Post by Shorttime on Jul 31, 2013 3:37:03 GMT -8
Well, I figured I would try to contribute some useful information, for a change.
The following article is from Lansky's website, and it talks about the various edge bevels you'll find on knives.
I put this in Knife Care, because these bevels sharpen differently, and some require more work than others to stay sharp.
Knife Edge Grinds and Uses
Flat
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
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
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
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.
Compound Bevel
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
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.
From "SharpeningSupplies.com", a primer on what the hell we actually mean when we talk about an edge bevel in terms of degrees.
Before getting into the detail, we’d like to make it clear how we talk about the angles on a knife. Most knives have a bevel on both sides. When we tell someone that they should put a 20 degree angle on a knife, we mean that they should sharpen each side to 20 degrees. This creates a total angle of 40 degrees. So when we’re talking about the angle on your knife, we’re talking about the angle at which you hold the knife to your stone.
The difference between a double and single bevel knife edge There are special cases where the total angle of the knife is not double the angle that you sharpen each side of your knife. Some traditional Asian knives are only beveled on one side. In this example, one side may be sharpened to 20 degrees while the other side is at 0 degrees for a total angle of 20.
However, in practice, we have found that the vast majority of Asian knives sold in the United States are not single bevel but rather traditional knives with a bevel on both sides. If you’re not sure, it is generally safe to assume that your knife has a bevel on both sides. Asian knives do typically have a slightly lower angle and both sides are sharpened to roughly 17 degrees.
Choosing and angle to sharpen your knife is essentially a compromise between the sharpness and the durability of an edge. The most important factor when determining the angle comes down to how you will be using your knife. Will you be shaving your face, filleting a fish, cutting vegetables, carving or chopping wood? From these examples, it is easy to see how each case requires a different edge.
Under 10 Degree Angles
The lowest angles are reserved for edges that are typically cutting softer materials. In this case, the edges are not subject to abuse so the lower angle can be maintained without damage or edge failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle which is roughly 7 to 8 degrees (although the back of the blade is used as a guide so knowing the angle isn’t important and nor is it adjustable). A straight razor has a very delicate edge that is very easy to damage. In proper usage, a straight razor would never see the type of use that would damage the edge.
10 to 17 Degree Angles
A sharpening angle of 10 to 17 degrees is still quite low for most knives. With a total angle of 20 to 34 degrees, this is still a very fine edge. This edge is typically too weak for any knife that might be used in any type of chopping motion. Also consider that harder steels are also more susceptible to impact damage because they are more brittle. If your knife is used for cutting soft items or slicing meats, this lower angle can hold up and provide a very smooth cutting action.
17 to 22 Degree Angles
A 17 to 20 degree angle covers most kitchen knives. Some knives (typically Japanese manufacturers) will sharpen their knives to roughly 17 degrees. Most western knives are roughly 20 degrees. It is our experience that kitchen knives sharpened to 15 to 20 degrees cut very well and are still durable. These angles are still not highly durable as a total angle under 40 degrees will not respond well to rougher treatment in harder materials.
22 to 30 Degree Angles
Most hunting and pocket knives are in this range, allowing them to resist the kind of treatment these knives are sometimes subjected to. Although an edge bevel in this range is less likely to burr or chip, some more effort is required to make deep cuts.
Over 30 Degree Angles
Any edged tool or knife that is sharpened past 30 degrees will be very durable. Its cutting ability will be noticeably reduced. This durability has an advantage because more force can be used to make the cut. While the majority of knives won’t benefit from this sharpening angle, an edged tool like a machete, cleaver or axe must be durable as the typical cutting action of these tools would damage other edges.
The following article is from Lansky's website, and it talks about the various edge bevels you'll find on knives.
I put this in Knife Care, because these bevels sharpen differently, and some require more work than others to stay sharp.
Knife Edge Grinds and Uses
Flat
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
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
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
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.
Compound Bevel
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
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.
From "SharpeningSupplies.com", a primer on what the hell we actually mean when we talk about an edge bevel in terms of degrees.
Before getting into the detail, we’d like to make it clear how we talk about the angles on a knife. Most knives have a bevel on both sides. When we tell someone that they should put a 20 degree angle on a knife, we mean that they should sharpen each side to 20 degrees. This creates a total angle of 40 degrees. So when we’re talking about the angle on your knife, we’re talking about the angle at which you hold the knife to your stone.
The difference between a double and single bevel knife edge There are special cases where the total angle of the knife is not double the angle that you sharpen each side of your knife. Some traditional Asian knives are only beveled on one side. In this example, one side may be sharpened to 20 degrees while the other side is at 0 degrees for a total angle of 20.
However, in practice, we have found that the vast majority of Asian knives sold in the United States are not single bevel but rather traditional knives with a bevel on both sides. If you’re not sure, it is generally safe to assume that your knife has a bevel on both sides. Asian knives do typically have a slightly lower angle and both sides are sharpened to roughly 17 degrees.
Choosing and angle to sharpen your knife is essentially a compromise between the sharpness and the durability of an edge. The most important factor when determining the angle comes down to how you will be using your knife. Will you be shaving your face, filleting a fish, cutting vegetables, carving or chopping wood? From these examples, it is easy to see how each case requires a different edge.
Under 10 Degree Angles
The lowest angles are reserved for edges that are typically cutting softer materials. In this case, the edges are not subject to abuse so the lower angle can be maintained without damage or edge failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle which is roughly 7 to 8 degrees (although the back of the blade is used as a guide so knowing the angle isn’t important and nor is it adjustable). A straight razor has a very delicate edge that is very easy to damage. In proper usage, a straight razor would never see the type of use that would damage the edge.
10 to 17 Degree Angles
A sharpening angle of 10 to 17 degrees is still quite low for most knives. With a total angle of 20 to 34 degrees, this is still a very fine edge. This edge is typically too weak for any knife that might be used in any type of chopping motion. Also consider that harder steels are also more susceptible to impact damage because they are more brittle. If your knife is used for cutting soft items or slicing meats, this lower angle can hold up and provide a very smooth cutting action.
17 to 22 Degree Angles
A 17 to 20 degree angle covers most kitchen knives. Some knives (typically Japanese manufacturers) will sharpen their knives to roughly 17 degrees. Most western knives are roughly 20 degrees. It is our experience that kitchen knives sharpened to 15 to 20 degrees cut very well and are still durable. These angles are still not highly durable as a total angle under 40 degrees will not respond well to rougher treatment in harder materials.
22 to 30 Degree Angles
Most hunting and pocket knives are in this range, allowing them to resist the kind of treatment these knives are sometimes subjected to. Although an edge bevel in this range is less likely to burr or chip, some more effort is required to make deep cuts.
Over 30 Degree Angles
Any edged tool or knife that is sharpened past 30 degrees will be very durable. Its cutting ability will be noticeably reduced. This durability has an advantage because more force can be used to make the cut. While the majority of knives won’t benefit from this sharpening angle, an edged tool like a machete, cleaver or axe must be durable as the typical cutting action of these tools would damage other edges.
