1.
Straight edge
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Straight edge is a subculture of hardcore punk whose adherents refrain from using alcohol, tobacco and other recreational drugs, in reaction to the excesses of punk subculture. For some, this extends to refraining from engaging in sex, following a vegetarian or vegan diet. The term straight edge was adopted from the 1981 song Straight Edge by the punk band Minor Threat. Straight edge emerged amid the early-1980s hardcore punk scene, since then, a wide variety of beliefs and ideas have been associated with some members of the movement, including vegetarianism and animal rights. Ross Haenfler writes that as of the late 1990s, approximately three out of four straight edge participants were vegetarian or vegan, disagreements often arise as to the primary reasons for living straight edge. Straight edge politics are primarily left-wing and revolutionary but there have been conservative offshoots, in 1999, William Tsitsos wrote that straight edge had gone through three eras since its founding in the early 1980s. Bent edge began as a counter-movement to straight edge by members of the Washington, D. C. hardcore scene who were frustrated by the rigidity and intolerance in the scene. During the youth crew era, which started in the mid-1980s, by the early 1990s, militant straight edge was a well-known part of the wider punk scene. In the early to mid-1990s, straight edge spread from the United States to Northern Europe, Eastern Europe, the Middle East, by the beginning of the 2000s, militant straight edge punks had largely left the broader straight edge culture and movement. While some straight edge groups are treated as a gang by law enforcement officials, Straight edge has often been approached with skepticism and hostility, despite the ideologically less dogmatic and more multifaceted character of contemporary straight edge. In the 1970s, the subculture was associated with the use of intoxicative inhalants. In 1999, William Tsitsos wrote that straight edge had gone through three eras since its founding in the early 1980s, later analysts have identified another era that has taken place since Tsitsoss writing. Straight edge grew out of punk in the late 1970s and early 1980s. Straight edge individuals of this era often associated with the original punk ideals such as individualism, disdain for work and school. Straight edge sentiments can be found in songs by the early 1980s band Minor Threat and this anti-inebriation movement had been developing in punk prior to Minor Threat, but their song Straight Edge was influential in giving the scene a name, and something of a figurehead. Minor Threat frontman Ian MacKaye is often credited with birthing the Straight edge name and movement, Straight edge sentiments can also be found in the song Keep it Clean by English punk band The Vibrators, and the 1970s Modern Lovers song Im Straight. As one of the few prominent 1970s hard rock icons to explicitly eschew alcohol and drug use, Straight edge started on the East Coast of the United States in Washington D. C. and quickly spread throughout the United States and Canada. By the 1980s, bands on the West Coast, such as Americas Hardcore, Stalag 13, Justice League, in the early stages of this subcultures history, concerts often consisted of both punk bands and straight edge bands
2.
Ruler
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A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing, engineering and building to measure distances or to rule straight lines. The ruler is a straightedge which may also contain calibrated lines to measure distances, rulers have long been made from different materials and in a wide range of sizes. Plastics have also used since they were invented, they can be molded with length markings instead of being scribed. Metal is used for more durable rulers for use in the workshop,12 inches or 30 cm in length is useful for a ruler to be kept on a desk to help in drawing. Shorter rulers are convenient for keeping in a pocket, longer rulers, e. g.18 inches are necessary in some cases. Rigid wooden or plastic yardsticks,1 yard long, and meter sticks,1 meter long, are also used, classically, long measuring rods were used for larger projects, now superseded by tape measure or laser rangefinders. Desk rulers are used for three purposes, to measure, to aid in drawing straight lines and as a straight guide for cutting and scoring with a blade. Practical rulers have distance markings along their edges, a line gauge is a type of ruler used in the printing industry. These may be made from a variety of materials, typically metal or clear plastic, units of measurement on a basic line gauge usually include inches, agate, picas, and points. More detailed line gauges may contain sample widths of lines, samples of common type in several point sizes, measuring instruments similar in function to rulers are made portable by folding or retracting into a coil when not in use. When extended for use, they are straight, like a ruler, the illustrations on this page show a 2-meter carpenters rule, which folds down to a length of 24 cm to easily fit in a pocket, and a 5-meter-long tape, which retracts into a small housing. A flexible length measuring instrument which is not necessarily straight in use is the tailors fabric tape measure and it is used to measure around a solid body, e. g. a persons waist measurement, as well as linear measurement, e. g. inside leg. It is rolled up when not in use, taking up little space, a contraction rule is made having larger divisions than standard measures to allow for shrinkage of a metal casting. They may also be known as a shrinkage or shrink rule, a ruler software program can be used to measure pixels on a computer screen or mobile phone. These programs are known as screen rulers. In geometry, a ruler without any marks on it may be used only for drawing lines between points. A straightedge is used to help draw accurate graphs and tables. A ruler and compass construction refers to using an unmarked ruler
3.
Euclidean geometry
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Euclidean geometry is a mathematical system attributed to the Alexandrian Greek mathematician Euclid, which he described in his textbook on geometry, the Elements. Euclids method consists in assuming a set of intuitively appealing axioms. Although many of Euclids results had been stated by earlier mathematicians, Euclid was the first to show how these propositions could fit into a comprehensive deductive and logical system. The Elements begins with plane geometry, still taught in school as the first axiomatic system. It goes on to the geometry of three dimensions. Much of the Elements states results of what are now called algebra and number theory, for more than two thousand years, the adjective Euclidean was unnecessary because no other sort of geometry had been conceived. Euclids axioms seemed so obvious that any theorem proved from them was deemed true in an absolute, often metaphysical. Today, however, many other self-consistent non-Euclidean geometries are known, Euclidean geometry is an example of synthetic geometry, in that it proceeds logically from axioms to propositions without the use of coordinates. This is in contrast to analytic geometry, which uses coordinates, the Elements is mainly a systematization of earlier knowledge of geometry. Its improvement over earlier treatments was recognized, with the result that there was little interest in preserving the earlier ones. There are 13 total books in the Elements, Books I–IV, Books V and VII–X deal with number theory, with numbers treated geometrically via their representation as line segments with various lengths. Notions such as numbers and rational and irrational numbers are introduced. The infinitude of prime numbers is proved, a typical result is the 1,3 ratio between the volume of a cone and a cylinder with the same height and base. Euclidean geometry is a system, in which all theorems are derived from a small number of axioms. To produce a straight line continuously in a straight line. To describe a circle with any centre and distance and that all right angles are equal to one another. Although Euclids statement of the only explicitly asserts the existence of the constructions. The Elements also include the five common notions, Things that are equal to the same thing are also equal to one another
4.
Compass (drawing tool)
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A pair of compasses, also known simply as a compass, is a technical drawing instrument that can be used for inscribing circles or arcs. As dividers, they can also be used as tools to measure distances, Compasses can be used for mathematics, drafting, navigation and other purposes. Compasses are usually made of metal or plastic, and consist of two connected by a hinge which can be adjusted to allow the changing of the radius of the circle drawn. Typically one part has a spike at its end, and the part a pencil. Prior to computerization, compasses and other tools for manual drafting were often packaged as a bow set with interchangeable parts, today these facilities are more often provided by computer-aided design programs, so the physical tools serve mainly a didactic purpose in teaching geometry, technical drawing, etc. Compasses are usually made of metal or plastic, and consist of two connected by a hinge which can be adjusted to allow the changing of the radius of the circle drawn. Typically one part has a spike at its end, and the part a pencil. The handle is usually half a inch long. Users can grip it between their pointer finger and thumb, there are two types of legs in a pair of compasses, the straight or the steady leg and the adjustable one. Each has a purpose, the steady leg serves as the basis or support for the needle point. The screw on your hinge holds the two legs in its position, the hinge can be adjusted depending on desired stiffness, the tighter the screw the better the compass’ performance. The needle point is located on the leg, and serves as the center point of circles that are drawn. The pencil lead draws the circle on a paper or material. This holds the lead or pen in place. Circles can be made by fastening one leg of the compasses into the paper with the spike, putting the pencil on the paper, the radius of the circle can be adjusted by changing the angle of the hinge. Distances can be measured on a map using compasses with two spikes, also called a dividing compass, to use a pair of compasses, place the points on a ruler and open it to the measurement of ½ of the measurement of the circle that is desired. For instance, if one desires to draw a 3 inch circle, next, place the point on the spot that you wish the center of your circle to be, and then rotate the section that has the pencil lead around the point, using the handle. Compasses-and-straightedge constructions are used to illustrate principles of plane geometry, although a real pair of compasses is used to draft visible illustrations, the ideal compass used in proofs is an abstract creator of perfect circles
5.
Metalworking
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Metalworking is the process of working with metals to create individual parts, assemblies, or large-scale structures. The term covers a range of work from large ships and bridges to precise engine parts. It therefore includes a wide range of skills, processes. Metalworking is a science, art, hobby, industry and trade and its historical roots span cultures, civilizations, and millennia. Metalworking has evolved from the discovery of smelting various ores, producing malleable and ductile metal useful for tools, modern metalworking processes, though diverse and specialized, can be categorized as forming, cutting, or joining processes. Todays machine shop includes a number of machine tools capable of creating a precise, the oldest archaeological evidence of copper mining and working was the discovery of a copper pendant in northern Iraq from 8,700 BCE. The earliest substantiated and dated evidence of metalworking in the Americas was the processing of copper in Wisconsin, Copper was hammered until brittle then heated so it could be worked some more. This technology is dated to about 4000-5000 BCE, the oldest gold artifacts in the world come from the Bulgarian Varna Necropolis and date from 4450 BCE. Not all metal required fire to obtain it or work it, isaac Asimov speculated that gold was the first metal. His reasoning is that by its chemistry it is found in nature as nuggets of pure gold, in other words, gold, as rare as it is, is sometimes found in nature as the metal that it is. There are a few metals that sometimes occur natively. Almost all other metals are found in ores, a mineral-bearing rock, another feature of gold is that it is workable as it is found, meaning that no technology beyond a stone hammer and anvil to work the metal is needed. This is a result of properties of malleability and ductility. The earliest tools were stone, bone, wood, and sinew, at some unknown point the connection between heat and the liberation of metals from rock became clear, rocks rich in copper, tin, and lead came into demand. These ores were mined wherever they were recognized, remnants of such ancient mines have been found all over Southwestern Asia. Metalworking was being carried out by the South Asian inhabitants of Mehrgarh between 7000–3300 BCE, the end of the beginning of metalworking occurs sometime around 6000 BCE when copper smelting became common in Southwestern Asia. Ancient civilisations knew of seven metals. Here they are arranged in order of their potential, Iron +0.44 V
6.
Bandsaw
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A bandsaw is a saw with a long sharp blade consisting of a continuous band of toothed metal stretched between two or more wheels to cut material. They are used principally in woodworking, metalworking, and lumbering, advantages include uniform cutting action as a result of an evenly distributed tooth load, and the ability to cut irregular or curved shapes like a jigsaw. The minimum radius of a curve is determined by the width of the band, most bandsaws have two wheels rotating in the same plane, one of which is powered, although some may have three or four to distribute the load. The blade itself can come in a variety of size and tooth pitch which enables the machine to be versatile and able to cut a wide variety of materials including wood, metal. Almost all bandsaws today are powered by an electric motor, line shaft versions were once common but are now antiques. Constant flexing of the blade over the wheels caused either the material or the joint welding it into a loop to fail, nearly 40 years passed before Frenchwoman Anne Paulin Crepin devised a welding technique overcoming this hurdle. She applied for a patent in 1846, and soon sold the right to employ it to manufacturer A. Perin & Company of Paris. Combining this method with new alloys and advanced tempering techniques allowed Perin to create the first modern band saw blade. The first American band saw patent was granted to Benjamin Barker of Ellsworth, Maine, the first factory produced and commercially available band saw in the U. S. was by a design of Paul Prybil. Power hacksaws were once common in the industries, but bandsaws. Many workshops in residential garages or basements and in light industry contain small or medium-sized bandsaws that can cut wood, metal, often a general-purpose blade is left in place, although blades optimized for wood or metal can be switched out when volume of use warrants. Most residential and commercial bandsaws are of the vertical type mounted on a bench or a cabinet stand, Portable power tool versions, including cordless models, are also common in recent decades, allowing building contractors to bring them along on the truck to the jobsite. Saws for cutting meat are typically of all steel construction with easy to clean features. The blades either have fine teeth with heat treated tips, or have plain or scalloped knife edges, bandsaws dedicated to industrial metal-cutting use, such as for structural steel in fabrication shops and for bar stock in machine shops, are available in vertical and horizontal designs. Typical band speeds range from 40 feet per minute to 5,000 feet per minute, although specialized bandsaws are built for friction cutting of hard metals, metal-cutting bandsaws are usually equipped with brushes or brushwheels to prevent chips from becoming stuck in between the blades teeth. Systems which cool the blade with cutting fluid are also common equipment on metal-cutting bandsaws, the coolant washes away swarf and keeps the blade cool and lubricated. Horizontal bandsaws hold the workpiece stationary while the blade swings down through the cut and this configuration is used to cut long materials such as pipe or bar stock to length. Thus it is an important part of the facilities in most machine shops, the horizontal design is not useful for cutting curves or complicated shapes
7.
Laser cutting
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Laser cutting works by directing the output of a high-power laser most commonly through optics. The laser optics and CNC are used to direct the material or the laser beam generated, a typical commercial laser for cutting materials would involve a motion control system to follow a CNC or G-code of the pattern to be cut onto the material. The focused laser beam is directed at the material, which then melts, burns, vaporizes away, or is blown away by a jet of gas. Industrial laser cutters are used to cut flat-sheet material as well as structural, in 1965, the first production laser cutting machine was used to drill holes in diamond dies. This machine was made by the Western Electric Engineering Research Center, in 1967, the British pioneered laser-assisted oxygen jet cutting for metals. In the early 1970s, this technology was put into production to cut titanium for aerospace applications. At the same time CO2 lasers were adapted to cut non-metals, such as textiles, because, at the time, generation of the laser beam involves stimulating a lasing material by electrical discharges or lamps within a closed container. As the lasing material is stimulated, the beam is reflected internally by means of a partial mirror, mirrors or fiber optics are typically used to direct the coherent light to a lens, which focuses the light at the work zone. The narrowest part of the beam is generally less than 0.0125 inches. Depending upon material thickness, kerf widths as small as 0.004 inches are possible, in order to be able to start cutting from somewhere other than the edge, a pierce is done before every cut. Piercing usually involves a high-power pulsed laser beam which slowly makes a hole in the material, taking around 5–15 seconds for 0. 5-inch-thick stainless steel, for example. The parallel rays of coherent light from the laser source often fall in the range between 0. 06–0.08 inches in diameter. This beam is focused and intensified by a lens or a mirror to a very small spot of about 0.001 inches to create a very intense laser beam. In order to achieve the smoothest possible finish during contour cutting, for sheet metal cutting, the focal length is usually 1. 5–3 inches. Advantages of laser cutting over mechanical cutting include easier workholding and reduced contamination of workpiece, precision may be better, since the laser beam does not wear during the process. There is also a chance of warping the material that is being cut. Some materials are very difficult or impossible to cut by more traditional means. There are three types of lasers used in laser cutting
8.
Plasma cutting
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Plasma cutting is a process that cuts through electrically conductive materials by means of an accelerated jet of hot plasma. Typical materials cut with a plasma torch include steel, Stainless steel, aluminum, brass and copper, Plasma cutting is often used in fabrication shops, automotive repair and restoration, industrial construction, and salvage and scrapping operations. Due to the speed and precision cuts combined with low cost. This is accomplished by a gas which is blown through a focused nozzle at high speed toward the work piece. An electrical arc is formed within the gas, between an electrode near or integrated into the gas nozzle and the work piece itself. The electrical arc ionizes some of the gas, thereby creating a conductive channel of plasma. As electricity from the cutter torch travels down this plasma it delivers sufficient heat to melt through the work piece. At the same time, much of the high velocity plasma and compressed gas blow the hot molten metal away, Plasma cutting is an effective means of cutting thin and thick materials alike. Hand-held torches can cut up to 38 mm thick steel plate. Since plasma cutters produce a hot and very localized cone to cut with. Plasma cutting grew out of plasma welding in the 1960s, and emerged as a productive way to cut sheet metal. It had the advantages over traditional metal against metal cutting of producing no metal chips, giving accurate cuts, early plasma cutters were large, somewhat slow and expensive and, therefore, tended to be dedicated to repeating cutting patterns in a mass production mode. These CNC plasma cutting machines were, however, generally limited to cutting patterns and parts in flat sheets of steel, proper eye protection and face shields are needed to prevent eye damage called arc eye as well as damage from debris. It is recommended to use green lens shade #5, OSHA recommends a shade 8 for arc current less than 300, but notes that These values apply where the actual arc is clearly seen. Experience has shown that lighter filters may be used when the arc is hidden by the workpiece, lincoln Electric, a manufacturer of plasma cutting equipment, says, Typically a darkness shade of #7 to #9 is acceptable. Plasma cutters use a number of methods to start the arc, in some units, the arc is created by putting the torch in contact with the work piece. Some cutters use a voltage, high frequency circuit to start the arc. This method has a number of disadvantages, including risk of electrocution, difficulty of repair, spark gap maintenance, Plasma cutters working near sensitive electronics, such as CNC hardware or computers, start the pilot arc by other means
9.
Water jet cutter
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Waterjet cutting is often used during fabrication of machine parts. It is the method when the materials being cut are sensitive to the high temperatures generated by other methods. Waterjet cutting is used in industries, including mining and aerospace, for cutting, shaping. These early applications were at a low pressure and restricted to soft materials like paper, Waterjet technology evolved in the post-war era as researchers around the world searched for new methods of efficient cutting systems. In 1958, Billie Schwacha of North American Aviation developed a system using ultra-high-pressure liquid to cut hard materials and this system used a 100,000 psi pump to deliver a hypersonic liquid jet that could cut high strength alloys such as PH15-7-MO stainless steel. Used as a honeycomb laminate on the Mach 3 North American XB-70 Valkyrie, while not effective for the XB-70 project, the concept was valid and further research continued to evolve waterjet cutting. In 1962, Philip Rice of Union Carbide explored using a pulsing waterjet at up to 50,000 psi to cut metals, stone, research by S. J. Leach and G. L.002 inches that operated at pressures up to 70,000 psi. High-pressure vessels and pumps became affordable and reliable with the advent of steam power, by the mid-1800s, steam locomotives were common and the first efficient steam-driven fire engine was operational. By the turn of the century, high-pressure reliability improved, with research leading to a sixfold increase in boiler pressure. Most high-pressure pumps at this time, though, operated around 500–800 psi, high-pressure systems were further shaped by the aviation, automotive, and oil industries. Aircraft manufacturers such as Boeing developed seals for hydraulically boosted control systems in the 1940s, higher pressures in hydraulic systems in the oil industry also led to the development of advanced seals and packing to prevent leaks. These advances in technology, plus the rise of plastics in the post-war years. The invention of Marlex by Robert Banks and John Paul Hogan of the Phillips Petroleum company required a catalyst to be injected into the polyethylene, mcCartney Manufacturing Company in Baxter Springs, Kansas, began manufacturing these high-pressure pumps in 1960 for the polyethylene industry. Flow Industries then combined the high-pressure pump research with their waterjet nozzle research, while cutting with water is possible for soft materials, the addition of an abrasive turned the waterjet into a modern machining tool for all materials. This began in 1935 when the idea of adding an abrasive to the stream was developed by Elmo Smith for the liquid abrasive blasting. The March 1984 issue of the Mechanical Engineering magazine showed more details and materials cut with AWJ such as titanium, aluminum, glass, dr. Mohamed Hashish, was awarded a patent on forming AWJ in 1987. Current work on AWJ nozzles is on micro abrasive waterjet so cutting with jets smaller than 0.015 inches in diameter can be commercialized. By January,1985, that system was being run 24 hours a day producing titanium parts for the B-1B largely at Rockwells North American Aviation facility in Newark, as waterjet cutting moved into traditional manufacturing shops, controlling the cutter reliably and accurately was essential
10.
Broaching (metalworking)
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Broaching is a machining process that uses a toothed tool, called a broach, to remove material. There are two types of broaching, linear and rotary. In linear broaching, which is the common process, the broach is run linearly against a surface of the workpiece to effect the cut. Linear broaches are used in a machine, which is also sometimes shortened to broach. In rotary broaching, the broach is rotated and pressed into the workpiece to cut an axis symmetric shape, a rotary broach is used in a lathe or screw machine. In both processes the cut is performed in one pass of the broach, which makes it very efficient, Broaching is used when precision machining is required, especially for odd shapes. Commonly machined surfaces include circular and non-circular holes, splines, keyways, typical workpieces include small to medium-sized castings, forgings, screw machine parts, and stampings. Even though broaches can be expensive, broaching is usually favored over other processes used for high-quantity production runs. Broaches are shaped similar to a saw, except the height of the teeth increases over the length of the tool, moreover, the broach contains three distinct sections, one for roughing, another for semi-finishing, and the final one for finishing. Broaching is a machining process because it has the feed built into the tool. The profile of the surface is always the inverse of the profile of the broach. The rise per tooth, also known as the step or feed per tooth, determines the amount of material removed, the broach can be moved relative to the workpiece or vice versa. Because all of the features are built into the broach no complex motion or skilled labor is required to use it. A broach is effectively a collection of single-point cutting tools arrayed in sequence, cutting one after the other, the process depends on the type of broaching being performed. Surface broaching is very simple as either the workpiece is moved against a stationary surface broach, the process begins by clamping the workpiece into a special holding fixture, called a workholder, which mounts in the broaching machine. The broaching machine elevator, which is the part of the machine moves the broach above the workholder. Once through, the broaching machines puller, essentially a hook, the elevator then releases the top of the pilot and the puller pulls the broach through the workpiece completely. The workpiece is then removed from the machine and the broach is raised back up to reengage with the elevator, the broach usually only moves linearly, but sometimes it is also rotated to create a spiral spline or gun-barrel rifling
11.
Chisel
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The handle and blade of some types of chisel are made of metal or of wood with a sharp edge in it. Chiselling use involves forcing the blade into some material to cut it, the driving force may be applied by pushing by hand, or by using a mallet or hammer. In industrial use, a ram or falling weight drives a chisel into the material. A gouge, one type of chisel, serves - particularly in woodworking, woodturning, gouges most frequently produce concave surfaces. A gouge typically has a U-shaped cross-section, chisel comes from the Old French cisel, modern ciseau, Late Latin cisellum, a cutting tool, from caedere, to cut. Chisels have a variety of uses. Many types of chisel have been devised, each suited to its intended use. Different types of chisel may be constructed differently, in terms of blade width or length, as well as shape. They may have a wooden or plastic handle attached using a tang or socket, woodworking chisels range from small hand tools for tiny details, to large chisels used to remove big sections of wood, in roughing out the shape of a pattern or design. Typically, in woodcarving, one starts with a larger tool, one of the largest types of chisel is the slick, used in timber frame construction and wooden shipbuilding. There are many types of woodworking chisels used for specific purposes, such as, Butt chisel, short chisel with beveled sides and straight edge for creating joints. Carving chisels, used for designs and sculpting, cutting edges are many, such as gouge, skew, parting, straight, paring. Corner chisel, resembles a punch and has an L-shaped cutting edge, cleans out square holes, mortises and corners with 90 degree angles. Bevel edge chisel, can get into acute angles with its bevelled edges, flooring chisel, cuts and lifts flooring materials for removal and repair, ideal for tongue-and-groove flooring. Framing chisel, usually used with mallet, similar to a chisel, except it has a longer. Slick, a large chisel driven by pressure, never struck. Mortise chisel, thick, rigid blade with cutting edge and deep, slightly tapered sides to make mortises. Paring chisel, has a long blade ideal for cleaning grooves, skew chisel, has a 60 degree cutting angle and is used for trimming and finishing
12.
File (tool)
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A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking, metalworking, and other similar trade, most are hand tools, made of a case hardened steel bar of rectangular, square, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted, a rasp is a form of file with distinct, individually cut teeth used for coarsely removing large amounts of material. Files have also developed with abrasive surfaces, such as natural or synthetic diamond grains or silicon carbide, allowing removal of material that would dull or resist metal. Relatedly, lapping is also ancient, with wood and beach sand offering a natural pair of lap. The Disston authors state, To abrade, or file, ancient man used sand, grit, coral, bone, fish skin, the Bronze Age and the Iron Age had various kinds of files and rasps. Archaeologists have discovered rasps made from bronze in Egypt, dating back to the years 1200–1000 BC, archaeologists have also discovered rasps made of iron used by the Assyrians, dating back to the 7th Century BC. During the Middle Ages files were already advanced, thanks to the extensive talents of blacksmiths. By the 11th century, there already existed hardened files that would seem quite modern even to todays eyes. For example, in the 13th century, ornamental iron work at Paris was done skillfully with the aid of files, but the process was a secret known only to a master craftsman. The Disston authors state, It was not until the fourteenth century, however, that those who practiced art in ironwork began to use tools, besides heat. This statement could mislead in the sense that stoning and lapping have never been rare activities among humans, but by the late Middle Ages, however, the transition was extensive. The Disston authors mention Nuremberg, Sheffield, and Remscheid as leading centers of production for files as well as tools in general, the activity in Remscheid reflects the metalworking spirit of the Rhine-Ruhr region in general rather than representing a single village of geniuses in isolation. Most files of the period were smithed by hand in a sequence in which the iron was forged, then the teeth were cut with a chisel, among the drawings of Leonardo da Vinci is a sketch of a machine tool for the cutting of files. Prior to the industrialization of machining and the development of parts during the 19th century. Component parts were roughly shaped by forging, casting, and by primitive machining operations and these components were then individually hand-fit for assembly by careful and deliberate filing. The potential precision of fitting is much higher than generally assumed. Locks, clocks, and firearms were manufactured in this way for centuries before the Industrial Revolution, machining in the mid-19th century was heavily dependent on filing, because milling practice was slowly evolving out of its infancy
