49. The spokeshave (Fig. 64) should not be used in any place where a plane can be used, but only upon concave or convex surfaces; when used, it maybe either pushed or pulled.
Fig. 65.—Auger Bit.
50. Bits (A.) are of many different types, the most common being the auger bit (Fig. 65). The use of the “worm” (a) is to draw the bit into the wood, thus making a heavy pressure upon the bit unnecessary. The “lips” (bb) make an incision on the wood below the cut made by the “cutters” (cc), which take the shavings out and into the “twist,” which in turn lifts them out of the hole.
Fig. 66.—Cross-handled Auger.
(B.) Care should be used when boring a deep hole that the bit is removed before the shavings clog in the twist, which will happen if the hole becomes full of shavings which cannot be lifted out. Should clogging occur, do not use a great deal of strength in trying to back the bit out, or its “shank” may be twisted off; it is better to pull it out with a straight pull by means of a lever, if sufficient strength cannot be otherwise exerted, the pull being straight over the center of the bit from the “chuck,” not from the head of the bitbrace.
After boring the hole to the desired depth, do not turn the bit backward to remove it, as shavings will be left in the hole, but give it one turn back to loosen the worm, then turn as though boring the hole deeper, lifting under the head of the bitbrace in the meantime, by which process the shavings will be lifted out. These bits are numbered from ³⁄₁₆ths to ¹⁶⁄₁₆ths inch by 16ths of an inch. Sizes larger than these are known as augers.
Fig. 67.