Re: [CAD_CAM_EDM_DRO] making a digitizer probe

Hi Graham,

As I've posted before, I've made a small digitizer, very similar to
MaxNC's.

I believe to a simpler extent, that the MaxNC probe is of a similar
design to the Renishaw. As I suspect you're interested in making one,
I'll describe the MaxNC probe.

Basically, in the MaxNC, there is a triangular piece of PCB material
connected to the probe. This piece is pressed (with a spring) against a
round PCB with three 2-56 screws protruding through the board. The
center of the round board has a hole that clears the long thin probe.
The three contact pairs thus formed are connected in series. If the
triangular board is tipped, then one or more pairs of contacts are
opened, and this event (with a pull up resistor) is read into the PC on
a parallel port line.

For the Renishaw, there are three small spheres, and they bridge three
pairs of round rods used as contacts, as I recall.

I built my own (PCB style) probe. I even explored using some small
bearings to more closely duplicate the Renishaw, but never got around to
it.

Contact me off list if you're interested in hearing more. Or I could
post pix.

Alan KM6VV



"Graham Stabler " wrote:

>
> I'd like to try and make myself a digitizer probe now that my mill is
> up and running but am not sure of how to go about it. So far I have
> come up with the idea of having a pointed probe running on a little
> precision slide that will block a slotted opto sensor when the tip is
> depressed.
>
> I'm not sure of the best way to get repeatability but I already have
> a tiny little THK slide that might form a basis of the unit. Having
> said that it would not mount easily into the tool holder.
>
> Anyone done this?
>
> Cheers,
>
> Graham Stabler
>
> www.indoor.flyer.co.uk