LEAD ANGLE

What bolts are these? I don't think M15 is made (though there may be a design for it). M18 is available but is non-preferred (M16 and M20 are preferred).

And pitch is not 1mm. Pitch of coarse metric bolts is usually 1/8 nominal dia. (M16 has pitch 2mm, M20 2.5mm). Metric coarse threads are normally used, fine is special. Fine is about 1/10 nominal dia. if I remember right, I haven't got the data to hand.

Cheers........Codey

It seems fairly obvious that the threads are non std or "bastard" threads.

Here's a fairly comprehensive list of threads arranged by size.

Useful list! I thought after posting that I'd jumped to the conclusion he was talking about bolts, when he hadn't said so. There are also metric electrical threads which have different nominal sizes from (preferred) bolt sizes, and have much smaller pitch than bolts.

Cheers..........Codey

"There are also metric electrical threads which have different nominal sizes from (preferred) bolt sizes, and have much smaller pitch than bolts"

Yup ..Fine metric threads might well be the norm in electrical applications or other specialised areas.
Glad you liked my threads page.