Misplaced Pages

#76923

48-482: The tool forms discovered include side and end scrapers , notches, burins , and disc cores. Although it is generally more difficult to date Asian sites than African sites because Asian sites typically lack volcanic materials that can be dated isotropically, the age of the tools has been magnetostratigraphically dated as 1.36 million years. This method hinges upon dated reversals in the Earth's magnetic field . The site

96-411: A blade may be used to slash or puncture, and may also be thrown or otherwise propelled . The function is to sever a nerve, muscle or tendon fibers, or blood vessel to disable or kill the adversary. Severing a major blood vessel typically leads to death due to exsanguination . Blades may be used to scrape, moving the blade sideways across a surface, as in an ink eraser , rather than along or through

144-407: A blade or flake, whereas side scrapers have a working edge along one of the long sides. There are a couple of types of scrapers based on their specific use when it comes to wood and hide or based on the shape and design of the scraper itself. The grattoir is a type of scraper usually made of flint and its main uses were to work wood and to clean hides. This type of scraper has its working edge along

192-417: A body that is tough. Prehistorically, and in less technologically advanced cultures even into modern times, tool and weapon blades have been made from wood, bone, and stone. Most woods are exceptionally poor at holding edges and bone and stone suffer from brittleness making them suffer from fracture when striking or struck. In modern times stone, in the form of obsidian, is used in some medical scalpels as it

240-469: A convex section to avoid getting stuck in the wood where chopping axes can be flat or even concave. A khopesh , falchion , or kukri is angled and/or weighted at the distal end so that force is concentrated at the faster moving, heavier part of the blade maximizing cutting power and making it largely unsuitable for thrusting, whereas a rapier is thin and tapered allowing it to pierce and be moved with more agility while reducing its chopping power compared to

288-418: A low elastic modulus (is soft) but high yield strain (loosely, can be stretched or squashed by a large proportion without breaking), drawing serrations across the loaf with little downward force will allow each serration to simultaneously cut the bread with much less deformation of the loaf. Similarly, pushing on a rope tends to squash the rope while drawing serrations across it sheers the rope fibers. Drawing

336-404: A material into dust along a narrow channel, the kerf , whereas knives and similar act by forcing the material apart. This means that saws result in a loss of material and the serrations of a saw also serve to carry metal swarf and sawdust out of the cut channel.) Fullers are longitudinal channels either forged into the blade or later machined/milled out of the blade though the latter process

384-423: A material that is about as hard , though usually harder, than the material to be cut. Insufficiently hard blades will be unable to cut a material or will wear away quickly as hardness is related to a material's ability to resist abrasion . However, blades must also be tough enough to resist the dynamic load of impact and as a general rule the harder a blade the less tough (the more brittle) a material. For example,

432-399: A million years but also found, among many things, a flint tool. It was the oldest stone tool found at the time - so old, in fact, that even Chardin himself had suspicions about its authenticity. Barbour invited French archaeologists Pierre Teilhard de Chardin and Émile Licent . In 1935 Teilhard found a stone (flint) tool and determined the age of the site to be over a million years – it

480-552: A paleolithic site. In the basin, Archaeologists have identified 40 "million year old sites". In 1982, Wei Qi(衛奇), then 44, found a huge hominid settlement at Donggutuo(東谷坨) Village. He took samples to Pei, whose Peking Man was not half as old. "He said nothing," said Wei. "But I guess he had accepted it." Pei died of a heart attack a few days later. Scraper (archaeology) In prehistoric archaeology , scrapers are unifacial tools thought to have been used for hideworking and woodworking. Many lithic analysts maintain that

528-519: A proper cut without an edge, and so in competitive fencing such attacks reward no points. Some variations include: Blades are sometimes marked or inscribed, for decorative purposes, or with the mark of either the maker or the owner. Blade decorations are often realized in inlay in some precious metal (gold or silver). Early blade inscriptions are known from the Bronze Age , a Hittite sword found at Hattusa bears an inscription chiseled into

SECTION 10

#1732776612077

576-399: A similarly sized sword. A serrated edge, such as on a saw or a bread knife , concentrates force onto the tips of the serrations which increases pressure as well as allowing soft or fibrous material (like wood, rope, bread, and vegetables) to expand into the spaces between serrations. Whereas pushing any knife, even a bread knife, down onto a bread loaf will just squash the loaf as bread has

624-547: A smooth blade is less effective as the blade is parallel to the direction draw but the serrations of a serrated blade are at an angle to the fibers. Serrations on knives are often symmetric allowing the blade to cut on both the forward and reverse strokes of a cut, a notable exception being Veff serrations which are designed to maximize cutting power while moving the blade away from the user. Saw blade serrations, for both wood and metal, are typically asymmetrical so that they cut while moving in only one direction. (Saws act by abrading

672-413: A steel axehead is much harder than the wood it is intended to cut and is sufficiently tough to resist the impact resulting when swung against a tree while a ceramic kitchen knife, harder than steel, is very brittle (has low toughness) and can easily shatter if dropped onto the floor or twisted while inside the food it is cutting or carelessly stored under other kitchen utensils. This creates a tension between

720-423: A surface. For construction equipment such as a grader , the ground-working implement is also referred to as the blade, typically with a replaceable cutting edge. A simple blade intended for cutting has two faces that meet at an edge. Ideally, this edge would have no roundness but in practice, all edges can be seen to be rounded to some degree under magnification either optically or with an electron microscope. Force

768-408: A thinner one of similar design while also making it experience more drag while slicing or piercing. A filleting knife will be thin enough to be very flexible while a carving knife will be thicker and stiffer; a dagger will be thin so it can pierce, while a camping knife will be thicker so it can be stronger and more durable. A strongly curved edge, like a talwar , will allow the user to draw the edge of

816-568: A wide range of physical and chemical properties desirable for blades. For example, surgical scalpels are often made of stainless steel so that they remain free of rust and largely chemically inert; tool steels are hard and impact resistant (and often expensive as retaining toughness and hardness requires expensive alloying materials, and, being hard, they are difficult to make into their finished shape) and some are designed to resist changes to their physical properties at high temperatures. Steels can be further heat treated to optimize their toughness, which

864-418: Is applied it them, forming a section like the bottom part of a letter "J". For this reason, straight edge razors are frequently stropped to straighten the edge. Drawing a blade across any material tends to abrade both the blade, usually making it duller, and the cut material. Though softer than glass or many types of stone used in the kitchen, steel edges can still scratch these surfaces. The resulting scratch

912-414: Is applied to the blade, either from the handle or pressing on the back of the blade. The handle or back of the blade has a large area compared to the fine edge. This concentration of applied force onto the small edge area increases the pressure exerted by the edge. It is this high pressure that allows a blade to cut through a material by breaking the bonds between the molecules, crystals, fibers, etc. in

960-461: Is capable of being formed into an exceedingly fine edge. Ceramic knives are non-metallic and non-magnetic. As non-metals do not corrode they remain rust and corrosion free but they suffer from similar faults as stone and bone, being rather brittle and almost entirely inflexible. They are harder than metal knives and so more difficult to sharpen, and some ceramic knives may be as hard or harder than some sharpening stones. For example, synthetic sapphire

1008-484: Is common at Paleo-Indian sites in North America . Scrapers are one of the most varied lithic tools found at archaeological sites. Due to the vast array of scrapers there are many typologies that scrapers can fall under, including tool size, tool shape, tool base, the number of working edges, edge angle, edge shape, and many more. The edge of the scraper that is extremely angled is the working edge. This edge

SECTION 20

#1732776612077

1056-399: Is extremely uncommon for there to be a scraper with three working edges. Edge angle: Some scrapers have vertical working edges while other scrapers have acute working edges. Edge shape: There is distinction between concave, straight, and convex working edges on scrapers. Location of functional edges: One of the main distinctions in scrapers, depends on if the working edge is on the end or

1104-448: Is full of very fine particles of ground glass or stone which will very quickly abrade the blade's edge and so dull it. In times when swords were regularly used in warfare, they required frequent sharpening because of dulling from contact with rigid armor, mail, metal rimmed shields, or other swords, for example. Particularly, hitting the edge of another sword by accident or in an emergency could chip away metal and even cause cracks through

1152-717: Is harder than natural sharpening stones and is as hard as alumina sharpening stones. Zirconium dioxide is also harder than garnet sharpening stones and is nearly as hard as alumina. Both require diamond stones or silicon carbide stones to sharpen and care has to be taken to avoid chipping the blade. As such ceramic knives are seldom used outside of a kitchen and they are still quite uncommon. Plastic knives are difficult to make sharp and poorly retain an edge. They are largely used as low cost, disposable utensils or as children's utensils or in environments such as air travel where metal blades are prohibited. They are often serrated to compensate for their general lack of sharpness but, as evidenced by

1200-477: Is important for impact blades, or their hardness, which allows them to retain an edge well with use (although harder metals require more effort to sharpen). It is possible to combine different materials, or different heat treatments, to produce desirable qualities in a blade. For example, the finest Japanese swords were routinely made of up to seven sections of metals and even poorer quality swords were often made of two. These would include soft irons that could absorb

1248-454: Is less desirable. This loss of material necessarily weakens the blade but serves to make the blade lighter without sacrificing stiffness. The same principle is applied in the manufacture of beams such as I-beams . Fullers are only of significant utility in swords. In most knives there is so little material removed by the fuller that it makes little difference to the weight of the blade and they are largely cosmetic. Typically blades are made from

1296-472: Is often used to soften hides or to clean meat off of the hides, in addition to being used for wood work. As the term scraper suggests, this tool was scraped at the hide or wood in order to reach the end goal. Scrapers were also made in order to skin animals. Scrapers tended to be large enough to fit comfortably in the hand and could be used without being mounted on wood or bone. However, it is very likely that scrapers were mounted on short handles even though it

1344-418: Is particularly true of acute blades and those made of soft materials. Dulling usually occurs due to contact between the blade and a hard substance such as ceramic, stone, bone, glass, or metal. The more acute the blade, the more easily it will dull. As the blade near the edge is thinner, there is little material to remove before the edge is worn away to a thicker section. Thin edges can also roll over when force

1392-440: Is poorly suited for working stone. Bronze is superior in this regard, and was taken up by later civilizations. Both bronze and copper can be work hardened by hitting the metal with a hammer. With technological advancement in smelting, iron came to be used in the manufacturing of blades. Steel , a range of alloys made from iron, has become the metal of choice for the modern age. Various alloys of steel can be made which offer

1440-527: Is very rare to find mounted scrapers. As scrapers are used they have to be resharpened in order to stay effective. This causes them to get progressively smaller as they are used, resharpened, used, resharpened, and used again. Consequently, the majority of the scrapers that are found on sites are ones that have been resharpened and used to the point of being no longer functional. The two main classifications of scrapers are either end scrapers or side scrapers. End scrapers have working edges on one or both ends of

1488-414: The blade across the opponent's body and back. For straight-edged weapons, many recorded techniques feature cleaving cuts, which deliver the power out to a point, striking directly in at the target's body, done to split flesh and bone rather than slice it. That being said, there also exist many historical slicing techniques for straight-edged weapons. Hacking cuts can be followed by a drawing action to maximize

Xiaochangliang - Misplaced Pages Continue

1536-420: The blade against an opponent even while close to the opponent where a straight sword would be more difficult to pull in the same fashion. The curved edge of an axe means that only a small length of the edge will initially strike the tree, concentrating force as does a thinner edge, whereas a straight edge could potentially land with the full length of its edge against a flat section of the tree. A splitting maul has

1584-541: The blade. Soft-cored blades are more resistant to fracturing on impact. Folding pocket knives often have a groove cut in the side of the blade near the spine. This is called a nail pull and allows the fingernail to be inserted to swing the blade out of the holder. Some of the most common shapes are listed below. The sharp edges of a sword may be either curved or straight. Curved blades tend to glide more easily through soft materials, making these weapons more ideal for slicing. Techniques for such weapons feature drawing

1632-486: The classification for the shape of the scraper. The shape of the scraper is often considered diagnostic. Shaping vs. Use Damage: Scrapers are often divided between ones that have been purposefully shaped for a specific use and ones that have been shaped due to their use. Tool base: Scrapers are classified based on if they originated from a blade or a flake . Number of working edges: Some scrapers have only one working edge while other scrapers have two working edges. It

1680-441: The cut's effectiveness. For more information see Western Martial Arts or kenjutsu . Some weapons are made with only a single leading edge, such as the sabre or dusack . The dusack has a 'false edge' near the tip, which only extends down a portion of the blade's backside. Other weapons have a blade that is entirely dull except for a sharpened point, like the épée or foil , which prefer thrusts over cuts. A blade cannot perform

1728-439: The cutting edge. Design variations, such as serrated edges found on bread knives and saws , serve to enhance this force concentration, adapting blades for specific functions and materials. Blades thus hold a significant place both historically and in contemporary society, reflecting an evolution in material technology and utility. During food preparation, knives are mainly used for slicing, chopping, and piercing. In combat,

1776-426: The end of a flake of stone in order to create one sharp side and to keep the rest of the sides dull to facilitate grasping it. Most scrapers are either circle or blade-like in shape. The working edges of scrapers tend to be convex, and many have trimmed and dulled lateral edges to facilitate hafting. One important variety of scraper is the thumbnail scraper , a scraper shaped much like its namesake. This scraper type

1824-427: The energy of impact without fracturing but which would bend and poorly retain an edge, and hard steels more liable to shatter on impact but which retained an edge well. The combination provided a sword that would resist impact while remaining sharp, even though the edge could chip if abused. Pattern welding involved forging together twisted bars of soft (bendable) low carbon and hard (brittle) higher carbon iron. This

1872-408: The fact they can cut food, they are still capable of inflicting injury. Plastic blades of designs other than disposable cutlery are prohibited or restricted in some jurisdictions as they are undetectable by metal detectors. Native copper was used to make blades by ancient civilizations due to its availability. Copper's comparative softness causes it to deform easily; it does not hold an edge well and

1920-411: The intended use of the blade, the material it is to be made from, and any manufacturing processes (such as heat treatment in the case of steel blades that will affect a blade's hardness and toughness). A balance must be found between the sharpness and how well it can last. Methods that can circumvent this include differential hardening . This method yields an edge that can hold its sharpness as well as

1968-613: The long axis of the blade. The nose scraper typically has a smaller working edge either at both ends or just one end. This type of scraper is made from a convex blade and is used in more fine tuning work. The hollow scraper is a type of scraper that has a notch worked into the side or end of the scraper. Tool size: This can be determined by either weight or dimensions and typically divided into either large or small scrapers. Tool shape: There are many different shapes scrapers can be, including rectangular, triangular, irregular, discoidal, domed, or keeled. In many cases it can be hard to determine

Xiaochangliang - Misplaced Pages Continue

2016-440: The material. This necessitates the blade being strong enough to resist breaking before the other material gives way. The angle at which the faces meet is important as a larger angle will make for a duller blade while making the edge stronger. A stronger edge is less likely to dull from fracture or have the edge roll out of shape. The shape of the blade is also important. A thicker blade will be heavier and stronger and stiffer than

2064-457: The only true scrapers are defined on the base of use-wear, and usually are those that were worked on the distal ends of blades —i.e., " end scrapers " (French: grattoir ). Other scrapers include the so-called " side scrapers " or racloirs , which are made on the longest side of a flake , and notched scrapers , which have a cleft on either side that may have been used to attach them to something else. Scrapers are typically formed by chipping

2112-742: The side of the scraper. Blade A blade is the sharp, cutting portion of a tool , weapon , or machine , specifically designed to puncture, chop, slice, or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are intended to cut. This includes early examples made from flaked stones like flint or obsidian , evolving through the ages into metal forms like copper , bronze , and iron , and culminating in modern versions made from steel or ceramics . Serving as one of humanity's oldest tools, blades continue to have wide-ranging applications, including in combat, cooking , and various other everyday and specialized tasks. Blades function by concentrating force at

2160-442: The technique of differential hardening by covering their sword blades in different thicknesses of clay before quenching . Thinner clay allowed the heated metal to cool faster, particularly along the edge. Faster cooling resulted in a finer crystal structure, resulting in a blade with a hard edge but a more flexible body. European sword makers produced similar results using differential tempering . Blades dull with use and abuse. This

2208-508: Was done because furnaces of the time were typically able to produce only one grade or the other, and neither was well suited for more than a very limited use blade. The ability of modern steelmakers to produce very high-quality steels of various compositions has largely relegated this technique to either historical recreations or to artistic works. Acid etching and polishing blades made of different grades of steel can be used to produce decorative or artistic effects. Japanese sword makers developed

2256-475: Was first discovered by the Scottish geologist George Barbour in 1923. He was amazed when he saw the ancient sediments from the lake. Although he guessed wrong about how old they were and found basically nothing, Barbour invited Pere Licent and Pierre Teilhard de Chardin, two of the most brilliant prehistoric archaeologists of that time, for a visit. Licent and Chardin not only pushed the sediment's age to over

2304-473: Was the oldest artefact then known. Many scientists, including Teilhard, debated whether this tool might not be naturally formed. The discovery by Pei Wenzhong of Peking Man hundreds of kilometers to the south (followed by wars and revolution) distracted the attention of the world's scientific community. However, from 1972 to 1978 more than 2000 pieces of stone tools were discovered, together with some bone tools, which confirmed Xiaochangliang (or Nihewan ) as

#76923