clare at snyder.on.ca wrote:
I think it is also used on some electronics devices - the thread on
some control stems (potentiometers) is 18 TPI from what I remember - I
know neither UNC or UNF nuts fit, and nor do metric standards.

I worked in the electronic field for nearly 60 years and never saw
a potentiometer with a coarse thread. The 3/8 ones were 32 and the
"modern" 1/4 are 40. The damn metric ones I don't know about. :-)
...lew...