My Hall effect switches work so well, I also added one to the upper Z, for homing the Z axis before I use the touchplate to re-home Z-zero to the material or spoilboard surface.
These Hall Effect Switches (AH3391Q; not analog Hall sensors) have the following advanges:
- Cheap. Much cheaper than inductive sensors.
- Very reproducible (15 microns repeatability)
- The chip and magnet are very small so don’t get in the way or hook on things.
- Won’t ever break due to mechanical wear or metal fatigue.
- Not susceptible to dust or a metal object near them (unless it is the South pole of a magnet)
- Switching is in a few ns, with NO bouncing.
- I verified that by using the least-sensitive variety available, they are not influenced by the Earth’s magnetic field (important for a portable CNC).
- They can be powered off anywhere from 3 to 28VDC.
They do require a pull-up resistor (1k) and capacitor (10-100nF) but those can be located near the controller instead of by the switch where I put them.