is a tool for driving screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
s and often rotating other machine element
Machine elements are basic mechanical parts used as the building blocks of most machines. Most are standardized to common sizes, but customs are also common for specialized applications.-Types:*Shafts**Couplings*Keys*Splines*Bearings**Roller bearings...
s with the mating drive system. The screwdriver is made up of a head or tip, which engages with a screw, a mechanism
A mechanism is a device designed to transform input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam and follower mechanisms, and linkages as well as friction devices...
to apply torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...
the tip, and some way to position and support the screwdriver. A typical hand screwdriver comprises an approximately cylindrical handle of a size and shape to be held by a human hand, and an axial shaft fixed to the handle, the tip of which is shaped to fit a particular type of screw. The handle and shaft allow the screwdriver to be positioned and supported and, when rotated, to apply torque. Screwdrivers are made in a variety of shapes, and the tip can be rotated manually or by an electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
or other 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.
The earliest screwdrivers of which written evidence remains were used in Europe in the late Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
. It seems that they were probably invented in either Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, in the late 15th century. The tool's original names in German and French were Schraubendreher
(screwturner) and tournevis
(turnscrew), respectively, reflecting the native linguistic patterns of Germanic and Romance languages ("noun-verber" and "verb-noun", respectively). The first documentation of the tool is in The Medieval Housebook of Wolfegg Castle
, a manuscript written sometime between 1475 and 1490. These earliest screwdrivers had pear-shaped handles and were made for slotted screws (diversification of the many types of screwdrivers did not emerge until the Gilded Age
In United States history, the Gilded Age refers to the era of rapid economic and population growth in the United States during the post–Civil War and post-Reconstruction eras of the late 19th century. The term "Gilded Age" was coined by Mark Twain and Charles Dudley Warner in their book The Gilded...
). The screwdriver remained inconspicuous, however, as evidence of its existence throughout the next 300 years was based primarily on the presence of screws.
Screws were used in the 15th century for constructing screw-cutting lathes, securing breastplates, backplates, and helmets on medieval jousting
Jousting is a martial game or hastilude between two knights mounted on horses and using lances, often as part of a tournament.Jousting emerged in the High Middle Ages based on the military use of the lance by heavy cavalry. The first camels tournament was staged in 1066, but jousting itself did not...
armor, and eventually for multiple parts of the emerging firearms
Gunpowder was invented in the 9th century and firearms in the 12th century in China. These inventions were later transmitted to the Middle East and to Europe.-Firearms in China:...
, particularly the matchlock. Screws, hence screwdrivers, were not used in full combat armor, most likely to give the wearer freedom of movement.
The jaws holding the pyrites inside medieval guns were secured with screws, and the need to constantly replace the pyrites resulted in considerable refinement of the screwdriver. The tool was much more documented in France, and took on many different shapes and sizes, though every version was still for slotted screws. There were large, heavy duty screwdrivers for building and repairing large machines, and smaller screwdrivers for refined cabinet work.
The screwdriver was entirely dependent on the screw, and it was not until several advances that the screw became easy enough to produce to become popular and widespread. The most popular door hinge
A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation. Hinges may be made of flexible material or of moving components...
at the time was the butt-hinge, but it was considered a luxury. The butt-hinge was handmade, and its constant motion meant that it required the security of a screw.
Screws were very hard to produce before the First Industrial Revolution, requiring manufacture of a conical helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
. The brothers Job and William Wyatt found a way to produce a screw on an assembly line
An assembly line is a manufacturing process in which parts are added to a product in a sequential manner using optimally planned logistics to create a finished product much faster than with handcrafting-type methods...
machine that first cut the slotted head, and then carved the helix. Though their business ultimately failed, their contribution to the screw ultimately led to a vast increase in the screw and the screwdriver’s popularity.
The increase in popularity ultimately lead to refinement and eventually diversification of the screwdriver. Refinement of the precision of screws also significantly contributed to the boom in production, mostly by increasing its efficiency and standardizing sizes, important precursors to industrial manufacture.
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
P.L. Robertson, although he was not the first person to patent the idea of socket-head screws, was the first person to successfully commercialize them, starting in 1908. Socket screws rapidly grew in popularity, and are still a favorite of mechanics today for their resistance to wear and tear, compatibility with hex key
A hex key, Allen key, or Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head .- Nomenclature :...
s, and ability to stop a power tool
A power tool is a tool that is actuated by an additional power source and mechanism other than the solely manual labour used with hand tools. The most common types of power tools use electric motors. Internal combustion engines and compressed air are also commonly used...
when set. Though immensely popular, Robertson had trouble marketing his invention to the newly booming auto industry, for he was unwilling to relinquish his patents.
Meanwhile, Henry F. Phillips
Henry F. Phillips was a U.S. businessman from Portland, Oregon. The Phillips-head screw and screwdriver are named after him....
patented his own invention, an improved version of a deep socket with a cruciform
Cruciform means having the shape of a cross or Christian cross.- Cruciform architectural plan :This is a common description of Christian churches. In Early Christian, Byzantine and other Eastern Orthodox forms of church architecture this is more likely to mean a tetraconch plan, a Greek cross,...
, today known as the Phillips Screw. The Phillips screw was offered by Phillips to the American Screw Company, and after a successful trial on the 1936 Cadillac
Cadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...
, quickly swept through the American auto industry. With the Industrial Revival at the end of the Great Depression
The Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...
and the onslaught of World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, the Phillips screw quickly became, and still remains, the most popular screw in the world. A main attraction for the screw was that conventional slotted screwdrivers could also be used on them, which ostracized the Robertson Screw, still a favorite among experts.
The screwdriver remains one of the most common tools both in household use and in professional manufacture.
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 and perhaps other trades.
The cabinet-maker's screwdriver is one of the longest-established handle forms, somewhat oval or ellipsoid 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 hexagon
al cross section to achieve these same two goals, a far cry from the pear-shaped handle of the original 15th century screwdriver.
Screwdrivers come in a large variety of sizes to match those of screws, from tiny jeweler's screwdrivers up.
If a screwdriver that is not the right size and type for the screw is used, it is likely that the screw will be damaged in the process of tightening it. This is less important for PoziDriv and SupaDriv, which are designed specifically to be more tolerant of size mismatch. When tightening a screw with force, it is important to press the head hard into the screw, again to avoid damaging the screw.
Some screwdriver tips are magnetic, so that the screw remains attached to the screwdriver without requiring external force. This is particularly useful in small screws, which are otherwise difficult to handle.
Many screwdriver designs have a handle with detachable head (the part of the screwdriver which engages with the screw), called bits
as with drill bit
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
s, allowing a set of one handle and several heads to be used for a variety of screw sizes and types.
Many modern electrical appliances, if they contain screws at all, use screws with heads other than the typical slotted or Phillips styles. Torx
Torx developed by Camcar Textron, is the trademark for a type of screw head characterized by a 6-point star-shaped pattern. People who are unfamiliar with the trademark generally use the term star, as in star screwdriver or star bits...
is one such pattern that has become very widespread. The main cause of this trend is manufacturing efficiency: Torx and other types are designed so the driver will not slip out of the fastener as will a Phillips driver. (Slotted screws are rarely used in mass-produced devices, since the driver is not inherently centered on the fastener.) A benefit/disadvantage of non-typical fasteners (depending on your point of view) is that it can be more difficult for users of a device to disassemble it than if more-common head types were used, but Torx and other drivers are widely available. Specialized patterns of security screws are also used, such as the Line Head (LH) style by OSG System Products, Japan, as used in many Nintendo consoles, though drivers for the more common security heads are, again, readily available.
The handle and shaft of screwdrivers have changed considerably over time. The design is influenced by both purpose and manufacturing requirements. The "Perfect Handle" screwdriver was first manufactured by HD Smith & Company that operated from 1850 to 1900. Many manufacturers adopted this handle design worldwide. The "Flat Bladed" screwdriver was another design composed of drop forged steel with riveted wood handles.
There is no such thing as a "left-handed screwdriver", as the device can easily be wielded in either hand. To be sent to find a left-handed screwdriver is a fool's errand
A snipe hunt, a form of wild-goose chase that is also known as a fool's errand, is a type of practical joke that involves experienced people making fun of credulous newcomers by giving them an impossible or imaginary task...
, often used as a test of stupidity, or is used as a metaphor for something useless. The term "Birmingham screwdriver" (like "Glasgow socket set") is used jokingly in the UK to denote a hammer or sledgehammer.
Among slotted screwdrivers, there are a couple of major variations at the blade or bit end involving the profile of the blade as viewed face-on. The more common type is sometimes referred to as keystone
, where the blade profile is slightly flared before tapering off at the end. To maximize access in space-restricted applications, the same edges for the cabinet
variety, in contrast, are straight and parallel, meeting the end of the blade at a right angle; this is frequently used in jeweler's screwdrivers, among other applications. Many text books and vocational schools will instruct mechanics to grind the tip of the blade, which will increase the thickness of the tapered tip for a more precise engagement with the slot in the screw. This approach will create a set of graduated slotted screwdrivers that can be select fitted to a particular screw for a tighter engagement and to reduce the deformation of the screw head.
Phillips screwdrivers come in several standard sizes, ranging from tiny "jeweler's" to those used for automobile frame assembly, or #00 to #3 respectively. This number is stamped onto the shank (shaft) for identification. Each bit size can fit a range of screw sizes. Each Phillips screwdriver size also has a related shank diameter. The driver has a 57 degree point and tapered, unsharp (rounded) flutes. By far the most commonly found size around the household, automobile, and office is the #2, —which fits computers, printers and photocopiers, light switches, carburetors, furniture, household appliances, door hinges, and so forth. The second most commonly seen household Phillips screw is the #1, which fits calculators, cameras, smaller toys, and cell phone sized devices. The #1 and smaller bits come to a blunt point, but the #2 and above have no point, but rather a nearly squared-off tip, making each size incompatible with the other. The rounded, tapered slots were designed for the screwdriver to cam out (pop out) of the screw under high torque in assembly lines. This prevents stripping damage, but in some applications camout
can be a disadvantage. A "#2 x 6 Phillips screwdriver
" designation as commonly seen in the tool catalogs describes a number two bit with a six-inch-long shank.
Reed and Prince,
also called Frearson
, is another historic cross-head screw configuration. The cross in the screw head is sharper and less rounded than a Phillips, and the bit has 45-degree flukes and a sharper, pointed end. Also, the Phillips screw slot is not as deep as the Reed and Prince slot. In theory the different size R&P screws will fit any R&P bit size.
is the de facto standard in Europe and most of the Far East. While these more bluntly tipped drivers and seemingly "sloppy cross" screws seem to look more like Phillips, the Pozidriv design also allows for higher torque than Phillips. In fact it is often claimed that they can apply more torque than any of the commonly used crosshead screwdriver systems due to a complex fluting (mating) configuration.
Japanese Industrial Standard (JIS)
cross head screwdrivers are still another standard, often improperly referred to as Japanese Phillips. Heads are usually identifiable by a single raised dot or an "X" to one side of the cross slot. This is a screw standard throughout the Asia market and Japanese imports. The driver has a 57 degree point with a flat tip.
Interchangeable bits allows the use of powered screwdrivers, commonly using an electric or air motor to rotate the bit. Cordless drills are commonly used as power screwdrivers, with many models featuring a torque-limiting clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
to prevent over driving or breaking the screws.
Some manual screwdrivers have a ratchet
A ratchet is a device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Because most socket wrenches today use ratcheting handles, the term "ratchet" alone is often used to refer to a ratcheting wrench, and the terms "ratchet"...
action whereby the screwdriver blade is locked to the handle for clockwise rotation, but uncoupled for counterclockwise rotation when set for tightening screws; and vice versa for loosening.
Manual screw drivers, often colloquially called "Yankee Screwdrivers", with a 'spiral ratchet' mechanism to turn pressure (linear motion) into rotational motion also exist, and predate electric screwdrivers. The user pushes the handle toward the workpiece, causing a pawl in a spiral groove to rotate the shank and the removable bit. The ratchet can be set to rotate left or right with each push, or can be locked so that the tool can be used like a conventional screwdriver. Once very popular, these spiral ratchet drivers, using proprietary bits, have been largely discontinued by manufacturers such as Stanley
Stanley Black & Decker , formerly known as The Stanley Works, is a manufacturer of tools and hardware and provider of security products and locks headquartered in New Britain, Connecticut...
, although one can still find them at vintage tool auctions. Companies such as Lara Specialty Tools now offer a modernized version that uses standard 1/4-inch hex shank power tool bits. Since a variety of drill bits are available in this format, it allows the tool to do double duty as a push drill
While screwdrivers are designed for the above functions, they are commonly abused as improvised substitutes for pry bars, levers, and hole punches, as well as other tools. This is often discouraged, as screwdrivers are not designed for this purpose, and such use can damage the screwdriver—chipping the blade or bending the shaft, for instance—or more seriously may injure the user when the screwdriver fails.