Re: Synchronizing Two Servo Motors

This sounds like a pretty good solution, and doesn't require any custom
hardware, mechanical or electrical. I probably will go with this. Thanks
guys.
--
Phil Mattison

----- Original Message -----
From: H & J Johnson <hjjohnson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, March 10, 2009 2:27 PM
Subject: Re: [CAD_CAM_EDM_DRO] Synchronizing Two Servo Motors


> Steve, I started out w/ steppers but changed "up" do to not having enough
> power out of the steppers. It still worked w/ Steppers, it's not to often
that
> one will die and the other not... maybe lose some steps but a few steps
> doesn't bother my gantry. On the other hand my servos need to fault
> out [as you pointed out] before Mach stops. However this is a grand
> total of 0.025" rack.. again.. not really an issue.
>
> Driving two Step/dir drives off of one set of S/D pins is a no-no in that
> it's NOT absolute, there is no way of knowing where each drive is in
> relation to the other and whether each drive is seeing an equal number
> of steps, your much better off seperating the pulse trains via the control
> and slaving them, in the control.
>
> As far as I'm concerned, Mach does it and it IS turnkey [select three
radio
> buttons in the config settings].. I've been running my machine for more
> than 2 yrs this way.. and it works great.
>
> Fwiw
>
> Jarrett
>
>
> >
> > Note that Jarrett's setup (with Mach) can't detect if a motor dies
> > until
> > a drive faults or a limit is hit. If you use steppers, then the
> > drive
> > will never fault since there's no feedback. With servos you could
> > get a
> > drive fault which would stop Mach.
> >
> > - Steve
>