Post by Lobster on Feb 17, 2016 14:17:07 GMT 3
Sharpening vs. honing
Sharpening is defined by the act of grinding material off the blade’s edge. The process of sharpening includes setting a bevel so that both sides of the blade form a symmetrical edge. Knives with a chisel grind have a bevel on one side of the blade only.
Sharpening requires a low grit, coarse medium. Sharpening leaves the blade’s edge rough with what is known as a wire edge. A wire edge is a thin microscopic edge that is very sharp but also very weak.
The process of honing uses finer grit to refine the rough surface of the edge and slowly polishing the wire edge away
The most important thing when sharpening or honing a blade is to maintain a consistent angle of contact between the knife and the sharpening medium. This presents the greatest challenge when sharpening or honing any blade. Use a sharpie and paint the cutting edge with it. That gives you a perfect visual reference as to what angle you are holding the blade. If all the sharpie is removed from the edge, the angle is right, if not adjust accordingly.
The angle of the bevel
The angle of the bevel is always a compromise between the sharpness and the durability. The lower the angle, the weaker the cutting edge will be. Therefore it is very important to choose the angle according to the intended use of a blade. Do you want to shave or curt through drywall, filleting fish or chop wood? Each case requires a different edge.
Angles below 10 degrees
The lowest angles are used on edges that are cutting soft materials, where the edge is not subject to force and abuse so the edge can be maintained without damage or failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle of 7 to 8 degrees. A straight razor has a very delicate edge that is very easy to damage.
10 to 17 Degrees Angles
A sharpening angle of 10 to 17 degrees is still quite low and still a very fine edge. This edge is typically too weak for any knife that might be used in any type of chopping but might be applied for special kitchen knives.
17 to 22 Degree Angles
Generally cover kitchen knives. Knives sharpened to 15-20 degrees cut very well and are durable but still won’t respond well to rougher treatment.
22 to 30 Degree Angle
Make the knife’s edge considerably more durable. A pocket knife or a hunting knife will inevitably see abuse so this bevel is common in EDC knives.
Angles above 30 Degrees
Any edged tool or knife that is sharpened past 30 degrees will have a very durable edge but its cutting ability will be noticeably reduced. High impact tools like machetes, cleavers and axes are ground at these high angles.
What to use for sharpening & honing
Sharpening stones are used freehand or guided. Many different kinds of stones are available, some stones are natural, others are synthetic. Some stones require oil or water on them, some can be used dry. The great advantage of stones is that you can sharpen any size of blade with them, from the smallest to the largest. While it takes practice to master, most people agree that stones yield the best results for a proper sharp edge.
Guided sharpeners are contraptions the enable you to maintain a constant fixed angle during sharpening and honing giving a consistent result. Some are rod guided, others clamp onto the blade to maintain the desired angle. There are many DIY systems to be found on the Internet.
A unique system worth mentioning is the Sharpmaker, where 2 triangular sharpening rods are inserted into a base forming a V shape at a predetermined angle. The blade is then swept downwards in a slicing motion against the rods.
Slot sharpeners are used in kitchens and as pocket field sharpeners. They usually have tungsten or ceramic rods or wheels aligned in a slot and you pull the knife through the slot to sharpen it. Tungsten slot sharpeners tend to pinch the edge and rip out steel from the blade leaving a ragged edge that cannot be honed properly. Ceramic ones can work well for honing but they don’t sharpen.
A wide variety of power tools for sharpening available, ranging from small battery powered ones to bench grinders and belt sanders. These machines tend to remove a lot of steel and can damage a knife when too much heat is created during the sharpening process so they should be used with care. A popular option are paper wheels that can be mounted on a bench grinder. They allow for very quick sharpening and a honing without excess heat being applied to the blade and they yield great results.
Sandpaper A cheap but very effective method for knife sharpening is to affix sandpaper to an even surface like a tile or sheet glass and sharpen your knife just like you would with a stone. Sandpaper can be used freehand or with a guided system and it works for sharpening and honing. Some people use sandpaper on a computer mouse pad using a trailing stroke. The trailing stroke is great at removing small burrs. The flex of a mouse pad also allows you to create convex edges.
Stropping is drawing the edge along a leather or canvas strip that can be treated with an additional rubbing compound. Stropping removes any burr or false wire-edge and it's what barbers are doing when they run their straight razors up and down leather belts. This is the finishing touch for a very sharp edge.
A word about the steel
Generally speaking, the cheaper the steel, the easier it is to sharpen and hone because it is not as hard as high end steel. Knives like the Swiss Army Knife or Opinel are made from inexpensive, soft steel. And while they don’t retain an edge very well, they can be made from dull to very sharp in a matter of minutes. The modern super steels used by some knife manufacturers are much more resilient and have excellent edge retention, They don’t need to be sharpened and honed that often but when the time comes, they take a lot more work and time so this might become a problem when you are out in the field.
There are always exceptions and variations but here is a rough guide listing various blade steels according to the time it takes to sharpen them, 1 being the slowest and 3 the qickest:
1: S110V, S90V, M390, ZDP-189, CPM 20CV, M4, Elmax, D2
2: S35VN, S30V, 154CM, ATS34
3: VG10, N680, 440steels, 13C26, AUS-8, 8Cr13MoV, 1095
Sharpening is defined by the act of grinding material off the blade’s edge. The process of sharpening includes setting a bevel so that both sides of the blade form a symmetrical edge. Knives with a chisel grind have a bevel on one side of the blade only.
Sharpening requires a low grit, coarse medium. Sharpening leaves the blade’s edge rough with what is known as a wire edge. A wire edge is a thin microscopic edge that is very sharp but also very weak.
The process of honing uses finer grit to refine the rough surface of the edge and slowly polishing the wire edge away
The most important thing when sharpening or honing a blade is to maintain a consistent angle of contact between the knife and the sharpening medium. This presents the greatest challenge when sharpening or honing any blade. Use a sharpie and paint the cutting edge with it. That gives you a perfect visual reference as to what angle you are holding the blade. If all the sharpie is removed from the edge, the angle is right, if not adjust accordingly.
The angle of the bevel
The angle of the bevel is always a compromise between the sharpness and the durability. The lower the angle, the weaker the cutting edge will be. Therefore it is very important to choose the angle according to the intended use of a blade. Do you want to shave or curt through drywall, filleting fish or chop wood? Each case requires a different edge.
Angles below 10 degrees
The lowest angles are used on edges that are cutting soft materials, where the edge is not subject to force and abuse so the edge can be maintained without damage or failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle of 7 to 8 degrees. A straight razor has a very delicate edge that is very easy to damage.
10 to 17 Degrees Angles
A sharpening angle of 10 to 17 degrees is still quite low and still a very fine edge. This edge is typically too weak for any knife that might be used in any type of chopping but might be applied for special kitchen knives.
17 to 22 Degree Angles
Generally cover kitchen knives. Knives sharpened to 15-20 degrees cut very well and are durable but still won’t respond well to rougher treatment.
22 to 30 Degree Angle
Make the knife’s edge considerably more durable. A pocket knife or a hunting knife will inevitably see abuse so this bevel is common in EDC knives.
Angles above 30 Degrees
Any edged tool or knife that is sharpened past 30 degrees will have a very durable edge but its cutting ability will be noticeably reduced. High impact tools like machetes, cleavers and axes are ground at these high angles.
What to use for sharpening & honing
Sharpening stones are used freehand or guided. Many different kinds of stones are available, some stones are natural, others are synthetic. Some stones require oil or water on them, some can be used dry. The great advantage of stones is that you can sharpen any size of blade with them, from the smallest to the largest. While it takes practice to master, most people agree that stones yield the best results for a proper sharp edge.
Guided sharpeners are contraptions the enable you to maintain a constant fixed angle during sharpening and honing giving a consistent result. Some are rod guided, others clamp onto the blade to maintain the desired angle. There are many DIY systems to be found on the Internet.
A unique system worth mentioning is the Sharpmaker, where 2 triangular sharpening rods are inserted into a base forming a V shape at a predetermined angle. The blade is then swept downwards in a slicing motion against the rods.
Slot sharpeners are used in kitchens and as pocket field sharpeners. They usually have tungsten or ceramic rods or wheels aligned in a slot and you pull the knife through the slot to sharpen it. Tungsten slot sharpeners tend to pinch the edge and rip out steel from the blade leaving a ragged edge that cannot be honed properly. Ceramic ones can work well for honing but they don’t sharpen.
A wide variety of power tools for sharpening available, ranging from small battery powered ones to bench grinders and belt sanders. These machines tend to remove a lot of steel and can damage a knife when too much heat is created during the sharpening process so they should be used with care. A popular option are paper wheels that can be mounted on a bench grinder. They allow for very quick sharpening and a honing without excess heat being applied to the blade and they yield great results.
Sandpaper A cheap but very effective method for knife sharpening is to affix sandpaper to an even surface like a tile or sheet glass and sharpen your knife just like you would with a stone. Sandpaper can be used freehand or with a guided system and it works for sharpening and honing. Some people use sandpaper on a computer mouse pad using a trailing stroke. The trailing stroke is great at removing small burrs. The flex of a mouse pad also allows you to create convex edges.
Stropping is drawing the edge along a leather or canvas strip that can be treated with an additional rubbing compound. Stropping removes any burr or false wire-edge and it's what barbers are doing when they run their straight razors up and down leather belts. This is the finishing touch for a very sharp edge.
A word about the steel
Generally speaking, the cheaper the steel, the easier it is to sharpen and hone because it is not as hard as high end steel. Knives like the Swiss Army Knife or Opinel are made from inexpensive, soft steel. And while they don’t retain an edge very well, they can be made from dull to very sharp in a matter of minutes. The modern super steels used by some knife manufacturers are much more resilient and have excellent edge retention, They don’t need to be sharpened and honed that often but when the time comes, they take a lot more work and time so this might become a problem when you are out in the field.
There are always exceptions and variations but here is a rough guide listing various blade steels according to the time it takes to sharpen them, 1 being the slowest and 3 the qickest:
1: S110V, S90V, M390, ZDP-189, CPM 20CV, M4, Elmax, D2
2: S35VN, S30V, 154CM, ATS34
3: VG10, N680, 440steels, 13C26, AUS-8, 8Cr13MoV, 1095