CNC Mill - Z Axis Zero Tool, Spring Loaded

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The Z Axis Zero Tool works by placing a sensor on your work piece under the cutter, then initiating 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. CNC 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 okay for larger end mill cutters, but thin long tungsten carbide engravers snap or crumble if driven into a hard surface. This will vary depending on your print and circuit board thickness used. I used common scrap box garage components that I thought would be suitable. A spring was taken from an old bathroom tap cover holder, and a 29mm copper disc was cut out of a piece of circuit board. You can use any spring or springs. Any material like copper, aluminum, or stainless steel for the disc, making the appropriate modifications to the spring guide to suit. The disc was super glued to the spring-loaded plastic end stop plate. You can modify the height of the housing to suit the sensor height you require. After assembly modifications: wire placements on disc and path through enclosure. I would solder the wire more to the outer edge of the disc, or even underneath. I initially used a knot in the wire to prevent it being pulled out, but this restricted the up-down movement of the sensor pad. So, I drilled holes in the cross-shaped spring guide and threaded the wire through so it won't get pulled out of the sensor. The parallel accuracy was excellent. Now I just have to modify my Mach3 software and CNC driver to accept the sensor. This is a video that gave me the idea: https://youtu.be/1psOL-pVZXE This is another video that helped me with the project: https://youtu.be/tvV2Vmrxarc?list=RDtvV2Vmrxarc&t=21