A knife is a sharp object used for cutting things, based on the simple machine concept of a wedge. The most common design for a knife is that of a sharp metal blade[?] attached to a handle by means of a tang[?]. Knives have been used as weapons and tools since the stone age, and various developments include the sword and the machete.
Together with the fork and spoon it is a very common eating utensil. According to etiquette it is held in the right hand, and the fork in the left.
A knife is such a basic tool that it is helpful in almost any environment.
Knives were among the first tools used by man in the Stone age, originally consisting of a single piece of sharpened flint.
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Using knives
Keep the knife clean, dry and sharp. If the blade can rust, oiling it will help it stay sharp.
Never use a knife to pry or as a screwdriver. A piece is likely to break off the blade.
In the woods, use the knife as a tool to make tools, rather than as the only tool. For example, rather than using it as a skewer, use it to cut skewers from a nontoxic wood.
To cut thick wood, chopping with a knife is almost always faster than using a saw on the back of the knife.
Sharpening
The trick is to control the angle between the stone and knife. It should be constant. A tool is very helpful. Very sharp knives sharpen at 12 degrees. Typical knives sharpen at 22 degrees. Knives that chop may sharpen at 25 degrees.
Remove a wire edge if one forms during sharpening. Use 30 degrees to do so. If not removed, it will break off in use, and the knive will instantly become dull.
The best sharpening stones are industrial diamonds embedded in plastic. These are more expensive, but affordable. They cut about twice as fast as other stones.
Knives to carry
Many authorities recommend carrying a lockback knife, about 4" (10cm) long. It should be one which can be opened with one hand. The main use is a tool, not a weapon.
One authority recommends, for wilderness use, carrying a large knife like a machete or kukri, for chopping wood, serious fighting and heavy camp chores, a 6" knife for dressing animals and use as a spear-head, and to back-up the fighting knife, a lock-back folder for light tasks, and swiss-army knife for all the little tools.
The best place to carry a large knife is in the back waistband, or under a skirt strapped to the thigh. A sheath for the back waistband can be held in place with a small button that keeps it above the waistband. Tactical nylon is stronger, and more water resistant than leather.
Carrying of knives in public is forbidden by law in many countries. Exceptions may be made for hunting knives, and for knives used for work-related purposes (eg.chef's knives). Knives are forbidden on aeroplanes and are among the illegal imports that may be confiscated at airports by customs staff.
Anatomy of a Knife
A knife has a blade, a tang and a handle. The tang is an extension of the blade into the handle, so that the handle can be strongly attached to the blade.
Some knives have quillions between the blade and the handle, so that fingers cannot slip onto the edge and be cut. Quillions should be rounded so that they do not cut fingers, and strong enough so that they do not bend before the knife breaks. A nice feature is to curve the top quillion so a thumb can be placed on it.
Some knives have a choil, a crack, finger-hole or other space between the edge and the handle. A functional choil is a circular cut-out between the blade and the handle. It's often knurled. A functional choil lets the user grip a knife with the bottom quillion between the index and middle finger. This lets one use the index finger to feel where the edge is cutting. For less-delicate cuts, the index finger is kept safe behind the quillion. Some pocket knives have only a choil, and no quillion, so they can slip easily into a pocket.
A blood groove is a large groove up the side of a blade. According to a popular myth, it lets bleeding occur from an artery without removing the knife. In reality, its only function is to make larger knives and swords lighter; on smaller knives it's purely decorative.
Some knives also have a shoulder in which the blade thickens as it meets the handle. This helped keep the knife from jamming in bone. In kitchen knives, it keeps chopped items from moving back toward the hand.
The handle should be thick enough that one's fingers just meet one's palm when the knife is gripped as tightly as possible. Most knife handles are much too thin, and a knife for serious use may need to have its handle built up with cord and tape. A favorite handle material is a sticky non-slip rubber material called Kraton.
Almost all knives are improved when the handle has a hole in the end. Cooking and utility knives can be hung, which helps preserve their edge. Fighting and survival knives can be placed on a lanyard. A lanyard can be used to pull knives out (with a lever, if necessary) when they jam. It can also prevent loss.
On folding knives, the tang has special features. The kick is the front (edge) locking surface of the blade. The back square is where the blade is locked in the back.
Serrations on a blade help keep the blade sharp. The points protect the slicing areas from nicks. A good serration pattern will help a knife stay sharp three to ten times as long as a straight edge. They are also difficult to sharpen at home.
The edge is sharpened at different angles for different purposes. 15 to 25 degrees is a good all-around angle. Slicing knives should have sharper angles, down to ten degrees. Chopping knifes need blunter angles, out to thirty degrees.
Blades
Blades should be rust-proof. The current (2002) recommended materical is a steel called ATS-34. A former favorite was 440-C stainless steel.
City knives should be four inches or less. Country or fighting knives should be six inches.
There are several basically different types of knife blades: normal, spey, clipped, sheeps-foot, tanto and ulu.
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A normal (1) blade has a curving edge, and flat back. A dull back lets one use fingers to concentrate force, and makes the knife heavier and stronger for its size. The curve concentrates force, making cutting easier. Therefore, it can chop as well as pick and slice. The single edge is also less expensive to produce than a double edge.
A curved or trailing-point (2) knife has a back edge that curves upward. This lets a lightweight knife have a larger curve on its edge. Such a knife is better for slicing than a normal knife.
A spey (3) blade has two curved edges. The idea is to make a blade that slices in either direction, with a strong sharp point. This is the strongest traditional style of knife. It's used for fighting knives (dagger, switchblades, etc.) because it can cut both directions, has a point and is strong. Many persons believe that the best all-around blade is an asymmetric spey, with the larger curve on the lower side. This is called a dropped spey.
A clipped (4) blade is like a normal blade with a clip off the tip to make the tip thinner and sharper. The back edge of the clip can have a "cut swedge" that can be sharpened to make second edge. The sharp tip makes the blade exceptional as a pick, or for cutting in tight places. If the clip is sharpened, this is an attempt to make a working knife double as a fighting knife. This is another favorite knife shape, although it is not as strong as a spey. The Bowie is an attempt to make a clipped blade that's good for fighting, and as strong as a spey.
A sheepsfoot (5) knife has a straight edge, and a curved dull back. It give the most control, because the back, dull edge is made to be held by fingers. It's good for whittling, including sheep's hooves.
A tanto (6) knife is thick, almost a bar. The edge is straight. The point is actually a second edge on the end of the blade, swept back from the point at 80-60 degrees.
An ulu knife is a sharpened half-circle. It's all edge, with no point, and a handle in the middle. It's good for scraping, and sometimes chopping. It is the strongest knife-shape.
Types of knives
Solid tang knives are the strongest and simplest type.
A lockback knife is a folding knife with a lock. One should be able to open it with one hand, using a stud or fingerhole to get leverage. If one must carry just one knife, many authorities agree that this is the one.
A hunting knife is normally used to dress large game. It is often a normal, mild curve or a curved and clipped blade.
A trapper's knife is made to kill and dress small animals, and help with simple machinery. It's a small folding knife with three blades: a clip, a spey and a normal. It is one of the most popular folding knives ever made.
A pocket knife is a folding knife, without locks. Some brands, such as Victorinox, have a wide variety or tools available.
A classic lady's knife is a small curved knife that folds into a handle and then resembles a silver leaf.
Pure fighting knives are always speys, so that either edge can cut. Modern fighting knives have large curves, to concentrate the force to permit slicing. Classic fighting knives have straight edges and a very strong point.
A machete is a large normal blade, used to chop through brush. Interestingly, some experts are now arguing that a long, very sharp blade is superior to a traditional heavy machete for cutting brush.
A kukri is a fighting knife with a deep forward curve. In use, it swings into a person. The kukri is also good for chopping. Some shapes actually chop better than a hatchet, because they balance better.
A survival knife is a sturdy knife, sometimes with a hollow handle filled with equipment. In the best hollow-handled knives, both blade and handle are cut from a single piece of steel. The end has an O-ring seal to keep water out of the handle. Often a small compass is set in the inside, protected part of the pommel/cap. The pommel may be adapted to pounding or chipping. Recommended fillings for the handle: a compass (usually in the pommel). Monofilament (for snares, fishing), 12 feet of black nylon thread and two needles, a couple of plastic ties, two barbed and one unbarbed fishhook (unbarbed doubles as a suture needle), butterfly bandages, halizone tablets, waterproof matches.
Knife modifications
Most knives need a fatter handle to fit most people's hands. The handle should get a hole, if it doesn't have one. The handle can have a couple notches to make it easier-to use plastic ties to mount it on a spear.
The tang should be covered on the handle, so that it cannot burn, freeze or electrocute the knife's user.
The pommel might be modified to be sturdy enough to pound or chip. One can drive a large machine screw in. The sheath should permit one to hold the blade for pounding and chipping.
One side of the blood groove or blade could be polished to make a signal mirror. If this is done, drill a small hole to act as the aiming hole. One aims a signal mirror by looking through the hole, and moving the reflection of the beam through the hole over the target seen through the hole.
A knife with simple surveying instruments is more useful. One standard system puts a sighting hole in the upper quillion to aim over the point. A weighted string draped on a notch is the indicator. A sundial and half-circle degree protractor is marked on the right side of the knife. In the afternoon, sighting the sun, the sundial should show the hours to darkness. On the left side, put two trig scales. Sighting up gives a sine scale, in percent of the distance, to measure height. Sighting down gives a tangent scale, in percent of the distance, to measure the observer's height. A main use of these is for navigation. Another is to estimate rope use, and climbing effort.
Books:
The Knife Bible by Don Paul
Knives designed for specific purposes exist in large numbers. Some examples include butchering[?], hunting, curing, fishing, woodcarving[?], cooking and combat.