what dimensions are used to make the cone?
cue tip and end of butt diameter? joint? cue length? all of the above?
I'm trying to design a cue, and am wondering how variable these dimensions can be/
what dimensions "fix" the cone shape
thanks for any info.-
I believe your thread topic asks the most important question concerning playability.
I am the biggest fan of DPK. He is the Tiger Woods of Cuemakers.
On my Esoteric Cue Design the first 12 inches of the butt from the joint to the A Joint is conical .850 to .1004. From 12" to 29 I have a slight constant parabolic curve to the end. If you put a straight edge against my profile you see an air gap.
Also IMO, the best shaft taper has three major segments.
1. From 0 to ten inches
2. From 10 inches to 15"
3. From 15" to 29".
If you have the good playable geometry, the cue will flex at 6 to 8" from the tip when you bend it while you hold two fingers on top of the shaft and your thumb underneath on the very ends of the shaft.
Why is this important?
The flex point needs to be in the area of your bridge hand which acts as a steady rest. Why? Because when the tip contacts the stationary cue ball the shaft wants to deflect behind the bridge at the moment of inertia if the taper does not have a strong climb at the #2 segment of the total profile geometry 35 to 40 thou from 10 to 15".
If you shaft bends closer the the middle it negates the steady rest effect of a closed bridge and just a slight deflection toward the center of the shaft will cause the tip to move on the cue ball during what Newton refers to the elastic collision. Depending on the velocity it can squirt and apply unintended english on the ball. And the player does not even understand what happened when the object ball misses the pocket. Bad equipment will not make you get better no matter how many L drills you perform.
From 15" to the joint, the geometry can be anything you want as long as you land on the number of the joint dia. Here is where the shaft can incorporate a parabolic taper or as some refer the the coke bottle.
Again, these observations are based on physics. The interpretation I have just stated are only my approach to this subject. If the reader does not agree, please just agree to disagree with me because I will not get into any pissing matches.
Of coarse this steady rest effect is not as effective with an open bridge but the described geometry above will still out perform any shaft that flexes closer to the center.
BTW, the next time you have a Cog or Gina shaft at hand, try the test and observe with your own eyes.
So my advise to new cuemakers is if your shafts bend toward the center, go back to the drawing board.
I will not share my geometry numbers but a good place to start your investigation is to mic a Predatator Z Shaft as your start point.