Fig. 69.—Filing an Auger Bit.
In doing this, it should be remembered that the bit progresses into the wood as it cuts, and unless the under side of the cutter is filed properly, it will bear upon the wood beneath it, back of the cutting edge, and prevent the bit from advancing. To remedy this, be sure that the cutter is kept filed thin, and that the under side is straight from the edge to the beginning of the twist.
(I.) If the lips (Fig. 65, bb) are filed off, an auger bit bores into the end wood easily.
51. The bitbrace, or stock.—(A.) This tool is used to hold the bit, and to furnish sufficient leverage to turn the bit into the wood. Bitbraces are made of different sizes, and with different devices for holding the “tangs” of the bits. A workman should own an 8” and a 10” swing bitbrace, as it is often necessary to use different sizes or kinds of bits alternately.
Fig. 70.—Ratchet Bitbrace.
(B.) The ratchet bitbrace (Fig. 70) differs from the ordinary brace only in the ratchet attachment. It is an indispensable tool to an up-to-date workman, as it may be used in many places where an ordinary brace would be useless; for general work, however, being heavier, it is less convenient than the plain brace.
52. The Screwdriver (A.) is one of the most important tools in a carpenter’s kit, and to be of use should be of finely tempered steel, for if too soft, it will turn over, and if too hard, it will break. The edge should be as thick as the slot of a screw will allow, in order to have as much strength as possible.
(B.) A round-handled screwdriver is not so satisfactory as one with an elliptical or polygonal handle, as it is impossible to obtain as good a grip upon the former as upon the latter; a round handle, planed flat upon the two opposite sides, is quite commonly used.