High Reduction Ratio Planetary Drive
by mkeveney, published
This model illustrates an interesting planetary drive variation that produces a very low gear ratio.
Click the video link to see it in action:
The video shows how it works and includes some construction tips.
You'll probably want to make the Tube cutting tool as well:
I started designing this in metric units, but was only able to find brass tubing in imperial sizes, so I simply used both measurement systems. If you live in a metric part of the world, you should be able to adapt to locally available materials by drilling out the bearing holes as necessary