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Encyclopedia > Screw
Screws come in a variety of shapes and sizes for different purposes. U.S. quarter coin (diameter 24 mm) shown for scale.
Screws come in a variety of shapes and sizes for different purposes. U.S. quarter coin (diameter 24 mm) shown for scale.

A screw is a shaft with a helical groove or thread formed on its surface and provision at one end to turn the screw. Its main uses are as a threaded fastener used to hold objects together, and as a simple machine used to translate torque into linear force. It can also be defined as an inclined plane wrapped around a shaft. Image File history File links Question_book-3. ... Screw can refer to several different articles: Look up screw in Wiktionary, the free dictionary. ... Various screws: differing sizes and colors, several Phillips, a flathead, and a Torx. ... The quarter is 1/4th of a United States dollar or 25 cents. ... A helix (pl: helices), from the Greek word έλικας/έλιξ, is a twisted shape like a spring, screw or a spiral (correctly termed helical) staircase. ... Screw thread, used to convert torque into the linear force in the flood gate. ... A fastener is a hardware device that mechanically joins or affixes two or more objects together. ... This article is about the concept in physics. ... For other senses of this word, see torque (disambiguation). ... The inclined plane is one of the classical simple machines; as the name suggests, it is a flat surface whose endpoints are at different heights. ...

Contents

Screws and Bolts

A screw used as a threaded fastener consists of a shaft,which nomaly usually cylindrical and in many cases tapering to a point at one end and with a helical ridge or thread formed on it, and a head at one end which can be rotated by some means. The thread is essentially an inclined plane wrapped around the shaft. The thread mates with a complementary helix in the material. The material may be manufactured with the mating helix using a tap, or the screw may create it when first driven in (a self-tapping screw). The head is specially shaped to allow a screwdriver or wrench (British English: spanner) to rotate the screw, driving it in or releasing it. The head is of larger diameter than the body of the screw and has no thread so that the screw can not be driven deeper than the length of the shaft, and to provide compression. Taps and dies are generally metalworking tools for the creation (cutting) of screw threads in metal parts. ... This page is a candidate to be moved to Wiktionary. ... A basic screwdriver made by Craftsman (slotted tip shown) A rechargeable battery-powered electric screwdriver from Black & Decker The screwdriver is a device specifically designed to insert and tighten, or to loosen and remove, screws. ... Combination wrench, or combination spanner (left: box-end/ring, right: open-end) A wrench or spanner is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other hard-to-turn items. ... British English (BrE, BE, en-GB) is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere in the Anglophone world. ...


Screws can normally be removed and reinserted without reducing their effectiveness. They have greater holding power than nails and permit disassembly and reuse. A pile of nails. ...


The vast majority of screws are tightened by clockwise rotation; we speak of a right-hand thread. Screws with left-hand threads are used in exceptional cases, when the screw is subject to anticlockwise forces that might undo a right-hand thread. Left-hand screws are used on rotating items such as the left-hand grinding wheel on a bench grinder or the left hand pedal on a bicycle (both looking towards the equipment) or hub nuts on the left side of some automobiles. A clockwise motion is one that proceeds like the clocks hands: from the top to the right, then down and then to the left, and back to the top. ... An electrically driven abrasive wheel (normally a pair of wheels) mounted securely on a pillar or a bench. ... A bicycle pedal is the part of a bicycle that the rider places their feet on when cycling. ... For other uses, see Bicycle (disambiguation). ... Hub may refer to: Look up hub in Wiktionary, the free dictionary. ...


Threaded fasteners were made by a cutting action such as dies provide, but recent advances in tooling allow them to be made by rolling an unthreaded rod (the blank) between two specially machined dies which squeeze the blank into the shape of the required fastener, including the thread. This method has the advantages of work hardening the thread and saving material. A rolled thread can be distinguished from a thread formed by a die as the outside diameter of the thread is greater than the diameter of the unthreaded portion of the shaft. Bicycle spokes, which are just bolts with long thin unthreaded portions, always use rolled threads for strength. Taps and dies are generally metalworking tools for the creation (cutting) of screw threads in metal parts. ... For other uses of this term, see Die. ... Work hardening, or strain hardening, is an increase in mechanical strength due to plastic deformation. ...


Differentiation between bolt and screw

Carriage bolt with square nut.
Carriage bolt with square nut.
Structural bolt DIN 6914 with DIN 6916 washer and UNI 5587 nut.
Structural bolt DIN 6914 with DIN 6916 washer and UNI 5587 nut.

A universally accepted distinction between a screw and a bolt does not exist. Look up din in Wiktionary, the free dictionary. ...


In common usage the term "screw" refers to smaller (less than 1/4 inch) threaded fasteners, especially threaded fasteners with tapered shafts and the term "bolt" refers to larger threaded fasteners that do not have tapered shafts. The term "machine screw" is commonly used to refer to smaller threaded fasteners that do not have a tapered shaft.


Various methods of distinguishing bolts and screws exist or have existed. These methods conflict at times and can be confusing. Old SAE and USS standards made a distinction between a bolt and a cap screw based on whether a portion of the shaft was un-threaded or not. Cap screws had shafts that were threaded up to the head and bolts had partially threaded shafts. Today a bolt that has a completely threaded shaft might be referred to as a "tap bolt".


ASME B18.2.1 defines a bolt as "an externally threaded fastener designed for insertion through the holes in assembled parts, and is normally intended to be tightened or released by torquing a nut". Using this definition to determine whether a particular threaded fastener is a screw or a bolt requires that an assumption be made about the intended purpose of the threaded fastener and as a practical matter doesn't seem to be followed by most threaded fastener manufacturers. It also conflicts with common usage such as the term, "head bolt", which is a threaded fastener that mates with a tapped hole in an engine block and is not intended to mate with a nut.


It is possible to find other distinctions than those described above, but regardless of the particular distinction favored by an individual or standards body the use of the term "screw" or "bolt" varies. More specific terms for threaded fastener types that include the word “screw” or "bolt" (such as "machine screw" or "carriage bolt") have more consistent usage and are the common way to specify a particular kind of fastener.


The US government made an effort to formalize the difference between a bolt and a screw because different tariffs apply to each. The document seems to have no significant effect on common usage and does not eliminate the ambiguous nature of the distinction for some fasteners. It is available here.


Other fastening methods

Alternative fasteners to screws and bolts are nails, rivets, roll pins, pinned shafts, welding, soldering, brazing, gluing (including taping). The word nail has several meanings: In anatomy, a nail is a hard covering to the tip of fingers or toes In engineering, a nail is a metal pin-shaped object used to hold things together This is a disambiguation page — a navigational aid which lists other pages that might... Solid rivets Metal wheel with riveted spokes and tyre. ... Clinker is a boat building technique used for constructing hulls of boats and ships by fixing wooden planks and in the early nineteenth century, iron plates to each other so that the planks overlap along their edges. ... Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ... A solder is a fusible metal alloy, with a melting point or melting range of 180-190°C (360-370 °F), which is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering. ... This article is about the metal joining process. ... Polyvinyl acetate formula Polyvinyl acetate or PVA is a rubbery synthetic polymer. ... Look up Tape in Wiktionary, the free dictionary. ...


Another option is the threaded insert. Examples include Helical Inserts [1] and Keensert [2]. The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...


Materials and strength

Screws and bolts are made in a wide range of materials, with steel being perhaps the most common, in many varieties. Where great resistance to weather or corrosion is required, stainless steel, titanium, brass, bronze, monel or silicon bronze may be used, or a coating such as brass, zinc or chromium applied. Electrolytic action from dissimilar metals can be prevented with aluminium screws for double-glazing tracks, for example. Some types of plastic, such as nylon or Teflon, can be threaded and used for fastening requiring moderate strength and great resistance to corrosion or for the purpose of electrical insulation. Even porcelain and glass can have molded screw threads that are used successfully in applications such as electrical line insulators and canning jars. For other uses, see Steel (disambiguation). ... General Name, symbol, number titanium, Ti, 22 Chemical series transition metals Group, period, block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... Brazen redirects here. ... This article is about the metal alloy. ... General Name, symbol, number zinc, Zn, 30 Chemical series transition metals Group, period, block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... REDIRECT [[ Insert text]]EWWWWWWWWWWWWW YO General Name, symbol, number chromium, Cr, 24 Chemical series transition metals Group, period, block 6, 4, d Appearance silvery metallic Standard atomic weight 51. ... Aluminum redirects here. ... For other uses of this word, see nylon (disambiguation). ... In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer which finds numerous applications. ... This article or section is in need of attention from an expert on the subject. ... This article does not cite any references or sources. ...


The same type of screw or bolt can be made in many different grades of material. For critical high-tensile-strength applications, low-grade bolts may fail, resulting in damage or injury. On SAE-standard bolts, a distinctive pattern of marking is impressed on the heads to allow inspection and validation of the strength of the bolt. However, low-cost counterfeit fasteners may be found with actual strength far less than indicated by the markings. Such inferior fasteners are a danger to life and property when used in aircraft, automobiles, heavy trucks, and similar critical applications. For other uses, see Counterfeit (disambiguation). ...


Mechanical analysis

Rotating screw and fixed trough
Rotating screw and fixed trough

A screw or bolt is a specialized application of the inclined plane. The inclined plane, called its thread, is helically disposed around a cylinder or shaft. That thread usually either fits into a corresponding (negative or female) helical thread in a nut, or forms a corresponding helical cut in surrounding softer material as it is inserted. A simple screw, such as for fastening, is typically pointed, and thereby is commonly distinguished (in informal terminology) from a bolt or machine screw. Common screws, and usually bolts, have a head which may be mechanically driven or rotated, which usually serves as a stop, and may have an unthreaded shoulder portion beneath the head. Screw and trough. ...


The technical analysis (see also statics, dynamics) to determine the pitch, thread profile, coefficient of friction (static and dynamic), and holding power of a screw or bolt is very similar to that performed to predict wedge behavior. Wedges are discussed in the article on simple machines. Statics is the branch of physics concerned with physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at rest under the action of external forces of equilibrium. ... In physics, dynamics is the branch of classical mechanics that is concerned with the effects of forces on the motion of objects. ... This article is about the concept in physics. ...


Critical applications of screws and bolts will specify a torque that must be applied when driving it. The main concept is to tension the bolt, and compress parts being held together, creating a spring-like assembly. The stress thus introduced to the bolt is called a preload. When external forces try to separate the parts, the bolt experiences no strain unless the preload force is exceeded. For other senses of this word, see torque (disambiguation). ... For other uses, see Spring. ... This article is about the deformation of materials. ...


As long as the preload is never exceeded, the bolt or nut will never come loose (assuming the full strength of the bolt is used. If the full strength of the bolt is not used (for example, a steel bolt threaded into aluminium, then a thread-locking adhesive or insert may be used. Aluminum redirects here. ...


If the preload is exceeded during normal use, the joint will eventually fail. The preload is calculated as a percentage of the bolt's yield tensile strength, or the strength of the threads it goes into, or the compressive strength of the clamped layers (plates, washers, gaskets), whichever is least. Yield strength, or the yield point, is defined in engineering as the amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... Assorted washers: flat, split, star and insulated A washer is a thin disk with a hole, usually in the middle. ... Some seals and gaskets 1. ...


Tensile strength

Rusty hexagonal bolt heads
Rusty hexagonal bolt heads

Screws and bolts are usually in tension when properly fitted. In most applications they are not designed to bear large shear forces. For example, when two overlapping metal bars joined by a bolt are likely to be pulled apart longitudinally, the bolt must be tight enough so that the friction between the two bars can overcome the longitudinal force. If the bars slip, then the bolt may be sheared in half, or friction between the bolt and slipping bars may erode and weaken the bolt (called fretting). For this type of application, high-strength steel bolts are used and should be tightened to a specified torque. A rusty bolt on a bridge over a small stream. ... A rusty bolt on a bridge over a small stream. ... In physics, a net force acting on a body causes that body to accelerate; that is, to change its velocity. ... There are three kinds of fastener given the name bolt. ... For other uses, see Friction (disambiguation). ... For other senses of this word, see torque (disambiguation). ...


High-strength steel bolts usually have a hexagonal head with an ISO strength rating (called property class) stamped on the head. The property classes most often used are 5.8, 8.8, and 10.9. The number before the point is the tensile ultimate strength in MPa divided by 100. The number after the point is 10 times the ratio of tensile yield strength to tensile ultimate strength. For example, a property class 5.8 bolt has a nominal (minimum) tensile ultimate strength of 500 MPa, and a tensile yield strength of 0.8 times tensile ultimate strength or 0.8(500) = 400 MPa. “ISO” redirects here. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... The megapascal, symbol MPa is an SI unit of pressure. ...


Tensile ultimate strength is the stress at which the bolt fails (breaks in half). Tensile yield strength is the stress at which the bolt will receive a permanent set (an elongation from which it will not recover when the force is removed) of 0.2 % offset strain. When elongating a fastener prior to reaching the yield point, the fastener is said to be operating in the elastic region; whereas elongation beyond the yield point is referred to as operating in the plastic region, since the fastener has suffered permanent plastic deformation. Yield strength, or the yield point, is defined in engineering as the amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. ...


Mild steel bolts have property class 4.6. High-strength steel bolts have property class 8.8 or above. An M10, property class 8.8 bolt can very safely hold a static tensile load of about 15 kN. For other uses, see Newton (disambiguation). ...


There is no method to measure the tension of a bolt already in place other than to tighten it and identify at which point the bolt starts moving. This is known as 're-torqueing'. An electronic torque wrench is used on the bolt under test, and the torque applied is constantly measured. When the bolt starts moving (tightening) the torque briefly drops sharply - this drop-off point is considered the measure of tension.


Types of screws and bolts

Threaded fasteners either have a tapered shaft or a non-tapered shaft. Fasteners with tapered shafts are designed to either be driven into a substrate directly or into a pilot hole in a substrate. Mating threads are formed in the substrate as these fasteners are driven in. Fasteners with a non-tapered shaft are designed to mate with a nut or to be driven into a tapped hole.

A phillips wood screw being driven into a board with a drill
A phillips wood screw being driven into a board with a drill

Image File history File linksMetadata Size of this preview: 400 × 600 pixels Full resolution (1000 × 1500 pixel, file size: 225 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Screw Metadata This file contains... Image File history File linksMetadata Size of this preview: 400 × 600 pixels Full resolution (1000 × 1500 pixel, file size: 225 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Screw Metadata This file contains... For other uses, see Drill (disambiguation). ...

Fasteners with a tapered shaft (tapping screws)

  • Screw - There is not a universally accepted definition of the word, “screw”. It generally refers to a smaller threaded fastener with a tapered shaft. See the Differentiation Between Bolt and Screw section above for a more detailed discussion.
  • Wood Screw – Generally has an un-threaded portion of the shaft below the head. It is designed to attach two pieces of wood together.
  • Lag Screw (Lag Bolt) – Similar to a wood screw except that it is generally larger and it generally has a hexagonal head drive.
  • Sheet Metal Screw (Self-tapping Screw, thread cutting screws) - Has sharp threads that cut into a material such as sheet metal, plastic or wood. They are sometimes notched at the tip to aid in chip removal during thread cutting. The shaft is usually threaded up to the head. Sheet metal screws make excellent fasteners for attaching metal hardware to wood because the fully thread shaft provides good retention in wood.
  • Self-drilling screw (Teks(R) screw) - Similar to a sheet metal screw, but it has a drill-shaped point to cut through the substrate to eliminate the need for drilling a pilot hole. Designed for use in soft steel or other metals.
  • Drywall screw - Specialized screw with a bugle head that is designed to attach drywall to wood or metal studs, however it is a versatile construction fastener with many uses. The diameter of drywall screw threads is larger than the shaft diameter.
  • Particle Board Screw (Chipboard Screw) - Similar to a drywall screw except that it has a thinner shaft and provides better holding power in particle board.
  • Deck Screw - Similar to drywall screw except that it is has improved corrosion resistance and is generally supplied in a larger gauge.
  • Double ended screw (Dowel screw) - Similar to a wood screw but with two pointed ends and no head, used for making hidden joints between two pieces of wood.
  • Screw Eye(Eye Screw) - Screw with a looped head. Larger ones are sometimes call lag eye screws. Designed to be used as attachment point, particularly for something that is hung from it.
Combination flanged-hex/Phillips-head screw used in computers
Combination flanged-hex/Phillips-head screw used in computers

Image File history File links Download high resolution version (1280x1280, 150 KB) Summary A screw usually used in computers. ... Image File history File links Download high resolution version (1280x1280, 150 KB) Summary A screw usually used in computers. ...

Fasteners with a non-tapered shaft

  • Bolt - There is not a universally accepted definition of the word, “bolt”. It generally refers to a larger threaded fastener with a non-tapered shaft. See the Differentiation Between Bolt and Screw section above for a more detailed discussion.
  • Cap Screw – In places the term is used interchangeably with bolt. In the past the term, “cap screw” was restricted to threaded fasteners with a shaft that is threaded all the way to the head, however this is now a non-standard usage.
  • Hex Cap Screw – Cap screw with a hexagonal head, designed to be driven by a wrench (spanner). An ASME B18.2.1 compliant cap screw has somewhat tighter tolerances than a hex bolt for the head height and the shaft length. The nature of the tolerance difference allows an ASME B18.2.1 hex cap screw to always fit where a hex bolt is installed but a hex bolt could be slightly too large to be used where a hex cap screw is designed in.
  • Hex Bolt - At times the term is used interchangeably with hex cap screw. An ASME B18.2.1 compliant hex bolt is built to different tolerances than a hex cap screw.
  • Socket Cap Screw – Cap screw with a hexagonal recessed drive (Allen), usually with a cylindrical head, but can also be found with a rounded button head or a countersunk flat head.
  • Machine screw - Generally a smaller fastener (less than 1/4 inch in diameter) threaded the entire length of its shaft that usually has a recessed drive type (slotted, Phillips, etc.).
  • Self Tapping Machine Screw – Similar to a machine screw except the lower part of the shaft is designed to cut threads as the screw is driven into an un-tapped hole. The advantage of this s crew over a self tapping screw is that if the screw is reinstalled new threads are not cut as the screw is driven.
  • Set screw (grub screw) - Generally a headless screw but can be any screw used to fix a rotating part to a shaft. The set screw is driven through a threaded hole in the rotating part until it is tight against the shaft.
  • Tap Bolt - A bolt that is threaded all the way to the head. An ASME B18.2.1 compliant tap bolt has the same tolerances as an ASME B18.2.1 compliant hex cap screw.
  • Stud - similar to a bolt but without the head. Studs are threaded on both ends. In some cases the entire length of the stud is threaded, while in other cases there will be an un-threaded section in the middle. (See also: screw anchor, wedge anchor.)
  • Eye Bolt – A bolt with a looped head.
  • Toggle Bolt – A bolt with a special nut known as a wing. It is designed to be used where there is no access to side of the material where the nut is located. Usually the wing is spring loaded and expands after being inserted into the hole.
  • Carriage Bolt (Coach Bolt) - Has a domed or countersunk head, and the shaft is topped by a short square section under the head. The square section grips into the part being fixed (typically wood), preventing the bolt from turning when the nut is tightened. A rib neck carriage bolt has several longitudinal ribs instead of the square section, to grip into a metal part being fixed.
  • Stove Bolt - Similar to a carriage bolt, but usually used in metal. It requires a square hole in the metal being bolted to prevent the bolt from turning.
  • Shoulder Screw - Screw used for revolving joints in mechanisms and linkages. The shaft of the screw is smooth and works as a bearing surface. There is a reduced diameter thread at the end of the cylindrical bearing surface.
  • Thumb Screw – A threaded fastener designed to be twisted into a tapped hole by hand without the use of tools.
  • Tension Control Bolt (TC Bolt) – Heavy duty bolt used in steel frame construction. The head is usually domed and is not designed to be driven. The end of the shaft has a spline on it which is engaged by a special power wrench which prevents the bolt from turning while the nut is tightened. When the appropriate torque is reached the spline shears off.

It has been suggested that wall plug be merged into this article or section. ... A wedge anchor is an anchor used to fasten a fixture to a solid base material (such as concrete). ...

Other threaded fasteners

  • Thread rolling screws - have a lobed (usually triangular) cross section. They form threads by pushing outward during installation. They may have tapping threads or machine threads.
  • Superbolt, or Multi-Jackbolt Tensioner Alternative type of fastener that retrofits or replaces existing nuts, bolts, or studs. Tension in the bolt is developed by torquing individual jackbolts which are threaded through the body of the nut and push against a hardened washer. Installation and removal of any size tensioner is achieved with hand tools, which can be advantageous when dealing with large diameter bolting applications.
  • Hanger Screw – A headless fastener that has machine screw threads on one end and self tapping threads on the other designed to be driven into wood or another soft substrate.

Teks(R) is a registered trademark of ITW Buildex


Shapes of screw head

Image:Screw head types.svg
(a) pan, (b) button, (c) round, (d) truss, (e) flat (countersunk), (f) oval
  • pan head: a low disc with chamfered outer edge.
  • button or dome head: cylindrical with a rounded top.
  • round head: dome-shaped, commonly used for machine screws.
  • truss head: lower-profile dome designed to prevent tampering.
  • flat head or countersunk: conical, with flat outer face and tapering inner face allowing it to sink into the material.
  • oval or raised head: countersunk with a rounded top.
  • bugle head: similar to countersunk, but there is a smooth progression from the shaft to the angle of the head, similar to the bell of a bugle.
  • cheese head: disc with cylindrical outer edge, height approximately half the head diameter.
  • fillister head: cylindrical, but with a slightly convex top surface.
  • socket head: cylindrical, relatively high, with different types of sockets (hex, square, torx, etc.).
  • mirror screw head: countersunk head with a tapped hole to receive a separate screw-in chrome-plated cover, used for attaching mirrors.
  • headless (set or grub screw): has either a socket or slot in one end for driving.

Some varieties of screw are manufactured with a break-away head, which snaps off when adequate torque is applied. This prevents tampering and disassembly and also provides an easily-inspectable joint to guarantee proper assembly. Image File history File links This is a lossless scalable vector image. ... For other uses, see Button (disambiguation). ... Look up round in Wiktionary, the free dictionary. ... Look up truss in Wiktionary, the free dictionary. ... A countersink is a tapered hole drilled with a wide outer portion. ... This oval, with only one axis of symmetry, resembles a chicken egg. ... Example of a chamfer A Chamfer is a beveled edge connecting two surfaces. ... Military bugle in B♭ The bugle is one of the simplest brass instruments; it is essentially a small natural horn with no valves. ... A socket generally designates a cavity or region used for fitting and connecting some specific device. ... TORX, developed by Camcar LLC of Acument Global Technologies (formerly Camcar Textron), is the trademark for a type of screw head characterized by a 6-point star-shaped pattern (in the same way that slotted heads, Phillips, Hex, and Robertson have flat, ×-shaped, hexagonal, and square tips, respectively). ...


Types of screw drive

Part of the series on
Screw drive types
Slotted (Commonly, erroneously "Flathead")
Phillips ("Crosshead")
Pozidriv (SupaDriv)
Torx
Hex (Allen)
Robertson
Tri-Wing
Torq-Set
Spanner Head
Triple Square (XZN)
This box: view  talk  edit
Phillips vs. Frearson
Phillips vs. Frearson
BNAE driver bit
BNAE driver bit

Modern screws employ a wide variety of drive designs, each requiring a different kind of tool to drive in or extract them. The most common screw drives are the slotted and Phillips; hex, Robertson, and TORX are also common in some applications. Some types of drive are intended for automatic assembly in mass-production of such items as automobiles. More exotic screw drive types may be used in situations where tampering is undesirable, such as in electronic appliances that should not be serviced by the home repair person. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Henry F. Phillips (1890 – 1958) was a U.S. businessman from Portland, Oregon, has the dubious honour of having the Phillips-head screw and screwdriver. ... Image File history File links This is a lossless scalable vector image. ... The Pozidriv screw type is patented, similar to cross-head but designed not to slip, or cam out. ... Image File history File links This is a lossless scalable vector image. ... TORX, developed by Camcar LLC of Acument Global Technologies (formerly Camcar Textron), is the trademark for a type of screw head characterized by a 6-point star-shaped pattern (in the same way that slotted heads, Phillips, Hex, and Robertson have flat, ×-shaped, hexagonal, and square tips, respectively). ... Image File history File links This is a lossless scalable vector image. ... Hex keys of various sizes. ... Image File history File links This is a lossless scalable vector image. ... Robertson screwdrivers A Robertson screwdriver is a type of screwdriver with a square-shaped tip with a slight taper (in the same way that flatheads, Phillips, Allen, and Torx have flat, ×-shaped, hexagonal, and hexagrammal tips, respectively). ... Image File history File links This is a lossless scalable vector image. ... The Tri-Wing is a type of screw and screw head. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links BNAE_driver_bit. ... Image File history File links BNAE_driver_bit. ...

  • Slot head has a single slot, and is driven by a flat-bladed screwdriver. The slotted screw is common in woodworking applications, but is not often seen in applications where a power driver would be used, due to the tendency of a power driver to slip out of the head and potentially damage the surrounding material.
  • Cross-head, cross-point, or cruciform has a "+"-shaped slot and is driven by a cross-head screwdriver, designed originally for use with mechanical screwing machines. There are five types:
    • The Phillips screw drive has slightly rounded corners in the tool recess, and was designed so the driver will slip out, or cam out, under high torque to prevent over-tightening. The Phillips Screw Company was founded in Oregon in 1933 by Henry F. Phillips, who bought the design from J. P. Thompson. Phillips was unable to manufacture the design, so he passed the patent to the American Screw Company, who was the first to manufacture it.
    • A Reed & Prince or Frearson screw drive is similar to a Phillips but has a more pointed 75° V shape. Its advantage over the Phillips drive is that one driver or bit fits all screw sizes. It is found mainly in marine hardware and requires a special screw driver or bit to work properly. The tool recess is a perfect cross, unlike the Phillips head, which is designed to cam out. It was developed by an English inventor named Frearson in the 19th century and produced from the late 1930s to the mid-1970s by the former Reed & Prince Manufacturing Company of Worcester, Massachusetts, a company which traces its origins to Kingston, Massachusetts, in 1882, and was liquidated in 1990 with the sale of company assets.
    • A JIS (Japanese Industrial Standard) head, commonly found in Japanese equipment, looks like a Phillips screw, but is designed not to cam out and will, therefore, be damaged by a Phillips screwdriver if it is too tight. Heads are usually identifiable by a single dot to one side of the cross slot. The standard number is JIS B 1012:1985
    • French Recess, also called BNAE NFL22-070 for Bureau de Normalisation de l'Aéronautique et de l'Espace, a French standards organization.
    • Pozidriv is patented, similar to cross-head but designed not to slip, or cam out. It has four additional points of contact, and does not have the rounded corners that the Phillips screw drive has. Phillips screwdrivers will usually work in Pozidriv screws, but Pozidriv screwdrivers are likely to slip or tear out the screw head when used in Phillips screws. Heads are marked with single lines at 45 degrees to the cross recess, for identification. (note that two lines at 45 are a different recess: a very specialised Phillips screw). Pozidriv was jointly patented by the Phillips Screw Company and American Screw Company in the USA. Developed by GKN in the 1960s, the recess is licenced from Trifast PLC in the rest of the world.
    • Supadriv is similar to Pozidriv.
  • TORX is a star-shaped "hexalobular" drive with six rounded points. It was designed to permit increased torque transfer from the driver to the bit compared to other drive systems. TORX is very popular in the automotive and electronics industries due to resistance to cam out and extended bit life, as well as reduced operator fatigue by minimizing the need to bear down on the drive tool to prevent cam out. TORX screws were found in early Apple Macintosh computers, to discourage home repairs[citation needed]. TORX PLUS is an improved version of TORX which extends tool life even further and permits greater torque transfer compared to TORX. A tamper-resistant TORX head has a small pin inside the recess. The tamper-resistant TORX is also made in a 5 lobed variant. These "5-star" TORX configurations are commonly used in correctional facilities, public facilities and government schools, but can also be found in some electronic devices, such as Seagate's external drives.
  • TTAP is an improved "hexalobular" drive for without wobbling and stable stick-fit. TTAP is backward convertible with generic hexalobular drive.
Hex socket screws
Hex socket screws
  • Hexagonal (hex) socket head has a hexagonal hole and is driven by a Hex Wrench, sometimes called an Allen key or Hex key, or by a power tool with a hexagonal bit. Tamper-resistant versions with a pin in the recess are available. Hex sockets are increasingly used for modern bicycle parts because hex wrenches are very light and easily carried tools. They are also frequently used for self-assembled furniture (e.g. from Ikea).
  • Robertson head, invented in 1908 by P.L. Robertson, has a square hole and is driven by a special power-tool bit or screwdriver. The screw is designed to maximize torque transferred from the driver, and will not slip, or cam out. It is possible to hold a Robertson screw on a driver bit horizontally or even pendant, due to a slight wedge fit. Commonly found in Canada in carpentry and woodworking applications and in Canadian-manufactured electrical wiring items such as receptacles and switch boxes.
  • Square-drive head is an American clone of the Robertson that has a square hole without taper. Due to the lack of taper, the hole must be oversize relative to the screwdriver, and is much more likely to strip than the Robertson.
  • Tri-Wing head has a triangular slotted configuration. They were used by Nintendo on several consoles and accessories, including the Game Boy, Wii, and Wii Remote, and on some Nokia phones and chargers to discourage home repair.
  • Torq-Set or offset cruciform may be confused with Phillips; however, the four legs of the contact area are offset in this drive type. Is commonly used in the aerospace industry.
  • Spanner drive uses two round holes opposite each other, and is designed to prevent tampering. Commonly seen in elevators in the United States.
  • Clutch Type A or standard clutch head resembles a bow tie. These were common in GM automobiles, trucks and buses of the 1940s and 1950s, particularly for body panels.
  • Clutch Type G head resembles a butterfly. This type of screw head is commonly used in the manufacture of mobile homes and recreational vehicles.

To cam out (or cam-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. ... Henry F. Phillips (1890 – 1958) was a U.S. businessman from Portland, Oregon, has the dubious honour of having the Phillips-head screw and screwdriver. ... For other uses, see Worcester (disambiguation). ... Japanese Industrial Standards (JIS) specifies the standards used for industrial activities in Japan. ... A standards organization, also sometimes referred to as a standards body, a standards development organization or SDO (depending on what is being referenced), is any entity whose primary activities are developing, coordinating, promulgating, revising, amending, reissuing, interpreting, or otherwise maintaining standards that address the interests of a wide base of... The Pozidriv screw type is patented, similar to cross-head but designed not to slip, or cam out. ... GKN plc is a British engineering company formerly known as Guest, Keen and Nettlefolds and tracing its origins back to 1759 and the birth of the industrial revolution. ... The Pozidriv® is a type of screw head and screwdriver, jointly patented by the Phillips Screw Company and American Screw Company. ... TORX, developed by Camcar LLC of Acument Global Technologies (formerly Camcar Textron), is the trademark for a type of screw head characterized by a 6-point star-shaped pattern (in the same way that slotted heads, Phillips, Hex, and Robertson have flat, ×-shaped, hexagonal, and square tips, respectively). ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... Seagate Technology (NYSE: STX) is a major American manufacturer of hard drives, founded in 1979 and based in Scotts Valley, California. ... TTAPis an improved new hexalobular (hex-lob/Torx) screw drive system withouth the disadvantages of the generic hex-lob. ... Image File history File links Download high resolution version (1556x624, 78 KB) Allen screws (inbus), different sizes File links The following pages link to this file: Screw ... Image File history File links Download high resolution version (1556x624, 78 KB) Allen screws (inbus), different sizes File links The following pages link to this file: Screw ... Hex keys of various sizes. ... World Map showing locations of IKEA stores, where green in currently in operation and blue is proposed, as at 2007 IKEA is a privately-held, international home products retailer that sells low-price products, including flat pack furniture, accessories, bathrooms and kitchens at retail stores around the world. ... Robertson screwdrivers A Robertson screwdriver is a type of screwdriver with a square-shaped tip with a slight taper (in the same way that flatheads, Phillips, Allen, and Torx have flat, ×-shaped, hexagonal, and hexagrammal tips, respectively). ... The Tri-Wing is a type of screw and screw head. ... For the video game system, see Nintendo Entertainment System. ... For the entire Game Boy series of handheld consoles, see Game Boy line. ... The Wii (pronounced as the pronoun we, IPA: ) is the fifth home video game console released by Nintendo. ... The Wii Remote, sometimes nicknamed Wiimote, is the primary controller for Nintendos Wii console. ... This article is about the telecommunications corporation. ... This article is about the transportation device. ... One option to tie a bowtie The bowtie is a mens fashion accessory, popularly worn with other formal attire, such as suits. ... General Motors Corporation, also known as GM, is a multinational corporation headquartered in the United States and has been the worlds most dominant automaker since 1931. ... A modern double-wide mobile home Mobile homes are housing units built in factories, rather than on site, and then taken to the place where they will be occupied, usually by being carried by tractor-trailers over public highways. ... Recreational Vehicle (or RV) is a term used in North America to describe a large enclosed piece of equipment with wheels designed to be moved from place to place for people to temporarily live in and be protected from the elements while away from their permanent home. ...

Combination drives

Some screws have heads designed to accommodate more than one kind of driver. The most common of these is a combination of a slotted and Phillips head. Because of its prevalence, there are now drivers made specifically for this kind of screw head. Other combinations are a Phillips and Robertson, a Robertson and a slotted, and a triple-drive screw which can take a slotted, Phillips or a Robertson. The Recex drive system claims it offers the combined non-slip convenience of a Robertson drive during production assembly and Phillips for after market serviceability. Combination head screws are becoming more and more popular.


Tamper-resistant screws

Tamper-resistant external-TORX driver
Tamper-resistant external-TORX driver
One-way slotted screw
One-way slotted screw

Many screw drives, including Phillips, TORX, and Hexagonal, are also manufactured in tamper-resistant form. These typically have a pin protruding in the center of the screw head, necessitating a special tool for extraction. In some variants the pin is placed slightly off-center, requiring a correspondingly shaped bit. However, the bits for many tamper-resistant screw heads are now readily available from hardware stores, tool suppliers and through the Internet. What is more, there are many commonly used techniques to extract tamper resistant screws without the correct driver — for example, the use of an alternative driver that can achieve enough grip to turn the screw, modifying the head to accept an alternative driver, forming ones own driver by melting an object into the head to mould a driver, or simply turning the screw using a pair of locking pliers. Thus, these special screws offer only modest security. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... For the Jamaican singer, see Pliers (singer). ...


The slotted screw drive also comes in a tamper-resistant one-way design with sloped edges; the screw can be driven in, but the bit slips out in the reverse direction.


There are specialty fastener companies that make unusual, proprietary head designs, featuring matching drivers available only from them, and only supplied to registered owners[1]. An example of this would be the attachment for the wheels and/or spare tires of some types of car; one of the nuts may require a specialized socket (provided with the car) to prevent theft.


The break away bolt is a high security fastener that is extremely difficult to remove. It consists of a counter-sunk flat head screw, with a thin shaft and hex head protruding from the flat head. The hex head is used to drive the bolt into the countersunk hole, then the wrench or hammer is used to knock the shaft and hex head off of the flat head, leaving only a smooth screw head exposed. Removal is facilitated by drilling a small hole part way into the outer part of the head and using a punch and hammer at a sharp angle in a counter-clockwise direction. This type of screw is used primarily in prison door locks.
A variety of punches are used in engineering. ... For other uses, see Hammer (disambiguation). ...


Tools used

The hand tool used to drive in most screws is called a screwdriver. A power tool that does the same job is a power screwdriver; power drills may also be used with screw-driving attachments. Where the holding power of the screwed joint is critical, torque-measuring and torque-limiting screwdrivers are used to ensure sufficient but not excessive force is developed by the screw. The hand tool for driving cap screws and other types is called a spanner (UK usage) or wrench (US usage). A drill is a tool with a rotating drill bit used for drilling holes in various materials. ... For other senses of this word, see torque (disambiguation). ... Combination wrench, or combination spanner (left: box-end/ring, right: open-end) A wrench or spanner is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other hard-to-turn items. ...


Mechanics of use

An electric driver screws a self tapping phillips head screw into wood

When driving in a screw, especially when the screw has been removed and is being placed again, the threads can become misaligned and damage, or strip, the threading of the hole. To avoid this, slight pressure is applied and the screw is driven in reverse, until the leading edges of the helices pass each other, at which point a slight click will be felt (and sometimes heard.) When this happens, the screw will often assume a more aligned position with respect to the hole.


Immediately after the 'click', the screw may be driven in without damage to the threading. This technique is useful for re-seating screws in wood and plastic, and for assuring the proper fit when screwing down plates and covers where alignment is difficult.


Thread standards

See also: Screw thread

There are many systems for specifying the dimensions of screws, but in much of the world the ISO metric screw thread preferred series has displaced the many older systems. Other relatively common systems include the British Standard Whitworth, BA system (British Association), and the SAE Unified Thread Standard. Screw thread, used to convert torque into the linear force in the flood gate. ... The metric ISO screw threads are the world-wide most commonly used type of general-purpose screw thread. ... British Standard Whitworth (BSW) is one of three imperial unit based screw thread standards which use the same bolt heads and nut hexagonal sizes, the other two being British Standard Fine (BSF) and Cycle Engineers Institute (CEI). ... British Association or BA screw threads are a largely obsolete set of small screw threads, the largest being 0BA at 6mm diameter. ... SAE International (SAE) is a professional organization for mobility engineering professionals in aerospace, automotive and the commercial vehicle industries. ... The Unified Thread Standard (UTS) defines a standard thread form and series – along with allowances, tolerances, and designations – for screw threads commonly used in the United States and Canada. ...


ISO metric screw thread

The basic principles of the ISO metric screw thread are defined in international standard ISO 68-1 and preferred combinations of diameter and pitch are listed in ISO 261. The smaller subset of diameter and pitch combinations commonly used in screws, nuts and bolts is given in ISO 262. The most commonly used pitch value for each diameter is known as the "coarse pitch". For some diameters, one or two additional "fine pitch" variants are also specified, for special applications such as threads in thin-walled pipes. ISO metric screw threads are designated by the letter M followed by the major diameter of the thread in millimeters, e.g. "M8". If the thread does not use the normal "coarse pitch" (e.g., 1.25 mm in the case of M8), then the pitch in millimeters is also appended with a multiplication sign, e.g. "M8×1" if the screw thread has an outer diameter of 8 mm and advances by 1 mm per 360° rotation. Standards are produced by many organizations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... The metric ISO screw threads are the world-wide most commonly used type of general-purpose screw thread. ... The metric ISO screw threads are the world-wide most commonly used type of general-purpose screw thread. ... The symbol ×, pronounced times or multiplication sign, is primarily used in mathematics, to denote the multiplication of two numbers cross product of two vectors Cartesian product of two sets. ...


The nominal diameter of a metric screw is the outer diameter of the thread. The tapped hole (or nut) into which the screw fits, has an internal diameter which is the size of the screw minus the pitch of the thread. Thus, an M6 screw, which has a pitch of 1 mm, is made by threading a 6 mm shaft, and the nut or threaded hole is made by tapping threads in a 5 mm hole. A nominal is a word or a group of words that functions as a noun, i. ...


Metric hexagon bolts, screws and nuts are specified, for example, in British Standard BS 4190 (general purpose screws) and BS 3692 (precision screws). The following table lists the relationship given in these standards between the thread size and the maximal width across the hexagonal flats (wrench size): For other uses, see Hexagon (disambiguation). ... British Standards is the new name of the British Standards Institute and is part of BSI Group which also includes a testing organisation. ...

ISO metric thread M1.6 M2 M2.5 M3 M4 M5 M6 M8 M10 M12 M16 M20 M24 M30 M36 M42 M48 M56 M64
wrench size (mm) 3.2 4 5 5.5 7 8 10 13 17 19 24 30 36 46 55 65 75 85 95

In addition, the following non-preferred intermediate sizes are specified:

ISO metric thread M14 M18 M22 M27 M33 M39 M45 M52 M60 M68
wrench size (mm) 22 27 32 41 50 60 70 80 90 100

Whitworth

The first person to create a standard (in about 1841) was the English engineer Sir Joseph Whitworth. Whitworth screw sizes are still used, both for repairing old machinery and where a coarser thread than the metric fastener thread is required. Whitworth became British Standard Whitworth, abbreviated to BSW (BS 84:1956) and the British Standard Fine (BSF) thread was introduced in 1908 because the Whitworth thread was a bit coarse for some applications. The thread angle was 55° and a depth and pitch of thread that varied with the diameter of the thread (i.e., the bigger the bolt, the coarser the thread). The spanner size is determined by the size of the bolt, not the distance between the flats. For other uses, see England (disambiguation). ... Look up engineer in Wiktionary, the free dictionary. ... Sir Joseph Whitworth Sir Joseph Whitworth, Baronet (December 21, 1803 - January 22, 1887) was an English engineer and entrepreneur. ... British Standard Whitworth (BSW) is one of three imperial unit based screw thread standards which use the same bolt heads and nut hexagonal sizes, the other two being British Standard Fine (BSF) and Cycle Engineers Institute (CEI). ...


The most common use of a Whitworth pitch nowadays is the standard photographic tripod thread, which for small cameras is 1/4" Whitworth (20 tpi) and for medium/large format cameras is 3/8" Whitworth (16 tpi). A tripod, in the context of photography, is a three-legged stand for a camera, used to stabilize and elevate the camera. ...


British Association screw threads (BA)

A later standard established in the United Kingdom was the BA system, named after the British Association for Advancement of Science. Screws were described as "2BA", "4BA" etc., the odd numbers being rarely used, except in equipment made prior to the 1970's for telephone exchanges in the UK. This equipment made extensive use of odd-numbered BA screws, in order -- it may be suspected -- to reduce theft. While not related to ISO metric screws, the sizes were actually defined in metric terms, a 0BA thread having a 1 mm pitch. These are still the most common threads in some niche applications. Certain types of fine machinery, such as moving-coil meters, tend to have BA threads wherever they are manufactured. British Association or BA screw threads are a largely obsolete set of small screw threads, the largest being 0BA at 6mm diameter. ...


Unified Thread Standard

The United States of America has its own system, usually called the Unified Thread Standard, which is also extensively used in Canada and in most other countries around the world. At least 85% of the world's fasteners are dimensioned to Unified thread dimensions, and the biggest selection of fastener sizes and materials are found supplied in this standard.[2] A version of this standard, called SAE for the Society of Automotive Engineers, was used in the American automobile industry. The SAE is still associated with inch-based fasteners by the public, even though the U.S. auto industry (and other heavy industries relying on SAE) have gradually converted to ISO preferred series fasteners for some assemblies from the 1970s onward, because global parts sourcing and product marketing favor international standardization. However, all automobiles sold throughout the world contain both metric (engine assemblies) and Imperial fasteners (for example, lug nuts, oxygen sensors, internal electrical assemblies, body fasteners, lamps, steering, brake and suspension parts). The Unified Thread Standard (UTS) defines a standard thread form and series – along with allowances, tolerances, and designations – for screw threads commonly used in the United States and Canada. ... SAE International (SAE) is a professional organization for mobility engineering professionals in aerospace, automotive and the commercial vehicle industries. ... In 2005 in the United States were manufactured 11 980 912 motor vehicles. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ...


Machine screws are described as 0-80, 2-56, 3-48, 4-40, 5-40, 6-32, 8-32, 10-32, 10-24, etc. up to size 16. The first number can be translated to a diameter using a formula, the second is the number of threads per inch. There is a coarse thread and a fine thread for each size, the fine thread being preferred in thin materials or when slightly greater strength is desired.


The numbering system follows a roughly logarithmic series where an increase in each screw number size approximately doubles the tensile strength of the screw and the screw number is found by d=(# times .013'')+.060'', where "d" is the nominal diameter. Using this formula a #5 screw has a major diameter of .125" (1/8"), a #10 screw has a diameter of .190" (or 3/16" in practical terms), etc. The formula applies for screw thread numbers #0 and higher, but does NOT apply to smaller Unified miniature screw thread series. Typically screws smaller than size #0 are supplied in the Unified Miniature Series. The formula for number sizes smaller than size #0 is given by d=.060''- (#zerosize times .013), with the zero size being the number of zeros after the first. So a #00 screw is .047" dia, #000 is .034" dia, etc.


The number series of machine screws once included odd numbers (7, 9, etc.) and extended up to #16 or more. Standardization efforts in the late 19th and the early part of the 20th century reduced the range of sizes considerably. Now, it is less common to see machine screws larger than #14, or odd number sizes other than #1, #3 and #5. Even though #14 and #16 screws are still available, they are not as common as sizes #0 through #12.


Sizes 1/4" diameter and larger are designated as 1/4"-20, 1/4"-28, etc. the first number giving the diameter in inches and the second number being threads per inch. Most thread sizes are available in UNC or UC (Unified Coarse Thread, example 1/4"-20) or UNF or UF (Unified Fine Thread, example 1/4"-28).


Others

Other thread systems include Acme thread form, BSP (British standard pipe thread which exists in a taper and non taper variant; used for other purposes as well) and BSC (British Standard Cycle) a 26tpi thread form, CEI (Cycle Engineers Institute, used on bicycles in Britain and possibly elsewhere), British Standard Brass a fixed pitch 26tpi thread, NPT (National Pipe Thread) and NPTF (National Pipe Thread Fuel), and PG (German: "Panzer-Gewinde"), used in thin plate metal, such as for switches and nipples in electrical equipment housings. Threads formed around a shaft are used to translate rotational motion into linear motion. ... The British standard pipe thread (BSP thread) is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. ... Threaded pipe and elbow National Pipe Thread is a U.S. standard for tapered (NPT) or straight (NPS) threads used to join pipes and fittings. ...


History

Screw making machine, 1871
Screw making machine, 1871

In antiquity, the screw was first used as part of the screw pump of Sennacherib, King of Assyria, for the water systems at the Hanging Gardens of Babylon and Nineveh in the 7th century BC.[3] Image File history File links Size of this preview: 657 × 600 pixels Full resolution (767 × 700 pixel, file size: 103 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Screw ... Image File history File links Size of this preview: 657 × 600 pixels Full resolution (767 × 700 pixel, file size: 103 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Screw ... Archimedess screw (also the Archimedean screw) is one of several inventions and discoveries reputed to have been made by Archimedes. ... Sennacherib during his Babylonian war, relief from his palace in Nineveh Sennacherib (in Akkadian Śïn-ahhe-eriba (The moon god) Śïn has Replaced (Lost) Brothers for Me) was the son of Sargon II, whom he succeeded on the throne of Assyria (705 BC–681 BC). ... For other uses, see Assyria (disambiguation). ... Domestic water supply or system (DWS) is a comprehensive term for the potable water supply systems in residential, commercial, institutional, and industrial buildings. ... Hanging Gardens redirects here. ... , For other uses, see Nineveh (disambiguation). ... (2nd millennium BC - 1st millennium BC - 1st millennium) The 7th century BC started on January 1, 700 BC and ended on December 31, 601 BC. // Overview Events Ashurbanipal, king of Assyria who created the the first systematically collected library at Nineveh A 16th century depiction of the Hanging Gardens of...


The screw was later described by the Greek mathematician Archytas of Tarentum (428350 BC). By the 1st century BC, wooden screws were commonly used throughout the Mediterranean world in devices such as oil and wine presses. Metal screws used as fasteners did not appear in Europe until the 1400s. Greek mathematics, as that term is used in this article, is the mathematics written in Greek, developed from the 6th century BC to the 5th century AD around the Eastern shores of the Mediterranean. ... Archytas (428 BC - 347 BC), was a Greek philosopher, mathematician, astronomer, statesman, strategist and commander-in-chief. ... Centuries: 6th century BC - 5th century BC - 4th century BC Decades: 470s BC 460s BC 450s BC 440s BC 430s BC - 420s BC - 410s BC 400s BC 390s BC 380s BC 370s BC Years: 433 BC 432 BC 431 BC 430 BC 429 BC - 428 BC - 427 BC 426 BC... Centuries: 5th century BC - 4th century BC - 3rd century BC Decades: 400s BC 390s BC 380s BC 370s BC 360s BC - 350s BC - 340s BC 330s BC 320s BC 310s BC 300s BC 355 BC 354 BC 353 BC 352 BC 351 BC - 350 BC - 349 BC 348 BC 347... (2nd millennium BC - 1st millennium BC - 1st millennium) The 1st century BC started on January 1, 100 BC and ended on December 31, 1 BC. An alternative name for this century is the last century BC. The AD/BC notation does not use a year zero. ... The Mediterranean Sea is an intercontinental sea positioned between Europe to the north, Africa to the south and Asia to the east, covering an approximate area of 2. ... It has been suggested that this article or section be merged with cooking oil. ... For other uses, see Wine (disambiguation). ...


The metal screw did not become a common woodworking fastener until machine tools for mass production were developed at the end of the eighteenth century. In 1770, English instrument maker, Jesse Ramsden (1735-1800) invented the first satisfactory screw-cutting lathe. The British engineer Henry Maudslay (1771-1831) patented a screw-cutting lathe in 1797; a similar device was patented by David Wilkinson in the United States in 1798. A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by machining, which is the selective removal of metal. ... Mass production is the production of large amounts of standardised products on production lines. ... Jesse Ramsden (October 6, 1735 - November 5, 1800) was an English astronomical instrument maker. ... Henry Maudslay. ... 1797 (MDCCXCVII) was a common year starting on Sunday (see link for calendar) of the Gregorian calendar (or a common year starting on Wednesday of the 11-day-slower Julian calendar). ... David Roland Wilkinson (David Wilkinson, born July 11, 1982). ...


In 1908, square-drive screws were invented by Canadian P. L. Robertson, becoming a North American standard. In the early 1930s, the Phillips head screw was invented by Henry F. Phillips. A Robertson screwdriver (also called a square drive screwdriver) is a type of screwdriver with a square-shaped tip with a slight taper (in the same way that flatheads, Phillips, hex, and Torx have flat, ×-shaped, hexagonal, and hexagrammal tips, respectively). ... Peter Lymburner Robertson (1879-1951) is a Canadian inventor of the square-drive screw, first produced in his Milton, Ontario factory in 1908. ...


Standardization of screw thread forms accelerated during WWII so that interchangeable parts could be produced by any of the Allied countries. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000...


Prior to the mid nineteenth century, cotter pins or pin bolts, and "clinch bolts" (now called rivets), were used in ship building. Cotter pins: A. new B. as-installed C. spring type D. cross-section of traditional design A cotter pin is a metal fastener that is bent during installation, similar to a staple or rivet. ... Clinker is a boat building technique used for constructing hulls of boats and ships by fixing wooden planks and in the early nineteenth century, iron plates to each other so that the planks overlap along their edges. ... Solid rivets Metal wheel with riveted spokes and tyre. ...


In 1744, the flat-bladed bit for the carpenter's brace was invented, the precursor to the first simple screwdriver. Handheld screwdrivers first appeared after 1800.


Legal issues

In the United States a screw and a bolt have different import duties. The difference between them is therefore of keen interest to importers and customs authorities. An import duty is a tariff paid at a border or port of entry to the relevant government to allow a good to pass into that governments territory. ...


This was the subject of a court case Rocknel Fastener, inc v. United States: 34 page PDF. The position is outlined in a current US government document Distinguishing Bolts From Screws: 21 page PDF.


See also

Look up screw in Wiktionary, the free dictionary. ... Archimedes screw. ... A nut is a type of hardware fastener with a threaded hole. ... Three different sets of threading gauges Threading gauges, pictured on the right, are also referred to as pitch gauges and are used to measure the pitch or lead of screw threads. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Taps and dies are generally metalworking tools for the creation (cutting) of screw threads in metal parts. ... Screw thread, used to convert torque into the linear force in the flood gate. ... Screws can be used for vehicle propulsion. ... In electrical and mechanical trades and manufacturing, each of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. ...

References

  1. ^ Key-Rex Security Screws. Retrieved on April 2, 2008. “The keyway is licensed and private for each user”
  2. ^ World Fastener Review, Industrial Press, 2006
  3. ^ Stephanie Dalley and John Peter Oleson (January 2003). "Sennacherib, Archimedes, and the Water Screw: The Context of Invention in the Ancient World", Technology and Culture 44 (1).

Image File history File links Question_book-3. ... Image File history File links This is a lossless scalable vector image. ... Machinerys Encyclopedia, 1917 Boiler, Machinerys Encyclopedia, 1917 Machinerys Handbook for machine shop and drafting-room; a reference book on machine design and shop practice for the mechanical engineer, draftsman, toolmaker, and machinist (the full title of the 1st edition) is a classic reference work in mechanical engineering... One Good Turn: A Natural History of the Screwdriver and the Screw is a book published in 2000 by Canadian architect, professor and writer Witold Rybczynski. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ...

External links

Wikimedia Commons has media related to:
Screws
  • Lara Tools screw types - Specialty tool dealer documents more than two dozen different screw heads, along with their drivers.
  • Nut and Bolt information charts - Bolt grade markings and strength chart, metric and imperial from Bolt Depot.
  • American Fastener - A series of technical documents from an industrial fastener supplier
  • Efunda and Metrication.com provide tables for metric screw dimensions. Dimensions of the pitch versions are also available on the websites.
  • Socket Head Cap Screw - Interactive Dimension Workform
  • Spanner Jaw Sizes Additional background information and spanner jaw size table.
  • History of screw recesses from the makers of the ttap-drive fasteners.
  • UNICOIL - Manufacturer of thread repair system, wire thread inserts, wire insert thread repair taps, inserting tools, thread repair kits.
Image File history File links Commons-logo. ... TTAPis an improved new hexalobular (hex-lob/Torx) screw drive system withouth the disadvantages of the generic hex-lob. ...

  Results from FactBites:
 
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