Sunday, March 15, 2020

The History of Early and Modern Screws and Screwdrivers

The History of Early and Modern Screws and Screwdrivers A screw is any shaft with a corkscrew-shaped groove formed on its surface. Screws are used to fasten two objects together. A screwdriver is a tool for driving (turning) screws; screwdrivers have a tip that fits into the head of a screw. Early Screws Around the first century CE, screw shaped tools became common, however, historians do not know who invented the first. Early screws were made from wood and were used in wine presses, olive oil presses, and for pressing clothes. Metal screws and nuts used to fasten two objects together first appeared in the fifteenth century. Mass Production of Screws In 1770, English instrument maker, Jesse Ramsden (1735–1800) invented the first satisfactory screw-cutting lathe. Ramsden inspired other inventors. In 1797, Englishmen, Henry Maudslay (1771–1831) invented a large screw-cutting lathe that made it possible to mass-produce accurately sized screws. In 1798, American David Wilkinson also invented machinery for the mass production of threaded metal screws. Robertson Screw In 1908, square-drive screws were invented by Canadian P. L. Robertson. Twenty-eight years before Henry Phillips patented his Phillips head screws, which are also square-drive screws. The Robertson screw is considered the first recess-drive type fastener practical for production usage. The design became a North American standard, as published in the sixth edition of Industrial Fasteners Institute Metric and Inch Standards. A square-drive head on a screw can be better than a slot head because the screwdriver will not slip out of the screws head during installation. The Model T car made by the Ford Motor Company (one of Robertsons first customers) used over seven hundred Robertson screws. Phillips Head Screw In the early 1930s, the Phillips head screw was invented by Henry Phillips. Automobile manufacturers now used car assembly lines. They needed screws that could take greater torque and could provide tighter fastenings. The Phillips head screw was compatible with the automated screwdrivers used in an assembly line. Allen Key A hexagonal or hex screw head has a hexagonal hole turned by an Allen key. An Allen key is a hexagonally shaped wrench. Screwdriver In 1744, the flat-bladed bit for the carpenters brace was invented, the precursor to the first simple screwdriver. Handheld screwdrivers first appeared after 1800. Types of Screws Cap screw has a convex head, usually hexagonal, designed to be driven by a spanner or wrench.The wood  screw has a tapered shaft allowing it to penetrate the undrilled  wood.Machine screw has a cylindrical shaft and fits into a nut or a tapped hole, a small bolt.The self-tapping  screw has a cylindrical shaft and a sharp thread that cuts its own hole, often used in sheet metal or plastic.Drywall screw is a specialized self-tapping screw with a cylindrical shaft that has proved to have uses far beyond its original application.The set screw has no head and is designed to be inserted flush with or below the surface of the workpiece.The double-ended  screw is a wood-screw with two pointed ends and no head. It is used for making hidden joints between two pieces of wood. Shapes of Screw Head Pan head: disc with a chamfered outer edgeCheesehead: disc with a cylindrical  outer edgeCountersunk: conical, with flat outer face and tapering inner face allowing it to sink into the material, very common for wood screwsButton or dome head: flat inner face and hemispherical outer faceMirror screw head: countersunk head with a tapped hole to receive a separate screw-in chrome-plated cover; used for attaching mirrors Types of Screw Drive A variety of tools  exists  to drive screws into the material to be fixed. The hand tools used to drive slot-headed and cross-headed screws  are  called screwdrivers. A power tool that does the same job is a power screwdriver. The hand-tool for driving cap screws and other types is called a spanner (U.K. usage) or wrench (U.S. usage). Slot head is driven by a flat-bladed screwdriver.Cross-head or Phillips screw has an X-shaped slot and is driven by a cross-head screwdriver, designed originally in the 1930s for use with mechanical screwing machines, intentionally made so the driver will ride out, or cam out, under strain to prevent over-tightening.Pozidriv is patented, similar to cross-head but with better resistance to slipping, or cam-out.Hexagonal or hex screw head has a hexagonal hole and is driven by a hexagonal wrench, sometimes called an Allen  key or a power tool with a hexagonal bit.Robertson drive head has a square hole and is driven by a special power-tool bit or screwdriver (this is a low-cost version of the hex head for domestic use).Torx head has a splined socket and receives a driver with a splined shaft.Tamper-proof  Torxs drive socket has a projection to prevent a standard  Torx  driver being inserted.Tri-Wing screws were used by Nintendo on its  Gameboys. This discouraged even minor home repairs to the units. Nuts Nuts are square, round, or hexagonal metal blocks with a screw thread on the inside. Nuts help fasten objects together and are used with screws or bolts.

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