Gears vs. belts (and NOT about M/D's ) was Re: tensioned ballscrew

John,

You've got it right when you say "fearsomely expensive in the
accuracy and POWER transmitting ability needed". Belts are much more
suitable for machining type cnc...

You DO see the planetary drives where loads are lighter and/or cost
is no object. Shopbot even uses them now on their newest machines.

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "John H." <johnhe-uk@s...> wrote:
> Ballendo (And all),
>
> Why are planetary gears not used more in place of belts? Are
they
> fearsomely inaccurate or expensive for the level of accuracy
needed? They
> just seem like a 'clip it on' option in place of machining pulley
supports
> etc. Are they only used when you need very high gear ratios?
>
> John H.
>
> > Doug,
> >
> > Sounds like a lot of work, especially when there's a simple,
proven,
> > often-used solution.
> >
> > Spin the nut.
> >
> > You can still "adjustably" tension the screw if you want...
> >
> > Hope this helps.
> >
> > Ballendo
> >
> > P.S. K.I.S.S.