The jointer is a woodworking machine that is used to make two sides of a piece of wood perfectly square. To use the jointer, the workpiece is placed, cut target side down, and pushed through the machine between the red spring-loaded guard. This creates a flat edge that is 90 degrees relative to the top flat surface. The jointer is similar to the planer, but is more frequently used for the narrow faces of boards. Originally created to square two boards before joining them edge to edge, the jointer is good for ensuring that joints will meet at 90 degrees, and for creating vertical sides for drilling, joining, gluing, etc. The maximum depth of cut on the planer is 1/8-inch (0.125").