If you’ve spent any time in CAD software (Fusion 360, SolidWorks, or even FreeCAD), you know that making a spur gear is relatively straightforward. You draw a profile, extrude it, and you’re done.
: Users typically define the number of teeth, module (metric) or diametral pitch (imperial), helix angle, and pressure angle. helical gear generator
When you have a small number of teeth (e.g., 12 teeth), the root of the tooth gets eaten away by the generation process. Your generator needs a minimum tooth count warning or an automatic profile shift (addendum modification). If you’ve spent any time in CAD software
A: Theoretically up to 45°. Above 45°, axial thrust becomes enormous, and the gear becomes a "cross-helical" (screw gear) with very low efficiency. When you have a small number of teeth (e
The tooth profile in the transverse plane is an involute of the base circle. Parametric equations for an involute point at radius $r$ ($r_b \le r \le r_a$):