What I see as the problem with the razor blade idea is that it is
dependent on the shape of the tip of the tool cutting the thread. Any
wear and you are getting off in diameter. And if you were cutting a ASME
thread rather than a sharp Vee thread you would have another difference
to contend with. I believe that there are thread wire sets that hold onto
the calipers for easy measurment of the most critical dimension. However
if you can cut one to fit and measure it in a consistant way then
subsequent ones should trach that measurment.
Bill in Boulder "Engineering as an Art Form!"
