On Mon, 7 Feb 2005 11:53:23 -0800, "Harold and Susan Vordos"
wrote:


"Eric R Snow" wrote in message
.. .
snip----

Since the thread is tapered the depth is controlled by
P.D. (pitch diameter). So, if the P.D. is correct, the depth muist be
correct. Pipe taps are ground this way.

. I bet that if
a tap manufacturer were consulted they would be ablke to send you
written proof that the thread depth of a tapered pipe is controlled by
the tap cutting to the correct P.D.

Yep------and the rule of thumb is to tap until you have 5 threads (on the
tap) above the finished surface, unless you happen to have a plug gage to
check the proper depth. The rule may not be perfect, but it will always
yield a functional thread.

Harold

Harold,
I learned 7 threads. And when I checked this against my gauges it
worked. Most of the time.
ERS