I'd used a digital caliper, 5/16-32 screw, and an Enco/India gage, and the
thread count wasn't obvious over the short section of thread.

I've been aware of the close aproximation of 5/16" and 8mm as far as wrench
sizes and fastener diameters, although just not familiar with the 0.75mm and
other fine thread pitches (apparently there is also a 0.5mm pitch but don't
think I've encountered that).

The threads mated eventually, after running the tap thru the part
supplemented by
a little pushing and pulling applied to the tap.

I'll make another workpiece when I get the correct taps and use the goofy
one for something else, 'cuz in HSM metalworking, there really isn't much
that needs to be scrapped.. nearly everything can be repurposed.

--
WB
..........


"Bob La Londe" wrote in message
...
"Doug Miller" wrote in message
. ..
Counting the threads in 1/2" is sufficient to tell the two apart: 16 if
it's 32 tpi, 17 if it's 0.75mm
pitch.

Where ever possible I use a thread gage. If it doesn't fit cleanly that
isn't it.