View Full Version : Tapping Pipe Threads in Yup Stainless

03-18-2009, 03:38 PM
Im doing 3-8 -16 NPT pipe threads in blocks of 304 stainless. NOW i ended up opening up the holes quite a bit bigger BUT have heard of taper pipe reamers>? Now do you guys use these taper pipe reamers to prep a hole prior to tapping larger pipe threads in stainless steel. ?? Thanx I am having quite a time but since i sdtarted drilling all the holes (regular size not pipe threads) its been going way better, Thanx to all for the tips,

03-18-2009, 03:57 PM
Been there done that, too! :)

Oversize holes was not an option as it was for a High Vacuum system. A good sharp tap with the recommended hole size will do it ok. You just have to keep it cutting - no backing it out or working back and forth because it work hardens the material.

I've never tried the pipe reamers on SS. See here, though, for info on using the pipe taper reamers. Someone posted this link a while back. Not sure who, but it went into my favorites!


J. R. Williams
03-18-2009, 04:21 PM
!. Use a standard Pipe Taper Reamer
2. Use a high quality pipe tap with a good lubricant for stainles.
3. Purchase a standard pipe thread gage, (male plug unit for internal threads)

Thread mill the holes.


03-18-2009, 05:44 PM
I've had good luck with the interrupted thread taps in stainless and material as tough as Inconel 714.

03-18-2009, 07:04 PM
I want use any thing but interrupted thread taps in stainless steel. And we tap thousands of parts at work . .