When I teach edge-jointing by hand, I am surprised by how many woodworkers (even experienced ones) evaluate their work incorrectly.
For starters, every board has a “true face,” sometimes called a “datum surface.” This is the one surface that you should press the stock of the square against. This applies even to machine work – electric planers are notorious for creating boards that taper across their width.
So you should mark one true face and always check your progress against that face.
Second: Tilt the square so one arris touches the edge (see photo above). Putting the square flat on the edge will put small errors in shardow. Ergo: You think you have a perfect edge, but when you get to glue-up you learn the gappy truth.
— Christopher Schwarz
3 thoughts on “The Right Way to Use a Square”
Also, the tilted surface of the square can, somehow, catch the light and channel it into the edge. This emphasises the errors much more. Held vertical, the blade could be casting a shadow onto where you are trying to see the light.
I always thought when my square squealed when drug along the surface, it was in… 😉
(eh, not completely kidding. I have a square that actually does this. The tool itself is a cheap machinists-type and not actually square, so I no longer use it. It goes “Wwhhoooaaat!”)
I’m good with that. I’m right at home with a little tilt here and a bit of lean there, besides even my ex told me I’m a little off kilter!
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