How to Use a Layout Square

Use the square as a try square. Lay the square on a piece of material and hang the fence off one side of the material, a board for example. The fence is the lip that hangs off the square, perpendicular to the rest of the square's triangle. It acts as a stop or a guide. Lay the triangle over the face of a board, butt the fence up against the side of the board, and mark a straight line 90-degrees perpendicular to the sides of the board, from one side to the other.

Use the square as a miter square. Hold the speed square in the same position you hold the square to make a try square line. Rather than using the 90-degree side of the square's triangle shape to make a perpendicular line, use the 45-degree angle side to make a diagonal mark across the board.

Use the square as a protractor. The layout square has marks on each edge that indicate angles. Begin by holding the back side of the square at 90-degrees to the board -- the fence resting pressed against the side of the board. Move one end of the fence away from the board. The edge of the board will line up with the markings on the square. From these markings, choose the angle you want your cut.

Scribe lines with the square. Layout squares have notches machined into the fence. These notches are staggered every 1/4-inch. If you lay the face of the square on a board -- the fence pressed against the side of a board -- you can put your carpenter's pencil in one of the notchs and slide the square down the length of the board. This will give you a line running parallel to the face of the board 1/4-inch -- or whatever distance you choose -- below the board's top surface.

Use the square as a saw guide. Rest the plane of the saw on top of the square, the blade of the saw perpendicular the the edge of the square. Push the saw and the square down the board. Keep the fence against the back-side of the board to make sure your saw is cutting a straight line.