In my project a knob (usually rotated by hand) can be turned also by a stepper motor. On the other hand, when the motor is not energized, the knob can be rotated manually as normally.
To transmit the motion from the motor I would like to use three spur gears made in acetal (low friction material). My fear: when the motor is off will the operator receive a bad feeling if turning the knob manually? I mean: the teeth of the gears will not generate too much friction (and a "clunky" feedback) when compared to a timing belt? (See attached image.)
My intuition says that adopting a belt I should obtain a more smooth movement and low friction. Is my intuition right? Anybody has a direct experience in this kind of problems?
P.S. No high rotation speed here. The knob will be turned by the motor for max 180° at a speed comparable by a normal human wrist.