View Full Version : 316 s/s pipe

10-28-2008, 06:14 AM
Threading some stainless 316* pipe today (*pipe was made in Taiwain)
Making "close nipples" 3"-8tpi
Flood coolant and using kennametal NR-3 inserts grade kc5052.
Lots of tearing and poor finish.
Tried from 120 to 500 rpms

Running on a 11" swing lathe via Mach 3
Did these many times before with no problems
Wondering if it is the "steel". First batch I tried from Taiwain
Or should I try another grade/style inserts


10-28-2008, 09:55 AM
eddie, I would suspect the metal as you do. Have you tried taking finer cuts and/or raising or lowering the cutter tip? I found the only way to cut threads on some SS and Monel was with cuts of .002" each pass. Any more and it would rip metal out of the thread.

I am using a Dorian insert threading tool holder but not flood coolant, just paint it on with a brush.