For my JGRO CNC router I use a PC board as a touch plate. I wrote a MACRO for MACH3.
-
response = MsgBox( "Auto Zeroing, Put Ground Clip on Tool bit", 1 )
If IsSuchSignal (22) Then
code "G31 Z-3 F20"
While IsMoving()
Wend
Call SetDRO( 2, 0.0625 )
code "G1 Z1"
While IsMoving()
Wend
response = MsgBox( "Auto Zeroing Complete. Remove Ground Clip", 1 )
End If
Not a lot different than what you can buy from AliExpress or Amazon for under $10. But at the time those weren't available.
At this point, for the milling machine, I use a
Fowler Edge Probe for edge detection with my Shumatch DRO-350 and the Find Center function. Then, once at the XY==0 point has been determined I move to that based on the DRO readout and then zero the XY on LinuxCNC. For now I use the LED on the probe to know when I've touched an edge but the plan is to add a wire into the PC to provide the signal for when the edge is found.
I had ordered a tool touch sensor like this one
Touch Sensor from China this summer but after a month the sender bailed and I got my money back.
So I'm still undecided on which direction to go.