Re: DRO boards

>From what I can see of this project using the US Digital Linear strips is the
>best option.
>I would like to use one for a lathe application but bearing in mind that you
>need 1/2 switching even an application that can get 0.001" on a miller will be
>reduced to 0.002" on a lathe.
>Am I right on this one??

Yes, you're right about that. One option is to try out the system
with the USD encoders, then upgrade to a high-resolution version from
somewhere like Heidenhain or similar. I have seen just the encoders
being sold in MSC's catalog, but I don't know if they have quadrature
output. If you need a list of places to get high quality encoders,
email me, I have a few links I can dig up and send you. Oh, and I've
used linear encoders in resolutions as fine as 1 micron (around 40
millionths!) and I'm pretty sure it gets smaller than that, so if you
want to spend the cash, the performance can be yours :)

>I read the US Digital web site page and they advertise as making custom
>resolutions up. Has anybody asked them for something that will run with this
>package to give something like 0.005" resolution ??

The limiting factor here is the reader heads. Making the strips is
pretty easy from what I understand. USD gets the heads from Hewlett
Packard, and I think it would be a big deal to get them to make up
a custom head. If we can find a vendor with a head (of any brand) in
the resolution we want, I think we could get a package deal going
with USD to tool up the linear strips. I've been researching this
option, but I haven't made much progress. It's really weird, but you
just can't find linear encoder parts in the resolutions that we all
want (.0002, .0005, etc). The only real option is to buy the entire
encoder assembled to the length you need. And of course, this is not
a very low-cost option. Bummer.

>Will there be a keyboard input option on your final project.
>So that you will be able to key in a size and count down to zero.
>I saw an option the other day on the web that uses rotary encoders, might give
>some people food for thought. Site is at http://www.bwelectronics.co.uk

You bet there will be. In fact, on the SVGA version, there's even an
option for multiple, selectable origins. Not useful all the time,
but it was easy to code, so I put it in there. The text-based version
was originally meant to be a test bed, but it looked so good I decided
to get it polished before continuing with the graphics stuff.
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>Regards,
>John Stevenson
>Nottingham, England