Re: [CAD_CAM_EDM_DRO] run two geckos from same pins

Doug,

Many commercial machines ( I know that Multicam does) controls two X axis
stepper motors in software and drives them independently. This allows them
to include a special program that is run at initial power up when they home
the system. The program then can rack the gantry to square the table.

The amount of racking is determined during the install process. I believe
that the cnc controller from Microsystems has that feature built in.

Squaring the table can be a problem on some gantry systems.

Bob Campbell

----- Original Message -----
From: "Doug Fortune" <pentam@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 05, 2002 11:21 PM
Subject: Re: [CAD_CAM_EDM_DRO] run two geckos from same pins


> Doug Fortune wrote:
> >
> > Back to your XXYZ cnc router, it would be great to
> > to run a timing belt across both X axes (even though
> > you have 2 motors with 1 or 2 controllers), just to
> > keep them both honest (because steppers are <usually>
> > open loop systems).
> >
>
> I want to elaborate on the above comment: normally if
> a stepper system looses a step (or multiple steps), then
> your position is off - thus wrecking the part. This is
> unfortunate, but not a disaster.
>
> But in an XXYZ gantry, if the two X axes are not moving
> in unison (because of lost steps), there is enough power
> (through the screws leverage) to pull the gantry itself
> apart - thus wrecking your machine - a disaster indeed!
>
> Thats why I like tying two X axes together with a timing
> belt even though there are two X axes motors. As for
> servos, theoretically the two motors can't differ by more
> than a few steps if everything is working properly. If
> they do get too far apart, the system should stop with a
> a following error fault. But it is nice insurance anyway
> to have the two axes tied together.
>
> Doug Fortune
> http://www.cncKITS.com
>
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