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Re: Single point threading titanium tube

Posted: Sat May 21, 2016 10:44 pm
by kbillet
Based on the start of this thread I have question, why would anyone be threading Grade 2 Titanium?

Re: Single point threading titanium tube

Posted: Mon May 23, 2016 7:00 am
by Fulmen
Could you elaborate? I don't understand the question, what's wrong with threading Grade 2?

Re: Single point threading titanium tube

Posted: Thu May 26, 2016 5:12 pm
by kbillet
The tensile strength and yield strength of Grade 2 is less than 1/2 that of Grade 9 that is SRCW (stress relieved and cold worked).
Grade 2 has a tensile of approximately 50,000 PSI. Grade 9 is 125,000 PSI.

Re: Single point threading titanium tube

Posted: Fri May 27, 2016 1:05 am
by joe0121
I have a couple questions based on some advice I have gotten from machinist.

1st .001 per cut is pretty light and I was under the impression that carbide tools dont like light cuts because the tool is rubbing and not cutting.

2nd Those of you using carbide what insert geometry are you using?

3rd. saw where using un coated Carbide tooling was recommended. Would not a small radius tool say a 431 vs a 432 not accomplish the same thing albeit with a little less tool life.

Here is what I was recommended to use for Od turning

"I would find a CCMT turning tool and use Ingersoll CCMT32.51 PC TT9225. Around 125-150sfm, .005ipr and .020" doc"

Re: Single point threading titanium tube

Posted: Fri May 27, 2016 4:01 am
by Fulmen
Kbillet: Grade 2 is still a decent material. I used it for the barrel mount in my 222-silencer because it was available and stronger than the 6000 alu I had. Even if it wasn't stronger than aluminium it still has useful properties like better erosion resistance and lower thermal expansion rate.

Joe: Are we talking threading or general cutting?

Re: Single point threading titanium tube

Posted: Fri May 27, 2016 4:49 am
by joe0121
Fulmen wrote:Kbillet: Grade 2 is still a decent material. I used it for the barrel mount in my 222-silencer because it was available and stronger than the 6000 alu I had. Even if it wasn't stronger than aluminium it still has useful properties like better erosion resistance and lower thermal expansion rate.

Joe: Are we talking threading or general cutting?
Both really but threading in particular I would think a sharper radius tool geometry and TiAIN coating would be useful. Or am I way off? I ask because this is a subject close to my heart as my lathe is nearly back together and I have been googling and studying cutter catalogs recently.

Re: Single point threading titanium tube

Posted: Fri May 27, 2016 9:36 am
by Fulmen
Well, I just cut some 16TPI barrel threads using a universal insert. 0° feed, started with 0,5mm cuts and reduced it gradually to 0,1mm as I was getting close. Turned out smooth as always. For 1-2mm pitch I have full profile inserts, those are the best. Simply cut until the proper OD and you're done, perfect fit without any burrs or excessive deep roots.

For general turning in steel I usually run 1-2mm cuts if possible, depends on the material though. Whatever it takes to get short curly chips. I tend to use a VNMG (35° rhombic) holder for most work, as I have too few tool holders and that one fits almost any job. As far as coatings are concerned it really depends on the material and conditions. Many coatings only perform well at high loads and temperatures, so for fine cuts uncoated might be better. But as I use whatever I can get my hands on for cheap I really haven't looked into this. For general hobby work it really doesn't matter that much, so what if it takes a few minutes longer?

Re: Single point threading titanium tube

Posted: Fri May 27, 2016 10:33 pm
by cdrissel
Been enjoying this thread. Thanks.

A bit off topic - but it involved titanium and threading

Just did some thread milling today - made some custom 1.5" end caps.

20 TPI - three passes - less than 3 min.

Used a .375 micro thread mill. 3000 rpm at 30 IPM