Re: Driving gantry with two paired stepper motors

rumancik@... wrote:

>
> From: rumancik@...
>
>
> I have a question concerning the use of stepper
> motors to drive a gantry on an xyz table. One
> problem that sometimes arises is that if the gantry is
> driven on one side only, it exhibits a slip-stick
> phenomena, especially if there is a cutting load

In my far past I worked on a CAT Scanner that used two
conveyer belts to move a patient through the gantry
(x-ray beam). Each drive motor had an encoder that sent
its output to a digital up down counter and comparator.
If each motor moved the same distance the difference
would be zero, thus maintaining sync (and not stretching
the patient).

Earl