The first edge, or second surface, is examined in but two ways: for straightness, as in Fig. 2, and to see whether it is at right angles to the first surface, as in Fig. 12. In using the try-square press the head or beam firmly against the face surface. The face surface is always the one having the face-mark. If the blade of the try-square does not touch the edge across its entire width, plane down the high places until it does. Do not try to make the plane cut at one side by tilting it, but move the central part of the bit (the part which cuts the thickest shaving)

Fig. 12. A Try-Square on the First Edge. Observe carefully the position of the hands.

over the places requiring the heaviest shaving, as shown in Fig. 6.

Be careful to keep the edge straight and smooth. Avoid as much as you can taking shavings only a part of the length. Plan to have the last shaving extend the entire length of the piece. Move the plane parallel with the edge. Do not be satisfied until the try-square touches the entire surface. Be very particular to have the edge straight to the extreme ends. Do not put this piece in the vise. When this edge is finished, make a face-mark on it the same as on the first surface, as shown in Fig. 11. You should exercise care in selecting the edge to be first planed. Plan to remove as little material from this edge as possible, for this will become the working edge, and should therefore contain the best material. The greater part of the excess material is to be removed from the third and fourth surfaces. If the amount of waste is large enough, it may be removed by using the rip-saw first, and afterwards finishing with the plane.