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69-674: It was established in April 1996. There are currently 65 members. This standards - or measurement -related article is a stub . You can help Misplaced Pages by expanding it . Standardization Standardization ( American English ) or standardisation ( British English ) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardization can help maximize compatibility , interoperability , safety , repeatability , or quality . It can also facilitate

138-437: A nut . The three taps in the image illustrate the basic types commonly used by most machinists : Whether manual or automatic, the processing of tapping begins with forming (usually by drilling) and slightly countersinking a hole to a diameter somewhat smaller than the tap's major diameter. The correct hole diameter is listed on a drill and tap size chart , a standard reference in many machine shops . The proper diameter for

207-756: A 55° thread angle and a thread depth of 0.640327 p and a radius of 0.137329 p , where p is the pitch. The thread pitch increased with diameter in steps specified on a chart. An example of the use of the Whitworth thread is the Royal Navy 's Crimean War gunboats. These were the first instance of "mass-production" techniques being applied to marine engineering. With the adoption of BSW by British railway lines, many of which had previously used their own standard both for threads and for bolt head and nut profiles, and improving manufacturing techniques, it came to dominate British manufacturing. American Unified Coarse

276-404: A larger network and attracting more consumers to use the new technology, further enhancing network effects. Other benefits of standardization to consumers are reduced uncertainty, because consumers can be more certain that they are not choosing the wrong product, and reduced lock-in, because the standard makes it more likely that there will be competing products in the space. Consumers may also get

345-441: A measuring instrument or procedure is similar to every subjects or patients. For example, educational psychologist may adopt structured interview to systematically interview the people in concern. By delivering the same procedures, all subjects is evaluated using same criteria and minimising any confounding variable that reduce the validity . Some other example includes mental status examination and personality test . In

414-504: A merger of two predecessor organizations (Bern and Paris treaties) that had similar objectives, but in more limited territories. With the advent of radiocommunication soon after the creation, the work of the ITU quickly expanded from the standardization of Telegraph communications, to developing standards for telecommunications in general. By the mid to late 19th century, efforts were being made to standardize electrical measurement. Lord Kelvin

483-448: A metal fastening on the other side were usually fastened in non-threaded ways (such as clinching or upsetting against a washer). Maudslay standardized the screw threads used in his workshop and produced sets of taps and dies that would make nuts and bolts consistently to those standards, so that any bolt of the appropriate size would fit any nut of the same size. This was a major advance in workshop technology. Maudslay's work, as well as

552-443: A normalization of formerly custom processes. In social sciences , including economics , the idea of standardization is close to the solution for a coordination problem , a situation in which all parties can realize mutual gains, but only by making mutually consistent decisions. Divergent national standards impose costs on consumers and can be a form of non-tariff trade barrier . Standard weights and measures were developed by

621-1028: A regional level (e.g. Europa, the Americas, Africa, etc) or at subregional level (e.g. Mercosur, Andean Community, South East Asia, South East Africa, etc), several Regional Standardization Organizations exist (see also Standards Organization ). The three regional standards organizations in Europe – European Standardization Organizations (ESOs), recognised by the EU Regulation on Standardization (Regulation (EU) 1025/2012) – are CEN , CENELEC and ETSI . CEN develops standards for numerous kinds of products, materials, services and processes. Some sectors covered by CEN include transport equipment and services, chemicals, construction, consumer products, defence and security, energy, food and feed, health and safety, healthcare, digital sector, machinery or services. The European Committee for Electrotechnical Standardization (CENELEC)

690-507: A scientific basis, the robustness and applicability of a scientific basis, whether adoption of the certifications is voluntary, and the socioeconomic context (systems of governance and the economy ), with possibly most certifications being so far mostly largely ineffective. Moreover, standardized scientific frameworks can enable evaluation of levels of environmental protection, such as of marine protected areas , and serve as, potentially evolving, guides for improving, planning and monitoring

759-402: A set of screws set in to the die holder (termed a "die stock"). Integral adjusting screws may be arranged to work axially, where the movement of the adjusting screw into a threaded hole in the die forces the slit section of the die open, or tangentially where a screw threaded in to one side of the slit bears against the opposite side of the slit. Dies without integrated screws are adjusted inside

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828-638: A thread, which is called chasing . However, using an ordinary tap or die to clean threads generally removes some material, which results in looser, weaker threads. Because of this, machinists generally clean threads with special taps and dies—called chasers —made for that purpose. Chasers are made of softer materials and don't cut new threads. However they still fit tighter than actual fasteners, and are fluted like regular taps and dies so debris can escape. Car mechanics, for example, use chasers on spark plug threads, to remove corrosion and carbon build-up. While modern nuts and bolts are routinely made of metal , this

897-406: A tip that is split through the flutes and an axial screw which forces the cutting edges slightly apart. The work piece (blank) to be threaded, which is usually slightly smaller in diameter than the die's major diameter, is given a slight taper (chamfer) at the end that is to be threaded. This chamfer helps center the die on the blank and reduces the force required to start the thread cutting. Once

966-520: A variety of benefits and drawbacks for firms and consumers participating in the market, and on technology and innovation. The primary effect of standardization on firms is that the basis of competition is shifted from integrated systems to individual components within the system. Prior to standardization a company's product must span the entire system because individual components from different competitors are incompatible, but after standardization each company can focus on providing an individual component of

1035-497: Is a Canadian Crown Corporation , DGN is a governmental agency within the Mexican Ministry of Economy, and ANSI and AENOR are a 501(c)(3) non-profit organization with members from both the private and public sectors. The determinants of whether an NSB for a particular economy is a public or private sector body may include the historical and traditional roles that the private sector fills in public affairs in that economy or

1104-408: Is called threading . Many are cutting tools ; others are forming tools. A tap is used to cut or form the female portion of the mating pair (e.g. a nut ). A die is used to cut or form the male portion of the mating pair (e.g. a bolt ). The process of cutting or forming threads using a tap is called tapping , whereas the process using a die is called threading . Both tools can be used to clean up

1173-419: Is faster, and generally more accurate because human error is eliminated. Final tapping is achieved with single tap. Although in general machine tapping is more accurate, tapping operations have traditionally been very tricky to execute due to frequent tap breakage and inconsistent quality of tapping. Common reasons for tap breakage are: To overcome these problems, special tool holders are required to minimize

1242-737: Is likely the sole member from that economy in ISO. NSBs may be either public or private sector organizations, or combinations of the two. For example, the three NSBs of Canada, Mexico and the United States are respectively the Standards Council of Canada ( SCC ), the General Bureau of Standards ( Dirección General de Normas , DGN), and the American National Standards Institute (ANSI). SCC

1311-578: Is not limited to the domain of electronic devices like smartphones and phone chargers but could also be applied to e.g. the energy infrastructure. Policy-makers could develop policies "fostering standard design and interfaces, and promoting the re-use of modules and components across plants to develop more sustainable energy infrastructure ". Computers and the Internet are some of the tools that could be used to increase practicability and reduce suboptimal results, detrimental standards and bureaucracy , which

1380-666: Is often associated with traditional processes and results of standardization. Taxes and subsidies, and funding of research and development could be used complementarily. Standardized measurement is used in monitoring, reporting and verification frameworks of environmental impacts, usually of companies, for example to prevent underreporting of greenhouse gas emissions by firms. In routine product testing and product analysis results can be reported using official or informal standards. It can be done to increase consumer protection , to ensure safety or healthiness or efficiency or performance or sustainability of products. It can be carried out by

1449-459: Is the thread pitch ( 1 ⁄ 16  inch in the case of a 3 ⁄ 8 -16 tap). For a 3 ⁄ 8 -16 tap, the above formula would produce 5 ⁄ 16 , which is the correct tap drill diameter. The above formula ultimately results in an approximate 75% thread. Since metric threads specify the pitch directly, the correct tap drill diameter for metric-sized taps is computed with: where T D {\displaystyle TD}

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1518-707: Is the European Standardization organization developing standards in the electrotechnical area and corresponding to the International Electrotechnical Commission (IEC) in Europe. The first modern International Organization ( Intergovernmental Organization ) the International Telegraph Union (now International Telecommunication Union ) was created in 1865 to set international standards in order to connect national telegraph networks, as

1587-472: Is the tap drill size, M D {\displaystyle MD} is the major diameter of the tap (e.g., 10 mm for a M10×1.5 tap), and pitch is the pitch of the thread (1.5 mm in the case of a standard M10 tap) and so the correct drill size is 8.5 mm. This works for both fine and coarse pitches, and also produces an approximate 75% thread. With soft or average hardness materials, such as plastic , aluminum or mild steel , common practice

1656-456: Is to use an intermediate (plug) tap to cut the threads. If the threads must extend to the bottom of a blind hole, the machinist uses an intermediate (plug) tap to cut threads until the point of the tap reaches bottom, and then switches to a bottoming tap to finish. The machinist must frequently eject chips to avoid jamming or breaking the tap. With hard materials, the machinist may start with a taper tap, whose less severe diameter transition reduces

1725-576: The Indus Valley civilization . The centralized weight and measure system served the commercial interest of Indus merchants as smaller weight measures were used to measure luxury goods while larger weights were employed for buying bulkier items, such as food grains etc. Weights existed in multiples of a standard weight and in categories. Technical standardisation enabled gauging devices to be effectively used in angular measurement and measurement for construction. Uniform units of length were used in

1794-400: The machining industries evolved greatly, and the practice of buying taps and dies from suppliers specializing in them gradually supplanted most such in-house work. Joseph Clement was one such early vendor of taps and dies, starting in 1828. With the introduction of more advanced milling practice in the 1860s and 1870s, tasks such as cutting a tap's flutes with a hand file became a thing of

1863-543: The standard unit of electric current . R. E. B. Crompton became concerned by the large range of different standards and systems used by electrical engineering companies and scientists in the early 20th century. Many companies had entered the market in the 1890s and all chose their own settings for voltage , frequency , current and even the symbols used on circuit diagrams. Adjacent buildings would have totally incompatible electrical systems simply because they had been fitted out by different companies. Crompton could see

1932-654: The National Standardizing Associations (ISA) was founded in 1926 with a broader remit to enhance international cooperation for all technical standards and specifications. The body was suspended in 1942 during World War II . After the war, ISA was approached by the recently formed United Nations Standards Coordinating Committee (UNSCC) with a proposal to form a new global standards body. In October 1946, ISA and UNSCC delegates from 25 countries met in London and agreed to join forces to create

2001-681: The Organization for the Advancement of Structured Information Standards ( OASIS ). There are many specifications that govern the operation and interaction of devices and software on the Internet , which do not use the term "standard" in their names. The W3C , for example, publishes "Recommendations", and the IETF publishes " Requests for Comments " (RFCs). Nevertheless, these publications are often referred to as "standards", because they are

2070-462: The United States was Greenfield Tap & Die (GTD) of Greenfield, Massachusetts . GTD was so vital to the Allied war effort from 1940–1945 that anti-aircraft guns were placed around its campus in anticipation of possible Axis air attack . The GTD brand is now a part of Widia Products Group. A tap cuts or forms a thread on the inside surface of a hole, creating a female surface that functions like

2139-414: The benefit of being able to mix and match components of a system to align with their specific preferences. Once these initial benefits of standardization are realized, further benefits that accrue to consumers as a result of using the standard are driven mostly by the quality of the technologies underlying that standard. Tap and die Taps and dies are tools used to create screw threads , which

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2208-478: The chances of tap breakage during tapping. These are usually classified as conventional tool holders and CNC tool holders. Various tool holders may be used for tapping depending on the requirements of the user: The biggest problem with simple hand-tapping is accurately aligning the tap with the hole so that they are coaxial—in other words, going in straight instead of on an angle. The operator must get this alignment close to ideal to produce good threads and not break

2277-485: The chart provided by Albany County Fasteners. This chart includes detailed specifications for machine screw size, threads per inch, major and minor diameters, and appropriate drill sizes for different materials. A die cuts an external thread on cylindrical material, such as a rod, which creates a male threaded piece that functions like a bolt . Dies are generally made in two styles: solid and adjustable. An adjustable die may be adjusted either by an integrated screw or by

2346-491: The context of customer service , standardization refers to the process of developing an international standard that enables organizations to focus on customer service, while at the same time providing recognition of success through a third party organization, such as the British Standards Institution . An international standard has been developed by The International Customer Service Institute . In

2415-635: The context of supply chain management and materials management , standardization covers the process of specification and use of any item the company must buy in or make, allowable substitutions, and build or buy decisions. The process of standardization can itself be standardized. There are at least four levels of standardization: compatibility, interchangeability , commonality and reference . These standardization processes create compatibility, similarity, measurement, and symbol standards. There are typically four different techniques for standardization Types of standardization process: Standardization has

2484-683: The context of information exchange, standardization refers to the process of developing standards for specific business processes using specific formal languages . These standards are usually developed in voluntary consensus standards bodies such as the United Nations Center for Trade Facilitation and Electronic Business ( UN/CEFACT ), the World Wide Web Consortium ( W3C ), the Telecommunications Industry Association (TIA), and

2553-550: The context of social criticism and social science , standardization often means the process of establishing standards of various kinds and improving efficiency to handle people, their interactions, cases, and so forth. Examples include formalization of judicial procedure in court, and establishing uniform criteria for diagnosing mental disease. Standardization in this sense is often discussed along with (or synonymously to) such large-scale social changes as modernization, bureaucratization, homogenization, and centralization of society. In

2622-526: The contributions of other engineers, accomplished a modest amount of industry standardization; some companies' in-house standards spread a bit within their industries. Joseph Whitworth 's screw thread measurements were adopted as the first (unofficial) national standard by companies around the country in 1841. It came to be known as the British Standard Whitworth , and was widely adopted in other countries. This new standard specified

2691-521: The correct geometry (i.e., accurate coaxiality with the hole) without having to use freehand skill to approximate it: Generally the following features are required of tapping holders: Tapping case studies with typical examples of tapping operations in various environments are shown on source machinetoolaid.com [1] Double-lead taps and insert taps need different speeds and feeds, and different starting hole diameters than other taps. A comprehensive reference for US tap and drill bit sizes can be found in

2760-727: The country, and enabled the markets to act more rationally and efficiently, with an increased level of cooperation. After the First World War , similar national bodies were established in other countries. The Deutsches Institut für Normung was set up in Germany in 1917, followed by its counterparts, the American National Standard Institute and the French Commission Permanente de Standardisation , both in 1918. At

2829-420: The development stage of that economy. Standards can be: The existence of a published standard does not necessarily imply that it is useful or correct. Just because an item is stamped with a standard number does not, by itself, indicate that the item is fit for any particular use. The people who use the item or service (engineers, trade unions, etc.) or specify it (building codes, government, industry, etc.) have

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2898-493: The die has started, it self-feeds. Periodic reversal of the die is often required to break the chip and prevent crowding. Die nut s , also known as rethreading dies , are dies made for cleaning up damaged threads, have no split for resizing and are made from a hexagonal bar so that a wrench may be used to turn them. The process of repairing damaged threads is referred to as "chasing." Rethreading dies cannot be used to cut new threads as they lack chip forming teeth. However

2967-509: The die stock by radially-arranged screws. Two screws in the stock bear in to indentations on either side of the slit, tending to squeeze the slit closed, whilst a third screw with a tapered tip screws in to the slit forcing it open. Working these three screws against each other adjusts the die. Integrated screws appear to be common in the US but are almost unknown in the UK and Europe. The dies shown in

3036-405: The drill is called the tap drill size. Without a tap drill chart, you can compute the correct tap drill diameter with: where T D {\displaystyle TD} is the tap drill size, M D {\displaystyle MD} is the major diameter of the tap (e.g., 3 ⁄ 8 in for a 3 ⁄ 8 -16 tap), and 1 / N {\displaystyle 1/N}

3105-407: The foot or yard. This development eventually led to a complete replacement of wood parts with metal parts of an identical measure. When a wooden part broke, it usually snapped, ripped, or tore. With the splinters having been sanded off, the remaining parts were reassembled, encased in a makeshift mold of clay , and molten metal poured into the mold, so that an identical replacement could be made on

3174-411: The image to the right are adjustable: Solid dies cut a nominal thread form and depth, whose accuracy is subject to the precision the die was made with, and the effects of wear. Adjustable dies can be slightly compressed or expanded to provide some compensation for wear, or to achieve different classes of thread fit (class A, B and more rarely, C). Adjustable taps also exist but are not common. These have

3243-471: The international level . Standardization is also used to ensure safe design and operation of laboratories and similar potentially dangerous workplaces, e.g. to ensure biosafety levels . There is research into microbiology safety standards used in clinical and research laboratories. In the context of defense, standardization has been defined by NATO as The development and implementation of concepts, doctrines, procedures and designs to achieve and maintain

3312-630: The lack of efficiency in this system and began to consider proposals for an international standard for electric engineering. In 1904, Crompton represented Britain at the International Electrical Congress , held in connection with Louisiana Purchase Exposition in Saint Louis as part of a delegation by the Institute of Electrical Engineers . He presented a paper on standardisation, which was so well received that he

3381-645: The manufacturer, an independent laboratory, a government agency, a magazine or others on a voluntary or commissioned/mandated basis. Estimating the environmental impacts of food products in a standardized way – as has been done with a dataset of >57,000 food products in supermarkets – could e.g. be used to inform consumers or in policy . For example, such may be useful for approaches using personal carbon allowances (or similar quota) or for targeted alteration of (ultimate overall) costs . Public information symbols (e.g. hazard symbols ), especially when related to safety, are often standardized, sometimes on

3450-484: The new International Organization for Standardization (ISO); the new organization officially began operations in February ;1947. In general, each country or economy has a single recognized National Standards Body (NSB). Examples include ABNT , AENOR (now called UNE, Spanish Association for Standardization ) , AFNOR , ANSI , BSI , DGN , DIN , IRAM , JISC , KATS , SABS , SAC , SCC , SIS . An NSB

3519-754: The onset of the Industrial Revolution and the need for high-precision machine tools and interchangeable parts . Henry Maudslay developed the first industrially practical screw-cutting lathe in 1800. This allowed for the standardization of screw thread sizes for the first time and paved the way for the practical application of interchangeability (an idea that was already taking hold) to nuts and bolts . Before this, screw threads were usually made by chipping and filing (that is, with skilled freehand use of chisels and files ). Nuts were rare; metal screws, when made at all, were usually for use in wood. Metal bolts passing through wood framing to

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3588-426: The past. In the early 20th century, thread-grinding practice went through significant evolution, further advancing the state of the art (and applied science) of cutting screw threads, including those of taps and dies. During the 19th and 20th centuries, thread standardization was evolving simultaneously with the techniques of thread generation , including taps and dies. The largest tap and die company to exist in

3657-660: The planning of towns such as Lothal , Surkotada , Kalibangan , Dolavira , Harappa , and Mohenjo-daro . The weights and measures of the Indus civilization also reached Persia and Central Asia , where they were further modified. Shigeo Iwata describes the excavated weights unearthed from the Indus civilization: A total of 558 weights were excavated from Mohenjodaro, Harappa, and Chanhu-daro , not including defective weights. They did not find statistically significant differences between weights that were excavated from five different layers, each measuring about 1.5 m in depth. This

3726-497: The products of regular standardization processes. Standardized product certifications such as of organic food , buildings or possibly sustainable seafood as well as standardized product safety evaluation and dis/approval procedures (e.g. regulation of chemicals , cosmetics and food safety ) can protect the environment. This effect may depend on associated modified consumer choices , strategic product support/obstruction, requirements and bans as well as their accordance with

3795-457: The protection-quality, -scopes and -extents. Moreover, technical standards could decrease electronic waste and reduce resource-needs such as by thereby requiring (or enabling) products to be interoperable , compatible (with other products, infrastructures, environments, etc), durable , energy-efficient , modular , upgradeable / repairable and recyclable and conform to versatile, optimal standards and protocols. Such standardization

3864-627: The required levels of compatibility , interchangeability or commonality in the operational, procedural, material, technical and administrative fields to attain interoperability. In some cases, standards are being used in the design and operation of workplaces and products that can impact consumers' health. Some of such standards seek to ensure occupational safety and health and ergonomics . For example, chairs (see e.g. active sitting and steps of research ) could be potentially be designed and chosen using standards that may or may not be based on adequate scientific data. Standards could reduce

3933-591: The responsibility to consider the available standards, specify the correct one, enforce compliance, and use the item correctly: validation and verification . To avoid the proliferation of industry standards, also referred to as private standards , regulators in the United States are instructed by their government offices to adopt "voluntary consensus standards" before relying upon "industry standards" or developing "government standards". Regulatory authorities can reference voluntary consensus standards to translate internationally accepted criteria into public policy . In

4002-607: The size and weight of a girder to employ for given work." The Engineering Standards Committee was established in London in 1901 as the world's first national standards body. It subsequently extended its standardization work and became the British Engineering Standards Association in 1918, adopting the name British Standards Institution in 1931 after receiving its Royal Charter in 1929. The national standards were adopted universally throughout

4071-405: The spot. Metalworking taps and dies were often made by their users during the 18th and 19th centuries (especially if the user was skilled in tool making), using such tools as lathes and files for the shaping, and the smithy for hardening and tempering. Thus builders of, for example, locomotives, firearms, or textile machinery were likely to make their own taps and dies. During the 19th century

4140-465: The system. When the shift toward competition based on individual components takes place, firms selling tightly integrated systems must quickly shift to a modular approach, supplying other companies with subsystems or components. Standardization has a variety of benefits for consumers, but one of the greatest benefits is enhanced network effects. Standards increase compatibility and interoperability between products, allowing information to be shared within

4209-509: The tap. The deeper the thread depth, the more pronounced the effect of the angular error. With a depth of 1 or 2 diameters, it matters little. With depths beyond 2 diameters, the error becomes too pronounced to ignore. Another fact about alignment is that the first thread cut or two establishes the direction that the rest of the threads will follow. You can't correct the angle after the first thread or two. To help with this alignment task, several kinds of jigs and fixtures can be used to provide

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4278-497: The torque required to cut threads. To threads to the bottom of a blind hole, the machinist follows the taper tap with an intermediate (plug) tap, and then a bottoming tap to finish. Tapping may either be achieved by a hand tapping by using a set of taps (first tap, second tap & final (finish) tap) or using a machine to do the tapping, such as a lathe , radial drilling machine, bench type drill machine, pillar type drill machine, vertical milling machines, HMCs, VMCs. Machine tapping

4347-411: The variety of products and lead to convergence on fewer broad designs – which can often be efficiently mass-produced via common shared automated procedures and instruments – or formulations deemed to be the most healthy, most efficient or best compromise between healthiness and other factors. Standardization is sometimes or could also be used to ensure or increase or enable consumer health protection beyond

4416-420: The workplace and ergonomics such as standards in food, food production, hygiene products, tab water, cosmetics, drugs/medicine, drink and dietary supplements, especially in cases where there is robust scientific data that suggests detrimental impacts on health (e.g. of ingredients) despite being substitutable and not necessarily of consumer interest. In the context of assessment, standardization may define how

4485-464: Was an important figure in this process, introducing accurate methods and apparatus for measuring electricity. In 1857, he introduced a series of effective instruments, including the quadrant electrometer, which cover the entire field of electrostatic measurement. He invented the current balance , also known as the Kelvin balance or Ampere balance ( SiC ), for the precise specification of the ampere ,

4554-545: Was asked to look into the formation of a commission to oversee the process. By 1906 his work was complete and he drew up a permanent constitution for the International Electrotechnical Commission . The body held its first meeting that year in London, with representatives from 14 countries. In honour of his contribution to electrical standardisation, Lord Kelvin was elected as the body's first President. The International Federation of

4623-405: Was evidence that strong control existed for at least a 500-year period. The 13.7-g weight seems to be one of the units used in the Indus valley. The notation was based on the binary and decimal systems. 83% of the weights which were excavated from the above three cities were cubic, and 68% were made of chert . The implementation of standards in industry and commerce became highly important with

4692-552: Was not the case in earlier ages, when woodworking tools were employed to fashion very large wooden bolts and nuts for use in winches , windmills , watermills , and flour mills of the Middle Ages ; the ease of cutting and replacing wooden parts was balanced by the need to resist large amounts of torque , and bear up against ever heavier loads of weight. As the loads grew even heavier, bigger and stronger bolts were needed to resist breakage. Some nuts and bolts were measured by

4761-938: Was originally based on almost the same imperial fractions. The Unified thread angle is 60° and has flattened crests (Whitworth crests are rounded). Thread pitch is the same in both systems except that the thread pitch for the 1 ⁄ 2  in. (inch) bolt is 12 threads per inch (tpi) in BSW versus 13 tpi in the UNC. By the end of the 19th century, differences in standards between companies were making trade increasingly difficult and strained. For instance, an iron and steel dealer recorded his displeasure in The Times : "Architects and engineers generally specify such unnecessarily diverse types of sectional material or given work that anything like economical and continuous manufacture becomes impossible. In this country no two professional men are agreed upon

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