Re: Acme internal threading tool(s) needed

Tom Accuosti wrote:

I've been pricing out multi-lead Acme taps lately, and they're outrageous in price and in lead time. OTOH, I've been looking at teeny stuff, like 1/4" and 3/8", not big stuff.

2 1/2" thread depth sounds like a lot, but at 1.25" ID, the boring bar should be stable enough for you. But the *real* problem is going to be figuring out the lead and helix angle. We do a 3/8" 5-lead part in a Delrin-like material, and if you ask me, we're more broaching than cutting. We drew the part in Cadkey and then unwrapped it to figure out how to cut the front angle.

The other problem that you might have is that the lead may well be near the upper end of what you can cut with a thread cycle. Our Omniturns have a 300 ipm max, so it took about 2 minutes to cut these. Remember, too, that each lead has to start a little further back from the front of the part so you end up with a lot of non-productive time.

moT




It's just a single start thread. Minor diameter tolerance is 1.050 to 1.060 inches. The helix angle has eliminated a lot of tools we have found. 3.28 degrees IIRC. I've got 1200 IPM, and I've already tried the program at 360 sfm with a tool that didn't work. I think the IPM was around 216 when threading.

--
Steve Walker
res6nlr2@xxxxxxxxxxxxxxxxx (remove wallet to reply)
.