Some questions on threading titanium

Looking at threading 1/8 dia commercially pure titanium with a Geometric die head, thread is 5-40. Any suggestions on fpm I can crank into a formula I have here, or directly suggest a good rpm to start out at?

Would appreciate suggestions on lube too. Don't have much selection on hand, probably best of what I have would be Moly-Dee.

Last, would be using a Geometric head on an Omniturn... Never done this, I assume I would program a feed per rev that is slightly less than the pitch, letting the head float out a bit?

Part goes into musical instruments, not terribly critical in terms of stress, but do need a nice clean thread.

Thanks,

Jon

Jon Anderson wrote in news:MSWol.233925$se4.56065 @en-nntp-03.dc1.easynews.com:

Titanium likes to twist off if it's a long thread.

Thanks all for the suggestions. Material will be here tomorrow and I'm anxious to give it a try. I've been modifying titanium screws that my customer buys from a US supplier, that gets them from Germany. The supplier is out of stock and doesn't know when more will show up. His other alternative is a source in China. Under $2.50 each, in quantities of 1000, a 3-4 year supply.

I've established a great working relationship with this customer through design assistance and quality/delivery. He'd rather pay me more and have a reliable local source, buying as needed. So, if this works it'll be one minuscule victory for US based manufacturing...

Jon

---------- Not to reengineer your process/product, but have you considered thread rolling? Generally produces a superior thread to cutting.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

I discussed that with him, including the not insignificant cost of a thread rolling head. The quantities are likely to be pretty low overall. Maybe 300 pcs/year. Be nice if this Geometric head I bought some 6 years ago can finally pay for itself.... BTW, the German sourced screws are cut threads.

Jon

Just cut my first thread, and it was a total breeze. Threads look polished. Thanks again to all for the help!

Jon

======= Good to hear that American know-how and craftmanship came through again. Thanks for the follow-up.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

What did you use?

Geometric DSA head, 6-40 chasers adjusted down for the #5 diameter, Moly-Dee for lube. Being too lazy to reset the cam on the speed changer on my 50+year old chucker, I ran at 125 rpm it was set for on low. This was just to see if it was going to work out for me at all. I should be able to run about 600 rpm. But it's a low volume high value part, so I'm not going to push things too hard since I'm getting such a nice thread now.

Outside of making my wedding bands of Titanium, I've never machined it before.

Jon

Thread rolling Ti works pretty good, but it depends on the size. Ti doesn't like to be formed. The more you try to push it, the more it will fight back. Thread rolling works quite well on smaller pitches, but when you get up to pitches over 32tpi, you're simply trying to move too much material. I've had good luck with the tiny pitches, 120,

=46or the larger pitches you're better off cutting the threads, either with thread chasers or single point (depending on the quality thread you need). You're trying to move/form much more material, and like I said, the Ti will fight back. As in spring back, once the roll has made it's initial pass over the material. Consequently, as you reverse the spindle and feed off the part, the rolls are actually forming more material. You'll find that the thread is good at the beginning, but oversize towards the back. (unless, that is, you're using something like a Fetti releasing head)

The 5-40 thread Jon needs should be a piece of cake to thread roll. You can use a cheap floating head like the Habegger:

Matt

Titanium is pretty easy to cut. You need to use razor sharp tools, use slow to moderate speeds, and be rather aggressive with your feedrate, because it will work harden unbelievably fast.

Matt

------- Thanks for the insight and practical experience.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Thanks for that link, bookmarked for future reference. The Geometric head opens, so there's no dragging backward.

Learned about the work hardening making my wedding bands! It not only work hardens quickly, but is a real pain in the arse to get a good polish on. I found I had no choice but to start with 400 grit wet/dry paper and work my way down to 2000 grit. Even at that, under a microscope, it's not as polished a surface as could be readily achieved with most other metals.

Jon