The first surface - a broad surface, should the piece not be square in section, and the first edge selected or prepared have a special use and are given distinguishing names. The first surface is known as a face side or working face, and the first edge is known as a face edge or joint edge. They are marked as indicated in Fig. 43, the marks being made near the middle of the length of the piece, so that they may be distinguished from the other surfaces, which are not marked. From these two marked surfaces all testing, as described later, is done, the head of the gage and the beam of the try-square being held against these and these only. To do otherwise is to introduce additional chances for errors.
Fig. 43. Face Side; Face Edge.
Fig. 44. Faces Turned In.
Where the project is to consist of but one member, the better broad surface and the better edge are selected for face side and face edge. Frequently it is difficult to decide which is the better surface or edge. Usually, however, streaks of sapwood, or small knots, or checks appear more numerous upon one surface than the other.
Where several members are to be joined together to form a project, such as a table or chair, it is best to so select the faces that they may be turned in when the members are put together, Fig. 44. Faces are more likely to be accurately made than are the reverse surfaces and, for this reason, the joints are more likely to fit properly if the faces are placed so that the mortises or joints may be made in them. This would mean, of course, that the surfaces selected for faces should be the poorer rather than the good surfaces as in the case of the single piece project.