Gears 2.0 (work in progres), part V, a Blender add-on

I am happy to announce that version 0.0.5 of the Gears 2.0 script is now available on GitGub. Its main new feature is the option the create involute gears, the most widely used tooth shape in modern gearing designs.

Due to ongoing backproblems my time behind a desk is severely restricted. This does mean that while the code presented in this article is actively developed, progress will be slow. This is not necessarily a bad thing because it forces me to think things through thoroughly and discuss them at length with the community before actually implementing them, which probably will lead to better code in the end.

The accuracy of the involute curve can be controlled with the steps parameter and extra space below the dedendum can be created with the fillet parameter. Likewise, extra backlash can be created between the teeth with the backlash parameter. I haven't yet printed any gears so I can't vouch for their actual mechanical behavior but for now I think this is a good start (although the shape of the fillet/undercut could be better I guess). [edit: v0.0.6 now has a shift parameter which for positive values gives a taller addendum and a shallower dedendum and for negative values the opposite. This is useful to tweak the load a gear can bear. Obviously these values should best match on adjacent gears but that is not yet done automatically]

Although I do not approximate the involute curve of the tooth with splines, this article was invaluable in getting the equations correct without trying to find it out all by myself. An example set of parameter settings is shown at the end.

Gears 2.0, a work in progress

The script is discussed on this thread on Blenderartists, feel free to comment there. It also has its own entry in Blenders upload tracker.
The code is available from GitHub, install it in the usual way from

File->User preferences->Addons->Install from file and don't forget to check the checkbox to actually activate it.

As the example below shows for a 44 teeth gear of radius 1, the fillet/undercut needs some work (it's too wide/deep) but the shape of the involute tooth itself seems ok. The read circle is the pitch radius, the blue circle the base radius (that is pitch radius * cosine( pressure angle )).

The settings to produce the gear shown above were: