RE: [CAD_CAM_EDM_DRO] Re: Optical mouse for DRO anyone?

> 1. How to read a mouse is straightforward:
> http://www.computer-engineering.org/ps2protocol/
>
> 2. I need to measure cordage in lengths from 1 to 100 ft with
> precision of a couple of inches at 100 ft.
>
> If you check around, there is no readily available, simple
> tool to do this. There are the simple counters used by
> hardware stores and Home Depot Electrical Dept's everywhere,
> but none of these work with something similar to a shoe lace
> or any kind of rope like cord 3/8" in diameter or less....I
> know the exiting tools don't work because I've tried them all
> (or almost all...)
>
> CL

Hooray, actual specs!

So you're building a wire cutter. In your case, what Ron suggested will
work. Run the wire between 2 rollers, if you know the size of one of the
rollers you can count its revolutions, that gives you how much wire has been
played out.

For example, if the roller is 1 inch in diameter, 100 rotations would give
you a piece of wire 100 inches long. 1200 rotations would give you 100
feet. In this case you could simply mount a microswitch (or use a reed
relay & magnet) and count how many times it clicks. Dead easy. Low
resolution though.

You can then mount a slotted wheel on one of the rollers and measure it,
that will increase your resolution. The other case is if you're using a
third wheel running on the wire itself, maybe there's a problem with the
main rollers, like distortion or slippage.

You could also count the number of steps the stepper motor makes. Now you
don't even need a sensor, if it's a 200 step motor, then you can cut to
1/200th of an inch. To get 100 feet, that's 200 steps x 12 inches x 100
feet, or 24000 steps. This is by far the best way. You could use a
BasicStamp or a www.picaxe.com to control that. Or a DOS PC with 20 lines
of GW-Basic.

If you were cutting a lot of small pieces, you can use a technique that's
often used, a stop block. In the path of where the wire feeds out, you
place a switch at the distance you are cutting. If you want 6 inch pieces,
place the switch 6 inches from the cutter. Feed the wire out (using a
normal motor) and stop when the switch activated. Cut the wire, and repeat.
To change wire lengths just move the switch.

I don't know why you so hung up on optical mice, as you can see you don't
even need it.

Tony