Quote Originally Posted by irving2008 View Post
Trying to work out how to draw the teeth for this in my CAD program, but attached is an initial sketch of the epicyclic gears.

Current thinking is I basically want a mod 1.25 60 tooth internal ring with a couple of fixing lugs (the ring is static), a mod 1.25 30 tooth sun spur gear on a press fit 10 x 22 x 6mm bearing (this will be fixed to the rotor which will rotate freely on the 10mm axle using another 10 x 22 x 6 bearing), and 2 off mod 1.25 15mm planetary spur gears on press fit 3 x 9 x 5mm bearings (these will be fixed to a carrier thats connected to the 10mm axle ). Spinning the 10mm axle will spin the rotor at 1+60/30 = 3 times the rate or 180rpm. the torque in the gear train is around 6Nm
That looks ok for printing - probably best if I get the finer extruder going but I've made some gears about that size which work ok. Could the unit be thicker? I'm thinking that it's maybe a bit marginal on strength - probably easiest to just build it and test it than worry too much at this point though.

If you (or anyone else) can point me towards a gear profile calculator (can't find one that does the outer ring) I'll knock up something for a strength test.