Tony Smith wrote:

> Another reason plastic gears are used is that they are quieter than metal
> ones, not really an issue in a low RPM application.

It seems we don't really have a problem with the plastic gear per se, but
with the way it is connected to the output shaft. This connection
apparently strips (and is designed to do so) with higher torque shocks like
backlashes.

> Threaded rod isn't all that efficient, but there's different grades.
> Ballswcrews work the best, but are expensive by comparison.

Yes, that's true. I've read that ballscrews are more sensitive WRT
lubrification than normal screws. Is this true?

> Another method to get linear movement is to have the cable in a loop, with
> one end wound around the threaded rod, the other around a pulley.  Cable is
> tensioned by a spring.  Rod turns, cable winds 'on' one end, and 'off' the
> other.  Old timers would say "just like old radio tuners!" but I've seen the
> same setup in photocopiers.

But probably not pushing/pulling 800...1000 N?

Gerhard

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