Hand Ergometer

[irving2008]

Been looking for plastic internal (annulus) gear rings, to create an epicyclic gear train, but can't find a UK supplier. Any ideas?

Alternatives are a timing belt to drive the rotor at, say, 5x crank speed so can use smaller lighter magnets but that adds equal complexity

[FatFreddie]

Been looking for plastic internal (annulus) gear rings, to create an epicyclic gear train, but can't find a UK supplier. Any ideas?

Is this something that could be 3D printed? Not sure what sort of strength / wear characteristics you'll need...

I'm happy to have a go if you want to try it - max size is about 200 x 200 by 100 mm deep though print time / warping might be a problem if using the full envelope. I've got plenty of PLA in - not tried ABS or nylon yet but willing to experiment.