View Full Version : Please Help with bit size ASAP!!!

03-06-2002, 02:40 PM
I just got my pins and tap from atlas… they look good, I got 3/8"-10 tap and pins… to use for my sneaky petes. Well, I have a guide my dad brought from his machine shop that tells me what size hole to drill before I tap out the threads in the shaft, and or butt of the cue, but 3/8"-10 is not in the book, does anyone know what size bit to use for this?

03-06-2002, 04:14 PM
Well thats an interesting question. It's a special thread
and I'd think if you called or emailed anyone that used that thread you'll get the answer. q-guy or Blackheart has the answer. I'm kind of curious also, I figure it to be an I drill or .266 diameter. But I can't get to the bottom of the threads to be sure.

03-06-2002, 04:36 PM
5/16" should work as a start. Do a test on a scrap piece of Maple. If the thread is too loose, try reducing the tap drill size about 0.005" at a time or there abouts. You'll find a size that will work for your application. Also, keep in mind that you cannot use a normal lubricant when tapping wood! But that said, I often will use a little bit of wax on the threads to prevent tearing.

By the way, don't be too surprised if the quality of the threads cut with a 3/8 x 10 tap is not as good as you expected. Almost all of the custom cuemakers that use the 3/8 x 10 do not cut the threads with a tap at all! Rather, they use a tool post grinder mounted to the carriage of the lathe with a cutting tool that has the desired thread profile ground into it. Then the threads are cut using the thread cutting grears of the lathe. But this is usually done with a metal cutting lathe, not a cuemaking lathe.

The best wood to wood thread that I've seen cut with a tap is the Radial pin (by Uni-loc, available from Atlas). More expensive to be sure, but you will get a better result when using a drill and tap.

Good luck!


03-06-2002, 05:26 PM
I used a bit that was way to big, ad the threads barely cut, so i have to try again...

03-06-2002, 05:40 PM
Do not drill a 5/16 hole. The root diameter of the 3/8 x 10 pin used for cues is unique and is smaller then other 3/8 screws. You drill a 9/32 hole or .281 These bits don't usually come in a standard drill set. You may have to go to a machine supply. Bits come in different lengths. Buy the shortest to do the job for better accuracy.

03-06-2002, 06:17 PM
Let me add when you are getting that other bit also get a 17/64 for drilling a hole for the 5/16 x 14 pin and a 7/16 x 14 tap for the insert. You just drill a standard 3/8 hole for the insert and tap it. You probably already have one of those. I will instant message you in the future.

03-07-2002, 12:03 AM
"The root diameter of the 3/8 x 10 pin used for cues is unique and is smaller then other 3/8 screws."

I imagine that you are right. I've never tapped a 3/8" pin, I've only ever machined one. So I defer to your expertise!


03-07-2002, 01:08 AM
Rule of thumb is to drill a hole 75% of the screw size but that is usually referring to tapping metal. You are right about tapping wood with the 3/8 10 taps. They want to tear out wood. I don't use a 3/8 x 10 much except for some sneaky petes. In the butt it doesn't matter you are just gluing in the screw. In the shaft I have had good luck first drilling the hole. Then saturating it with Hot Stuff super glue It is very thin and soaks in. I then put the shaft back in the lathe, (tapping must be done in the lathe to get it perfect). And tap the hole. The threads look perfect. If I were really going to use a 3/8 x 10 pin on any high dollar cue though, I probably would mill the threads as you said. Using the radial screw is like stealing they are so easy to use. I love them, the work comes out so precision.