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

> Now I don't feel so bad - you are all (well, almost all)
> missing what I said about the medium, and coming up with the
> same ideas my co-workers offered...now...
>
> Imagine a shoelace, 100 ft long. Wire and flat strapping or
> webbing is child's play in comparison - been there, done all
> that 25 years ago.
> Woven cordage changes dimensionally when even the slightest
> mechanical pull, push or squeeze is applied. I have put
> various types of lacing (polyester, nylon, natural fiber,
> etc.) through wire measurement machines with all types of
> wheels of varying hardness, and they all performed horribly,
> losing or gaining as much as 10 inches in ten feet. The
> company that makes most of these machines even put together a
> custom unit for me that they swore would work, and it did no better.
>
> In theory, the optical mouse should be very accurate if used
> on a surface that has consistent chracteristics. On a Windoze
> PC, it would be difficult, since the pointer calls to the API
> do not seem to allow the low level of control one would
> expect - as I recall, the acceleration algorithm is tied to
> the travel distance in the available API function. Without
> being able to compile machine code, acceleration would be
> included with distance, hence raw distance throuh a PC would
> be an extremely difficult task.
>
> Reading the raw mouse output it seems, would be much easier
> to do with a PIC and a simple routine to read asynchronous
> serial. the velocity of mouse movement establishes the serial
> clock, and as long as the chip is clocked fast enough,
> distance should be a no-brainer. The problem I see with this
> approach is the storage and handling of so many variables -
> even if looped every inch.
>
> Time permitting, I'll put something together to try this.

By being obsessed with using a mouse (and optical, no less), you are blind
to a solution.

Seriously, what gives?

You right, I did assume wire when you actually said cord. Ok, you're
cutting something that distorts. The obvious solution is to determine its
maximum stretch, let's say it is 20%. So to cut 100 feet, stretch it as you
feed it into the cutter, and measure 120 feet going past the sensor.

A better solution is to place a bowl on a scale. Spool the cord into the
bowl, and monitor its weight. 100 feet may weigh a kilogram, so when the
scale reads 1kg, cut the cord, empty the bowl, repeat.

I can think of others, but unfortunately none involve an optical mouse.

Throw the mouse in the bin.

Tony