Anatomy of Knives

The two main components of modern day knives are the blade and the handle. Some knives also feature a barrier, known as a guard, between the blade and handle which serves to protect the hand from the blade, as well as from opponents in knife fighting.

1. The Knife Blade

The knife blade comprises the point, edge, grind, spine, fuller, and ricasso:

The Point

The point is the end of the knife used for piercing.

The Edge

The edge is the cutting surface which extends along the length of the blade from point to heel. The blade edge may be plain, serrated or a combination of the two. Featuring a saw-like blade, serrated edges are suited to actions that require sawing motions. In contrast, plain blades are suited to slicing chopping and other single-motion cutting actions.

The Grind

The grind is the cross-section shape of the blade.

The Spine

The spine represents the top section of the blade.

The Fuller

The fuller is a groove or cut out section incorporated along the top of the blade (opposite side to the edge) which serves to lighten the blade.

Ricasso

The ricasso is the strong region of the blade where the blade and handle join.

Blade Materials

Various materials are used in the manufacture of knife blades, typically metal alloys such as stainless steel (an alloy consisting mainly of iron and chromium, sometimes with nickel and molybdenum) and carbon steel (an alloy of iron and carbon). Blade materials generally have their own unique set of benefits and limitations. For example, carbon steel is strong, easy to sharpen and extremely sharp. Whilst stainless steel cannot produce an edge as sharp as carbon steel, it makes up for it with excellent corrosion resistance. A compromise is found with high carbon steel (stainless steel with higher proportions of carbon) which exhibits the aforementioned beneficial properties of both stainless steel and carbon steel. The manufacture of steel blades involves the forging of steel, followed by shaping with the use of a hammer or press, heat treating, quenching, and finally tempering.

In the case of laminate blades, metals are layered on top of each other for combining desirable properties. For example, a metal alloy exhibiting good corrosion resistance may form the outer layer, with an inner layer consisting of a stronger metal alloy for blade rigidity, ease of sharpening, and/or level of achievable sharpness. A common disadvantage of this kind of laminate blade is that whilst the main blade is protected by the outer later, the edge is part of the exposed inner layer and thus susceptible to corrosion. A technique similar to laminate blade construction is pattern welding in which layers of steel (of varying types and properties) are welded together. In comparison with steel, titanium demonstrates superior resistance to wear and greater flexibility, as well as a higher strength-to-weight ratio. Ceramic blades are lightweight and strong, albeit extremely brittle, with an ability to maintain a sharp edge for longer periods than most blades of metal construction. Despite the disadvantage of their brittle nature, ceramic blades have the added advantage of being completely resistant to normal corrosion. Carbide sandpaper and some grinding wheels may be used to sharpen ceramic blades.

Blade Types

Blades may be fixed, folding, or sliding.

Fixed blade knives, as their name suggests, have a solid rigid structures with no moving parts. The tang (discussed later) gives fixed blade knives, or sheath knives as they are otherwise known, their rigidity.

Folding knives have a blade that pivots at the handle and can be folded into the handle, thus hiding the blade edge for safety. Many folding mechanisms include a locking mechanism to protect the hand from the blade folding too quickly. Various locking mechanisms may be used, including the lockback, slip joint, button lock, liner lock, frame lock, pick lock, and axis lock. The opening mechanism of folding knives also varies amongst knives. Many modern folding knives use a stud, hole or disk located on the blade which allows the blade to be opened with one hand, whereas many traditional knives use a nail nick mechanism. Some knives have an automatic folding mechanism, where the blade is deployed rapidly by the release of a spring when a button on the handle is depressed. Referred to as automatic knives or switchblades, these knives are popular in the military and for law enforcement due to their single-handed ease of operation.

As with folding knives, the blade of sliding knives is concealed within the handle when closed. The mechanism by which the blade opens differs however. The blade of sliding knives opens by a sliding action from the front of the handle. When fully deployed, the blade locks in position. In the case of OTF (meaning out-the-front) switchblades, a button on the handle is pressed to deploy the blade. In order to retract the blade back into the handle, the button is again depressed (or a lever is pulled) to unlock the blade from the deployed position.

2. The Knife Handle

The purpose of the knife handle is of course for gripping and controlling the blade. The blade of many knives extends into the handle to varying degrees, with this overlapping area referred to as the tang. Where the tang extends along the full length of the handle (and often visible at the handle base), it is known as a full tang. In contrast, part tangs are tangs that extend only partly into the handle. The handle of some knives may include a component for balancing the knife, known as a bolster. Bolsters are typically constructed of metals and are positioned at the front of the handle where the blade joins. A component known as a choil is also positioned where the blade meets the handle. The function of a choil is twofold: to provide a forward finger grip and to protect the handle from damage (scratches and scuffs) when sharpening the blade. The base or end of the handle is referred to as the butt. The butts of some knives are designed to allow a chorded loop, known as a lanyard, to be attached which allows the knife to be secured to the wrist. The butt may also allow a full tang to protrude at the base which acts as a solid component for striking when the knife is held.

The design, style and manufacture of knife handles vary widely, as do the materials used in their construction. Handle materials include wood, rubber, stainless steel, plastic, leather, and micarta.