I have done some searching with Google and it is difficult to find a small tri square, carpenter's square or Crown Square. I see some at 3 inches, but that seems too large for use with the blade? This is the second time that I have been told that a small square would work, but I have been unable to find one. If anyone owns one please give me the make etc. I noticed that some good quality squares have specs as follows - 0.01 mm per cm of steel blade, it does not take much for your edge to be out, would this be significant? Perhaps not. Thanks - Alan