I write this guide with the belief that the vast majority of edged tools ship from the manufacturer with an edge that is not always optimized for the tasks it will perform. This guide will detail how the end user can correct that to achieve superior performance out of their tools, cutting performance that is multiple times better than the original edge allows.
The first thing you need to decide with the knife or tool in question, is what will the function of the tool be? This is the single most important question when determining what edge to put on your knife. For example, a large splitting maul that will be used to bust apart frozen wood is going to need a thicker edge than a paring knife that is used to peel potatoes.
In determining how thin you will take the edge, consider what the most edge abusive task the tool is likely to encounter. If possible, you want to be able to directly test the knife on that material as you experiment with how thin to take the edge.
As an example, my EDC folders are not likely to do anything more intense than slicing very thick cardboard, cutting dense, rigid plastic and carving wood. Anything else I'm likely to cut with them is softer. For random things that need cut that could possibly damage a thinned out edge, I have a serrated H1 hawkbill on me at all times, which is an extremely tough steel, one of the toughest steels available on folding knives.
If you are not careful with your knives, or loan them out to people who might not be as careful as you are with them, you may wish to go a bit thicker just in case.
The second thing to consider, which is less important than the first but still a factor in deciding which edge to use, is the type of steel and the hardness. As a rule of thumb, the higher the hardness, the better suited the steel will be to thin edges. Also, the tougher the steel, the less likely it is to experience significant edge damage, so these steels can be taken thinner than weaker steels. A good example of a tough steel that can be taken very thin is the Scrapyard Dogfather in S7 steel, which with an optimized edge for wood chopping, can out-chop the factory edge 2:1 easily.
The third thing to ponder is whether or not you will use a microbevel on the knife or tool. I highly recommend them if you are at all interested in optimizing your knife edge, because using them you will be able to thin out the edge bevel much more than if you do not. To read about microbevels and why I think they ought to be used, you can read this guide.
Now you are armed with the knowledge you need to properly optimize your knife edge. To actually optimize it, you will need to adjust the edge angle according to the information detailed above. For this there are many tools available, such as belt sanders and low grit diamond benchstones. I suggest in using a tool such as these, or if you are not confident in your own skills you can ship the knife to Tom Krein or someone similar who will regrind it for you according to your requested thinness, or you can use a guided system, which usually takes much more time than using a diamond benchstone, not to mention a belt sander.
Degrees are a nice reference point when discussing edge angles with others, but at this point don't be concerned with them. All that matters is your tool, the steel, and what you will be using it for. Seriously, do not concern yourself with numbers at all, just look at the knife in front of you and observe. Measure when you're done with the process if at all.
I previously mentioned that an EDC folder of mine is likely to encounter nothing rougher than wood, cardboard and rigid plastic. So when reprofiling my knife, I keep a stick of seasoned, knotty hardwood handy, as well as thick cardboard and rigid plastic. I take the edge down, then cut these materials. I keep doing this process, gradually going thinner and thinner, until I see edge damage. By edge damage I mean tiny chips in the edge barely visible to the eye, if at all. I check by running my fingernail along the edge to feel for these small chips.
Once I'm at this point, I am faced with two options. I can sharpen at a slightly more obtuse angle and use the knife as is, or I can apply a microbevel, re-do the test, and if it passes take the edge thinner and re-apply a microbevel for the next test. The latter is what I do, because it allows me to go even thinner. For EDC knives, I have taken some as thin as 5 degrees per side with a microbevel at 15 degrees per side. This has stood up to carving knotty hardwood and slicing thick cardboard, so it works for me.
At this point you might be thinking, 5 degrees per side sounds awfully thin. Much thinner than the often recommended 20 degrees per side, which is disgustingly thick for a folding knife. If you are not accidentally (Or intentionally
) hitting metal, rocks, glass etc. with your knives, there is little reason you can't go as thin as say, 8 degrees per side for a small pocket knife. If you don't believe me, and have 50$, I have a challenge for you. Buy two Byrd Cara Cara's, one in plain edge, one in combo edge. The plain edged ones are, I believe, ground at 15 degrees per side, for a total edge angle of 30 degrees. So are the combo edged version, except the combo edged versions are only ground on one side, bringing the inclusive edge angle to a whopping 15 degrees. Go cut everything you would typically cut with a small folding knife with both of them, and see if either gets any damage. If the one ground at 15 degrees inclusive doesn't receive damage, then why would you want to keep the PE one at 30 degrees inclusive?
If you truly want to get the best performance out of your cutlery, this is exactly what I would advise doing. To not even attempt to optimize your edge defeats the purpose of spending large amounts of money on fancy blade steels in my opinion, and you would be well served using the most basic of knife steels with their factory edges.
If you do this, it is possible to get up to 4 times better cutting performance. If you don't believe this claim, please try this test which I've done over 20 times.
Get a bathroom scale, place it on a counter. Put something to be cut on it, like a cable, a strip of cardboard held vertically, an apple to cut in half etc. Cut the object, and note the pounds of force it requires. Reprofile the knife with an optimized edge, then repeat the test. The results will speak for themselves.
The first thing you need to decide with the knife or tool in question, is what will the function of the tool be? This is the single most important question when determining what edge to put on your knife. For example, a large splitting maul that will be used to bust apart frozen wood is going to need a thicker edge than a paring knife that is used to peel potatoes.
In determining how thin you will take the edge, consider what the most edge abusive task the tool is likely to encounter. If possible, you want to be able to directly test the knife on that material as you experiment with how thin to take the edge.
As an example, my EDC folders are not likely to do anything more intense than slicing very thick cardboard, cutting dense, rigid plastic and carving wood. Anything else I'm likely to cut with them is softer. For random things that need cut that could possibly damage a thinned out edge, I have a serrated H1 hawkbill on me at all times, which is an extremely tough steel, one of the toughest steels available on folding knives.
If you are not careful with your knives, or loan them out to people who might not be as careful as you are with them, you may wish to go a bit thicker just in case.
The second thing to consider, which is less important than the first but still a factor in deciding which edge to use, is the type of steel and the hardness. As a rule of thumb, the higher the hardness, the better suited the steel will be to thin edges. Also, the tougher the steel, the less likely it is to experience significant edge damage, so these steels can be taken thinner than weaker steels. A good example of a tough steel that can be taken very thin is the Scrapyard Dogfather in S7 steel, which with an optimized edge for wood chopping, can out-chop the factory edge 2:1 easily.
The third thing to ponder is whether or not you will use a microbevel on the knife or tool. I highly recommend them if you are at all interested in optimizing your knife edge, because using them you will be able to thin out the edge bevel much more than if you do not. To read about microbevels and why I think they ought to be used, you can read this guide.
Now you are armed with the knowledge you need to properly optimize your knife edge. To actually optimize it, you will need to adjust the edge angle according to the information detailed above. For this there are many tools available, such as belt sanders and low grit diamond benchstones. I suggest in using a tool such as these, or if you are not confident in your own skills you can ship the knife to Tom Krein or someone similar who will regrind it for you according to your requested thinness, or you can use a guided system, which usually takes much more time than using a diamond benchstone, not to mention a belt sander.
Degrees are a nice reference point when discussing edge angles with others, but at this point don't be concerned with them. All that matters is your tool, the steel, and what you will be using it for. Seriously, do not concern yourself with numbers at all, just look at the knife in front of you and observe. Measure when you're done with the process if at all.
I previously mentioned that an EDC folder of mine is likely to encounter nothing rougher than wood, cardboard and rigid plastic. So when reprofiling my knife, I keep a stick of seasoned, knotty hardwood handy, as well as thick cardboard and rigid plastic. I take the edge down, then cut these materials. I keep doing this process, gradually going thinner and thinner, until I see edge damage. By edge damage I mean tiny chips in the edge barely visible to the eye, if at all. I check by running my fingernail along the edge to feel for these small chips.
Once I'm at this point, I am faced with two options. I can sharpen at a slightly more obtuse angle and use the knife as is, or I can apply a microbevel, re-do the test, and if it passes take the edge thinner and re-apply a microbevel for the next test. The latter is what I do, because it allows me to go even thinner. For EDC knives, I have taken some as thin as 5 degrees per side with a microbevel at 15 degrees per side. This has stood up to carving knotty hardwood and slicing thick cardboard, so it works for me.
At this point you might be thinking, 5 degrees per side sounds awfully thin. Much thinner than the often recommended 20 degrees per side, which is disgustingly thick for a folding knife. If you are not accidentally (Or intentionally
) hitting metal, rocks, glass etc. with your knives, there is little reason you can't go as thin as say, 8 degrees per side for a small pocket knife. If you don't believe me, and have 50$, I have a challenge for you. Buy two Byrd Cara Cara's, one in plain edge, one in combo edge. The plain edged ones are, I believe, ground at 15 degrees per side, for a total edge angle of 30 degrees. So are the combo edged version, except the combo edged versions are only ground on one side, bringing the inclusive edge angle to a whopping 15 degrees. Go cut everything you would typically cut with a small folding knife with both of them, and see if either gets any damage. If the one ground at 15 degrees inclusive doesn't receive damage, then why would you want to keep the PE one at 30 degrees inclusive?If you truly want to get the best performance out of your cutlery, this is exactly what I would advise doing. To not even attempt to optimize your edge defeats the purpose of spending large amounts of money on fancy blade steels in my opinion, and you would be well served using the most basic of knife steels with their factory edges.
If you do this, it is possible to get up to 4 times better cutting performance. If you don't believe this claim, please try this test which I've done over 20 times.
Get a bathroom scale, place it on a counter. Put something to be cut on it, like a cable, a strip of cardboard held vertically, an apple to cut in half etc. Cut the object, and note the pounds of force it requires. Reprofile the knife with an optimized edge, then repeat the test. The results will speak for themselves.
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Thin 'em out and microbevel and always carry a serrated hawkbill in H1.
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