I've personally used this gearing for a few different projects in the past year. The chief advantages to this system of gears are low profile, high possible ratios in only 2 stages, very few gears, and easy 3-D printability. I have seen this system 'in the wild' in the tiny motor behind my car side mirrors. A variation of this scheme is also demonstrated as the 'Grinder Gears' presented by Oskar van Deventer in his cool blog.

For those of you who have been reading my blog, you might recognize this gear system from my entry on the 3D printed stepper motor. I used a 2-planet system to gear down the motion of a spinning magnet.

I also used this technique to gear down a stepper motor in a newer version of the LibroStruder, a cool looking filament extruder for DIY 3-D printing.

Current projects of mine that use this system include a waterproof gearbox for an underwater robot arm I am designing. I also think this gearing would work very well for a solar tracking mirror or PV panel mount.

Anyway, if you're a 3D creator and want to make use of this powerful flexible gearing scheme, you can download an OpenOffice spreadsheet here: https://github.com/IdeaPropulsionSystems/CoolEpicyclicGearing

The sheet lets you enter different tooth counts and outputs the legality of your decision, as well as the final output ratio if the counts work.

When it comes to actually making the gears, I highly recommend using the online gear maker that I mentioned last month. It is an absolute joy to print gears and have them work, especially in an awesome semi-mind-blowing planetary arrangement! Yes. I think you'll absolutely LOVE the split ring compound planet epicyclic gear.

PS: If you think of a better name for it, PLEASE let me know!

PSS: If you have skills with OpenSCAD and wish to make a dynamic gearbox designer to share, please do it! I have a few other little equations that may help. Please let me know and I'll share. I'd love to link to your project! -David :-)