Time for an anatomy lesson:

The whole thing is shaped like an equilateral triangle and has one side with a flat edge, like a “T”.

It has lots of numbers on it. On the 2 adjacent sides, there are ruler markings (very handy) used to measure length. On the edge of the hypotenuse are angles in degrees.

And on the inner rail, there are a bunch of dashes and numbers. These are to find the pitch of a roof (4/12, 6/12, etc). 


*On that note, living in Arizona and our sea of 3/12 and 4/12 roofs, I’m so jealous of the rest of you with your stately 6/12 pitches! 

Although a speed square can be tremendously helpful in finding and ascribing angles, I typically reserve finding angles for my combination square.

90% of the time I use my speed square to mark lengths from an edge, giving me a way to draw a perfectly perpendicular line.

Or, to check if two boards are “square” with each other.

Plan on building or repairing a piece of furniture soon? I would highly recommend shelling out the $1 to get yourself a speed square. It will help you avoid stuck drawer boxes and wobbly legs.