Mortising bits can be used to cut slots into wood to allow for assembly. One of the most common uses is to cut out a space on the edge of a door for a recessed door hinge, allowing it to sit flush with the door's edge. The door will then close without an obvious gap.
A mortise router bit is capable of cutting through wood, plywood, plastic and other wood composites. If you need a square corner on your mortise, use a Whiteside Square Corner Chisel
. Screw Type Helix mortise bits are replaceable and screw onto Helix Mortise Arbors
for ease of changing out one for another.