Pantogragh style tracing torch project

[Frank S]

Out of idle curiosity, I spent 10 minutes looking at pipe thread tables. Both ISO & BSP have 19 tpi at that size, but I think the latter would be over13mm

The thing about fitting sizes is to make things proprietary it seems there is always some little something which sets one type of fitting in its own category be it diameter of pitch or possibly even pitch angle. Manufactures seem to love to create their own standard of measurement sometimes combining 1 unit of measurement with another.
It's a moot subject now since I have converted it to the US standard torch hose fitting size.

A couple years back I ran across fastener which was 5/8 12 TPI. my first thought was it had to be a 14mm bolt with a 2.125 thread. It clearly was not since a 14mm nut wouldn't even start over the bolt and a 14mm bolt was loose but bound after a few threads due to the differences in the pitch. SO I ordered the factory bolts and bought a 5/8-12 tap Like TM51 stated who knew that 12 was and odd number.

I have been building several tap and die sets with strange TPI I have a set that is all 40TPI now up to 1" 24TPI up to 1" My 12 TPI set currently goes up to 1-5/8" in 1/16" steps A lot of Hydraulic JIC fittings use the 12TPI above -12 size

Here is a good one 37°and 45° flare fittings share the same threads up to -10 or 5/8" (7/8-14) from -12 or 3/4" ( 1-1/16"-12 for the 37°)(1-1/4"-12 for the 45°)and above, the 45° fittings are 1/16" larger in diameter than their similar dash sized 37° fittings but sitll 12 TPI all the way up