"Ignoramus4181" wrote in message
...
On 2009-03-18, Bill Noble wrote:

"Ignoramus4181" wrote in message
...
On 2009-03-17, Wild_Bill wrote:
Making of a Big Tap at Widell

http://www.widell.com/bigtap01.html


Nice pictures. Interestingly, their grinder was imported by Shars,
which we just discussed here.


also interesting - I always figured you would first turn threads, then
cut
flutes, then harden, but clearly that is not the way it's done - cut
flutes
and heat treat, then cut threads

Somewhat unrelated, but my guess is that it is for a pipe inside a
pipe type of situation, maybe a huge heat exchanger.

--
well, if "I" had to guess, I'd say it is used on a christmas tree
(http://en.wikipedia.org/wiki/Christmas_tree_(oil_well)) but I'm not an
expert on oil field technology