Re: DIY probing

--- In CAD_CAM_EDM_DRO@y..., ccs@m... wrote:

> Anyone have plans or ideas for an inexpensive shop-built contact probe?

I did a little research just today on digitizing probes to prepare for mak=
ing one. The best source I found was the US Patent and Trademark Office:

http://www.uspto.gov/patft/index.html

Search for patents with "touch probe" in the title.

The typical design uses three metal rods in a plane perpendicular to the pr=
obe shaft and separated by 120°. The three rods are insulated from each oth=
er and each rests on two contacts that form a roughly V-shaped notch (either=
balls, cones or crossed rods). The members of each contact pair are insula=
ted from each other and the three pairs are connected in series. The circui=
t is closed as long as the three rods touch all six contacts. If the probe =
is tilted even slightly in any direction one of the rods will lift away from=
one of the contacts and open the circuit.

One thing to work out is a guide system to make sure that no matter how far=
the probe tilts it will settle back down with the rods against the contacts=
.