Three-Wire Thread Measurement
Three-wire measurement over a 60-degree thread.
Example
You enter
- Thread standard inch
- Threads per inch (TPI) 13
- Pitch diameter E (in) 0.45
You get
- Best wire 0.0444116
- Measurement over 3 wires 0.516617
Details, formula, and sources
Best wire W = 0.57735 x pitch, acceptable wire range, and measurement over three wires M = E + 3W - 0.86603 x pitch from the user-supplied pitch diameter (first-principles thread geometry).
Best wire W = P / (2 cos30) = 0.57735 x P (range 0.560P to 0.650P); measurement over three wires M = E + 3W - 0.86603 x P for a 60-degree thread.
The three-wire measurement-over-wires method for 60-degree threads and the best-wire / 0.86603 constant - first-principles geometry as in Machinery's Handbook (Industrial Press), by name; public domain.
Pure geometry, public; the pitch diameter E is user-supplied (no thread-class table lookup here).
Estimate. AHJ and licensed professional govern.
Field names used by the API: thread_standard, tpi, pitch_diameter_in, best_wire_in, measurement_over_wires_in
- Thread form 60-degree included angle (UN / ISO metric); the pitch diameter E is user-suppliedthree-wire geometry