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A screwdriver is a
tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tool A stone tool is, in the most general sense, a ...

tool
, manual or powered, used for driving
screw A screw and a bolt Bolt or bolts may refer to: Implements and technology * Bolt (fastener), similar to a screw, used with a nut * Bolt (climbing), an anchor point used in rock climbing * Bolt (firearms), a mechanism used in firearms * Crossbow ...

screw
s. A typical simple screwdriver has a handle and a shaft, ending in a tip the user puts into the screw head before turning the handle. This form of the screwdriver has been replaced in many workplaces and homes with a more modern and versatile tool, a
power drill A drill or drilling machine is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tools da ...
, as they are quicker, easier, and also can drill holes. The shaft is usually made of tough steel to resist bending or twisting. The tip may be hardened to resist wear, treated with a dark tip coating for improved visual contrast between tip and screw—or ridged or treated for additional 'grip'. Handles are typically wood, metal, or plastic and usually hexagonal, square, or oval in cross-section to improve grip and prevent the tool from rolling when set down. Some manual screwdrivers have interchangeable tips that fit into a socket on the end of the shaft and are held in mechanically or magnetically. These often have a hollow handle that contains various types and sizes of tips, and a reversible ratchet action that allows multiple full turns without repositioning the tip or the user's hand. A screwdriver is classified by its tip, which is shaped to fit the driving surfaces—slots, grooves, recesses, etc.—on the corresponding screw head. Proper use requires that the screwdriver's tip engage the head of a screw of the same size and type designation as the screwdriver tip. Screwdriver tips are available in a wide variety of types and sizes (
List of screw drives At a minimum, a screw drive is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. The following heads are ca ...
). The two most common are the simple 'blade'-type for slotted screws, and Phillips, generically called "cross-recess", "cross-head", or "cross-point". A wide variety of power screwdrivers ranges from a simple 'stick'-type with batteries, a motor, and a tip holder all inline, to powerful "pistol" type VSR (variable-speed reversible)
cordless drills A drill or drilling machine is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tools da ...
that also function as screwdrivers. This is particularly useful as drilling a pilot hole before driving a screw is a common operation. Special combination drill-driver bits and adapters let an operator rapidly alternate between the two. Variations include
impact driver Image:ImpactDriverWithBits.png, 250px, A manual impact driver with screwdriver bits and adapters A manual impact driver is a tool that delivers a strong, sudden rotational force and forward thrust when struck on the back with a hammer. It is often ...
s, which provide two types of 'hammering' force for improved performance in certain situations, and "right-angle" drivers for use in tight spaces. Many options and enhancements, such as built-in bubble levels, high/low gear selection, magnetic screw holders, adjustable-torque clutches, keyless chucks, 'gyroscopic' control, etc., are available.


History

The earliest documented screwdrivers were used in the late
Middle Ages In the history of Europe The history of Europe concerns itself with the discovery and collection, the study, organization and presentation and the interpretation of past events and affairs of the people of Europe since the beginning of ...
. They were probably invented in the late 15th century, either in
Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin Berlin (; ) is the Capital city, capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3,769,495 inh ...

Germany
or
France France (), officially the French Republic (french: link=no, République française), is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses ...

France
. The tool's original names in German and French were ''Schraubenzieher'' (screwpuller) and ''tournevis'' (turnscrew), 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 History of the United States, United States history, the Gilded Age was an era that occurred during the late 19th century, from the 1870s to about 1900. The Gilded Age was an era of rapid economic growth, especially in the Northern United St ...
). The screwdriver remained inconspicuous, however, as evidence of its existence throughout the next 300 years is based primarily on the presence of screws. Screws were used in the 15th century to construct screw-cutting
lathes File:Watchmaker's Lathe in use.jpg, A watchmaker using a lathe to prepare a component cut from copper for a watch A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, san ...
, for securing breastplates, backplates, and helmets on medieval
jousting Jousting is a martial game or ''hastilude Hastilude is a generic term used in the Middle Ages In the history of Europe, the Middle Ages or medieval period lasted from the 5th to the late 15th century. It began with the fall of the ...

jousting
armor Armour (British English British English (BrE) is the standard dialect of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, whi ...

armor
—and eventually for multiple parts of the emerging
firearms A firearm is any type of gun A gun is a ranged weapon designed to use a shooting tube ( gun barrel) to launch typically solid projectiles, but can also project pressurized liquid (e.g. water guns/ cannons, spray guns for painting ...
, particularly the matchlock. Screws, hence screwdrivers, were not used in full combat armor, most likely to give the wearer freedom of movement. The jaws that hold the
pyrites The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), luster ...

pyrites
inside
wheellock , c. 1580 A wheellock, wheel-lock or wheel lock is a friction-wheel mechanism which creates a spark that causes a firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined furth ...
guns were secured with screws, and the need to constantly replace the pyrites resulted in a considerable refinement of the screwdriver. The tool is more documented in France, and took on many shapes and sizes, though all for slotted screws. There were large, heavy-duty screwdrivers for building and repairing large machines, and smaller screwdrivers for refined cabinet work. The screwdriver depended entirely on the screw, and it took several advances to make the screw easy enough to produce to become popular and widespread. The most popular door
hinge A hinge is a mechanical 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: all other T ...

hinge
at the time was the butt-hinge, but it was considered a luxury. The butt-hinge was handmade, and its constant motion required the security of a screw. Screws were very hard to produce before the
First Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Europe and the United States, in the period from about 1760 to sometime between 1820 and 1840. This transition included going from craft production, hand production ...
, requiring the manufacture of a conical
helix A helix (), plural helixes or helices (), is a shape like a corkscrew or spiral staircase. It is a type of smooth Smooth may refer to: Mathematics * Smooth function is a smooth function with compact support. In mathematical analysis, the ...

helix
. The brothers Job and William Wyatt found a way to produce a screw on a novel machine that first cut the slotted head, and then cut the helix. Though their business ultimately failed, their contribution to low-cost manufacturing of the screw ultimately led to a vast increase in the screw and the screwdriver's popularity. The increase in popularity gradually led 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.
Canadian Canadians (french: Canadiens) are people identified with the country of Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the At ...
P.L. Robertson, though he was not the first person to patent the idea of socket-head screws, was the first to successfully commercialize them, starting in 1908. Socket screws rapidly grew in popularity, and are still used for their resistance to wear and tear, compatibility with
hex key Socket head screws of various sizes A hex key or Allen key is a simple tool used to drive bolts and screws with hexagonal sockets in their heads. The tool is usually formed of a single piece of hexagonal rod of hard steel, with blunt ends ...
s, and ability to stop a
power tool A power tool is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tools dates back hundreds of ...
when set. Though immensely popular, Robertson had trouble marketing his invention to the newly booming
auto industry The automotive industry comprises a wide range of company, companies and organizations involved in the design, Business development, development, manufacturing, marketing, and selling of motor vehicles. It is one of the world's largest industry ( ...
, for he was unwilling to relinquish his patents. Meanwhile, in
Portland, Oregon Portland (, ) is the list of cities in Oregon, largest and most populous city in the U.S. state of Oregon, and the county seat, seat of Multnomah County, Oregon, Multnomah County. It is a major port in the Willamette Valley region of the Pacif ...

Portland, Oregon
, Henry F. Phillips patented his own invention, an improved version of a deep socket with a
cruciform Cruciform is a term for physical manifestations resembling a common cross A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. ...

cruciform
slot, today known as the
Phillips Screw
Phillips Screw
. Phillips offered his screw to the American Screw Company, and after a successful trial on the 1936
Cadillac The Cadillac Motor Car Division is a division (business), division of the American automobile manufacturer General Motors Company (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadilla ...

Cadillac
, it 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 An economic depression is a sustained, long-term downturn in economic activity in one or more economies. It is a more severe economic downturn than a economic recession, recess ...
and the upheaval of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
, the Phillips screw quickly became, and 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 was not possible with the Robertson Screw.
Gunsmiths A gunsmith is a person who repairs, modifies, designs, or builds guns. The occupation differs from an armorer, who usually replaces only worn parts in standard firearms. Gunsmiths do modifications and changes to a firearm that may require a very ...
still call a screwdriver a ''turnscrew'', under which name it is an important part of a set of pistols. The name was common in earlier centuries, used by cabinetmakers, shipwrights, and perhaps other trades. The cabinetmaker'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 In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon or 6-gon. The total of the internal angles of any simple polygon, simple (non-self-intersecting) hexagon is 720°. Regul ...

hexagon
al cross-section to achieve these same two goals, a far cry from the pear-shaped handle of the original 15th-century screwdriver.


Handle

The handle and shaft of screwdrivers have changed considerably over time. The design is influenced by both purpose and manufacturing requirements. The "Perfect Pattern Handle" screwdriver was first manufactured by HD Smith & Company, which operated from 1850 to 1900. Many manufacturers adopted this handle design. At the time, the "flat bladed" screw type was prevalent and was the fastener with which they were designed to be used. Another popular design was composed of drop-forged steel with riveted wood handles. The shape and material of many modern screwdriver handles are designed to fit comfortably in the user's hand, for user comfort and to facilitate maximum control and
torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study. The concept originated with the studies ...

torque
. Designs include indentations for the user's fingers, and surfaces of a soft material such as
thermoplastic elastomer A thermoplastic, or thermosoftening plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular mass, molecular weight. The polyme ...
to increase comfort and grip. Composite handles of rigid
plastic Plastics are a wide range of syntheticA synthetic is an artificial material produced by organic chemistry, organic chemical synthesis. Synthetic may also refer to: In the sense of both "combination" and "artificial" * Synthetic chemical or s ...

plastic
and
rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much" ...

rubber
are also common. Many screwdriver handles are not smooth and often not round, but have flats or other irregularities to improve grip and to prevent the tool from rolling when on a flat surface. Some screwdrivers have a short hexagonal section at the top of the blade, adjacent to the handle, so that a ring spanner or open wrench can be used to increase the applied torque. Another option are "cabinet" screwdrivers which are made of flat bar stock and while the shaft may be rounded, will have a large flat section adjacent to the handle which a wrench (often an adjustable) may be used on for additional leverage. The offset screwdriver has a handle set at right angles to the small blade, providing access to narrow spaces and giving extra torque.


Drive tip

Screwdrivers come in a large range of sizes to accommodate various screws—from tiny jeweller's screwdrivers up. A screwdriver that is not the right size and type for the screw may damage the screw in the process of tightening it. Some screwdriver tips are magnetic, so that the screw (unless non-magnetic) remains attached to the screwdriver without requiring external force. This is particularly useful in small screws, which are otherwise very difficult to attempt to handle. Many screwdriver designs have a handle with a detachable tip (the part of the screwdriver that engages the screw), called ''bits'' as with
drill bit Drills are cutting tools used to remove material to create holes, almost always of circular cross-section. Drills come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes dri ...

drill bit
s. This provides a set of one handle and several bits that can drive a variety of screw sizes and types.


Drive types

File:Jeweler's screwdriver.jpg, A jeweler's screwdriver File:Magnetschraubendreher IMGP1940.jpg, Screwdriver with magnetic tip File:Set of security screw driver bits.jpg, A set of "secure" or otherwise less common screwdriver bits, including secure Torx and secure hex or "allen" variants. File:Frearson vs Phillips.svg, Comparison of Phillips and Frearson screw heads File:Robertson screwdrivers.jpg, A variety of Robertson sizes File:PHILLIPS and POZIDRIV screwdrivers and screw.JPG, Phillips and Pozidriv compared. The tool used to drive a slotted screw head is called a ''standard'', ''common blade'', ''flat-blade'', ''slot-head'', ''straight'', ''flat'', ''flat-tip'', or "''flat-head''" screwdriver. This last usage can be confusing, because the term ''flat-head'' also describes a screw with a flat top, designed to install in a countersunk hole. Furthermore, the term implies that a screwdriver has a "head"; it does not. Such a flat-headed screw may have a slotted, cross, square recessed, or combination head. Before the development of the newer bit types, the flat-blade was called the "Common-Blade", because it was the most common one. Depending on the application, the name of this screwdriver may differ. Within the automotive/heavy electric industries, it is known as a "flat head screwdriver"; within the avionics and mining industries, it is known as a "standard screwdriver". Though there are many names, the original device from 1908 was known as a "flat-head screw turner". Among slotted screwdrivers, variations at the blade or bit end involve the profile of the blade as viewed face-on (from the side of the tool). The more common type is sometimes called keystone, where the blade profile is slightly flared before tapering off at the end, which provides extra stiffness to the workface and makes it capable of withstanding more torque. To maximize access in space-restricted applications, the ''cabinet'' variant screwdriver blade sides are straight and parallel, reaching the end of the blade at a right angle. This design is also frequently used in jeweler's screwdrivers. Many textbooks and vocational schools instruct mechanics to grind down the tip of the blade, which, due to the taper, increases its thickness and consequently allows more precise engagement with the slot in the screw. This approach creates a set of graduated slotted screwdrivers that fit a particular screw for a tighter engagement and reduce screw head deformation. However, many better-quality screwdriver blades are already induction-hardened (surface heat-treated), and tip grinding after manufacture compromises their durability. Thus, it is best to select a tip made to fit precisely to begin with, and avoid weakening the factory heat-treatment. Phillips screwdrivers come in several standard sizes, ranging from tiny "jeweler's" to those used for automobile frame assembly—or #000 to #4 respectively. This size number is usually stamped onto the shank (shaft) or handle for identification. Each bit size fits a range of screw sizes, more or less well. Each Phillips screwdriver size also has a related shank diameter. The driver has a 57° point and tapered, unsharp (rounded) flutes. 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 design is often criticized for its tendency to
cam out Cam out (also cam-out or camming out) is a process by which a screwdriver slips out of the head of a screw being driven once the torque required to turn the screw exceeds a certain amount. Repeatedly camming out damages the screw, and possibly also ...
at lower torque levels than other "cross head" designs, an effect caused by the tapered profile of the flutes which makes them easier to insert into the screw than other similar styles. There has long been a popular belief that this was actually a ''deliberate'' feature of the design. Evidence is lacking for this specific narrative and the feature is not mentioned in the original patents. However, a subsequent refinement to the original design described in US Patent #2,474,994 describes this feature. Robertson, also known as a square, or Scrulox screw drive has a
square In Euclidean geometry Euclidean geometry is a mathematical system attributed to Alexandrian Greek mathematics , Greek mathematician Euclid, which he described in his textbook on geometry: the ''Euclid's Elements, Elements''. Euclid's method ...

square
-shaped socket in the screw head and a square protrusion on the tool. Both the tool and the socket have a taper, which makes inserting the tool easier, and also tends to help keep the screw on the tool tip without the user needing to hold it there. (The taper's earliest reason for being was to make the manufacture of the screws practical using
cold forming Cold forming or cold working is any metalworking Metalworking is the process of shaping and reshaping metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, ...
of the heads,. but its other advantages helped popularize the drive.) Robertson screws are commonplace in
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
, though they have been used elsewhere, and have become much more common in other countries in recent decades. Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken. They also allow for the use of angled screw drivers and trim head screws. The socket-headed Robertson screws are self-centering, reduce cam out, stop a power tool when set, and can be removed if painted over or old and rusty. In industry, they speed up production and reduce product damage. One of their first major industrial uses was the Ford Motor Company's Model A & Model T production. Henry Ford found them highly reliable and saved considerable production time, but he couldn't secure licensing for them in the United States, so he limited their use solely to his Canadian division. Robertson-head screwdrivers are available in a standard range of tip sizes, from 1.77mm to 4.85mm. 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° flukes and a sharper, pointed end. Also, the Phillips screw slot is not as deep as the Reed and Prince slot. In theory, different size R&P screws fit any R&P bit size. Pozidriv and the related Supadriv are widely used in Europe and most of the Far East. While Pozidriv screws have cross heads like Phillips and are sometimes thought effectively the same, the Pozidriv design allows higher torque application than Phillips. It is often claimed that they can apply more torque than any of the other commonly used cross-head screwdriver systems, due to a complex fluting (mating) configuration. Japanese Industrial Standard (JIS) cross-head screwdrivers are still another standard, often inaccurately called ''Japanese Phillips''. Compatible screw heads are usually identifiable by a single depressed 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° point with a flat tip. Many modern
electrical appliance A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household A household consists of one or several persons who live in the same dwelling and share meals. I ...
s, if they contain screws, use screws with heads other than the typical slotted or Phillips styles.
Torx . Torx (pronounced ) is a trademark for a type of screw drive characterized by a 6-point star-shaped pattern, developed in 1967, Bernard F. Reiland, "Coupling arrangement and tools for same", filed 1967-03-21 by Camcar Textron Textron Inc. is an ...

Torx
is one such pattern that has become widespread. It is a spline tip with a corresponding recess in the screw head. The main cause of this trend is manufacturing efficiency: Torx screwdriver tips do not slip out of the fastener as easily as would a Phillips or slotted driver. (Slotted screws are rarely used in mass-produced devices, since the driver is not inherently centered on the fastener.) Non-typical fasteners are commonplace in consumer devices for their ability to make disassembly more difficult, which is seen as a benefit for manufacturers but is considered a disadvantage by users than if more common head types were used. In microwave ovens, such screws deny casual access to the high-power kilovolt electrical components, which are very dangerous. However, Torx and other drivers have become widely available to the consumer due to their increasing use in the industry. Some other styles fit a three-pointed star recess, and a five-lobed spline with rounded edges instead of the square edges of the Torx. This is called a Pentalobe. 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 is a Japanese Multinational corporation, multinational consumer electronics and video game company headquartered in Kyoto, Japan. The company was founded in 1889 as by craftsman Fusajiro Yamauchi and originally produced handmade playing ca ...

Nintendo
consoles, though drivers for the more common security heads are, again, readily available. Another type of security head has smooth curved surfaces instead of the slot edges that would permit loosening the screw; it is found in public rest room privacy partitions, and cannot be removed by conventional screwdrivers.


Variations


Torque screwdrivers

Screwdrivers are available—manual, electric, and pneumatic—with a
clutch A clutch is a mechanical device that engages and disengages power transmission Transmission may refer to: Science and technology * Power transmissionPower transmission is the movement of energy from its place of generation to a location wh ...

clutch
that slips at a preset torque. This helps the user tighten screws to a specified torque without damage or over-tightening. Cordless drills designed to use as screwdrivers often have such a clutch.


Powered screwdrivers

Interchangeable bits allow the use of powered screwdrivers, commonly using an electric or air motor to rotate the bit. s with speed and torque control are commonly used as power screwdrivers.


Ratcheting screwdrivers

Some manual screwdrivers have a ratchet action whereby the screwdriver blade locks to the handle for clockwise rotation, but uncouples for counterclockwise rotation when set for tightening screws—and vice versa for loosening. Spiral ratchet screw drivers, often colloquially called '' Yankee screwdrivers'' (a brand name), provide a special mechanism that transforms
linear motion Linear motion, also called rectilinear motion, is one-dimensional motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon in which an object changes its position (mathematics), ...
into
rotational motion A rotation is a circular movement of an object around a center (or point) of rotation. The geometric plane along which the rotation occurs is called the '' rotation plane'', and the imaginary line extending from the center and perpendicular ...
. Originally the "
Yankee The term ''Yankee'' and its contracted form ''Yank'' have several interrelated meanings, all referring to people from the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or Amer ...
" name was used on all tools sold by the North Brothers Manufacturing Company but later, after
Stanley Stanley may refer to: People * Stanley (name) Stanley is a toponymic surname dating from the 11/12th century contraction of ''Stan'' (a form of "Stone") and ''wikt:leigh, Leigh'' (meadow), later also being used as a masculine given name. Pers ...
purchased the company, it became synonymous with only this type of screwdriver. The user pushes the handle toward the workpiece, causing a
pawl A pawl is a movable lever that engages a fixed component to either prevent movement in one direction or restrain it altogether. As such, it is a type of latch A latch or catch (called sneck in Northern England and Scotland) is a type of mech ...
in a
spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:
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. One disadvantage of this design is that if the bit slips out of the screw, the resultant sudden extension of the spring may cause the bit to scratch or otherwise damage the workpiece. Once very popular, versions of these spiral ratchet drivers using proprietary bits have been largely discontinued by manufacturers such as Stanley. Some companies now offer a modernized version that uses standard -inch hex shank power tool bits. Since a wide variety of drill bits are available in this format, the tool can do double duty as a "push drill" or
Persian drillA Persian drill is a drill which is turned by pushing a Nut (hardware), nut back and forth along a Screw (simple machine), spirally grooved Chuck (engineering), drill holder. It was formerly used for delicate operations such as jewellery making and d ...
.


See also

*
List of screw drives At a minimum, a screw drive is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. The following heads are ca ...
*
Wheel and axle The wheel and axle is a simple machine A simple machine is a mechanical device that changes the direction or magnitude of a force In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowl ...

Wheel and axle


References


Citations


Works cited

*


External links


Electric screwdriver
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