Reply by Planeman40

First of all, for woodworking you don’t need the precision of a machinist’s square. You can’t work to those tolerances in wood.

Second, It is easy to check the accuracy of a square. Just set it up on a straight edge and scribe a vertical line. Then flip the square over and see if the line aligns with the square edge. If it does, the square is square!

Personally, after 60+ years of machining and woodworking, I use a Harbor Freight combination square for both. I have checked it and it is SQUARE.

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