Fig. 583.
Fig. 584.
Fig. 585.
After cutting about half through the piece in this way, turn it over and repeat the process from the other side, the result being a hole like that shown in Fig. 585. Now turn the chisel around with the flat side toward either end of the hole, and you can pare down the ends to the line without danger of undercutting (Fig. 585).
Care must be taken not to jam the chisel down lengthways of the grain until the hole is practically cleared of wood, or the side of the mortise may be split off. Use the chisel lengthways of the grain only at the end of the process, to pare the sides of the mortise evenly, with light strokes, down to the line.
In all the use of the chisel, take pains to hold it vertically as regards the sides of the mortise—that is, do not tip it over sideways, or the mortise will be slanting or too wide at the bottom.
The common firmer-or paring-chisel can be used for all light mortising, but for heavy work the regular mortising-chisel should be used (see Chisel).