Originally Posted by
bebob1
Thats what I mean. It seems they get their 'zero' backlash capability based on having a high teeth count and a small gear module. This is not specific to harmonic drives. This is related to gear meshing principles in general. You can have a planetary gearbox reducer with tiny teeths and you can get 'zero' backlash effect also. The only advantage backlash wise, may be that harmonic drives involves use of less gear mesh stages, and so by means of additive backlash, it may have less since planetary reductions involve more stages of gear meshing so backlash can add up.
I always see the 'zero backlash' advertisement and sales pitch and I just dont see how 'harmonic drive' = zero backlash theoretically. I think its 'small gear teeth and low gear module' so close to zero backlash. Then again, any gearing system can do this. Use high teeth count and small teeth = low backlash at the expense of lower torque rating.
The only true zero backlash is a direct drive like a stepper motor.