Kim, I think this is what people are having difficulty understanding.
When the pin is originally installed on a straight shaft that was just faced, the pin is 90° to the face and perfectly in line with the axis of the shaft.
However, if the shaft warps (exaggerated), the pin is still 90° to the face but it is no longer perfectly in line with the axis of the shaft.
When the warp is machined away, the pin's center will be concentric to the shaft, however, the pin & tapped hole will be off-angle to the centerline of the shaft.
As far as I can see, the only way to reconcile this is to use a shaft blank that remains perfectly straight. I'm still looking for one.
Hi Bob,
The example you show on the drawing is a shaft that has moved to a configuration where the face angle moved 6 degrees and it would be absolutely non usable if it were to move that bad from .910 to .850 for sure.
Shafts that are rested and at .910 and move a thousand or two in the middle will cut out any centerline variance and the shafts re center when taking a .010 curf cuts in my experience. The larger ramp on the metal centers is seated on the dead side and remains 90 degrees to the face and any slight variance cuts on the middle taper contour equlize and after that and both sides is on centerline X.
As I said the shafts roll true on the surface plate by themselves as the air gap is not moving up and down when rolled and they roll true on the table joined to the butt and also at the joint and when rolled on the rail without an elevation bob at the joint. Is this not the standard as to how to judge a completed cue's construction concerning all the factors that can disrupt concentricity relative to pin, thread, and taper geometries.
Call me crazy but that's my standard for observation and completing a cue. The shafts coming off my machine have a very shinny rms finish and before and after the slight sanding they run true and do not wiggle in the wood lathe running at 1500 rpm between the metal dead center and wood center at the tip. What more can I say.
So if the shaft moves after the final cut, any variance in the contour as you show it on your print will reveal threads that will not be parallel to the x taper I agree. This would be a rejected shaft to those who tap after final taper cut also. So it is a moot point. Your 6 degree example is very extreme.
In the last year I have had 3 shafts go goofy from .910 to .850 which were shitcanned. The only draw back to my method is at that point if you lose a shaft you lose a joint collar and a ring also. As you might expect I have a contingencey with extra rings in reserve.
Your abilities and reputation as a super pro machinist is known by all including myself. It is not my intention to argue with you. All i can hope to do is report my observations and listen to anything you may say in responce to same. I am not a machinist but only someone who uses my machines as tools to build cue. When I need fixtures or devices made to build my cues I go to my machinist to that end.
Maybe my shaft processing procedure is part of the combination of singular events that has led to my sucess in this area. All my shaft @ .910 have been in my shop for at least six years and have been tapered to various dimensions and bad ones have been culled when they reveal themselves. The ones at .910 are ones that I have been close up and familiar with for many years and they recieve the concentric pin devices for tapering to final.
Many cue makers order shaft wood and start building cues with new blanks. I hand pick my planks, cut them on the bandsaw and then put them through my doweling machine before the initial tapering begins. Also my wood is killed dried and all the wood is from Iron Mt. Michigan where the iron and mineral content is very very high creating very dense hardwood. Then I select 5/4 planks not 4/4 and I get about two or three planks per bunk inspected which is about 200 boards. Perhaps this can be the step that some have said I may be omitting from my method that is integral to my overall system. I also coat my blanks with wood hardener between all cuts.
When you buy a cone from someone else you have no knowledge of it's perigee or how it has been processed to the form you have received it. Who knows?
JMO Respectfully,
Rick
