This tool, to be used with the bit-brace, for enlarging the outer part of a hole, thus forming a cavity or depression for receiving the head of a screw (Fig. 497), is quite important, as being much more convenient than to use gouge, chisel, or knife for the purpose. See page 205.

The rose form of countersink is common and good. The Clark double-cut countersink (for wood only) cuts smoothly and is easily sharpened. A countersink for metal is useful.

Fig. 497.