I may be getting old, but I still don’t believe it’s hip to be square. Nevertheless, I expect my carpenter’s square to be at least as square as Pat Boone. But how do you test a square to find out?

I suppose you could try to quiz them on their musical tastes, or see how they dress, or something. But I’ve found a much more reliable way to test whether a square is really square.

The pencil is required. You also need a straight edge. I am using the edge of the workbench. The paper (and tape, to keep the paper from moving) are nice to have but not absolutely necessary.

If you read my recent post about checking your level you’ll see some similarity in concept to this test. We’re going to line up one edge of the level with a straight edge, and draw a line with the other leg.

Then we flip the square over, and draw another line.

The two lines should be parallel to one another.

If they are, huzzah!

If not, there’s usually no practical way to fix them. In theory you could grind them with a specialized machine tool. But it would be way cheaper to buy a new square than to pay someone else with such a machine and the skill to use it.

I hope this helps you out the next time you buy a square!