How To Use Swanson Speed Squares

Do you know how to use a Swanson Speed Square? I’m sure you’ve seen a speed square before, most every carpenter you run into has one hanging from their tool belt. Learning how to use a speed square is a very valuable carpentry skill.

Most people use speed squares as a perpendicular cross-cutting guide for circular saws. This simple square allows you to cut nice square cuts with a circular saw each time. But a speed square is much more useful than that!

If you look closely at a speed square you’ll see all kinds of numbered scales on it. There is a short scale on each of the both perpendicular faces that are handy for laying out wall plates and other tasks. However, the most useful scales are the ones used for cutting rafters. There are two scales, one for cutting common rafters and one for cutting hips and valleys.

I’ll show you a simple example of cutting a common rafter with the adjacent photo. Let’s assume we’re cutting rafters for a 6:12 pitch roof (6 being the rise and 12 being the run).

Step 1 – Set the pivot point at the tip of the rafter with the guide tight against the wood.

Step 2 – Rotate the speed square about that point until the pitch (6 for our example) is lined up with the edge of the rafter as indicated with the arrow labeled pitch.

Step 3 – Draw a line along the line indicated as the cut line. Now just cut your rafter. This method will give you a plumb cut for the top of the rafter and the tail of the rafter.

It’s as simple as that. If you want to cut hip or valley rafters the method is the same you just use the other scale. So next time you need to cut some rafters give your Swanson Speed Square a try. It’s certainly much quicker and easier than pulling out the calculator! You can also buy the Essential Guide to the Steel Square which is a great book on how to use framing and speed squares.