On 7 Feb 2005 06:50:09 -0800, wrote:

I need a bit of advice. I just had a job completed by a machine shop
that called for a 1/2" NTP and 1/4" NPT hole. The part was titled
"manifold". The parts just arrived with the 1/2" NPT hole tapped to the
bottom of a 1 1/8" deep port (will never seal)and a correctly tapped
1/4" NPT hole. The machine shop says it was my fault because I didn't
specify the thread length and I will now have to pay for a "rush run"
if I need to meet my deadline. Isn't NPT supposed to be tapped within a
certain range? Shouldn't they have asked if there was any doubt? I
think that they should have asked. Am I wrong?

I have to chime in with the majority: You called for NPT threads in
the hole, that's what you should have gotten. I might even venture as
far as "someone at that machine shop is a moron", perhaps more than
one. Forget your paying them for a rush job, they should be bending
over backwards (and staying till Midnight if necessary) to make it
again and make it right.

NPT is all you needed to say, unless you wanted something done
differently. The T stands for Tapered, and there is a set standard
for it. If there were any questions about what you were calling for
on the prints, they should have called or written you and asked for
clarification before turning the part into scrap. Especially since
they got the 1/4" NPT hole right.

It works the same way for the male half of the threaded connection -
If I walk into a wholesale house and ask for a pipe or conduit nipple,
I get one with NPT threads on each end, a standard. A nipple cut 50
years ago will thread into (and create a seal) in a fitting made last
week, that's what standards are for.

If I want running threads all the way down the piece of conduit,
that's "allthread" and it's an entirely different animal. They do not
hand you allthread when you ask for a threaded nipple, or vice versa.

I've also worked in a print shop where the same principle stands -
we always got written confirmation of the proof sheet when they wanted
a word spelled wrong, and all our dictionaries and reference materials
disagreed with the customer. That way they couldn't come back later
and ask for the entire print run to be done again for free.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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