Figure 20.
Standard screwdriver.
(1) Common screwdriver. The common screwdriver (fig 21) has a round
steel blade anchored in a wood or plastic handle. The blade is forged from alloy
steel and tempered. The tip is flat, hot forged to size, and heat treated. Common
screwdrivers are tapered to give maximum strength. Handles are made of hardwood or
plastic composition, usually fluted for a good grip. The blade is anchored in the
handle by two or more tongs on the end of the blade, and in the case of a wood
handle by a pin or rivet through the ferrule, handle, and blade. Some handles are
integral; that is, the blade forms an integral part of some of the outside surface
of the handle and is locked in place by rivets. Integral blade screwdrivers are
used for heavy-duty work. The blade can be tapped with a hammer to seat the blade
tip in rusty screws. Other common heavy-duty screwdrivers have square blades so
that a wrench can be used to turn them.
Figure 21.
Common, flat-tip screwdrivers.
(2) Phillips screwdrivers (cross-tip). The tip of a Phillips screwdriver
(fig 22) is shaped like a cross so that it fits into Phillips-head screws.
Phillips-head screws have two slots which cross at the center. These screwdrivers
are made with four different sized tips. Size 1 will fit No 4 and smaller size
Phillips screws; size 2 will fit No 5 to 9 inclusive; size 3 will fit No 10 to 16
inclusive; and size 4 will fit No 18 and larger sizes. Phillips screwdrivers also
have different length blades ranging from 1 inch to 8 inches.
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