Keyhole Router Bits

I recently snagged the Rockler T Slot bit when it was on sale I've used it to slot both 34 Oak Plywood and MDF both are holding up fine

What do you choose, a circle the diameter of your keyhole bit or what exactly should you draw to choose to make a keyhole keyhole slot

keyhole slot bit Use this handy bit for flush mounting pictures, plaques, clocks or small cabinets Bit bores an entry hole, then cuts a 316 slot to secure a screw or nail

keyhole slot plug Carbide Specialty Key Hole Bit The dual-cutter head bores notches, grooves and slots into wood, laminates and other materials so screws and nails have