Originally Posted by BBray_T1296 (Post 1486809)

I just drew up and 3d printed a 6.66:1 one for a CIM, and it works like a charm. I can put enough torque on it I am worried the solid PLA will break and cannot backdrive it. With the drawing I was happy with, by swapping out 2 small parts I could easily change it to 5:1, 10.5:1, or 22:1. it is also super compact, being only 2x2x0.9", it is comparable in size to a versa-planetary and if made from alum/steel could easily handle more force*.

Another interesting point about this transmission is while the output is coaxial the input, they are counter-rotating

*Planetary gearboxes generally fail under load when teeth shear off inside. All failure points inside this gearbox are much thicker than the tiny gears we generally see and in theory would handle more force before shearing

Originally Posted by BBray_T1296 (Post 1486809)

I just drew up and 3d printed a 6.66:1 one for a CIM, and it works like a charm. I can put enough torque on it I am worried the solid PLA will break and cannot backdrive it. With the drawing I was happy with, by swapping out 2 small parts I could easily change it to 5:1, 10.5:1, or 22:1. it is also super compact, being only 2x2x0.9", it is comparable in size to a versa-planetary and if made from alum/steel could easily handle more force*.g

Originally Posted by tafipapi (Post 1488932)

Did you use the hypocycloidal ecuation to draw the profile of the gear??
I just designed one using tangent semicircles and im planning to build it, but im concerned that this characteristic may not contribute to the non-backdrivable feature.:confused: