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Re: Drill size for 1/8" NPT tap?

To: "Ken Landaiche" <ken.landaiche@dlcc.com>,
Subject: Re: Drill size for 1/8" NPT tap?
From: "Tony Clark" <lotus.tony@airmail.net>
Date: Fri, 18 Dec 1998 17:29:40 -0600

-----Original Message-----
From: Ken Landaiche


>What do you mean by "respect the taper"? I have tapped straight holes,
>so I have the basic idea. But I never did a tapered hole.
>
>Ken Landaiche


Oops!  Now everyone is gonna think I'm a plumber!

The acronymn "NTP"  (National Tapered Pipe) is the clue and to quote our
fearless leader, Carroll Smith:  "The threads themselves are so designed
that the male thread is an interference fit in it's female counterpart".
It's what keeps ordinary supply plumbing of (some) water and gas lines from
leaking.

The reason I warned Chris to "respect the taper" is that I've seen a few
botched jobs which resulted from oversize tap-drills and/or overzealous
tapping which resulted in threads which could not effect a seal.  There is a
varience in the taper and in the shank length of the male fittings which can
also "screw you up" (!)

Carroll continues:  "I flatly refuse to use pipe threads on high pressure
sustems.  etc., etc."

Tony



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