F. George McDuffee wrote:

On Fri, 13 Jan 2012 16:01:25 -0500, Randy333
wrote:

I need to do some thread milling, never did it before!! I need to cut
2- 1-1/4"-11.5 NPS exteranl threads, a 1-3/4"-16 external and a
1-7/8"-18 internal thread.

I found a thread mill for 11.5 NPS but in the catalog it's listed as
internal only, why? Any place I can get this at under $300 bucks that
MSC wants?

Remove 333 to reply.
Randy
====================
If these are one off you may consider a single point tool or
boring bar with formed cutter. Slow machining but cheap
tooling. Should also be good for special profile threads
like stub acme or buttress.

There are single-row thread mills that can do a fair range of thread pitches
with one tool. They generally are cheaper than true threadmills, too.
I have a small Micro-100 single row threadmill, and it works great.
I have only done internal threads, but I think that tool should be able
to do either.

Jon