Parametric 90 degree Bevel Gear Profile w/ FCGear

thingiverse

The geometry of bevel involute gears has been a mystery to me since I started getting into 3d printing even with the help of FCgear and the gear generated just doesn't look like [real-life bevel gears](https://stahlgear.com/wp-content/uploads/2019/08/Stahl-Gear-Bevel-Gear.png). So anyway, I came across this [video](https://youtu.be/1x-a8exa3mw) during my research and used the geometry explained to create this FreeCAD file to generate a pair of 90-degree bevel gears, driven by the parameters entered in the spreadsheet. It should calculate the pitch angle for each of the gears and generate the classic bevel gear profile. The thickness can be adjusted as well to make sure the mounting distance is a nice number to fit your design instead of some irrational number driven by some trigonometric functions. (I am reasonably confident at my back-of-the-envelop-geometry, but the calculation time for testings does add up so I haven't tried that many scenarios. Let me know if anything breaks.) All the parameters that need to be changed are in the left table. Some of them are driven by formula to prevent them from exceeding the physical limits and immediately break the sketch. The table on the right-hand side does the rest of the calculation and some helper calculations. Changing those numbers might cause things to break, so feel free to do whatever you want. **Make sure you have FCgear installed on your FreeCAD** as that is used to generate the actual gears. I have tried to understand involute profiles enough time to know it is time to give up. It looks like the fundamental geometry is quite similar for odd angle bevel gears. I might give that a crack next time.