Fixing up a cheap combination square

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My plywood order arrived earlier in the week and I hope to get a few hours this weekend to start on the bench. In the meantime I have been trying to educate myself on some of the basic techniques, for example, how to cut things square.

To show the level of my naivety, it had never occurred to me that the things I had been using to measure right angles might not actually be true right angles at all.

It turns out there is a very easy way to check this – lay one edge of your square against a flat surface with  a straight edge, draw a line along the other edge of the square; flip the square from right to left and draw another line. If the square is accurate the lines will overlap exactly – if not, they will diverge.

Nothing was square – rafter square, combination square, t-square , speed square, all were off. A bit disappointing, but it did lead me to read about two top tips, which I hope will be of use to others as inexperienced as I am.

1. don’t chuck away your unsquare squares – if you use the testing technique above the mid point between the two lines is exactly 90 degrees.

2. You can make your el-cheapo combination square really square in a matter of minutes – use the test above to find out which direction it is out and then use a small needle file to take a little of one or other edge of the brass hook that secures the ruler until it is correct. Simple, and I now have a perfectly square square!

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