Parametric Bevel Gear

A parametric 90° bevel gear, made with the involute curve tangent line [approximation](https://nptel.ac.in/courses/116102012/40), as Fusion 360 doesn't support equation driven curves (yet). Module, number of teeth, height, bore diameter, and pressure angle are adjustable parameters.

See Bevel Gear Test Model: https://www.thingiverse.com/thing:3336653

GitHub: https://github.com/vsergeev/3d-gears/tree/master/parametric-bevel-gear

Design on A360: https://a360.co/2F2h44H

### Usage

Standard ISO gears are specified by two top-level parameters: gear module and gear teeth. Gear module is the pitch of one tooth on its reference diameter, and should be equal between interacting gears. Gear teeth are chosen to achieve the desired gear ratio between interacting gears. These parameters are exposed in the design as `BEVEL_GEAR_MODULE` and `BEVEL_GEAR_TEETH`, respectively. Since this design is currently fixed to 90° placement of interacting bevel gears, `BEVEL_GEAR_TEETH` should also b