Re: Digitizer probe progress

Graham:

Thanks! Your description was extremely helpful.
Now I "get it." The patent number 6553682 (from
a subsequent post) was useful too.

Again, thanks!

-Wayne

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@n...>
wrote:

>
> OK, the probe itself is screwed into a hub and from this hub protrude
> three metal arms. These arms are insulated electrically. Each arm
> sits between two bearings and hence makes an electrical connection
> between them. The PCB clamps down onto the balls, holding them in
> place and also making an electrical connection to them. There are
> two wires from the probe one connects to one part of the pcb which
> goes to just one of the balls, the current goes from the pcb to ball
> to rod to ball ... until it leaves by the other wire.
>
> i.e.
>
> Wire
> pcb
> ball-rod-ball
> pcb
> ball-rod-ball
> pcb
> ball-rod-ball
> pcb
> wire
>
> So if the probe tilts in any direction or is pushed up then the
> circuit is broken and the computer knows to stop moving. The hub is
> held against the contacts using a spring BTW.
>
> I have uploaded pics of results now, see my other post.