Re: These servo motors worth a darn?

At 10:08 PM 10/19/99 -0700, you wrote:

> Can I put the encoders on the end of the screws or
>would that introduce some sort of servo error?

That should be the most accurate way to use them; connected directly to
screws the only errors you'll get would be in screws themselves.

I've seen comments on belts being subject to error. Many or most 'real'
machine tools use a timing belt drive to the screws and that doesn't seem
to be a problem. The precision of the belt follows the molds and the molds
can be made to very close tolerances. You do need to have a tensioner
arrangement; I just hang a ball bng on the mount for the motor and let it
impinge the backside of belt. By using a bng with a bigger bore than the
fastener and with two large OD washers to span the bore, you can make it
adjust very simply, IE by pushing it by hand onto belt and then clamping
the fastener. Works for me.


Best wishes,

Hoyt McKagen


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