Gauge the piece to 11/4 inches thick on each edge and plane down to these lines. Use the blade of the try-square as in Fig. 3 to see if the surface is straight from edge to edge or from line to line. You may also use the try-square as on the second and third surfaces, placing the head of the try-square against the surface which has a face-mark. Also measure with the rule at each corner, as in Fig. 17. If all these tests show your piece to be correct you will have done well. If the work is very accurate the square will fit the fourth surface when the beam is against the edge which does not have a face-mark. Do not plane the fourth surface to make the try-square fit in this position. This is only an additional test for proving the accuracy of the work. There should be no mark placed on this surface.

In case your piece is below size, do not discard it for another piece, but work it to a smaller size, testing it carefully to see that it is the same size at each end. Should you plane below your gauge line, do not attempt to complete the piece by simply planing and measuring, but set the gauge to the smaller end and draw a line entirely around the piece. Then plane carefully to this line, and test with the try-square and the rule.