The action of a chisel driven into the wood with a mallet is somewhat similar to that of a wedge. This must be taken into account when cutting dadoes, mortises, etc., where it is desired to cut away the waste exactly to a given line. If the chisel were beveled on two sides the action would be the same as that of a wedge; that is, the wood would be pushed to either side equally. Since the bevel is on one side only, beginners are prone to think that the wedging takes place on one side only, the bevel side. Most of the wedging does take place on the wood at the bevel side, but there is enough pressure against the bevel to force the flat side of the chisel over the line slightly onto the part which it is not desired to cut. To overcome this action, chisel a line parallel to the given line, about one thirty-second of an inch away from it, on the waste. When the opening has been cut to depth, the chisel may be set exactly in the given line and driven to depth. The narrow margin of waste wood breaks off; the pressure against the bevel is therefore almost nothing. [Fig. 89].
Fig. 90.
47. Horizontal Paring Across the Grain.
—In horizontal chiseling the work should be fastened so as to leave both hands free to guide the chisel. [Fig. 90] shows the manner of holding the chisel. The left hand rests against the piece of wood and the chisel is kept from cutting too far by the pressure of the thumb and fingers of this hand. With the bevel side of the blade up, move the handle from right to left carefully while pushing it forwards; pare off pieces about one-sixteenth of an inch thick half way across from edge to edge. [Fig. 91]. When within a thirty-second of an inch from the gage line hold the chisel so that its cutting edge shall move obliquely across the grain and pare just to the gage line. The direction of the grain will determine which corner of the chisel is to cut ahead. In starting the last cut place the chisel squarely in the gage line.
The piece should be reversed and the cut finished by cutting in a similar manner from the second side.
Fig. 91.
Fig. 92.