I see endmass as a variable. I see low deflection as an outcome. In between is a sequence of interactions and forces that I’m sure can be explained with some very complex math and equations. I expect they also could be dumbed down to explain to a layman. That’s my goal. The next time I talk to my brother, I’m willing to say endmass affects deflection but I’m looking to figure out an intuitive way to explain why that is. So far I’m not really getting that layman’s explanation from your site or this conversation. Everything just keeps going back to asserting the relevant variable without explaining why. I don’t mind dropping the subject if the conversation is never going to take that turn.
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I'm with you on this. I like simple explanations to complicated problems.
Put it this way: When a sliding (stun) CB strikes an OB at an off-center hit (not a straight on center to center hit), the OB is forced along the line from the contact point through the center of the OB, creating a cut shot. The CB's path is
deflected from the contact point at 90° from the direction the OB is sent. (This is ignoring OB throw and CB roll or spin.) Since friction is minimal at the contact point, there is maximum CB deflection away from the OB.
By comparison, when the cue tip strikes the CB at an off-center hit, the shaft gets deflected in a similar way as above. But the tip has mucho friction, which means it tries to hold on or grip the CB surface. But the ball weighs 6oz and the end of the shaft (last 7 or 8 inches) might be 2oz or less. So the 6oz ball exerts a greater force on the 2oz end mass of the shaft, forcing it away, and at the same time the friction between the tip and the ball is causing the ball to rotate. On top of being forced laterally by the CB's weight, the tip rides this rotation, and if the shaft has a very light end mass it will quickly be forced to deflect away from the CB to avoid excessive CB squirt.
No need to talk about equations or Newton's 3rd law of equal and opposite reactions. Just knowing that something must give, common sense means the lighter/smaller mass will give way to the larger mass every time. So more shaft deflection results in less CB deflection. But let's say a shaft is made to have zero flexibility (for whatever reason). And we used a fixed bridge and grip device that would ensure the cue stick remained on the stroke line throughout the entire stroke.
The full weight of the cue stick, say 19oz, would then be the dominant factor upon collision with the side of the cb. There would be no shaft deflection. The cue tip would push the cb aside with ease, despite shaft end mass. The 6oz ball can push back all it wants, but if the shaft doesn't give it will not deflect, and will therefore cause maximum cb squirt. That's an extreme example. At the other extreme we could shoot with a super light shaft made of flexible foam. In this case we'd have maximum shaft deflection and minimal cb squirt. But we also have less transfer of force to the cb.
I guess since every cue shaft has flexibility, making the tip end lighter is an automatic way to create less CB squirt. That's why shaft end mass is the main factor, and not shaft stiffness. Even the revo has enough flexibility so that its super light end mass is what makes the difference in minimizing cb squirt.
