Photo by Jim Ruen
Higher-quality framing squares have more tables and finer gradiations, which make them more useful tools.
To put your framing square to work, you need to know the parts. A typical square has a face (the side with the manufacturer’s logo), a tongue (the shorter and narrower 16- by 1½ -inch arm) and a blade (the longer and wider 24- by 2-inch arm). The heel is where the two arms meet.
Before you buy your square, look at the different tables offered on different brands. The better the square, the more tables and the finer the gradations on the straight edge. I expect to make good use of the rise per foot/degree conversion table as I do future work on my garden slopes.
It may also come in handy drawing circles and ellipses as well as finding centers of circles. To make a circle, draw a line equal to the diameter. Place the heel at the halfway point of the line and rotate the arm, marking the circle outline as you go. To find the center of a circle, set the square with the outside heel on the circumference and mark where the outside edges of the arms touch the circumference. Draw a line between the two marks for the diameter, move the square to a new spot and repeat. The center is where the lines cross. Ellipses are more complicated than can be explained here. However, there are a number of excellent descriptions on the web.
If your framing square doesn’t come with instructions, consider picking up a reference book. A great reference I found at a used books store is Tools, Steel Square and Joinery by John Ball (2005, Wiley Publishing). It is part of the Carpenters and Builders Library. As is the case with any tool, the more you know and understand it, the more value it has for you.