One of the things that I’ve been trying to do on my mill/lathe is to make the alignment and calibration easier. One of the add ons for mach3, MachStdMill makes this a lot easier through the use of probes. Unfortunately some of the probes are normally open and some are normally closed. He provides a schematic to make 3 varied probe types work to trigger the same input. I put the board into Eagle and had some made at oshpark. Then I made a 3d printed enclosure for it. You can see the board, and the video below. I’ll upload the Eagle files if anyone is interested.