can readily be sharpened by
grinding.

[Illustration: Fig. 123. Dowel-Pointer.]

[Illustration: Fig. 124. Cornering Tool.]

[Illustration: Fig. 125. Brad-Awl.]

[Illustration: Fig. 126. Twist-Drill.]

[Illustration: Fig. 127. Twist-Bit.]

[Illustration: Fig. 128. German Gimlet-Bit.]

[Illustration: Fig. 129. Bit-Point Drill.]

[Illustration: Fig. 130. Auger-Bit.]

[Illustration: Fig. 131. Plug-Cutter.]

[Illustration: Fig. 132. Center-Bit.]

[Illustration: Fig. 133. Foerstner Auger-Bit.]

[Illustration: Fig. 134. Expansive-Bit.]

[Illustration: Fig. 135. Reamer.]

[Illustration: Fig. 136. Rose Countersink.]

_Gimlets_ and _drills_ are alike in that they cut away material, but
unlike in that the cutting edge of the gimlet is on the side, while
the cutting edge of the drill is on the end.

_Twist-drills_, Fig. 126, are very hard and may be used in drilling
metal. They are therefore useful where there is danger of meeting
nails, as in repair work. Their sizes are indicated by a special drill
gage, Fig. 220, p. 117.

_Twist-bits_, Fig. 127, are like twist-drills except that they are not
hard enough to use for metal. Their sizes are indicated on the tang
in 32nds of an inch. Both twist-bits and drill-bits have the advantage
over gimlet-bits in that they are less likely to split the wood.

Twist-bits and twist-drills are sharpened on a grindstone, care being
taken to preserve the original angle of the cutting edge so that the
edge will meet the wood and there will be clearance.

_German gimlet-bits_, Fig. 128, have the advantage of centering well.
The size is indicated on the tang in 32nds of an inch. They are useful
in boring holes for short blunt screws as well as deep holes. They
cannot be sharpened readily but are cheap and easily replaced.

_Bit-point drills_, Fig. 129, are useful for accurate work, but are
expensive.

_Auger-bits_, Fig. 130, have several important features. The spur
centers the bit in its motion, and since it is in the form of a
pointed screw draws the auger into the wood. Two sharp nibs on either
side score the circle, out of which the lips cut the shavings, which
are then carried out of the hole by the main screw of the tool. The
size of auger-bits is indicated by a figure on the tang in 16ths of an
inch. Thus 9 means a diameter of 9/16".

There are three chief precautions to be taken in using auger-bits. (1)
One is to bore perpendicularly to the surface. A good way to do