I finally got around to connecting a touch-off plate and setting up LinuxCNC with a probe screen and a Z touch-off button.
Until now, I’ve always set up the workpiece coordinates on the machine manually. I usually used the “piece of paper method”, jogging the tool to the edges of the stock and sliding a piece of paper between the tool and the stock. Then I would click the Touch Off button and enter the proper offset to where the center point of my cutting tool was.
A probe routine can be used to detect the X, Y, and Z zero coordinates after you mount a part or piece of raw stock material on the CNC router bed. This sets the work offsets (e.g. G54) so the machine knows where the part is mounted on the bed and can command all the moves in the G code program relative to the zero point of the part, as was defined in the CAM programming.
If you’d like the details, here is the article on how to setup a touch plate and probing functionality in LinuxCNC.