Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw

Roman Black wrote:

> But they don't have to be on/off light
> beams. Shine one at an angled or curved
> surface and it returns a analogue value
> in volts. ANY movement of the reflecting
> surface will cause the exact amount of
> light to change, up or down, giving a
> "hit".

I had the misfortune to buy a "Spaceball" on eBay that didn't work with
my Cad program, and found another one that did cheaper than upgrading
the first one. A Spaceball is an input device for CAD that offers 6
degrees of freedom in moving and rotating a 3D object.
Needless to say, I took the NG one apart. There's a series of 6 sensors
arranged around a ball on axis' 90 apart from each other.
Each sensor consists of a "well" sunk into the ball, with a post at the
bottom that extends both up into the well and out from the other side
and is attached to a central hub inside the ball. The sensors are some
sort of light emitters and detectors and it appears that the edge of the
post inside the well intersects the center of the beam from the emitter.
Must be IR, as I didn't see any visible light.

Anyway, what this gives is 6 strain sensors, and the motion of the ball
is interpolated from sensor feedback and translated into movement of the
CAD model. I can say that this is very sensitive. It's difficult to even
touch the ball without the slight movement being sensed.
Unfortunately, I couldn't think of anything to do with the sensors, and
tossed them. If you can find a dead Space Ball, there's 6 of these
sensors to play with.

Jon