Fig. 1517.
If there are two keys the edges and one face may be trued up as just described, and both keys k, [Fig. 1517], chucked at once by inverting their tapers as shown in figure. But in this case unless the edges are quite true they may cause the keys not to bed fair on the underneath face, and the faces therefore to be out of parallel on either or both of the keys. If there are a number of keys to be cut to the same thickness it may be done as follows:—
Fig. 1518.
Plane or shape first one edge of all the keys; then plane up one face, chucking them with one planed edge against each vice jaw, and put little blocks (a, b, c, d, [Fig. 1518]) between the rough edges; then turn them over, chuck them the same way and plane the other face, resting them on parallel pieces; then plane the other edges last.
In place of the small blocks a, b, c, d, a strip of lead, pasteboard, or wood, or for very thin work a piece of lead wire, may be used.
