CNC Mill - Z Axis Zero Tool, Spring Loaded

Z Axis Zero Tool works by placing the sensor on your work piece under the cutter, then initiating the cnc software to lower the tool until it touches the sensor, sensing a closed circuit between the tip of a CNC cutting tool and the zero sensor.
The software will then raise the tool away from the sensor and calibrate the job top surface based on the height of the sensor calibrated in the software.

Cheap eBay units have no movement, this is ok for larger end mill cutters etc but the thin long tungsten carbide engravers snap/crumble if the driven into a hard surface.

This will vary on your print and the circuit board thickness used.

I used what I thought would be common scrap box ,garage components.

Spring was from an old bathroom tap cover holder.
and the 29mm copper disc was a piece of circuit board I cut out.

You can use any spring or springs.
Any material like copper, aluminium or stainless for the disc.
making the appropriate modifications to the spring guide to