FreeCAD 0.20+ scripted objects Python dealing with the design of worm drives (both gear and wheel). At high tesselation (angular resolution) make take some good minutes for FreeCAD.ActiveDocument.recompute() to finish generating the gear and/or wheel.
Warning: Work-in-progress
The worm gear looks like
The worm-wheel function fails to produce anything. after a second "hobbing" step the result is full of geom errors. With FreeCAD v0.20.1, Revision 29410, on a Windows 10 Home, Lenovo laptop AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx 2.10 GHz, 16GB RAM