Wanted: Fitting Air pump

[Mike K]

Originally Posted by Larry Mass

I have just picked up the fitting that Robert sent me I did some measuring the bolt has 18 threads per inch and is 1/2 inch in diameter, hopefully there is some other applications that uses that same size and thread.
Cheers
Larry

Hi Larry

That seems to be a oddball BS electrical fitting thread.. or conduit thread.

It doesn't measure up as being: BSF, SAE, UNF, UNC or NPT, BSP..

18 tpi 1/2" is a very unusual size. Measuring threads is a tricky job, I've been caught out a few times , I now use a magnifying glass and callipers. The thread cutting is done on a lathe , you don't need to begin with a bolt with a specific size thread, lathes have the ability to cut many sized threads , both Imperial and metric. This lady explains it https://www.youtube.com/watch?v=q7scadYptTI