Stackable Planetary Gear Mechanism (Reducer)

This is a fully functional hand-cranked model of a multi-stage planetary reducer. The photos and video show this model with 3 stages. Each stage has a gear ratio of 1:6, so the overall gear ratio of a 3-stage reducer is 1:216.

The design allows for an unlimited number of stages. However, for a hand-cranked model, the practical limit is 3 stages. Even with feverish cranking, the output shaft barely moves.

You need to print:

--- PER MODEL---
1 front
1 handle
1 shaft

--- PER STAGE---
1 ring
3 planets
1 carrier
1 sun
6 washers

Hardware:
2 Metric countersunk Phillips-head M3-12 screws PER MODEL
2 Metric countersunk Phillips-head M3-12 screws, and 2 Metric M3 nuts PER STAGE

Assembly Instructions:

Attach sun to the bottom side of carrier with two Phillips-head M2-12 screws and two M2 nuts (available cheaply on eBay.) The hexagonal holes in the sun should be pointing outwards.

Mount 3 planets onto carrier, secure each with a washer.

Insert the carrier with