RE: [CAD_CAM_EDM_DRO] Re: Optical mouse for DRO anyone? - not for WIRE!

> >I'm leaning toward a 'no tension' solution with an
> ultra-light metering
> >wheel with a simple optical encoder made from an old mouse wheel.
>
> Why? Newer technology mice use a small camera and see how
> the pixels move. They will work on any surface with a
> texture which is reflective to the light they use.
>
> Pull the cordage by it (with almost no tension) and get very
> close, add 1-2% (so you never short a customer) and you
> should be golden. Remember, if your customer wants cordage
> within 0.0005" at 100 feet, he is crazy!

Three problems:

1) Newer mice are USB, so hard to interface (you need an expensive PC). If
you must, then track down a serial port optical mouse, it's the eaiest to
hook up. You may be able to figure out PS2, the poster thinks it's simple
because he found the specs. I can point him to the USB specs...

2) Anything optical soon gets covered in crap. Open up a printer, and be
amazed at the amount of paper dust in there. A lot of printers do use
photo-interupters (like ball mice do), but they tend to leave them out of
the paper path, like as cover open sensors. Even then, they get covered in
crap. The trick is, however, they are set up as nomally closed, so getting
full of dust isn't a problem. When the cover is opened, the shutter moving
takes a lot of the dust with it. Not foolproof.

3) ...and how do you pull a cord with no tension? Ok, it can be done, but
that a lot of moving parts you don't need. Or a 100' building. Put the
roll in the rafters, unwind, and cut the the cord hits the floor. Forget
gravity makes stuff stretch and you'll be ok.

If it was my system, I'd use weight. No funny tensioning setup, cheap, less
moving parts, reliable and accurate enough for government work.

Of course, the poster hasn't gotten around to mentioning how the cut off
cord will be packaged, at this point they just end up on the floor. You
see, if it's to be wound onto a small roll (or into a ball or something,
then you can measure by volume. Wind the cord onto the new roll, and have a
microswitch trigger when it reaches a certain diameter.

As I said before, by being obsessing with part of a solution (optical
mouse), and not giving full specs, the poster will miss a lot of solutions.

Tony