true, what is the explanation for it? Seems to me tha,; all other things being equal, a stronger piece of wood will bend less than a weaker piece.
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"Deflection" refers to the cue ball path, not the bending of the shaft
 
VTEC John said:
A friend who follows this forum regularly has just informed me that it is accepted wisdom that a 13 mm shaft will produce more deflection than the 12-plus shafts currently popular. Is this true, what is the explanation for it? Seems to me tha,; all other things being equal, a stronger piece of wood will bend less than a weaker piece.
Click to expand...
JohnnyOzone said:
"Deflection" refers to the cue ball path, not the bending of the shaft
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Yes, and it's caused by the shaft's "end mass" (the weight of the 1st 6-8" of the shaft) "pushing" back as the CB's rotation pushes it aside. End mass, of course, (and therefore squirt) increases as the tip area gets wider (13mm vs. 12mm).

Think of two people facing each other on roller skates, one thin and the other fat, and they simultaneously push each other away. The heavier one will move the lighter one farther.

pj
chgo
 
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Fatboy said:
Taper as well
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To be clear, taper only affects squirt by increasing/decreasing end mass (thicker first 6-8" = more end mass). Shaft stiffness has negligible direct effect on squirt (I know that's counterintuitive). As an example of this, my shaft has a conical taper (gets thicker fast), so it's very stiff, but ultra low deflection (20") because of its small, hollowed tip width (10mm +/-).

pj
chgo
 
Patrick Johnson said:
To be clear, taper only affects squirt by increasing/decreasing end mass (thicker first 6-8" = more end mass). Shaft stiffness has negligible direct effect on squirt (I know that's counterintuitive). As an example of this, my shaft has a conical taper (gets thicker fast), so it's very stiff, but ultra low deflection (20") because of its small, hollowed tip width (10mm +/-).

pj
chgo
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Seems to me, I’m not a expert on this.

I know the end mass thing is a huge factor. That’s well established.

But a conical taper would seem to cause lots of squirt as well? Even with low mass
 
Patrick Johnson said:
To be clear, taper only affects squirt by increasing/decreasing end mass (thicker first 6-8" = more end mass). Shaft stiffness has negligible direct effect on squirt (I know that's counterintuitive). As an example of this, my shaft has a conical taper (gets thicker fast), so it's very stiff, but ultra low deflection (20") because of its small, hollowed tip width (10mm +/-).

pj
chgo
Click to expand...

So, what you're saying is taper does affect squirt :)

And I disagree stiffness has negligible effect. Take a steel shaft with minimal end mass and compare it to an identical wood shaft ;) Stiffness has a lot to do with squirt.

Giving it more thought, I think it has MORE to do with than people think. Regardless of how light the end of the shaft is, if it's not bending then the CB will.
 
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Fatboy said:
Seems to me, I’m not a expert on this.

I know the end mass thing is a huge factor. That’s well established.

But a conical taper would seem to cause lots of squirt as well? Even with low mass
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You'd think, but I have yet to find any pro taper shaft that generates less CB deflection than my predator Z2
 
Chili Palmer said:
I disagree stiffness has negligible effect. Take a steel shaft with minimal end mass and compare it to an identical wood shaft ;) Stiffness has a lot to do with squirt.
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My 10mm conical tapered shaft with a 20" pivot point (longest I've ever heard of) disagrees.

pj
chgo
 
Patrick Johnson said:
My 10mm conical tapered shaft with a 20" pivot point (longest I've ever heard of) disagrees.

pj
chgo
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Now if you could make a steel shaft with the same specs (including weight) which of the two would deflect the CB more...? ...and how insignificant do you think the difference might be..? Guess work on the last bit I know
 
Chili Palmer said:
Why not? Wood was the defacto standard for years now CF has come into play, why not steel, aluminum, etc.?
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"Stiffness has negligible effect on squirt" is a comparison of common shafts and materials used in pool/billiards. I'm pretty sure we could come up with a shaft material that squirts massively even with a pro taper - but it would never get used, so it would be a meaningless comparison for pool/billiards.

And, by the way, "not osmium" is because it's the densest material (no offense, Bob).

pj
chgo
 
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