Ever heard of “wood blowout”? It’s the nasty-looking tearout created by a drill bit when it breaks through the exit side of a workpiece you’re drilling. It’s especially ugly—and irreparable—on plywood, particleboard and laminates. Avoid it by always laying a backer board under the workpiece before drilling. As the drill exits the workpiece, the backer board supports the backside of the workpiece and keeps the drill from exploding through. Any waste piece of wood or plywood works well as a backer board, but be sure to line up each new hole you
want to drill with an undrilled section of the backer board.