A keyhole router bit is a cutting tool used in woodworking to create a keyhole-shaped slot in the back of a piece of wood, which can then be hung on a nail or screw head. The bit has a straight cutting edge that cuts a slot with a narrow circular entry hole and a wider oval or circular exit hole.
Keyhole router bits come in a variety of sizes and shapes, including straight bits, spiral bits, and carbide-tipped bits. They can be used on a wide range of materials, including wood, plastic, and metal.
When using a keyhole router bit, it's important to take proper safety precautions, such as wearing eye and ear protection and using a router table or other secure surface to hold the wood. It's also important to use the proper technique to ensure that the keyhole slot is centered and straight, as any deviations can affect the stability of the final piece. Some keyhole router bits come with a guide bearing that rides along the edge of the wood to help ensure a consistent cut.