Re: [CAD_CAM_EDM_DRO] Re: Make your own linear scales

Ken Jenkins wrote:

> I thought about it. I have access to a very high resolution
> film typesetter 2460 dpi. But after calculating it all out
> the resolution still comes out too low.
>
> >> Which brought up the idea. Has anyone ever tried
> >> making their own encoder scales?
> >> Are these things even called scales? Do I have the
> >> correct term?
> >> The first problem I see is variations due to
> >> temperature. But surely there is some stable plastic
> >> out there we could use for this?
>
> Mylar
>
> >> Will it or will it not work?
>
> My calculations say ... close but no cookie, at least
> for my typesetter here ...

Well, with 2460 pixels/inch, you could write every other pixel,
and get 1230 cycles/inch. With a quadrature read head, that would
give you 4920 counts/inch, or .0002" resolution (actually,
.00020325")

This sounds like what the standard commercial linear scale
does. Of course, this would be a plastic scale, unless you
printed the master onto a glass plate coated with tungsten
or similar metal, and then etched it through a resist.

Jon