Screwdrivers
A screwdriver is a tool for the insertion and tightening of screws. The screwdriver is made of a head, which engages with screws, a mechanism to apply torque by rotation, and some way to position the screwdriver. Typical screwdrivers comprise a cylindrical handle to be held by a human hand, and a shaft fixed to the handle. The screwdriver tip is shaped to fit a particular kind of screw. The handle and shaft allow the screwdriver to be positioned and supported and, when rotated, to apply torque. Screwdrivers tips can be rotated manually or by an electric motor.
A screw has a head with a contour such that an appropriate screwdriver tip can be engaged in it in such a way that the application of sufficient torque to the screwdriver will cause the screw to rotate.
Screwdrivers were invented in the Middle Ages in Europe and have undergone continuous improvement since. Gunsmiths still refer to a screwdriver as a “turnscrew”, under which name it is an important part of a set of pistols. The name was common in earlier centuries, used by cabinet makers and shipwrights.
The Cabinet-Maker’s screwdriver is one of the longest-established handle forms, somewhat oval or elipsoid in cross section. This is variously attributed to improving grip or preventing the tool rolling off the bench. The shape has been popular for a couple of hundred years. It is usually associated with a plain head for slotted screws, but has been used with many head forms. Modern plastic screwdrivers use a handle with a roughly hexagonal cross section to achieve these same two goals.