Ronald Walter's multi-layer planetary drive

Ronald Walters sent me some pictures and a description of a very complicated planetary gear drive that he built. You can click on any of the images for a larger view.

Ronald writes:

"The main purpose of this planetary was to see if I could make it with hand cut gears and how smoothly it would operate. Eventually it will be used to drive an Archimedes screw as a lifting mechanism for a marble machine.

Hand cut wood gear planetary drive. There are three separate planetary drives stacked on top of each other consisting of seventeen gears total.
Input motor speed is 80 RPM driving the input ring gear of the first planetary 20 RPM.
First planetary output speed 14.28 RPM.
Second planetary output speed 10.2 RPM.
Third (final) planetary output speed 7.29 RPM.
Planetary drives can be operated in several different ways. Driving the ring gear, driving the planets or driving the sun gear, each while freezing one of the other groups resulting in speed reduction, directional reverse or increased speed.

The gear layout is done using the gear template generator. Holes are drilled between the teeth to make it easier to cut out the part in between.

Tooth shapes rough cut. The gear teeth still need to be trimmed to length.

This is how the first layer fits on the machine. The first ring gear has teeth on the outside to allow it to be driven by the gear motor.

Individual layers assembled. The central sun gear for each layer is held fixed in place. Each planetary is driven by the ring gear, and output taken from the rotation of the planet gears about the sun gear.

The wood gears themselves are fairly quiet (as can be seen in the small poor quality clip of the first planetary I made). It is the induction motor gearbox that is loading up and resonating, making most of the noise you hear in the video of the triple stack drive.

Other projects by Ronald Walters:

Various Clock wheel
building experiments

See also: Calculating planetary gear ratios and Gear template generator

More reader projects on