Knife Edge Grinds and Uses
January 28, 2013
The knife is an amazing thing, so common that we often dismiss its importance and value in our everyday lives. Mankind has been using a sharpened edge to interact and manipulate our surrounding environment as far back as we have walked the earth. The knife is the original tool. Much like the human race, knives have gone through significant changes over time. We’ve clearly come a long way from stone tools (though I’m sure some primitive tool enthusiasts would be happy to argue with me). Today you can find knives made from a variety of material from ceramic to steel and even; simple stone blades.
As I mentioned in my post “A Sharp Knife”, proper maintenance of your blades should be a priority. This can be difficult and a little confusing with the large variety of knives and knife grinds on the market. First things first, it is all about the edge with grinds and is different from the type of blade. The different knife grinds (edge!) have different qualities that include strengths, weaknesses and preferred uses. They also have different maintenance needs including styles of sharpening. Stay with me as I walk you through the different knife grinds and give you the pros and cons.
Flat ground blades can be considered the simple edge. They are very simple but can come in a couple different varieties. A full flat ground blade classically refers to blades that form a classic “V” shape, where both sides taper toward each other at a consistent angle until they meet. Examples of true full flat ground blades are difficult to find now as most blade manufacturers include a second or compound bevel (explained below). Common examples include chef’s knives and the popular line of affordable Spyderco™ Tenacious knives (though these knives may be considered in the High Flat family) .
High Flat grinds and Sabre (Scandi) grinds are far more common today, though they often have a slight compound bevel as well. These grinds will be a uniform thickness starting at the spine. The V shaped, flat grind bevel often starts between the spine and the edge and tapers evenly towards the edge. High Flat ground blades bevel starts high up near the spine. With Scandi (Sabre) blades the grind will start below the midway point, towards the edge. The High Flat and Scandi grinds are ideal for whittling or woodworking. The pronounced bevel allows you to easily follow the edge in relation to the wood grain. Flat ground blades have the advantage of being very sharp and extremely easy to sharpen on a flat stone and in the field. The disadvantage is that the edge isn’t terribly durable and will (turn) dull quickly.
Convex edges are some of the most difficult to sharpen but they are extremely durable and sharp. A convex edge is where the bevel on each side of the blade is slightly rounded (convex!) as they taper to form the edge. Convex edges are truly difficult to accomplish by hand on a flat stone and are considered a highly specialized grind. Convex grinds are ideal for chopping and splitting tools such as axes and machetes. The durability combined with the shape make quick work of splitting/chopping. The rounded shape of the edge doesn’t get clinched up in wood and also helps separate the two halves of the wood you’re splitting. This is why it is also referred to as the “Axe grind”.
Hollow ground blades have been very popular in the hunting and sporting community. Think of your father’s or grandfather’s hunting knife, I bet your thinking of a hollow ground blade. Examples of hollow ground blades include the classic Buck Knife, straight razors and the Legendary American Bowie Knife. The hollow ground blade has a characteristic concave grind to the edge, so that both sides of the knife have a bevel that is bowing inward until they meet. This produces a thin and wickedly sharp edge but it’s not durable and needs constant maintenance. The hollow grind has a long history of use in the hunting community because the thin and extremely sharp edge is great for field dressing animals.
Chisel ground blades are exactly what you think they might be, chisel shaped. This grind is most often found on chisels but can also be found on other types of blades such as high end Japanese chef knives, modern folders and some modern “art” tactical knives. Chisel ground blades have only a single bevel on one side of the blade and the other side is completely flat. Similar to a flat Sabre ground blade the bevel of a chisel ground blade will start about mid-way between the spine and edge and will then taper in a straight line towards the edge, but this only happens on one side of the blade. Chisel grind creates a sharp edge but requires constant maintenance due to the single bevel. Often the angle of the bevel for chisel ground blades is slightly more obtuse (25°-35°) to create a more durable edge. This grind is ideal for woodworking because you can follow the wood grain in relation to the bevel. It is also used in kitchen knives because the flat side of the blade helps separate slices of food being chopped up.
The Compound Bevel (also known as the double bevel) is the most common grind that you will find on knives today and is present on almost any modern blade. The compound bevel is added to a blade grind and generally cannot be present without some incarnation of the grinds mentioned above. The compound bevel is another, secondary bevel that is added to an existing grind. The compound bevel is more obtuse than the primary bevel and will form the actual edge of the knife, this helps adds durability to a blades edge and will lower the likelihood of an edge turning.
Asymmetrical grinds simply describe a grind that uses separate bevel angles for each side of the blade. Asymmetrical grinds are most often found either with convex grinds or with flat grinds. This grind is often used to produce a more durable edge and can be found on some popular folders on the market. The Asymmetrical grind is can be found on tactical style knives because of the combination of a durability, strength and sharpness.
Well folks, that’s the basics of knife grinds. Many of these grinds can be modified or combined to form specialized grinds. Understanding the basics of how they differ and what tasks they are appropriate for will hopefully help you select the right tool for the job and help you learn some basic sharpening skills. Make sure to bookmark this blog, email it to a friend or add our RSS feed. Stay tuned as we explore knives and sharpening techniques for all different styles of blades. Stay an Edge Above the Rest!
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Thanks for the great posts! Please keep them coming!
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