Re: new

["Peter Cook" <kf2qd-at-terraworld.net>]

As to encoders and glass scales - Glass scales (or magnetic) have some
environmental considerations - plasma and oxy/fuel cutting put out a lot of
fine metal dust (from vaporizing the metal) that gets into everything and
tends to cause wear in any assemly with close sliding tolerances - a rotary
encoder is probably a better device to use in this application.

Pete Cook
----- Original Message -----
From: "Paul" <paul.corner-at-tesco.net>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Sunday, April 14, 2002 11:47 AM
Subject: Re: new


>
>
> Hi AJ Hettema
>
> A couple of links to get you going :-
> http://www.ktmarketing.com/faq.html
> http://206.19.206.56/
>
> Most certainly EMC can be used with encoder feedback with both servo and
> stepper drives. The resolution is only limited by the encoders fitted - If
> you used some of the high end linear scales, sub-micron resolution is
> possible. It is unlikely that your machine tool would be able to position
to
> this sort of accuracy, and for a plasma cutter, it is not necessary.
Standard
> 20 micron scales will give you 0.005mm, and using cheap rotary encoders on
> the end of the feed screws will still give you better than 0.1mm accuracy.
>
> There are a few papers on the usdigital.com web site that lightly cover
the
> principals of encoder technology.
>
> Regards, Paul.
>
>
> On Sunday 14 April 2002 16:30, AJ Hettema wrote:
> > I think we can manage it to build such a machine with the documents we
have
> > on cnc, and the EMC-software (ofcourse we need to feed it with nc-code,
but
> > that's not such a big problem). What we would like to know is, is it
> > possible to build a EMC-machine that's controlling servomotors and has
> > something like feedback from the X and Y axis about posistion. Or are
> > servomotors accurate enough to reach a 0.1 mm accuracy??? We couldn't
find
> > a document which describe's the use of encoders to give the exact
position
> > of the X or Y axis.
>
>