DRO card and future projects

I guess you've all seen the posts about the DRO card I built. I've
got an update to the software, adding metric support, cleaning up a
few things I didn't like, and changing the 4th axis to display in
degrees instead of linear units. I haven't posted it to the webpage
yet because I wanted to add backlash compensation first. That's the
problem.

The big drawback of backlash compensation is that you are forced to
make sure that all of the slop is cranked to one side of the travel
before you can zero that axis. If you don't, the computer doesn't
know where you are inside the backlash zone, and you can't trust the
numbers on the display.

My question is this: Do those of you who want to use rotary encoders
have a problem with this? Keep in mind, you won't be able to zero
the axis until you are certain that you've moved all the way to the
left or the right of the slop. I can think of more than one occasion
where this would be *really* annoying, but usually it would just be a
matter of getting in the habit of watching what you're doing a bit
more so than normal.

So, did I get that across clear enough? Is it worth it to add this
feature? I don't want to spend a whole bunch of time working on a
feature that nobody will want to use, especially since I've got a new
project I want to start.

Speaking of that new project, I've been following the comments about
the EMC software (gotta love the free stuff ;) with interest, and got
to thinking about how I'd go about trying it out here at home. I was
thinking that buying a motion control card is pretty pricey, and that
my DRO card makes a great jumping-off point for bigger and better
things. With a little extra work, and probably an extra 200 bucks, I
could come up with a 3-axis servo controller card design. It's a
little more involved, but using PWM for the output signal cleans it up
nicely, bringing it into the 'definately doable' range, even for
beginners.

I think that this group could easily write plans to build the card,
the servo amps, and the guidance you'd need to assemble the lot into
a really good webpage. I can handle the card OK, but I need to know
how the card interfaces with the EMC stuff, or if I could provide all
the register-level programming info to somebody who could write a
driver or whatever is needed to get things going. I don't yet have
Linux here at home, so I can't really experiment much. If there's
interest in this, I'll order Redhat next month.

What do you say, guys? Sound like fun?

-Tom Kulaga