Guide to Knife Grinds and Edge Geometry

An overview of various blade grinds and edge geometry

When most people think of a knife, they think of it as consisting of two parts: a blade and a handle.

In reality, knives, swords, and other bladed items are shaped in different ways and ground to varying edges in order to bring about their full purpose, bolster the strengths of the steel, and minimize the weaknesses of the chosen steel.

Wait, you thought they were shaped differently to look cool?  Did you really think the power of a samurai’s katana over that of the knight’s broadsword came solely from the chosen metal?

Yes, the kind of steel (or iron) plays a huge role in determining the strengths and weaknesses of a blade (click here for more info), as was the case in the much-feared Ulfbehrt sword, but many times the geometry of the edge and grind of the knife play their role, too.  This guide is here to teach you the most common knife grinds (pictured above) so you can see how the grind and geometry of your blade enhance its intended use.  To this end, I jumped down the rabbit hole to ensure everything I knew about knife grinds and edge geometry was correct.

Let’s dive in and discover the world of knife edges.

Table of Contents

The Hollow Grind

STRENGTH: Easy to sharpen, great for slicing
WEAKNESS:
Doesn’t chop well, edge can be fragile, dulls easily
MOSTLY USED IN:
Hunting knives, fishing knives, EDC, straight razors

Hollow grinds are popular with hunting knives, as they make skinning and flaying easy.  The grind is concave, which means that the sides curve inward, meeting at a razor-sharp edge.  A full hollow grind means that the grind goes from the edge to the spine.  Unfortunately, this thin, concave shape means that the edge won’t last that long.  Pairing a hollow grind with a stronger kind of steel can sometimes offset this a little.

Hollow grinds aren’t typically found on thick blades, hence the need for stronger steel.  This allows for quicker, cleaner slicing, and as you sharpen your knife, it’ll remain thin.  Unfortunately, that thinness also means it’s prone to chipping, especially if ground from a hard steel.  As such, Bowie knives, machetes, and other large blades seldom use the hollow grind.

The Flat Grind

STRENGTH: Is strong, chops great when paired with thicker blades, is good for cutting things
WEAKNESS:
Doesn’t slice as well as a hollow grind
MOSTLY USED IN:
Kitchen cutlery, hunting knives, EDC knives, and most other knives

The full flat grind is a great all-around kind of knife grind that can be found on most knives.  It’s a versatile grind that can be thin and sharp or thick depending on the design and the knife’s intended use.

As you can see in the image, it’s thick at the spine, lending the edge strength, but can taper down into a fine edge for slicing purposes.  This tapering allows the blade to move through material easier than knife grinds that like the hollow or the sabre. 

There’s also a high flat grind, which is another type of flat grind.  The full flat grind starts to taper toward the spine’s edge, but the high flat grind leaves a tiny bit of the blade the same thickness as the spine before it begins tapering into a point.  This type of knife grind is often found in survival knives, as it’s easier to sharpen when out in the field.

The Sabre Grind

sabre grindSTRENGTH: Very durable, good for chopping
WEAKNESS:
Not so great at cutting and slicing
MOSTLY USED IN:
Camp knives, self-defense knives, tactical knives

A sabre grind differs from a high flat grind in that it can be either flat or hollow.  A sabre hollow ground knife means the blade has a hollow grind that begins partway down the blade.

Why would you want a sabre grind?  Because a sabre grind can make for a stronger flat or hollow grind.  It’s usually a little thicker than the previous two, so the blade can do things like chop better than a normal hollow or flat grind.  Granted, the trade-off here is that it doesn’t slice as well as other grinds.

The Chisel Grind

STRENGTH: Very strong, easy to sharpen (partially depending on steel used), incredibly strong, good for cutting, usually good for woodworking
WEAKNESS:
Cutting isn’t symmetrical, a wide variety of quality and performance
MOSTLY USED IN:
Japanese handmade kitchen knives, machetes, bushcraft knives

When an edge is using a chisel grind, it’s completely flat on one side all the way from spine to edge.  The other side has a single bevel that begins in the middle(ish) of the blade, then tapers in a straight line toward the edge.  The Japanese are fond of this grind in their kitchen knives, but they’re also found on machetes and chisels.

Because it’s flat on one side, a chisel grind is pretty easy to make and sharpen.  You can make thin edges, so they can get pretty sharp. 

However, these grinds aren’t too common, despite being easy to make.  This is likely due to how difficult it can be to achieve accurate cuts.  Because of the unsymmetrical design of the grind and edge, the blade has a tendency to curve as it’s moving through the material.  This is great if you’re making sushi (the Japanese use this grind often), as you’re not so likely to cut into your hand, and for some woodworking where you want a slight curve, but it’s not so great for many other uses.

The Convex Grind

STRENGTH: Strong edge, chops good
WEAKNESS:
Difficult to sharpen, doesn’t slice well, abilities vary depending on working angles
MOSTLY USED IN:
Machetes, axes

Convex grinds are an old kind of knife grind because they could be made easier with a hammer.  It’s sometimes known as the Moran Grind because of Ken Warner and Bill Moran.

Convex grinds arc into a convex curve towards the edge of the blade, similar to the sabre grind.  Both retain thickness in the middle of the blade, reinforcing the edge.  There’s no bevel most of the time, but occasionally there’s a small one near the edge.

They’re mostly used with axes and machetes.  Once in a while, you might find a larger bushcraft knife with a convex edge, but most agree that the edge isn’t all that useful in smaller knives that aren’t used for chopping.  This is because these grinds can stand up to a lot of abuse, but it’s difficult to get a consistent quality of edges, even when made by a factory.

One of the main gripes about these edges is that they’re hard to sharpen.  Slack belt grinders are usually used to make the convex grind.

The Scandi (Scandinavian) Grind

Scandi Grind Knife GrindSTRENGTH: Easy to sharpen (although you must sharpen the entire bevel), doesn’t chip too easily
WEAKNESS:
Not great at slicing
MOSTLY USED IN:
Woodworking knives, bushcraft, outdoor knives, hunting knives

The scandi grind comes from Scandinavia and is sometimes called the V Grind.  It’s similar to a flat grind, although the scandi grind doesn’t begin tapering until closer to the edge than a high flat grind.  This means that there’s a lot of steel left behind the edge, lending extra strength to it.

For these reasons, the scandi grind is used in all kinds of knives.  Woodworkers love this knife grind, but people who love camping, hiking, and enjoying the outdoors love it, too. 

It’s easy to sharpen, as you can use the entire primary bevel to guide your knife along the stone when you’re sharpening it.

There are downsides when sharpening, though.  It’s easy to make the edge too thin and therefore vulnerable to chipping.  If you make a mistake, you’ll have to remove a lot of steel to correct it.

A Note About Edge Geometry

Steel is important and grind is important.  I hope this site has given you a good, general understanding of them.  However, there are a few more notes I’d like to share with you just to tie them all together.

Blade Thickness

Blade thickness affects the strength of the blade and its cutting ability.  Thicker blades are stronger than thin blades, but they don’t slice as well.  This is why we need to balance what we need a knife for (its purpose) with the kind of steel and the kind of knife grind used in making the knife.

For example, taking a box cutter or Exacto knife into the wilderness isn’t a very good idea.  They aren’t bushcraft knives, they’re office knives and craft knives.  This is why taking into account what you need a knife for is an important step in choosing a knife.  If your knife is meant to defend you, then it needs to be sturdy, but if your knife is going to slice vegetables, it needs to be sharp.  A diving knife needs to stand up against the harsh saltwater of the ocean.

Even everyday carry knives (EDC) vary greatly in their intended purpose.  Someone working in an office needs to be able to quickly slice through things like cardboard or paper, but someone who enjoys camping or hiking needs to be able to cut firewood, tear through rope, or have something that can whittle.  In other words, they have a variety of different purposes their EDC has to fulfill, so if you’re in the market for an everyday carry knife, make sure you look for something that matches your everyday tasks.

Edge Thickness

Edge thickness isn’t the same as blade thickness.  Edge thickness is, instead, closer to the bevel than it than the actual thickness of the blade.

That being said, edge thickness still has the same trade-off as blade thickness when it comes to slicing and cutting abilities.  The thicker, the more abuse it can withstand, but it’ll be duller and not as precise.

Thin edges chip easier and can’t take much abuse.  They’ll also need to be sharpened more often to maintain the cutting and slicing abilities they’re known for.  Also, it’s good to remember that a sharp knife isn’t as dangerous as a dull one when it comes to the wielder’s fingers.

A thicker edge bevel, on the other hand, can help offset a thin edge.  Big, thick knives can still have extremely thin, sharp edges.  The opposite is also true: a knife with a thick edge can come from a rather thin blade.

Now would probably be a good time to get into bevel.  There are two of them: primary and secondary.

If you have a knife in which a bevel starts from around the middle of the knife and extends almost all the way to the edge, you’re looking at the primary bevel.  You don’t have to have a scandi or chisel grind to have a bevel, though; even flat grinds have steel that slopes down and toward the edge, which is the primary bevel.

After the primary, at the very edge of the blade is the secondary bevel.  This comes when a tiny bit wider edge bevel sprouts from a more narrow primary bevel.  The thicker edge bevel bolsters the durability of the edge, sometimes allowing for better piercing.

Of course, there are knives that don’t bother with a secondary bevel whatsoever.  Sabre grinds, for example, have only a primary bevel that extends the entire way.  This leads to a thin blade that specializes in cutting and slicing, not in strength and chopping.

Final Thoughts

Hopefully, this article has given you a better idea of blades and edges so you can understand your knife, its purpose, and its strengths and weaknesses better.  It’ll also help you when shopping for your own knives so you can get the tool you’re looking for without buyer’s remorse.

If you’re feeling unsure about knife steel, I invite you to check out this article: What’s the Best Knife Steel?