>Some years ago in the dim past when production and shop machinery was
gear driven, it was somewhat common for companies to use odd ball threads
that were not "standard" to the industry. Another example would be the
threads used on gasoline pumps and hoses. These were threads that fell
"in between". This meant that the average feller could not run down to
the local machine shop and have parts made or repaired. Instead, a new
"factory made" part would have to be ordered and purchased. Today with
the use of CNC lathes (computer controlled) all threads are generated by
using the "lead" (pronounced leed) method. This is 1 divided by the
number of threads. So a 20 thread per inch screw would have a "lead" of
.05 of an inch, or 50 thousands of an inch. (Note: Metric threads are all
given by "lead", not threads per meter, or anything like that). This
"lead" system is true regardless of the diameter of the shaft. Usually
the decimal accuracy is carried out to 5 or six places, so the 23 TPI
would have a lead of .043478 inch. The error by rounding at this point is
insignificant. Modern machines have no problem running ANY thread on ANY
shaft because of this. BTW...I researched and could find no "known"
source common to industry that makes a die of this size. Re-cutting an
existing or damaged thread is expensive due to the time involved in
setting up. The thread cutting tool must be perfectly aligned with the
existing thread. This is true of ANY rethreading job, manual OR CNC.
That's my 2 cents worth. I will now fade back to the rear of the
room.........W8FAX
----- Original Message -----
From: "Rich" <rdjmgmt@socket.net>
To: <amps@contesting.com>
Sent: Monday, March 13, 2006 3:58 PM
Subject: Re: [Amps] Proof of idiocy
>
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