Toolbox: Combo Square

A combination square, or combo square, is one of the most compact and versatile tools around when it comes to doing carpentry work around the house. You can check inside or outside 90-degree angles.

It also has a built in 45-degree angle, which is especially useful when you're marking for miter cuts...say you want to put together two pieces of molding or window casing at a 90-degree angle.

Most combo squares come with a level or plumb vial that will allow you to level a surface and make sure that it's straight up and down. Also one of the great advantages of a combination square is you can draw a straight long line real quick by just making a few adjustments. Just place your pencil at the end of the rule and draw the combination square towards you very slowly, keeping the pencil in place.

It can also be disassembled and you can use the rule to draw a straight line. The higher quality models will have the numbers and fractions etched into the blade.

If you want to measure how deep a cut is, you can use a combination square for that also.