This is a fully functional hand-cranked model of a multi-stage planetary reducer. The photo below shows 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 because of the very high gear ratio.
You need to print:
--- PER MODEL---
--- PER STAGE---
2 Metric Phillips-head countersunk M3-12 screws PER MODEL
2 Metric Phillips-head countersunk M3-12 screws, and 2 Metric M3 nuts PER STAGE
- Attach sun to the bottom side of carrier with two Phillips-head M3-12 screws and two M3 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 the planets and sun on them into ring. The sun goes in first.
- Attach ring to front (for stage 1) or to previously installed ring (for stages 2, 3, etc.) The sun needs to be pushed hard into the following stage's planets.
- Secure the ring with three washers.
- Once all stages are assembled, insert shaft through the hole in front. Push hard.
- Attach handle to shaft and secure with two M3-12 screws.
Enjoy your planetary gear model!
Related: How to Model a Planetary Gear Drive in Blender, Internal/External Gear Calculator