CNC Touchoff

thingiverse

Touch off pad for a CNC mill. It is extremely probable (unless you deliberately took steps to prevent it) that your CNC structure is grounded. So this includes a plastic T slot nut and plastic pad to insulate from the machine. This is a snug fit on a 7/16" T slot. Insert 8mm hot melts into the back end of the T nut ensuring it is recessed enough not to touch the bed. PRO TIP: Thread the bolt through the T nut out the back end and finger tighten a few turns with a hot melt. Insert soldering iron. The brass hot melts will heat up long before the steel fastener does, and the fastener will keep the hot melt aligned in axis with the bolt hole. For the top touch off pad use two countersunk bolts to secure to the table. Finally, you need a 1" diameter metal puck. I used aluminum, about 15mm thick. Face and chamfer it. Then chuck it up in a vise and face off a flat and drill/tap as M3. Thread your probe wire through the plastic touch off holder and unsheathe end. Insert into M3 hole and use a M3 grub screw to secure wire to puck. Then gently tap puck into the holder, and ensure a nice flush fit. 7/16"