Re: [CAD_CAM_EDM_DRO] Newb question....

Aiden wrote:

>I'm a lurker here, as time and money problems don't allow me to
>actively pursue this hobby at present, but a question has occured
>(sp?) to me. Is there any reason why you would not use stepper
>motors with encoders or resolvers in a closed loop to minimize lost
>steps or similar error?
>
>

Yes. When a stepper motor loses a step under load, it cannot recover
in any smooth manner. At best there will be a big jerk backwards and
then forwards, again. At worst, and the usual state, any attempt to
catch up
to the desired position will just maje the motor stall.

Secondly, none of the hobby-level software has any provisions to handle
this. The only software I know of that could make a crude attempt would
be EMC, but it would be totally closed-loop, and still could not recover
from a lost step. The actual position would always be known, which would
be a big help, but it when the motor loses a step, there's no way to command
it to "try harder".

If you want a servo system, which CAN do this, then just get a servo system,
and solve the problem the right way.

Jon