Problem- Threading 99.9% Tungsten Rod?!?!?!

[stuby]

Hello. I have a customer who needs me to cut threads on a pure tungsten rod. I have machined I.D./O.D. on it before, and as usual, sharpen the tool many times, and go slow. But, I need to cut a 1.25-18 thread on the O.D. I have carbide inserts that I have been trying to use, but to no avail. The insert breaks down, and tears the sides of the threads, causing the entire outside edge to tear off, ruining the thread. I have read a few posts around that say the only way to cut a useable thread into pure tungsten is to grind it; and I would really like to single point it if at all possible. I have been told to try some Poly-crystalline diamond coated inserts, however they cost a fortune, and Id love some input from you guys before I buy a $155 insert.


So I guess my question really is....Can you successfully single point a thread into tungsten, or should I stop wasting my time all together? Any help/input at all would be more than appreciated.

[PEU]

I think tungsten is machinable, not a piece of cake, but doable nevertheless, what is really hard is tungsten carbide, but thats another story.


Pablo

[stuby]

Thanks, but as I said, I already machined the OD/ID, but I cannot thread successfully on it. I have had several people tell me to use Poly-crystalline diamond inserts, however Id like to hear some imput on them before I spend $155 on a single insert. I can machine a diameter just fine, but as I said, having real problems with threading it. I had an old piece of hardened 4140 that I made a test thread on, and it fit sweeet, but the tungsten is apparently a lot harder, heh. Anyways, thanks again.



EDIT : Someone also said, if I can find any Triple 9 carbide inserts. They say they are old inserts which are 99.9% carbide, Ive never heard of them before; Anybody think they will cut it?