Knife Blade Geometry

To many people, there are two main parts that make up a knife: the handle and the blade. This is adequate knowledge until you go to try to purchase your own knife and you are immersed in a world of vocabulary that you have never heard before. One of these words that many people don’t understand is the grind. The grind of the blade refers to the “shape of the cross-section of the blade”. This is different from the profile or shape of blade, such as drop point, etc. The grind is how the blade is thinned to reveal the cutting edge. There are eight popular grinds in the knife world: hollow grind, asymmetrical grind, flat grind, convex grind, compound grind, and the chisel grind. This article is going to discuss what each of these popular grinds are and what makes them good options as well as some cons to each of the grinds. Before we begin, there is one word that we should know what it means: the bevel. According to the Merriam-Webster, the bevel is the ground angle and shape of the blade’s cutting edge. Let’s begin.

 

Hollow Grind:

This style of grind has been popular through the ages, because it is very classic style of grind. It has a thin edge, which helps create the least amount of cutting drag. The hollow grind is concave, meaning that both sides of the blade curve symmetrically inwards until the point where they meet. However, the hollow grind doesn’t give the strongest edge offered, so it isn’t ideal for use on hard materials. Also, because it isn’t the strongest edge out there, the grind isn’t super durable and dulls quicker than most grinds. This grind is great for straight shaving razors, axes, culinary knives, and hunting knives. For use on a hunting knife, the hollow grind is especially ideal for slicing and skinning.

Advantages of having a hollow grind:

• A classic, popular style of grind.
• The thin edge creates the least amount of cutting drag.
• Fantastic for hunting knives.

Disadvantages of having a hollow grind:

• The hollow grind doesn’t create the strongest edge that you can get.
• Isn’t the most durable of grinds that you can find.
• This style of grind will dull quicker than the other styles of grinds.

 

Asymmetrical Grind:

The asymmetrical grind is a unique grind because it has two different styles of grind on the same blade. The two edges of an asymmetrical grind tapers from both sides, but the bevel angles are uneven, as opposed to different grinds, where they are symmetrical or even. There is a large variety of grinds that you can put together to create the asymmetrical grind and each one has its own advantages and disadvantages. One of the most popular combinations on this grind is with convex grinds or flat grinds. Because of the two different grinds, it produces a more durable edge. This style of grind is often found on tactical knives because it creates a more durable edge, it is stronger than other grinds, and has decent sharpness to it.

Advantages of a having an asymmetrical grind:

• This style of grind is ideal for tactical knives.
• An asymmetrical grind produces a more durable edge than other grinds.
• This style of grind is super strong.
• With this style of grind, you can create many different combinations of angles to get exactly what you need for your task.

Disadvantages of having an asymmetrical grind:

• Because this style creates such a durable edge, you do sacrifice some sharpness.

 

Flat Grind:

The flat grind is the simplest profile that you can find. There are actually three different styles of flat grind: full flat grind, high flat grind, and the Scandi or Sabre grind. Having a flat grind means that you will have low cutting drag and still keep more strength than you would have with something such as a hollow grind. Flat grinds are great for woodworking, culinary knives, whittling, and general use knives. These knives are easy to maintain and sharpen.

The Full Flat Grind:

The full flat grind has a single, symmetrical V-bevel. This means that the blade tapers from the spin evenly from both sides into the point. Because of this, the edge can be crazy sharp, but you do sacrifice some of the durability. A true full flat grind is actually rare to find these days, because often times a secondary bevel is included on this style of grind. A full flat grind is best for pushing the knife into something, so you’ll see a full flat grind often on chef’s knives.

The High Flat Grind:

The High Flat Grind is the second style of flat grind. This style of flat grind is more popular than the full flat grind.  The difference between a full flat grind and a high flat grind is that a high flat grind leaves a small portion of the blade the same thickness. This portion is found adjacent to the handle at the bottom of the blade. After this portion ends, it tapers down to the point, just like the full flat grind does. This style is great for survival situations because it is very easy to sharpen in the field.

The Scandi Flat Grind:

The last style of flat grind is the Scandi flat grind. This style has many names including the Scandi grind, the Scandinavian Grind, the V grind, and the Sabre grind. The Scandi grind is similar to the high flat grind because it too has a portion of the blade that stays the same thickness before it tapers to the point. However, with this style, the portion that is the same thickness is much larger. The Scandi style of flat grind is also ideal for survival situations because it is very easy to sharpen while in the field.

Advantages of the flat grinds:

• A flat grind is ideal for woodworking, whittling, culinary knives, and general use.
• This style is easy to maintain and sharpen.
• The flat grind sports an extremely strong edge.
• This grind is ideal for survival situations because it is easy to sharpen in the field.

Disadvantages of the flat grinds:

• The flat grinds are not very durable and lose their edge quickly.
• The full flat grind style is rare to find these days.

 

Convex Grind:

On a hollow grind, the grind curves inward; however, on a convex grind it sports a slightly outward rounded curve that comes to a point. This is extremely similar to the Scandi flat grind, but instead of the straight grind, it is curved. This grind is one of the most durable grinds and they stay super sharp. On the flip side, they are one of the most difficult grinds to sharpen. This style of grind is considered to be the most difficult grind to produce, but they are considered to be a highly specialized grind. The convex grind is also known as an axe grind because axes are most commonly found with a convex grind. Because it is such a durable grind it is ideal for axes, chopping, splitting, hunting, woodworking, culinary knives, and general use knives. The convex grind is becoming an extremely popular style of blade grind.

Advantages of a convex grind:

• The convex grind is ideal for axes, hunting, woodworking, and culinary knives.
• This style is considered a specialty grind.
• This grind is the most durable grind, making it great for chopping, splitting, and heavy duty tasks.
• The convex grind will stay sharp for a very long time period.

Disadvantages of a convex grind:

• This style is the hardest grind to sharpen.
• This style is also one of the hardest grinds to manufacture.

 

Compound Grind:

The compound grind is also known as the double-bevel grind. The compound grind takes any other grind of grind and then ads in the second V-bevel to produce the cutting edge. The compound grind is one of the most commonly found grinds in knives today because it does incorporate any of the grinds that you like, plus the extra bevel. So what is the reason to adding an extra bevel onto your blade? It adds to the cutting ability and it is less likely to chip. However, because it is more durable than other grinds, you do have to give up some of the sharpness that you would get with some of the other grinds offered. The compound grind cuts better than the V edge grind, plus it lasts longer than the V edge grind would. This style of grind is ideal for woodworking, general use knives, whittling, and culinary knives.

Advantages of a compound grind:

• The compound grind is much more durable than other grinds, so this is a great option if you have a softer steel blade.
• You can take any grind and then add the second bevel to make this style of grind.
• The second bevel on this grind adds cutting ability.
• The compound grind is much less likely to chip than other grinds.

Disadvantages of a compound grind:

• The compound grind isn’t as sharp as the other grinds offered.

 

Chisel Grind:

The chisel grind is very similar to the Scandi grind except that one side is completely flat. The flat side starts at the bottom of the spine and is straight until the other side meets it at the point. The opposite side has a bevel that starts close to the middle of the blade and then tapers in a straight line to the end. The only side of the blade that is sharp is the tapering side. The angle degree that you are most likely to find is anywhere between 25 and 30 degrees, which works to create a more durable edge. Not surprisingly, this grind is found most commonly on chisels. However, they are also found on some tactical knives, and also in culinary knives, especially Japanese culinary knives. The chisel grind is ideal for woodworking because the grind works to help follow the grind of the work. The chisel grind is considered to be one of the easiest grinds to sharpen, which is good, because chisel grinds need constant maintained and re-sharpening. But, when it is sharp, it can get an extremely sharp edge.

Advantages of a chisel grind:

• You can get an extremely sharp edge with a chisel grind.
• The chisel grind is ideal for woodworking and culinary knives.
• The chisel grind is one of the easiest grinds to sharpen.

Disadvantages of a chisel grind:

• The chisel grind needs constant maintenance.
• The chisel grind does not keep its sharp edge well at all.

 

We have now covered the most popular six grinds, but there are some other grinds that are not as common. One of the most popular unpopular (what an oxymoron) grinds is the Semi-Convex grind:

Semi-Convex Grind:

The semi-convex grind is also known as the asymmetrical convex grind. This one combines the convex edge and the V edge. They combine these two because the convex grind offers fantastic durability and the V edge is very easy to sharpen. Like I said, this grind is not very popular, but you will see it from time to time.

Advantages of a semi-convex grind:

• This grind uses the durability that the convex grind offers.
• The semi-convex grind gets the ease of sharpening from the V edge aspect that it sports.

Disadvantages of a semi-convex grind:

• This style is not found often.
• The edge of this style can get very dull quickly.

 

Conclusion:

There are many intricate aspects that determine how quality your knife is. One of the most overlooked of these aspects is the grind style. There are six popular grinds: hollow grind, asymmetrical grind, flat grind, convex grind, compound grind, and the chisel grind. These six include the basic grinds, but the compound grind and the asymmetrical grind will combine two of your favorite grinds to create the perfect blade for you. Each grind excels at something unique, so before purchasing your next blade, check and see if the grind is the perfect option for you.