My solution was to hook up two wires with alligator clips on the ends , and as I usually work in aluminum hook one end to the cutter , the other to the plate , and then manually change the tool offset to zero. This works for both Z , and X and Y probing . If using wood I just use tin foil wrapped at the appropriate corner . For my needs this works well. I am in the process of switching to bcnc to have greater control and to allow runs with one file with z probing at tool changes .