The Cogulator, a large plywood cycloidal drive gear

A large cycloidal drive, made by laser-cutting plywood and complicated geometry!

This was made for our steampunk festival, the Waltz on the Wye.

Cycloidal drives are used in industry, but are machined from steel to make high torque drives for heavy machinery. Cutting one from plywood was a rather novel approach.

Our expectation was that the laser could cut the shape visually, but a pleasant surprise was to find that the mechanism also worked so well. This is made from two layers of ¼" plywood, stacked to give a relief effect. The rear layer is solid and includes the spokes, the front layer is just a thickness doubler for the rim and it also has the "Waltz on the Wye" lettering laser cut through it. Both sheets aligned perfectly on assembly and only a little sanding was needed on the edges.

The design of a cycloidal drive involves some complicated maths. Andy Payne of CamBam, one of our favoured CAD packages, added it as a design tool.

Thanks to Russell Couper for motorising it.