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Sharpening is the process of creating or refining the edge joining two non-coplanar faces into a converging apex, thereby creating an edge of appropriate shape on a tool or implement designed for cutting. Sharpening is done by removing material on an implement with an abrasive substance harder than the material of the implement, followed sometimes by processes to polish/hone the sharp surface to increase smoothness.
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There are many ways of sharpening tools. Malleable metal surfaces such as bronze, iron and mild steel may be formed by beating or peening a flat surface into a sharp edge. This process also causes work hardening.
An abrasive material may be rubbed against the cutting edge to be sharpened. The most traditional abrasive material is a natural stone such as sandstone or granite. Modern synthetic grinding wheels and flat sharpening stones can be manufactured in precise grades of abrasiveness according to the intended process. A sharp edge may be 'dressed' using a Honing steel
The substance on the sharpening surface must be harder (hardness is measured on the Mohs scale) than the material being sharpened; diamond is extremely hard, making diamond dust very effective for sharpening, though expensive; less costly, but less hard, abrasives are available, such as synthetic and natural Japanese water-stones. Several cutlery manufacturers now offer electric knife sharpeners with multiple stages with at least one grinding stage. These electric sharpeners are typically used in the kitchen but have the ability to sharpen blades such as pocket or tactical knives. The main benefit of using an electric sharpener is speed with many models that can complete the sharpening process in one to two minutes. The disadvantage is that the sharpening angle is fixed so some specialized knives, like a Japanese style Santoku, may need additional attention to sharpen to the ideal angle.
Very sharp knives sharpen at about 10 d.p.s (degrees per side) (which implies that the knife's edge has an included angle of 20-degrees). Generally speaking, razors, paring knives, and fillet knives should be the sharpest knives at an angle of 12° – 18°. Most kitchen knives, like utility/slicing knives, chef's knives, boning knives, carving knives, should be sharpened to 15° – 25°. The exceptions are Japanese style knives that are usually sharpened to 14° – 16° depending on the knife maker. Japanese style knives utilize a much harder steel, and are therefore more brittle than their Western style counterparts. This means care should be taken when handling these knives as they are susceptible to chipping and breaking. The sporting knife category, including pocket knives, survival knives, and hunting knives, sees more intense action and should be sharpened to the 25° – 30° angle range. The less sharp angle means there is more metal there to cut, thus providing more durability out in the field. For an extremely durable edge, a machete, chisel, drawknife or ax should be sharpened down to 30° – 40° providing even more ruggedness and longer lasting sharpness.
The sharpness is measured at the microscopic level where the face of your implement may have an angle however at the convergence of the two angles is a joining point called the "Apex".
Many implements have a cutting edge which is essentially straight. Knives, chisels, straight-edge razors, and scissors are examples. Sharpening a straight edge is relatively simple, and can be done by using either a simple sharpening device which is very easy to use but will not produce the best possible results, or by the skillful use of oil or water grinding stones, grinding wheels, hones, etc.
Sharpening these implements can be expressed as the creation of two intersecting planes which produce an edge that is sharp enough to cut through the target material. For example, the blade of a steel knife is ground to a bevel so that the two sides of the blade meet. This edge is then refined by honing until the blade is capable of cutting.
The extent to which this honing takes place depends upon the intended use of the tool or implement. For some applications an edge with a certain amount of jaggedness is acceptable, or even desirable, as this creates a serrated cutting edge. In other applications the edge must be as smooth as possible.
Sharpening straight edges (knives, chisels, etc.) by hand can be divided into phases. First the edge is sharpened with an abrasive sharpening stone, or a succession of increasingly fine stones, which shape the blade by removing material; the finer the abrasive the finer the finish. Then the edge may be stropped by polishing the edge with a fine abrasive such as rouge or tripoli on a piece of stout leather or canvas. The edge may be steeled or honed by passing the blade against a hard metal or ceramic "steel" which plastically deforms and straightens the material of the blade's edge which may have been rolled over irregularly in use, but not enough to need complete rehappening.
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Different techniques are required where the edges are not straight. Special tools and skills are more often required, and sharpening is often best done by a specialist rather than the user of the tool.
Examples include:
A number of blade sharpeners operate a mobile business, [1] [2] traveling to their customers locations, often in highly equipped vehicles.
Less common in developed nations. Still very common in many areas of the world, skilled craftsmen provide a roadside sharpening service for kitchen knives and cleavers, scissors, and sometimes other blades.
They commonly have a 'round' which may include trades such as butchers or barbers some of whom, in addition to using the service for their own tools may act as 'agents' collecting instruments for the general public.
Sharpeners may also have regular 'stops' in busy streets or residential areas, calling out to people from their homes or businesses using musical instruments such as handbells or pipes.
The sharpener usually has some sort of mobile work bench with a grinding wheel which may be powered by hand, using a bicycle mechanism or electric motor.
As well as coarse grinding, sharpeners also typically 'dress' the cutting edges with a sharpening stone or honing steel, secure or replace loose handles and generally offer advice and assistance regarding best practice. Some also sell knives and related products.
Modern mobile sharpening services will travel in a Van or Bus and have a workshop inside that allows them to service the edges of different various tools and instruments. There are two major forms of sharpening or sharpeners where you sharpen as a hobbyist and "make it work" or you are a craftsman that strives to learn different styles of sharpening and how they perform under different applications.
A knife is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidenced by the Oldowan tools. Originally made of wood, bone, and stone, over the centuries, in step with improvements in both metallurgy and manufacturing, knife blades have been made from copper, bronze, iron, steel, ceramic, and titanium. Most modern knives have either fixed or folding blades; blade patterns and styles vary by maker and country of origin.
A chisel is a tool with a characteristically shaped cutting edge of blade on its end; for carving or cutting a hard material such as wood, stone, or metal by hand, struck with a mallet, or mechanical power. The handle and blade of some types of chisel are made of metal or wood with a sharp edge in it.
A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historically, humans have made blades from flaking stones such as flint or obsidian, and from various metal such as copper, bronze, and iron. Modern blades are often made of steel or ceramic. Blades are one of humanity's oldest tools, and continue to be used for combat, food preparation, and other purposes.
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.
A Japanese kitchen knife is a type of a knife used for food preparation. These knives come in many different varieties and are often made using traditional Japanese blacksmithing techniques. They can be made from stainless steel, or hagane, which is the same kind of steel used to make Japanese swords. Most knives are referred to as hōchō or the variation -bōchō in compound words but can have other names including -kiri. There are four general categories used to distinguish the Japanese knife designs: handle, blade grind, steel, and construction.
A blade's grind is its cross-sectional shape in a plane normal to the edge. Grind differs from blade profile, which is the blade's cross-sectional shape in the plane containing the blade's edge and the centre contour of the blade's back. The grind of a blade should not be confused with the bevel forming the sharpened edge; it more usually describes the overall cross-section of the blade, not inclusive of the beveled cutting edge which is typically of a different, less acute angle as the bevel ground onto the blade to give it a cross-sectional shape. For example, the famous Buck 110 hunting knife has a "hollow ground" blade, with concave blade faces, but the cutting edge itself is a simple, flat-ground bevel of lesser angle. It would be difficult, if not impossible, to put a "hollow grind" onto the actual cutting edge of the blade itself, which is a very narrow and small bevel.
A razor strop or simply a strop is a flexible strip of leather, canvas, denim fabric, balsa wood, or other soft material, used to straighten and polish the blade of a straight razor, a knife, or a woodworking tool such as a chisel. In many cases stropping re-aligns parts of the blade edge that have been bent out of alignment. In other cases, especially when abrasive polishing compound is used, stropping may remove a small amount of metal. Stropping can also burnish the blade.
A kitchen knife is any knife that is intended to be used in food preparation. While much of this work can be accomplished with a few general-purpose knives – notably a large chef's knife, a tough cleaver, a small paring knife and some sort of serrated blade – there are also many specialized knives that are designed for specific tasks. Kitchen knives can be made from several different materials.
In cooking, a chef's knife, also known as a cook's knife, is a cutting tool used in food preparation. The chef's knife was originally designed primarily to slice and disjoint large cuts of beef. Today it is the primary general-utility knife for most Western cooks.
The Santoku bōchō or Bunka bōchō (文化包丁) is a general-purpose kitchen knife originating in Japan. Its blade is typically between 13 and 20 cm long, and has a flat edge and a sheepsfoot blade that curves down an angle approaching 60 degrees at the point. The term Santoku may refer to the wide variety of ingredients that the knife can handle: meat, fish and vegetables, or to the tasks it can perform: slicing, chopping and dicing, either interpretation indicating a multi-use, general-purpose kitchen knife. The Santoku's blade and handle are designed to work in harmony by matching the blade's width and weight to the weight of the tang and the handle.
A straight razor is a razor with a blade that can fold into its handle. They are also called open razors and cut-throat razors. The predecessors of the modern straight razors include bronze razors, with cutting edges and fixed handles, produced by craftsmen from Ancient Egypt during the New Kingdom. Solid gold and copper razors were also found in Ancient Egyptian tombs dating back to the 4th millennium BC.
A sharpening jig is often used when sharpening woodworking tools. Many of the tools used in woodworking have steel blades which are sharpened to a fine edge. A cutting edge is created on the blade at the point at which two surfaces of the blade meet. To create this cutting edge a bevel is formed on the blade, usually by grinding. This bevel is subsequently refined by honing until a satisfactorily sharp edge is created.
Sharpening stones, or whetstones, are used to sharpen the edges of steel tools such as knives through grinding and honing.
A ceramic knife is a knife with a ceramic blade typically made from zirconium dioxide (ZrO2; also known as zirconia), rather than the steel used for most knives. Ceramic knife blades are usually produced through the dry-pressing and firing of powdered zirconia using solid-state sintering. The blades typically score 8.5 on the Mohs scale of mineral hardness, compared to 4.5 for normal steel and 7.5 to 8 for hardened steel and 10 for diamond. The resultant blade has a hard edge that stays sharp for much longer than conventional steel blades. However, the blade is brittle, subject to chipping, and will break rather than flex if twisted. The ceramic blade is sharpened by grinding the edges with a diamond-dust-coated grinding wheel.
A cleaver is a large knife that varies in its shape but usually resembles a rectangular-bladed hatchet. It is largely used as a kitchen or butcher knife and is mostly intended for splitting up large pieces of soft bones and slashing through thick pieces of meat. The knife's broad side can also be used for crushing in food preparation and can also be used to scoop up chopped items.
Cutlery and Allied Trades Research Association (CATRA) is an internationally known research and technology organisation in Sheffield, England which specialises in knives, cutlery, tableware, metallic holloware, shaving razors, industrial knives, blades and garden tools.
Knife sharpening is the process of making a knife or similar tool sharp by grinding against a hard, rough surface, typically a stone, or a flexible surface with hard particles, such as sandpaper. Additionally, a leather razor strop, or strop, is often used to straighten and polish an edge.
A honing steel, sometimes referred to as a sharpening steel, whet steel, sharpening stick, sharpening rod, butcher's steel, and chef's steel, is a rod of steel, ceramic or diamond-coated steel used to restore keenness to dulled blade edges. They are flat, oval, or round in cross-section and up to 30 centimetres (1 ft) long. The steel and ceramic honing steels may have longitudinal ridges, whereas the diamond-coated steels are smooth but embedded with abrasive diamond particles.
Thiers Issard or Thiers Issard Sabatier is a French cutlery manufacturer; they are one of a number of companies using the Sabatier name. It exports a wide range of knives and straight razors to approximately thirty countries. They are viewed as one of the top cutlery firms in Europe.
A scissor grinder, sometimes also scissor and knife grinder or knife and scissor grinder, for short also knife grinder, is a craftsman who sharpen and repair blunt knives, scissors and other cutting tools. It is an apprenticeship profession that nevertheless requires much experience.
John Pool - Craftsman Sharpener and Artisan of Shears and Cutlery - http://www .Battlebornbladesharpening.com