Originally Posted by
joeavaerage
Hi,
the only problem with harmonic drives is the deep reduction, 50:1 is the typical minimum reduction, great for high torque but SLOW as a wet week.
Cycloidal gear reducers work well at ratios around 20:1.
When I built my mini-mill seven years ago I use low lash (<2 arcmin) planetary gearboxes of 10:1. They have been superb. They allow very modest steppers to have
GREAT torque, but only at the expense of speed. To be honest I've never been able to measure or even notice the lash. So I would say that any of the cheap Chinese
made planetary gearboxes of less than 15 arcmin lash would be fine for hobby purposes, and they are available at ratios of 3:1, 5:1, 10:1 etc. Over 10:1 then your into
a two stage reduction and increase in lash.
Craig