Re: [CAD_CAM_EDM_DRO] Re: z axis drive question

I can see the calculation gives 0.0005", which I am sure would be fine for
my
needs, but I can't seem to visualise how the DC servo motor can move such a
SMALL amount - is the motor not governed by its commutators and magnetic
pole
pieces ?

Dave

----- Original Message -----
From: "turbulatordude" <davemucha@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, November 13, 2003 2:03 AM
Subject: [CAD_CAM_EDM_DRO] Re: z axis drive question


> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dave Fisher" <dave@d...>
> wrote:
> > I am in the process of building a Z axis for an X Y table I am
> converting into
> > a CNC router. I plan to use Artsoft mach2 software with Rutex
> servo amps to drive the system.
> >
> > Can anyone give me any more info on the following:
> >
> > I have a quality 25 mm thick ball nut screw cut to 5 tpi - I have a
> choice of rotary
> > encoders from 400 to 2000 steps per rev. I intend to drive the
> screw
> > direct from my DC servo motor shaft.
> >
> > Not being that familiar with servo systems (the amps haven't
> arrived yet !) I am concerned
> > that when I turn the ball screw by hand, a mere fraction of a turn
> seems to move the ball nut a long way !
> > Can a DC servo system with my proposed setup resolve enough
> resolution to move the ball a few thou,
> > typically for fine, milling depth cuts for finishing etc.
> >
> > Any info would be most appreciated
> >
> > Rgds
> >
> > Dave Fisher
> >
> >
> >
> > [Non-text portions of this message have been removed]
>
>
> Hi Dave,
>
> the simple starting point is that 5 TPI means 0.2" per revolution.
> An encoder that output 400 points per revolution would resolve that
> to 0.0005"
>
> how fine of a resolution do you want or need ?
>
>
> Dave
>
>
>
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