Hand Ergometer

[irving2008]

Looks good tho :) Are those full thickness?

When you say the ring gear 'bows out under pressure' what exactly do you mean? I've changed the design of that, see attached. It will be bolted to a pair of 10mm sq ally columns which will add considerable rigidity.

[FatFreddie]

Looks good tho :) Are those full thickness?

When you say the ring gear 'bows out under pressure' what exactly do you mean? I've changed the design of that, see attached. It will be bolted to a pair of 10mm sq ally columns which will add considerable rigidity.

Yes - that's full thickness (6mm).

The majority of the deflection is where the gear is closest to the outer edge of the piece - the straight edges by the gears become convex and the ones on the side away from the gears become concave - it moves enough for the teeth to slip over the tops. Moving to three or four planet gears may be a simple way to alleviate this without having to make the ring gear much stiffer. Your new design will also be somewhat stiffer - is there much room to play with?