if you want to scan, or digitize a model in a cnc program, it requires a digitizer probe.. unfortunately they are expensive, or, hard to
lots of examples use ball bearings, 3 contacts, for sideway forces, a spring...
here is one solution i didn't find... an easy one..,
while looking for a cheap solution (DIY) i couldn't help thinking about a very sensitive device, the needle of a turntable..
or something equivalent..
a nail soldered on a piezo buzzer,
with a microprocessor as a converter,
with adjusable threshold..
While it can be done cheaper, i think this is the easiest way...
it takes about 10 minutes to make one... and is very sensitive, adjusable, easy to use, or to custom, to your own needs
what you need
1 small piezo buzzer
1 film can
foam (mousepad or something softer) for mechanical vibration-insulation)
an arduino, or other micro processor
(or use electronics, like an op-amp etc)
If using an arduino, download the knock program from arduino..
and read up on piezo as a sensor
the led should light up, when just scratching the nail....
then connect the ground, and an output port (saay 13) to your input (parallel port) as an digitizer..
the rest is up to you... digitizer is connected to the limit switch of the z axis but there are to many programs and cnc machines to tell what step is next to take...
here it is in it's first test
and one to test it in digitizer probe style (apparently)