Split gear epicyclic reductor 1:176

thingiverse

This is a split ring epicyclic drive design, it has an insanely high reduction ratio of 1:176 in a very tight package due to the epicyclic reduction (1:4) combined with the split-gear design.The ring gear is fixed (number of teeth Nr), the sun gear is the input (number of teeth Ns, rotation speed Ws). The planet gears will rotate around the sun with a rotation speed Wp=(WsNs)/(Ns+Nr). With Nr=15, Ns=Np=15, this stage provides a reduction of 1:4The top and bottom ring will align at every rotation of the planets, since the top gera has Nr-1 teeth, it will rotate by 1/Nr of a turn each time. For this design, Nr=45 so this stage provides a reduction of 1:44.In order to have the same pitch diameter, the top ring has a module of MrNr/(Nr-1), the very small difference does not impact gear meshing but is crucial to have the system working.I would advise the following:-using some grease helps a lot-printing with a raft to avoid elephant's foot issues print the gears slowly, outer layer then inner layer to have the best qualityThere are many possible improvements to implement: add more planet gears to carry more torque, here are just three of themadjust the relative ring heights to the actual torques, the bottom ring should be much thinner than the top oneput a carrier with bearings or at least some kind of support to the planet gears as they tend to bend inwards under loadThis design is made to fit a bearing with ID=50mm, height 12mm, feel free to adapt it to your own bearing, I included the .f3z and .step. Sorry in advance to those using the .f3d, this is not a good parametrisation. If you remix it, publishing a cleaner version will be a nice thing!