Point of Clarification
Hi,
It depends how good your RMS finish is on the shaft after the last pass and how much sanding need to be done to have a smooth finish ready for burnishing.
I used to use a router on a lathe saddle with auto feed and I had tiny little lines that had be to sanded down in the center of the shaft especially. I would have to leave quite a bit on for sanding.
When I changed to my table saw shaft machine with 80 carbide teeth, I bring the joint to about .002 over and sand in my shaft just a little for a very smooth finish.
It all depends how well your set up works and how much sanding you need to do. The less sanding you have to do the more consistent you shaft geometry will be.
Rick G
Excuse me for quoting my own post but I need to share some information and make a point of clarification.
After making the post above I received a PM for someone that I don't know but is a fellow cue maker here on AZ. He accused me of bullshitting Trent who was asking a question about landing a dimension and sanding tolerances.
I should have included some more information to illustrate my procedure concerning what you do before and after your get the the final number because therein lies the details of the info this guy was after.
I have left the name of this person out of this post as I never nor will never flame someone.
Here is his PM and my answer that may be something other cue makers might want to try:
name removed said:
.002 that is such bullshit you should buy a new caliper or a new realism to what you are telling people
a sheet of paper is .001 from enco im sure you can sand and feel that last .002 in .
that is pathetic that you put that out and people believe that.
get real
Here is my reply to the PM:
Hi,
For the record, my table saw shaft and butt machines are so accurate and precise that we land our shaft collars on the money +.002 over my desired landing number .841 and just barely touch the collar with sand paper later as they are as close to perfect as obtainable coming off the machines as far as concentricity is concerned.
We don't turn our shafts into the cues or use sanding mandrels like most cue makers do as we use a center alignment pin jig (one of our pins cut in half with a 60 degree center drilled into a the face of the middle cut off section).
When the shafts are inserted in the shaft tapering machine the outside diameter becomes concentric with the inside centerline within the thread center of the shaft joint. This technique is like boring in reverse and is very accurate because my pins have such a tight interference fit. We also engineer tolerances and grind CNC drill taps for this reason.
Conversely when our butts are tapered down to the final number by + .002 it is also spinning between centers with the joint pin installed before tapering. We sand the shafts very little before burnishing as the RMS finish is very good. This helps us maintain a repeatable geometry on the taper. I only touch off at the joints as a prep for the epoxy sealer base coat. Hence the .002
When we sand our shafts, I leave the pin centering device in the shaft as the driver on the live side of the wood lathe and this ensures that I will not go eccentric after coming off the tapering machine.
Again, I don't rely on a chamfer cut on the face of the threads to act as the alignment driver while tapering or sanding. We are aligned by the insertion of my pin on a zero degree axis to the centerline of the shaft before the taper is executed.
When we join our shafts to the butt to verify the concentricity and dimensional sizing, it is on the money and is repeatable every time.
I guess I should have posted some extra details. Sharing info and our method with Trent (a fellow CM) was my only intent.
As for you, I would have appreciated a more civil and respectful debate or argument demeanor while asking me a question or are making your point. You lose all credibility to you persona and character when you judge people or call them names before you get all of the facts.
As for me, I am not the smart guy here. I am lucky to have a partner who was a Tool & Die engineer for 40 years as my mentor.
Rick Geschrey
PS
Note to fellow Cue Makers:
I am not the type of person who ever tries to hide so called inside information or secrets concerning our trade. I have learned so much here on AZ from so many people that not sharing info is not in me.
Mr. Hoppe is my close friend and builds some of his his cues at our shop and he can attest that there is no intention by me to bullshit anyone about sharing information here.
One of the biggest problems I had to overcome concerning repeatable process control was in the area of joint concentricity. After many sleepless nights pondering this issue my partner Ray introduced me to this simple idea to use the pin jig that I described in the above.
I have queried many CMs and all have talked about sanding mandrels or described their way of turning the shaft into the cue while holding the butt in the chuck and rear chuck while the shaft is connected and centered on the tail stock. This is also what we were doing until about 2 years ago. The new process eliminated the hassle of all that.
If anyone is interested in this stuff, let me know and I will post pictures of the close action of this procedure on a new thread.
