Cutting threads with a milling machine - GIF

[Altair]

Cutting threads with a milling machine.




Previously:

Thread rolling cylindrical dies - GIF
80 threads per inch fastener close-up - photo
Thread rolling machine - GIF
Bolt threading GIF

[hemmjo]

I have often wondered about doing something similar on a lathe with a cutter like that in a tool post grinder. I guess I will just go buy myself a CNC mill instead. LOL!!!

[Elizabeth Greene]

I've heard this called threadmilling. The appeal is that if the cutting tool breaks off it is a lot easier to get it out of a hole compared to a tap.

[old kodger]

Yeh, and the thread is only worth $100,000.

[hemmjo]

Yes but think of all the trips you would save running to the hardware for the right size bolts!!

[dagrizz]

Actually, the idea of adapting a post grinder has merit; the only problem I can see with the one I have is that it's limited to 1/6" - 1/4" shank tooling. You would definitely want a good carriage stop, though. And maybe a REAL slow lathe for us chicken-types.

[hemmjo]

I am fortunate my lathe has variable speed belt drive and I got a VFD to run the 3 phase motor it came with. I can put it in back gear, set the VFD to low speed and the variable belt drive to low speed, I have never measured the RPM but it is very slow.

You can also set the VFD start and stop speeds individually, for example slow start and quick stop, where the VFD actually will feed the motor with a bit of REVERSE to stop near instantly.

You can get a thread mill with 1/4" shank, for small pitch threads.

[Elizabeth Greene]

And maybe a REAL slow lathe for us chicken-types.

It's grinding, so the cutting force is practically zero. You could do it with the lathe off and spinning the chuck by hand.

[old kodger]

"You would definitely want a good carriage stop,"

Why would you not start at the chuck end and cut away from it.......lathe in reverse and tooling at the back of the job?

[hemmjo]

If you are cutting away from the chuck, with the spindle in reverse, using a milling cutter, you do not need to be behind the workpiece.



I have never done this. But the idea is intriguing.

John