The simplest method of checking a low grade square for accuracy is to draw a line across a board with a flat face and straight edge. Then flip the square over 180 degrees and check if the blade aligns with the line just drawn. Any error is multiplied by two and appears as a wedge or taper In the example seen opposite, the try-square is used to test that a 90 degree angle exists across the edge of the steel. Although a burr exists on the edge of the steel it fits into the slot and does not affect the way the try-square is used. Weight: 0.81 Kg