How do I cut keyhole slots so my sign hangs flush on the wall? (Keyhole Toolpath gadget)

What it does

The Keyhole Toolpath gadget (Gadgets menu) automates the slot that lets a sign or plaque hang flush over a screw head. The slot is cut into the back of the piece with a keyhole (T-slot style) cutter: the tool plunges at an entry point deep enough that the cutter's wide section is below the surface, travels the length of the slot to undercut it, then retraces the same path back to the entry hole and retracts. Because the cut is on the back face, remember your design is mirrored relative to the front; place slots accordingly (a two-sided job setup handles this cleanly).

Workflow

1. Draw and select one or more circular vectors marking where each keyhole entry point goes. The gadget warns and stops if nothing is selected.
2. Run the gadget and fill in Slot Parameters: the machining direction the slot travels, the slot depth, and the slot length.
3. Optionally enable Preview Drawing to have the gadget draw outline vectors of the finished slot: you supply the entry hole diameter (the hole the cutter's wide section makes), the slot surface diameter (the shank-width slot visible at the surface), and a layer name for the preview vectors.
4. Set Toolpath Parameters: pick the tool, confirm the feed and plunge rates it inherits, and name the toolpath. The docs recommend selecting an end mill entry to represent the cutter, since keyhole cutters are not a native tool type; for how to define the bit itself in the database, see the odd-bits entry (keyhole and specialty cutters).
5. Calculate, preview, and save through the normal toolpath workflow.

Pro tips

• Orient the slot so it points upward when the piece hangs; the entry hole sits at the bottom of the slot.
• Depth matters twice: too shallow and the screw head won't slip behind the surface; too deep and you risk punching through the front. Check depth against remaining material thickness.
• Cut a test slot in scrap and hang it on an actual screw before running the real piece.
• Official documentation: Keyhole Toolpath