On Wed, 15 Jul 2009 02:09:19 -0700 (PDT), Nicht die Bohne
wrote:

Hello everyone!

I restore vintage espresso machines and right now I have one machine
with really strange threads, which are used on pipe connections. The
machine was manufactured in Italy in the 50s. Here are some examples:

TPI 20 diameter 14.9mm = 0.5866"
TPI 20 diameter 19.25mm = 0.7578"
TPI 16 diameter 20.25mm = 0.7972"
TPI 16 diameter 22.8mm = 0.8976"
TPI 16 diameter 27.7mm = 1.0905"

Does anyone know what kind of threads it might be?

Many thanks,
Julius
========
While this may not be *THE* answer, it is "A" answer.

During the time period immediatly after WW2 many surplus INCH
standard lathes were sent overseas as part of the post-war
reconstruction effort.

In many cases the parts these produced were ******* metric/inch
as you describe with inch threads but metric
diameters/lengths/thread forms, with the inch thread selected as
close as possible to the metric size.


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).