Tiny Planetary Gearbox

thingiverse

This is an emergency planetary gearbox (not mine). See original page for details. When you inevitably fail to print the little bolts and/or they break really easily, try BoltModified.stl. It'll print a threaded rod on its side, making it much stronger. There's no bolt head, cut with scissors or wire clippers to size. You may need to print more than one depending on which gear kit you're going with. And when the annoying pins on the carrier inevitably pop off, try CarrierModified.stl. Instead of printing the pins, it has holes so you can add your own (of a suitably strong material).