Hand Ergometer

[FatFreddie]

I've got a variety of odds and ends - mostly silver, black and red but I've probably got enough fluoro pink to do the 15t gears if necessary ;-)

Can't say I've noticed much difference in strength between the colours but some manufacturers are decidedly worse for inter layer adhesion - I've got some that I only use for early prototypes.

Attached picture shows the (very crude) test rig - current limit is the stiffness of the ring gear - it bows out under pressure and skips. I'm printing one with a thicker outer now.

I've also got some issues with the first layer being oversized (the slicers tend to make the first layer slightly thinner to get good adhesion to the bed by squashing the plastic between the head and the base) which should tune out but which would be very easy to fix if Alibre was man enough to let me put a chamfer on the teeth :-(



The 'feel' of the gears is a bit rough (though this will improve), if it's important for it to feel very smooth, maybe some belt drive arrangement would be better - it needn't be any bigger. Alternatively we could use double helical gears which should print ok as long as the helix angle is fairly shallow. Probably best for me to get something working and send it to you for comments - I'm away this weekend but should be able to do some more next week.