Re: Driving gantry with two paired stepper motors

Richards,

I can't comment on your stepper motor idea, however
you might look at a parallel rule (as used on drafting tables)
and note the clever cable arrangement that "fastens" both ends
of the rule "together" so the rule remains at right angles to the
table. If you have room, etc. you could take this idea to
effectively drive both sides of the gantry with one motor.

Regards,
George Potter
Placerville, California

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
> 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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