Something of a failed experiment. It works - it's just very difficult to grab the spherical shape and turn the gears. I don't recommend printing this for that reason. However, I think it's a good example of turning your own models into gears with the excellent parts this is derived from.
TODO: Upgrade the model to use eccentric gears so they extend out of the sphere when rotated, making them easier to grab.
The license is CC BY-SA 3.0.
Make sure you have Tony Buser's pins - thingiverse.com/thing:10288 Greg Frost's involute gear library should be included with OpenSCAD.
The STL files take a long time to generate, because of all the polygons. I modified the Screwless Heart Gear .scad file to accept command line parameters telling OpenSCAD what part to generate. This could be automated in a Makefile. To generate, I run:
openscad -D part=X -o earthgears_X.stl earthgears.scad
where X is 1-8 for the 8 gears. For the center and pins, I run:
openscad -D part=9 -o earthgears_center.stl earthgears.scad openscad -D part=10 -o earthgears_pins.stl earthgears.scad
If you want to generate a complete STL for visualization purposes, run:
openscad -D part=11 -o earthgears_complete.stl earthgears.scad
Note these can take a LONG time to generate, and consume lots of ram if the mesh is too big. If you have a multicore processor and ram to spare, you can run more than one job at a time.