The detail that grabbed me first is the probe surface itself: instead of a machined metal block, the touching faces are just metallic conductive foil tape. This Designed That formed the jig from two orange 3D printed components, with that foil lining the inner surfaces and the recessed base. On paper it sounds too simple to trust, yet the machine went on to carve a letter M into a plywood workpiece, and the maker reports it works a treat.
Putting it together looks refreshingly straightforward. Two parts were printed and then carefully superglued into one body, and the aluminum tape was laid onto the faces of the touchplate. For wiring, a DC barrel plug with red and black wires runs to the CNC probe input, while alligator clips tie the wiring to the aluminum tab and to the collet or tool bit. My view is that the clips make swapping between machines far less of a chore than soldered leads would.
The software side is where the numbers live. The probing code came from the CNC Router Parts website, and the maker opened the VB Script Editor through the Edit Button Script function on the Auto Tool Zero button in Mach3. In the Select Axis to Auto Zero dialog, Z, X and Y were all enabled, and the router then probes down in Z before touching the interior side walls in X and Y. The entered values were a plate height of 0.12 inches measured with the foil included, a probe width of 1.47 inches, a probe distance of 1.4 inches, and a 6 mm tool diameter.
Two open points stand out. Being only plastic, mistakes will not damage the endmill, which in my opinion is a genuinely useful property for a shop jig. The maker is still unsure whether the script was meant to run in Mach3, and an aluminum version for use with metal is planned. If contact ever fails, checking for a signal in Mach3 Diagnostics is the advised first step.
Project by This Designed That. Watch it on their YouTube channel: