Make/Model: Porter Cable Model 556 Documentation: Biscuit Joiner Manual General Information What is a biscuit joiner? A biscuit joiner or biscuit jointer (or sometimes plate joiner) is a woodworking tool used to join two pieces of wood together. A biscuit joiner uses a small circular saw blade to cut a crescent-shaped hole (called the mouth) in the opposite edges of two pieces of wood or wood …