vogel_3_wire.exe
3-Wire Screw Measurement Calculator- ver 1.00
(C) C. Hoffman 2010

Freeware with no guarantee of suitability for any purpose. No liability is assumed for any loss or damage
under any circumstances. It is the users responsibility to confirm the output of this program before
making use of it.

It was my intention to write a quick utility for 3-wire measurements of threads. The more I examined the
commonly available equations, the less certain of the results I became. The Van Keuren Company is the
best known source of highly accurate thread wires, and they describe the research of Dr. Werner Franz Vogel
in one of their older catalogs. Dr. Vogel probably made the most in-depth analysis of screw threads any
human has attempted, along with splines and gears. The math was extremely tedious back in the '40s when he
did the work, but today even a slow computer can perform the calculations in a few milliseconds. His
breakthrough was to offer an exact solution, as opposed to various approximations, several of which are
(inexplicably to me) still used today.

The difference between the approximations and the exact solution isn't important for most purposes, but if
you're dealing with multiple start screws having steep walls, acme and trapezoidal for example, the errors
can be of importance.

One note of significance- Dr. Vogel took pitch diameter as a fixed number, with other parameters varying
around it. This is the reason the input requires pitch diameter, and doesn't attempt to calculate it from
other dimensions.

This is a new and untested utility. The results agree with Dr. Vogel's worked examples, but there is always
the possibility of unforseen errors. If you discover any unexpected or unusual results, please send me an
email describing such. (address is on my web site- http://www.conradhoffman.com)

version 1.00   first release
version 1.01   fixed error when angles are small, i.e., large diameter fine single start threads

Enjoy,
CRH
