Re: [CAD_CAM_EDM_DRO] DIY probing

ccs@... wrote:

> Anyone have plans or ideas for an inexpensive shop-built contact probe?
>
> I keep being amazed by cheap import indicators (plunger and lever
> style) and being tempted to try to detect the needle position
> optically. Say put a thin sheet metal flag on the needle that will
> block a photointerrupter like used for home switches... or even put a
> rotary encoder wheel on the indicator.

An idea I had for scanning surfaces was to use a plunger-style dial
indicator, and replace the pointer with the code wheel out of an optical
encoder. The CNC control would read the position of the indicator, and
move the quill to keep it within range.

But, using a DTI might be better, as it might be able to detect a vertical
wall as well, and just pull the quill up until it clears the wall.

The best thing would be to use part of the indicator movement, but add
a 3-axis mechanism that could handle being moved in X, Y or Z
without bending anything. if you've ever seen a co-ax indicator, you
should be able to figure out how to generalize that mechanism to
accept a deflection in any direction.

About 6 months ago there was a lot of discussion of how a Renishaw
probe was made, and it didn't sound real hard to duplicate.

Jon