Re: Digitizers, Renishaw

--- In CAD_CAM_EDM_DRO@egroups.com, Doug Fortune <pentam@h...> wrote:

>
> "Roman Black" <fastvid@e...> wrote:
>
> > How about a vertical hanging probe, with
> > like a disc at the top. The disc sits on/in
> > a ring. The exact mech design I leave to
> > the experts!
>
> How about instead a "jack", something like
> Alan Marconett KM6VV <KM6VV@a...>
> suggested:
>
> >The tips of the star are indeed conductive, but I'm thinking the

three

> >"arm" contacts need to be insulated from each other. 3 pole,

single


I would stay well away from electrical contacts.
To get reliable conduction requires pref silver
plated contacts, and high contact pressure and
velocity. Switch theory is all old hat. Just
lightly touching two contacts together will
NOT give a reliable confirmation. Sometimes
it will work, sometimes not. As you increase
the voltage the contact detection gets better
but arcing starts, which is a whole new problem.
All pushbuttons, switches and relays are
designed to have high velocity and good pressure
at the contacts. You are not going to get that.
:o) Opto's or other non-contact sensing is the
best. Optos and circuit are maybe $10 tops.
-Roman