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 (meaning the shape of the blade when viewed from the side, i.e. clip point, spear point, etc.). 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 (which aid in slicing through materials), 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.
16-400: Grind is the cross-sectional shape of a blade. Grind , grinds , or grinding may also refer to: Grind Grinding is the process of creating grinds. It involves removing significant portions of material from a blade, which distinguishes it from honing and polishing . Blades are ground during their initial sharpening or after having been sufficiently damaged, such as by breaking
32-451: A goniometer , or blade edge protractor. Typical grinds include: It is possible to combine grinds or produce other variations. For example, some blades may be flat-ground for much of the blade but be convex ground towards the edge. Hairpin turn A hairpin turn (also hairpin bend or hairpin corner ) is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn about 180° to continue on
48-401: A blade's ability to take an edge and its ability to keep one. Some grinds are easier to maintain than others, better retaining their integrity as repeated sharpening wears away the blade. Harder steels take sharper edges, but are more brittle and hence chip more easily, whereas softer steels are tougher . The latter are used for knives such as cleavers , which must be tough but do not require
64-405: A concave – but the blade also contains a second, less acute, conventional bevel that makes up the cutting edge. A classic Opinel folding knife has a "flat grind" blade, meaning that the faces of the blade are flat, without convexity or concavity, tapering towards the cutting edge: but the actual cutting edge is again formed of another, less acute bevel ground on the narrow edge. A classic Morakniv has
80-683: A direct, steep climb and descent, at the price of greater distances of travel and usually lower speed limits , due to the sharpness of the turn. Highways of this style are also generally less costly to build and maintain than highways with tunnels . On occasion, the road may loop completely, using a tunnel or bridge to cross itself at a different elevation (example on Reunion Island : 21°10′52″S 55°27′17″E / 21.18111°S 55.45472°E / -21.18111; 55.45472 ; example near Ashland, Oregon 42°05′31″N 122°35′21″W / 42.09194°N 122.58917°W / 42.09194; -122.58917 ). When this routing geometry
96-513: A high pressure due to the very small area of the edge, but high pressures can nick a thin blade or even cause it to roll over into a rounded tube when it is used against hard materials. An irregular material or angled cut is also likely to apply much more torque to hollow-ground blades due to the "lip" formed on either side of the edge. More blade material can be included directly behind the cutting edge to reinforce it, but during sharpening some proportion of this material must be removed to reshape
112-407: A saber or "Scandi" grind, with flat, perpendicular sides on the body, with a secondary bevel formed below to create a tapered edge, but again, the actual cutting edge comprises a third, less-acute bevel. Thus the "grind" of the blade most often refers to the overall cross-section of the blade and should not be confused with the actual style of cutting edge put in the blade, even though this cutting edge
128-524: A sharp edge. In the range of blade materials' hardnesses, the relationship between hardness and toughness is fairly complex and great hardness and great toughness are often possible simultaneously. As a rough guide, Western kitchen knives are generally double-bevelled (about 15° on the first bevel and 20°–22° on the second), whereas East Asian kitchen knives, made of harder steel and being either wedge- (double-ground) to 15°–18° or chisel-shaped (single-ground) to 20°–30°. Care should be taken to avoid confusing
144-423: A tip, chipping, or extensive corrosion. Well-maintained blades need grinding less frequently than neglected or maltreated ones do. Edge angle and included angle typically characterize a blade's grind. An edge angle is measured between a line lying in the plane of one of the edge's faces and a second line intersecting the back's centre contour, both lines lying in the same plane normal to the edge. The included angle
160-415: Is created by grinding as well. If the cutting edge was included in the description of the "grind", the vast majority of blades would have to be described as "compound angle grind". And of course one can purchase an unsharped blade in any style grind you desire, and there is rarely need to grind the entire surface of the blade to create a cutting edge. A sharp object works by concentrating forces which creates
176-408: Is the sum of the edge angles. Ceteris paribus, the smaller the included angle, the sharper the blade and the more easily damaged its edge. An appropriate grind depends upon a blade's intended use and the material composing it. Knife manufacturers may offer the same blade with different grinds and blade owners may choose to regrind their blades to obtain different properties. A trade-off exists between
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#1732775576977192-537: Is used for a rail line, it is called a spiral , or spiral loop. In trail building, an alternative to switchbacks is the stairway . If a railway curves back on itself like a hairpin turn, it is called a horseshoe curve . The Pennsylvania Railroad built one in Blair County, Pennsylvania , which ascends the Eastern Continental Divide from the east. However, the radius of curvature
208-463: The edge in this way is made easier by introducing a curve in the blade, as seen in sabers , tulwars , shamshirs , and katanas , among many others. Some old European swords (most memorably Hrunting ) and the Indonesian style of kris have a wavelike shape, with much the same effect in drawing or thrusting cuts. If it is required to measure the angles of cutting edges, it is achieved by using
224-401: The edge, making the process more time-consuming. Also, any object being cut must be moved aside to make way for this wider blade section, and any force distributed to the grind surface reduces the pressure applied at the edge. One way around this dilemma is to use the blade at an angle, which can make a blade's grind seem less steep, much as a switchback makes a trail easier to climb. Using
240-417: The grind of the blade as describing its cross-section and the angle that is ground onto the edge to form a cutting edge. It is very rare to have a knife with a single ground angle forming both the profile and the cutting edge (the exception being perhaps straight razors). For example, the famous Buck 110 folding hunting knife is described as having a "hollow grind" - meaning the faces of the blade are ground into
256-563: The road. It is named for its resemblance to a bent metal hairpin . Such turns in ramps and trails may be called switchbacks in American English , by analogy with switchback railways . Hairpin turns are often built when a route climbs up or down a steep slope, so that it can travel mostly across the slope with only moderate steepness, and are often arrayed in a zigzag pattern. Highways with repeating hairpin turns allow easier, safer ascents and descents of mountainous terrain than
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