screwdrivertool
Main
tool, usually hand-operated, for turning screws with slotted heads. For screws with one straight diametral slot cut across the head, standard screwdrivers with flat blade tips and in a variety of sizes are used. Special screws with cross-shaped slots in their heads require a special screwdriver with a blade tip that fits the slots. The most common special screw is the Phillips head (Phillips Screw) as shown in the Figure![Screwdrivers (Top) Offset screwdriver; (middle) parts of a screwdriver; (bottom) …[Credits : Encyclopædia Britannica, Inc.]](http://media-2.web.britannica.com/eb-media/42/3942-003-52E1DFC6.gif "Screwdrivers (Top) Offset screwdriver; (middle) parts of a screwdriver; (bottom) …[Credits : Encyclopædia Britannica, Inc.]"){kind=small}
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The screwdriver shank is made of tough steel, and the tip is hardened to minimize wear. The handle is made of wood, metal, or plastic.
If a screw cannot be reached with a straight-shank screwdriver, an offset screwdriver is used; this tool has no handle but has a shank with a right-angle bend at both ends. One blade tip is in line with the shank, and the other is at right angles to the shank.
Screwdriver bits can be clamped in a brace, an automatic handle that rotates on being pushed toward the screwhead, or a gear reduction drive in a power drill.
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