When creating helical gears:
It is necessary to understand the difference between transverse and normal diametral pitches. The normal diametral pitch is defined as normal to the cutter. The transverse pitch is on the plane of rotation.
Normal diametral pitch = Transverse diametral pitch / cos(helix angle)
If Diametral pitches are selected, the drop down box displays the transverse pitch and the Diametral pitch box displays the normal pitch.
If Module pitches are selected the drop down box displays the module transverse pitch and the Module pitch box displays the normal module.