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I loved Openscad ! For parametric design it is the tool to master. I will need a lot of grear to test my final project design ideas.

I started using openscad with that in mind. Gear design isn’t very easy enough to start using cad tools. So I started designing a manual wave generator. In other word, an eliptic shape that fit into the flexspline gear.

I manage to write this piece of code :

Then I clicked the generate button and… !

This is essentially an elliptic shape with a knob.

Gear library

After a bunch of research I remember that gearing need a bit of engineering to be functionnal :) Fortunately people on the internet are very helpful. I found a gear library for openscad made by eleotlecram on Thingiverse

Using these parameters, I design two gear for the harmonic drive.

The outer gear is composed of 52 teeth, the inner flexible gear is composed of 50 teeth. Both have a module of 1 and a pressure angle of 20°. I used straight teeth.

When a part is finish openscad only allows STL export… Which is frustrating because it meens that only dead solid can be exported. I need to test Openscad module of freecad to see if it use also dead solid…

Openscad controls

I tried to 3D print these gear using Cura slicer.


You can find all my STL files here :

Here is the code I used

Last update: September 23, 2021