Threadmilling Acme Threads

[Michael Sullivan]

Anyone out there Thread mill internal Acme threads before?

I have to mill 3/8-12 through 1" of 17-4.

Can't find much in the line of tools. it's been done here before I came but they used some crazy half a** offset lathe threading tool and an offset bushing with lots of manual editing to the NC and a lot of good luck during the setup it seems. Not a Pretty sight.

Some how it worked which I am getting a little closer to understanding now but I was hoping there was a better tool out there for the job.

Any Ideas?

 

Thanks,

 

-Mike

[mtnflyr]

We use a lathe 1" dia. boring bar with an Acme threading insert mounted in a solid mill holder. We measured the cutting dia. on a presetter and programmed the cut by that. We are cutting plastic with it but I think the setup would work in any kind of material. It's been working great for us. If you need more specifics I can find the tool to get you insert and bar type.

[Guest CNC Apps Guy 1]

I've always use an ID boring bar and single point'ed it. Worked every time like a charm.

[Michael Sullivan]

Because on the size of the minor diameter(.296)

I need something no bigger than that.

[within a thou]

If you have a tool grinder and a shadow graph you can get a carbide blank grind it to your pitch reduce the rest of the shank to clear your minor put it in a boring head and run it in a G84 on a mill adjusting the boring head to bring it to the proper size.

[mtnflyr]

Sorry Mike. I didn't focus on the size of your thread. I think for a thread that small I would rather tap it. I haven't tried it myself, but I found these Acme taps you can check out.

TAPS

 

HTH

[Michael Sullivan]

Thanks for the Link Chris. I do have a couple if these taps and thought about trying to use them in the machine but I would have to tap more than 3.5 deep in order for the threads to go all the way through. I don't have that much clearance under the part in the vice to do this so I would have to tap them all by hand. It's just a really ugly scenario.

I'm thread milling it with the hokey setup I have now But I have to do a lot of manual editing and I'm trying to sneak up on the thread fit which requires countless attempts of toolpath editor changes, reposting and MDI editing .

I think I will get it eventually though.

I'll update when I finally beat it.

Thanks for the help guys,

 

-Mike