The Swanson Speed Square is one of the most indispensable framing tools, but the true value is only obvious to those who understand how to use it properly. Learning to use the square only takes an hour or two of practice, and before long it will be doing the job that once took several other measuring tools to do. The only thing you will need for practicing is a Speed Square and some scrap lumber.
Measure along the board and make a mark at the position where you want to make the cut.
Set the square flat against the side of the board and push the edge of the protruding lip against the edge of the board at the side that is marked. Slide the edge of the square straight across the board at the pencil mark.
Put your pencil on the mark and push the edge of the square against it while making sure that the lip of the square stays against the edge of the wood.
Slide your pencil back and forth along the edge of the square, making a straight cut line.
Measure and mark the spot where you want to make an angled cut. Place the square flat on top of the board and push the lip against the edge of the board.
Slide the lipped edge of the square along the board until one end is lined up with your mark, which is also known as the pivot point. Hold this end of the lipped edge of the square tightly against the side of the board.
Slide the other end of the lip away from the board until the edge of the board lines up with the correct angle on the scale stamped on the adjoining edge of the square.
Line the edge of the board up with the proper pitch on the common scale of the square for any rafter cuts you have to make. Line the edge up with the proper pitch on the "Hip-Val" scale when making hip or valley cuts on the beam.
Make a pencil line along the shorter edge of the square over the top of the board, and use a straight edge to extend the angle line to the other side of the board.