A combination square is used in woodworking to help achieve the angles necessary to complete the project. It is typically used for framing houses or in small woodworking projects, such as cabinets and dressers. There are several different types of squares available for woodworking, such as the framing square, try square, and precision steel square, but the combination square is the most popular and is generally considered to be the most useful.
In addition to helping the woodworker measure a 90° angle for the pattern being created, the combination square has a 45° shoulder that is used to check and lay out miters. This feature is useful to the woodworker because it eliminates the need to use a separate tool for laying out the miter. This type is more efficient than other types of squares because it is capable of completing two jobs.
A knob located on the rule-type blade is used to reposition the combination square's head. This helps create a tight fit along the desired angle. When purchasing a square, it is essential to choose one that is easy to adjust. Otherwise, the tool can be frustrating and difficult to use.
The combination square also has a scriber, which is housed in the head, and a vial used to determine if the wood is level and plumb. This is useful when creating angles because it ensures they are accurate. Even the slightest inaccuracy can cause the entire project to be flawed. Drawers in small projects may stick or open on their own, doors in houses may not shut properly, and an entire house can look lopsided or crooked if the square is inaccurate or not used properly.
Fortunately, a combination square can easily be tested for accuracy by taping a sheet of paper to a board with a straight edge. It is important for the edge of the board to be perfectly straight. Otherwise, the tool will not be accurate after realignment.
After taping the paper to the board, the combination square should be held against the ledge and a line should be drawn along the outer edge of the blade. Next, the square should be turned over so the opposite side of the blade is facing up. It must then be aligned to the edge of the stock and a second line should be drawn about 1/32 inches (0.079 centimeters) away from the first. If the combination square is accurate, these lines will be perfectly parallel.
