Re: digitizer arm?

> Holy cats, I contacted a sales rep, who called me back a short

while ago,

> these things are $3500 list price!
> For a few cheap rotary encoders, simple framework, glue electronics

and

> interface software, that sure is steep!
> I guess if they were sold like PC game joysticks, they'd be

cheaper...
Bill,
I went through that exercise before I bought mine. If you start to
play with the actual geometry/arm lengths US Digital 4000 CPR
encoders just wont give you the resolution you need. 360/4000 sounds
like a big number until you work out just how small a rotary movement
a .001 deflection makes at 12 inches. I looked at gearing to really
spin the encoder up but even that didn't work. I don't know how
Microscribe is doing it. The only thing that I can think of that
gives you that number of clicks per revolution is a reolver and I
don't know if you could fit that much electronics in a Microscribe.
Faro makes arms that are that accurate with a 6 foot reach.

A mystery... but I'm not about to take mine apart.

Roger S