[js machine]

Just wondering if anyone can give me some advice. I'm tapping 440C stainless with a Haas SL-10 lathe and have busted many taps. 0-80 thread .17 deep.

[mad mark]

I use a 0-80 coated roll form tap, #54 stub drill .055" dia. @ s3000rpm f1.7 q.025. Rigid tap @ 1200 rpm. Watch your drill dia. really closely!!!

Mark

[msomerville]

I agree with the above statement about roll form taps. If you could add High Pressure coolant also that would make your day that much better

[Delcamfan]

Generally roll form is form aluminum and some other alloys, not stainless.......I would switch up and cut the material with a gun style, coated, carbide..not roll form

[HuFlungDung]

Can you switch the job off to a mill? You need to be super extra fussy about getting a tiny tap like that perfectly centered. Maybe you are lucky

I would also use a sulferized tapping fluid, or an equivalent.

If the hole is blind, you can use a gun tap (pretty difficult to find spiral flute that size) or a hand tap (as a powered tap), and peck tap several times per hole to break the chip so as to not jam a birds nest tightly at the bottom of the hole. Most likely you should blow the hole out periodically if you are lacking extra depth for the chips. You may have to drill the chips out to clean out the hole afterwards.

[Surfacefeet]

I would go with the best quality Roll tap as well.In Stainless we always use Roll Taps for anything under 3/8.No problem on 316 or 15-5 heat treated stainless.

[msomerville]

One of my customers that occasionally gives us some work. He was drilling and tapping the stainless balls that are use in body piercing. He went from 400 pcs per tap to something like 1200 with just adding the high pressure coolant. I have not tried this and I know the tap he was using wasn't quite as small as 0-80 might have been a 2-56 not sure.
All I know is that I have externally thread rolled on titanium and that worked great.