This has been a bit of a challenge for me. I use modified 3/8 10 with a smooth barrel. The hole is always straight as the pins always turn with less than .001 runout on the tip dry. I have drilled them with a three flute carbide bit, bored them, reamed them. Tried it all and it's all straight.
I have tried a tight fit, a thou or so of clearance, a deeper barrel hole, a deeper threaded end. The problem comes in when gluing the pin in. My pins have a glue relief slot. I have used 5 minute epoxy, 20 minute epoxy, west systems, max 1618. After I put the pin in with the glue I can chuck it up and it's usually off by maybe a couple of thou max. I can push it over with a tiny thumb pressure and get it turning within a thou every time. Baby sit it for an hour with it sitting in the lathe and it's still dead on. Take it out of the lathe and stand it on end and the next day when the glue is cured the damn thing might have three thou of runout at the end of an inch of pin sticking out. Now of course this doesn't make the cue crooked as the joint faces take care of that and you really can't even see it with your naked eye spinning but it's frustrating as of course I want it perfect if possible. I have checked a lot of pins on other cues and they really aren't as good or better but that's not the point.
Any tricks or tips?
JC,
I feel you pain and had to learn my o
wn method.
For many years I was tapping the bottom of the hole and I aimed for a close fit when boring the barrel dim. After about 150 cues under my belt I saw this as the root cause of my inability to see zero tro after the epoxy cured.
My corrective action was to eliminate the bottom tapping and create the barrel dimension .010 oversize to allow for tweaking the pin while indicating during the curing.
The lessoned learned by me was i am able to build my last 100 cues or so and ship them without rolling them to check them on the table or the rail.
Before It was hit or miss for trying to get zero run out. Then I started do this procedure and I never looked back:
Chuck up the cue and shim to zero run out + or minus .0005.
The barrel on my pin is .375.
Drill .312 to 1.3 depth
Bore to .350
Follow bore with a .384 stub drill
I do not tap the bottom of the hole
This gives me a .005 annulus clearance in the bore. Then I heat up 30 min epoxy to over 100 degrees and mix for 30 seconds.
I take a heat gun a and focus on the barrel and thread area of the pin to get it to warm to 100 or so.
Fill hole with warm epoxy and fit pin to the bottom burping any internal pressure in the hole.
I use a dial indicator calibrated to .0005 increments.
Then for the next 20 minutes I check the pin and am pushing the pin 1/2 way between high and low point over and over till the the distance is only about 2 thou.
Then I turn the lathe on at my slowest rotation speed and turn it off every minute to push the pin about three 3 more times.
When I get to zero I turn the lathe off and let the cue stay in that lathe for at least 1 hour.
When I reChekck the pin before extracting the cue from the chuck is always between zero and .0005. Once and awhile it stays on zero after curing.
Root cause of my woes before this procedure was by trying to keep a tight bore fit to the barrel and tapping the bottom of the hole, I was screwed sometime because if my bore was canted even a cunt hair I could not force the end of the pin in one direction during the Chem cure because of the tight bore fit.
By allowing the 5 thou annulus float, my y and z axis was able to be tuned in while the epoxy cured.
Today I have eliminated the shimming of the cue in the the chuck since I purchased a Hardinge secondary tool room lathe with collet chuck ( thank you Jeff Prather and his Dad ) and installed new bearings. Because this awesome lathe has as zero run out as i have ever seen. ( the indicator only trembles on the .0005 line of my dial at 1500 rpm ) I only experience a slight error of between 0 and .0005 after the cure takes place. This is a good indicated measurement with out compound error from a shimming process that is hard to reach that close to zero.
That's my story and I am sticking to it. LOL.
Good luck.
Rick
Center drill