Basic Knife Anatomy

In this post I'm going to write about the basic anatomy of a knife. Not all features will be present in all knives, although some are basic, others are not entirely necessary, depending on your situation.

Each knife is made obviously of a blade and a handle. Essentially that's all you need to classify something as a knife, a sharp cutting edge and someplace to hold it in your hand. But modern knife construction (which began as an art somewhere in the early bronze age) has added many additional pieces to this simple design.

This guide will specifically relate to fixed blade knives, rather than folding or pocket knifes. Keeping that in mind, there is one component above all others that will determine the style and function of a knife.

The Tang

The "Tang" of a knife is that piece of the knife that is covered by the handle material. There are two basic categories of knifes, Full Tang and Partial Tang.

Full Tang knives are constructed so that the tang of the knife is the same width and depth of the blade itself. The handle merely covers the tang and is superficial in these designs. A full tang offers the strongest type of knife (one that is less likely to bread when stress is applied to it) but is also the heaviest type of knife.

Partial Tang knives are a whole category onto themselves. A partial tang is, as the name implies, one that is smaller than the knife itself. These can be a simple as loosing only a few centimeters on each side to nearly disappearing entirely underneath the handle material. As a general rule, partial tang knives are lighter than their full tang counterparts, at the cost of being less sturdy. Since there is less material of the knife to support the handle, the knife has an increased risk of breaking out of the handle when stress is applied to it.

Which tang a knife has will depend entirely upon its designed function. A bowie knife (which is designed for chopping) should have a full tang. A carving knife (whose design is to cut or slice weak material such as flesh or rope) will most likely have a partial tang, which will reduce weight. The added strength of a full tang is not needed for many tasks and the added weight can oftentimes be detrimental.

Balance

One exceedingly important feature of a good knife, whatever it's design, is balance. A properly balanced blade, whether it be a knife, sword or dagger, should weigh the same on the blade side and on the handle side. Were you to balance the knife on your finger, it should rest right where the handle meets the blade (or hilt/hand-guard). If this is not achieved, the knife should at least be heavier on the blade side, never on the handle side.
Balance is important because you don't want to have to expend too much energy lifting the knife itself. A fully balanced knife offers the best control when using the tool. A handle heavy knife will be difficult to control when carving, cutting or slicing. A blade heavy knife may be appropriate if you plan to use the knife as a sort of axe, but is not preferred in most situations.

The Handle

The handle of the knife is simply that portion of the knife that is held in the hand. Different handle materials will have different benefits as well as costs in knife construction.

Wood: The standard handle material, until the last century, was wood. Wood is easy to work, and can be either rigid or flexible, heavy or lightweight, depending on need. As a general rule, the wood on a handle should be hard, yet not too brittle so that it will not crack when stress is applied. All organic material will break down over time, but a good hardwood handle that has been properly prepared will last decades, perhaps even centuries.

Bone and Antler: Bone and Antler handles have some benefits over wood, but are become more scarce and expensive. Bone and Antler can be more flexible than certain woods and can last even longer if treated properly. Bone is often lighter than the same volume of many (though not all) hardwoods. Bone is considerably harder, and more unpleasant, to work with than wood. On a side note, for the knifes that I make, I NEVER use bone or antler for one reason: the smell. Working bone releases the same powder that you'll smell if a dentist grinds into your teeth and it's just... well I've done it a few times and decided never again.

The KABAR Combat Knife features a leather handle over
a full tang. Image courtesy of flickr user Rich Bowen

Leather: Many knives, such as the transitional KABAR combat knife, uses leather as its handle material. The leather is stacked onto the tang itself. Leather is very lightweight, flexible and long lasting. It does have a greater tendency to absorb the oils of your hand, which may damage some leathers if not treated properly. One disadvantage to this method is that the handle material itself weighs almost nothing, and if you're handle is particularly heavy you may need to adjust the balance of the knife with something a little bit more substantial on the handle. However, if your handle side is already a bit to heavy then leather may be the way to go.

Synthetics: Many industrial manufactures are moving toward synthetic materials. These are things such as plastic, rubber, kraton, kevlar... too many to list on this page. As a general rule, synthetics will last longer than natural materials. They can be heavy or lightweight, absorb shock or remain rigid, and repel water and oil with 100% efficiency. Most higher end knife manufacturers know what they're doing and have chosen a good quality handle material for the designed use of the knife.

The handle should be securely fastened to the blade. Most partial or hidden tang knives have handles that can easily be removed for cleaning, whereas most full tang knives have handles designed to remain permanent. Handles can be fastened with epoxy or other glues, and the traditional method is to use pins or rivets to fasten a knife.

A Note on Pins: Most full tang knives are secured to their handles with pins or rivets. These are small rods of steel (or other materials) that fit through a hole that is drilled into the tang. These secure the handle to the blade, usually with the additional help of glue. Although drilling a hole through the tang does weaken the blad slightly, a pin has two advantages. First it is a secure way to attach a handle, and second, the pin material itself may provide extra weight to the handle which helps in the overal balance of the knife.

The Butt or Pommel

The Pommel refers to a piece of metal at the end of the knife. The pommel serves three functions. First, it will help to prevent the knife from slipping out of your hand when it is being used. Second, it will add weight to the handle, which can often correct an improperly balanced knife. Third, it can be used as a hammer or grinding surface.

Pommels are usually attached to the knife by a piece of threading that extends beyond the tang. Cheaper knifes usually have this threading welded onto the tang after the blade itself is manufactured, while higher quality knives will have the threading as a piece of the tang itself. Many pommels are also attached with pins as is the case with the current design of the standard KABAR knife.

Of course a pommel is not always necessary. In addition, the handle material may be shaped to act as a butt or pommel in itself.

The Blade

The blade is the most complicated portion of the knife. Different shapes or grind types can influence the design and function of a knife. First we'll go over some basic terms.

A partially serrated knife with a drop point.
Courtesy of flickr user Mike Petrucci

The Hilt or Hand-guard is designed to protect your hand from slipping up onto the blade, as well as prevent whatever you're carving or cutting from bashing your fingers. Not all knives have them, and many handles are shaped to function as a hand-guard (a hilt is the term specifically used for a piece of metal at the top of the handle, as seen in the diagram).

The Spine is the back, or "top" of the knife. It is usually flat, although can often be serrated or have a saw component.

The Edge is the cutting area of the knife. These can also be serrated or straight.

The Point or Tip of the knife is the point where the edge meets the spine. There are varios shapes that this point may take, depending on the design of the knife.

I'll start with the most important part of the blade, the edge, and go into detail on each component mentioned above.

The Edge

The Edge of the knife is your cutting/slicing surface. It can be made in many different styles depending on function.

Straight Edge blades are most common, and most versatile. A straight edge should "slice" through material if sharpened properly, rather than tear it. This can be used as an axe as well to "chop" though harder material. These are easiest to sharpen and care for, and despite what many people think are capable of performing any cutting task, depending on thickness and sharpness.

Serrated edges do not cut. They "shear" material and act as a saw. Although many people will say that serrated knives never dull, they are wrong. Serrated knives may cut through things like bread or tomatoes easier than a dull straight edged knife, but there is a reason why professional chefs don't carve with serrated knives. Serrations are generally used for bread, and even then a truly razor sharp blade can slice circles around a serrated knife. Two main deficits of serrated knives are that they are harder to sharpen, and you cannot carve or chop with them.

Choil: The Choil of a edge is a small oval cut into the blade just as the cutting edge begins. Its purpose is to ease in sharpening. These are features on many higher quality knives, though certain knives may be designed where a choil is either not necessary or detrimental.

Three Types of "Grinds": A knife's cutting edge is eventually ground down to create a uniform shape and the initial sharpness. There are three general types of grinds and each have benefits and costs.

A "Hollow Grind" edge is one where the grinding stone cut into the knife, so that the shape of the edge is concave. This makes for a very thin cutting edge. The two main benefits are that it reduces the mass (and hence the weight) of the blade and it allows for thinner metal, which means you can sharpen it to a razor edge. However, this type of grind makes the edge more brittle and likely to chip. A hollow grind is designed for a blade that will be slicing through soft material.
A "Oval Grind" is the opposite of a hollow grind. In an oval grind will allow the cutting edge to be stronger (i.e. less likely to chip) but cannot be sharpened as finely as a hollow grind. An oval grind edge will be best used for a chopping tool, such as an ax.
A "Straight Grind" is a hybrid of the two above grinds. Thinner than an oval grind, it allows the blade to be sharpened to a finer edge yet stronger than a hollow grind. For a general purpose knife, this is the way to go.

These are the three general shapes that can be put on the edge of the knife. Of course these three basic shapes can be combined to create more variations. When applied to the entirety of the knife rather than the cutting edge itself there are other considerations, which will become the focus of another article entirely.

Looking at the diagram above you can see that the blade is ground down beginning at roughly in the middle of the blade's face. Here's a front view of the same hypothetical knife.

In the first diagram, the blade is straight ground at two different angles. The first, wider angle helps to reduce the weight of the blade, while the final grind is narrower and forms the cutting edge.
With the second diagram, the overall blade itself is hollow ground, but the cutting edge is straight ground.
This method reduces not only the overall mass of the blade, but allows for the strength associated with a straight grind.

Fuller: The fuller is often mistakenly referred to as a blood groove. The fuller is in fact not designed to allow blood to flow through it's cavity (one wonders what the benefit of such a function would be) but rather to reduce the overall weight of the blade without reducing its strength. The math is rather complicated, but suffice it to say that when a fuller is combined with proper heat treatment (tempering) and blade shape (grind and taper) a blade with a fuller can be as much as 35% lighter than the same blade without one, yet it is just as strong.

The Point

As mentioned above, the point is the area of the blade where the cutting edge meets the spine. There are many styles of points, and I'll try to describe a few here.

Drop Point: A drop point blade is one in which the spine tapers toward the point. This is the "strongest" type of point, and is very good for general purposes. It allows for a point that can easily be forced into an object (i.e. stabbed) but the spine of the blade retains its thickness throughout, resulting in optimum strength of the tip. Clip point blades are the most common, and is usually used in the standard bowie knife as show in the pattern at the top of the page.

Clip Point: A clip point (also known as a trailing point) bevels down and upward to create a finer point. This allows for deeper penetration when stabbing objects. To facilitate this, many add a Swage to the clip point. A swage is simply a cutting edge ground onto the top of the clip point. Because both the top and bottom of the knife is sharpened, the point can penetrate deeper with less effort.