Mounting and flange threads

[pgk]

I have a few Victorian era lenses (1860~1900) and need to have some mounting flanges made. Is there any resource which specifies the threads used by the various manufacturers? I can measure the outer diameter of the threads easily enough and will get a thread gauge to work out tpi, but what of the thread angle? Was 60 degrees used as a 'standard' before ~1900? if not what other threads were used. I query if there was any standardisation because I have items with threads from different manufacturers, and at least a couple of decades apart, which seem to be the same so it would be really useful to know specifics to discuss my needs with the machinist who will make the flanges.

[Jim Jones]

Matching the thread angle is not critical where modest strain is imposed upon the threads, as in mounting lenses. Master machinists may disagree, but good enough is usually good enough.

[Jac@stafford.net]

it would be really useful to know specifics to discuss my needs with the machinist who will make the flanges.

Hand the lens to the machinist. They have the precision instruments to measure and they know the appropriate allowances which are, as Jim Jones mentioned, rather generous for our application.