Re: [CAD_CAM_EDM_DRO] 2 steppers-one axis?

Kelly of www.Kellyware.com has a picture of his machine and
he has to x axis speppers. I asked if that was correct and he
said he just drove both motors from the same driver .
Jim

----- Original Message -----
From: Alan Marconett KM6VV <KM6VV@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Thursday, July 13, 2000 12:38 PM
Subject: Re: [CAD_CAM_EDM_DRO] 2 steppers-one axis?


> Jon,
>
> I know it's possible, as the super-tech site does it. I agree, they
> must be "in step". If not, terrible things happen ;>) If the
drivers
> take PH1 - PH4 to drive them, that might simplify the sync. I don't
> remember if super-tech relies on having the "4-phase" drive signals
> common, I think so (Dennis, are you there?). I do recall that
> super-tech runs TWO separate limit switches, one for each "Y". I
think
> I'd study what super-tech has already worked out.
>
> Terry, any further thoughts? Try it yet?
>
> Alan
>
>
> > Jon Elson wrote:
> >
> > Alan Marconett KM6VV wrote:
> >
> > > Terry,
> > >
> > > There should be no problem, just feed the extra Y driver with
the SAME
> > >
> > > pulses as the current Y (or whatever) you want to duplicate
(wire
> > > motor
> > > for the same effective rotation).
> >
> > The problem is you need to keep the motors synchronized. If they
are
> > run
> > off the same driver, then at least they will always be on the same
phase
> >
> > at the same time. Then, you could tighten the shaft couplings
with the
> > driver turned on, and the motors would be happy to make a pair.
If
> > you use separate step and direction drivers, then there is only a
25 %
> > chance that they will maintain the same phase relationship as when
the
> > shafts were coupled together the first time. If the coupling is
fairly
> > stiff, and the phasing is different, then the motors will be
severely
> > fighting each other, and neither will be near its resting position
for
> > that
> > step, but somewhere 1 or 2 steps leading or lagging. This will
cause
> > HORRIBLE loss of torque, and much rattling and stalling. I really
> > think the results will be much worse that one motor properly
driven,
> > or two motors driven off a driver that can support both.
> >
> > One other possibility is if you have one step-to-phase converter
> > driving two phase-input drivers and motors. Then, the motors
> > would again always have the same electrical phases active.
> >
> > Jon
> >
>
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