Re: Driving gantry with two paired stepper motors

I have put two stepper motors on the same axis one turning cw and 1 turning
ccw off the same driver. It worked fine driving a rack and pinion driven
gantry without any torque compensation. They both produced the same torque.
I simply made a Y splitter to connect both motors to one driver cable and
then I reverse the phases on one so I could get the cw, ccw motion that I
wanted.
Dan
-----Original Message-----
From: rumancik@... <rumancik@...>
To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
Date: Thursday, January 13, 2000 9:05 PM
Subject: [CAD_CAM_EDM_DRO] Driving gantry with two paired stepper motors

>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
>furthest away from the driven side. There are a few
>solutions that I have seen. One is to use dual
>leadscrews and mechanically couple the two
>together, so that torque (and therefore force) is
>applied to both sides of the gantry. Another is to
>use two stepper motors. SuperTech uses this
>technique with their XYYZ 3-axis driver boards.
>They have two completely separate stepper driver
>channels for the y axis.
>
>
>I have seen someone suggest that you can couple 2
>stepper motors in parallel on a one-axis drive. I
>have tried this with a simple L297/L298 driver
>board. The two motors appear to be staying in
>phase with each other. I realize that you can't get
>the same torque from each motor (as you would if
>driven individually) but if you have a mechanical
>transmission, you also split the torque.
>
>
>My question: are there any potential problems with
>this technique, electrical or otherwise?
>
>-Richard-
>
>
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