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History
The earliest knives were shaped by knapping (percussive flaking) of rock, particularly harder rocks such as obsidian and flint. During the Paleolithic era Homo habilis likely made similar tools out of wood, bone, and similar highly perishable materials that have not survived. As recent as five thousand years ago, as advances in metallurgy progressed, stone, wood, and bone blades were gradually succeeded by copper, bronze, iron, and eventually steel. The first metal (copper) knives were symmetrical double edged daggers, which copied the earlier flint daggers. In Europe the first single edged knives appeared during the middle bronze age. These replaced daggers, which by that time had evolved into swords. Modern knives may be made from many different materials such as alloy tool steels, carbon fiber, ceramics, and titanium. There is a very active community of modern custom knife makers and collectors, whom often pioneer the use of new materials in knives. In the United States, The American Bladesmith Society promotes forged blades; the Knifemakers Guild promotes all custom knives.  Knife making Today, knives come in many forms but can be generally categorized between two broad types: fixed blade knives and folding, or pocket, knives. Characteristic parts of the knife Modern knives consist of a blade and handle. The blade edge can be plain or serrated or a combination of both. The handle, used to grip and manipulate the blade safely, may include the tang, a portion of the blade that extends into the handle. Knives are made with partial (extending part way into the handle) and full (extending the full length of the handle, often visible on top and bottom) tangs. The handle can also include a bolster, which is a piece of material used to balance the knife, usually brass or other metal, at the front of the handle where it meets the blade. The blade consists of the point , the end of the knife used for piercing, the edge, the cutting surface of the knife extending from the point to the heel, the grind, the cross-section shape of the blade, the spine, the top, thicker portion of the blade, the fuller, the groove added to lighten and stiffen the blade, and the ricasso, the thick portion of the blade joining the blade and the handle. The guard is a barrier between the blade and the handle which protects the hand from an opponent, or the blade of the knife itself. A choil, where the blade is unsharpened and possibly indented as it meets the handle, may be used to prevent scratches to the handle when sharpening or as a forward-finger grip. The end of the handle, or butt, may allow a lanyard, used to secure the knife to the wrist, or a portion of the tang to protrude as a striking surface for pounding or glass breaking. Knife blade mass production. Knife blades can be manufactured from a variety of materials, each of which has advantages and disadvantages. Carbon steel, an alloy of iron and carbon, can be very sharp, hold its edge well, and remain easy to sharpen, but is vulnerable to rust and stains. Stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon. It is not able to take quite as sharp an edge as carbon steel, but is highly resistant to corrosion. High carbon stainless steel is stainless steel with a higher amount of carbon, intended to combine the best attributes of carbon steel and stainless steel. High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge. Laminate blades use multiple metals to create a layered sandwich, combining the attributes of both. For example, a harder, more brittle steel may be sandwiched between an outer layer of softer, tougher, stainless steel to reduce vulnerability to corrosion. In this case, however, the part most affected by corrosion, the edge, is still vulnerable. Pattern-welding is similar to laminate construction. Layers of different steel types are welded together, but then the stock is manipulated to create patterns in the steel. Titanium is metal that is lighter, more wear resistant, and more flexible than steel. Although less hard and unable to take as sharp an edge, carbides in the titanium alloy allow them to be heat-treated to a sufficient hardness. Ceramic blades are incredibly hard, lightweight blades; so hard that they will maintain a sharp edge for months or years with no maintenance at all. They are immune to corrosion, but can only be sharpened on silicon carbide sandpaper and some grinding wheels. Plastic blades are not very sharp at all but are typically serrated, and are usually considered disposable.
Steel blades are commonly shaped by forging or stock removal. Forged blades are made by heating a single piece of steel, then shaping the metal while hot using a hammer or press. Stock removal blades are shaped by grinding and removing metal. With both methods, after shaping, the steel must be heat treated. This involves heating the steel above its critical point, then quenching the blade to harden it. After hardening, the blade is tempered to remove stresses and make the blade tougher. Mass manufactured kitchen cutlery uses both the forging and stock removal processes for their knife blades. Forging tends to be reserved for manufacturers' more expensive product lines, and can often be distinguished from stock removal product lines by the presence of an integral bolster, though integral bolsters can be crafted through either shaping method.
The edge of the knife can be sharpened to a cutting surface in a number of different ways. Flat ground blades have a profile that tapers from the thick spine to the sharp edge in a straight or convex line. Seen in cross section, the blade would form a long, thin triangle, or where the taper does not extend to the back of the blade, a long thin rectangle with one peaked side. Hollow ground blades have concave, beveled edges that are ground starting midway down the blade, instead of at the spine. The resulting blade has a thinner edge, so it may have better cutting ability, but it is lighter and less durable than flat ground blades. Serrated blade knives have a wavy, scalloped or saw-like blade. Serrated blades are more well suited for tasks that require aggressive 'sawing' motions, whereas plain edge blades are better suited for tasks that require push-through cuts (e.g., shaving, chopping). Fixed blade features A fixed blade knife does not fold or slide, and is typically stronger due to the tang, the extension of the blade into the handle, and lack of movable parts. Folding blade features A folding knife connects the blade to the handle through a pivot, allowing the blade to fold into the handle. To prevent injury to the knife user through the blade accidentally closing on the user's hand, folding knives typically have a locking mechanism. Different locking mechanisms are favored by various individuals for reasons such as perceived strength (lock safety), legality, and ease of use. Popular locking mechanisms include: • Slip joint - Found most commonly on traditional pocket knives, the opened blade does not lock, but is held in place by a spring device that allows the blade to fold if a certain amount of pressure is applied. • Lockback - Also known as the spine lock, the lockback includes a pivoted latch connected to a spring, and can be disengaged only by pressing the latch down to release the blade. • Liner Lock - Uses a leaf spring-type liner within the groove of the handle that snaps into position under the blade when it is deployed. The lock is released by pushing the liner to the side, to allow the blade to return to its groove set into the handle. • Frame Lock - Also known as the integral lock or monolock, this locking mechanism was designed by custom knifemaker Chris Reeve as an update to the liner lock. The frame lock works in a manner similar to the liner lock but uses a partial cutout of the actual knife handle, rather than a separate liner inside the handle to hold the blade in place. • Button Lock • Axis Lock - A locking mechanism exclusively licensed to the Benchmade Knife Company. Another prominent feature on many folding knives is the opening mechanism. Traditional pocket knives and Swiss Army Knives commonly employ the nail nick, while modern folding knives more often use a stud, hole, disk, or flipper located on the blade, all which have the benefit of allowing the user to open the knife with one hand. Automatic or switchblade knives open using the stored energy from a spring that is released when the user presses a button or lever or other actuator built into the handle of the knife. Automatic knives are popular amongst law enforcement and military users for their ease of rapid deployment and their ability to be opened using only one hand. Automatic knives are severely restricted by law in most states. Increasingly common are assisted opening knives which use springs to propel the blade once the user has moved it past a certain angle. These differ from automatic or switchblade knives in that the blade is not released by means of a button or catch on the handle; rather, the blade itself is the actuator. Most assisted openers use flippers as their opening mechanism. Assisted opening knives can be as fast or faster than automatic knives to deploy. Sliding knife A sliding knife is a knife which can be opened by sliding the knife blade out the front of the handle. One method of opening is where the blade exits out the front of the handle point-first and then is locked into place (an example of the this is the gravity knife). Another form is a O-T-F (out-the-front) switchblade, which only requires the push of a button or spring to cause the blade to slide out of the handle, and lock into place. To retract the blade back into the handle, a release lever or button, usually the same control as to open, is pressed. Handle (grip) The handles of knives can be made from a number of different materials, each of which has advantages and disadvantages. Handles are produced in a wide variety of shapes and styles. Handles are often textured to enhance grip. • Wood handles provide good grip and are warm in the hand, but are more difficult to care for. They do not resist water well, and will crack or warp with prolonged exposure to water. Modern stabilized and laminated woods have largely overcome these problems. Many beautiful and exotic hardwoods are employed in the manufacture of custom and some production knives. • Plastic handles are more easily cared for than wooden handles, but can be slippery and become brittle over time. • Rubber handles such as Kraton or Respirine-C are generally preferred over plastic due to their durable and cushioning nature. • Micarta is a very popular handle material on user knives due to its extreme toughness and stability. Micarta is impervious to water, is grippy when wet, and is an excellent insulator. Micarta has come to refer to almost any fibrous material cast in resin. There are many varieties of micarta available. One very popular version is a fibreglass impregnated resin called G-10. • Leather handles are seen on some hunting and military knives, notably the KA-BAR. Leather handles are typically produced by stacking leather washers, or less commonly, as a sleeve surrounding another handle material. • Skeleton handles refers to the practice of using the tang itself as the handle, usually with sections of material removed to reduce weight. Skeleton handled knives are often wrapped with parachute cord or other wrapping materials to enhance grip. • Stainless steel handles are durable and sanitary, but can be slippery. To counter this, many premium knife makers make handles with ridges, bumps, or indentations to provide extra grip. More exotic materials usually only seen on art or ceremonial knives include: Stone, bone, mammoth tooth, mammoth ivory, oosic (walrus penis bone), walrus tusk, antler (often called stag in a knife context), sheep horn, buffalo horn, teeth, etc. Almost any hard material can (and has been) employed as a knife handle. |
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