I need pitch diameters for unusual external and internal Unified Screw
threads that aren't in _Machinery's Handbook_, which glibly says, "Thread
data for special combinations ... are also given in the Standard but are
not given here." This is for optical instruments that use ultra-fine
threads. Examples would be 2"-40 (typical inch size), or M58x0.75 (typical
metric size, like a camera filter thread). The handbook is rather poorly
written concerning the exact standard used to make the tables, but it
appears they mean ANSI/ASME B1.1-1989, "Unified Inch Screw Threads".
[These organizations want to monopolize technical information by not
publishing it except on costly paper versions.]
Anyway, the formulas for the external vs internal pitch diameter are hidden
in "the Standard" which doesn't seem to be available online. All I want is
the formulas. Anyone have this information?
17 years ago