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This isn't definitive, it is simply a few things I have learned, seen, borrowed, etc... from all over ze internets, mostly from here though. Sharpening is at times made out to be this giant beast that is impossible to slay and I get it, when I first started learning how to convex a knife it was difficult, it didn't make a lot of sense, it was new and scary, but eventually you have to break down and jump in and just do the dang thing.
First, you decide what you want. A flat V edge, or a rounded Convex edge.
In the picture below, you have three typical grinds. The first is a v type of grind in that the edgemost portion looks like a "V". Knives that just have the vertical flats and a large v grind are "scandi" knives. We don't really deal with those much in terms of Becker knives, but it is useful to know they exist.
The middle design has a double bevel, so a flat vertical portion, then a long primary grind, then a short secondary grind. The transition between the primary and the secondary bevels is known as the shoulder. This comes into play here because most of the Becker knives have this style of grind, which, if you look at the edgemost portion, is also a v-grind.
The right shows a convexed shoulder, or what you can turn the middle one into with a little bit of work removing the sharp transition between the primary and secondary grinds. A full convex would be a smooth continuous curve from edge to spine that would mimic the shapes shown in an abstract way, but as it is incredibly difficult to manage to do with a Becker knife since we already have a flat then other bevels ground into the blade, we primarily concern ourselves with the middle or right designs as they are both easily achieved and maintained on a Becker knife.
So, the first question is, which do you want? The middle, or the right? Ffor most of us, it will be a choice between the middle, or the right.
I have more experience with the right, but the middle option is fairly easy so we will cover that first.
With any type of v-grind edge, your goal is to refine the secondary bevel to an apex between each side, typically at an angle such that it is "sharp". This is done by refining the faces of the secondary bevel, usually on a stone or other flat surface (ceramic plate, diamond plate, etc...).
To sharpen this, we mate the flat part of the secondary bevel to the stone.
These parts meeting up will refine the face of the secondary bevel, and as you alternate between sides, will refine the apex, or very tip where the faces meet, thus creating a sharp edge.
When sharpening on a stone I find it easier to cut into the stone as this leaves less chance for a "burr" to form, and also leaves only one direction of scratches to remove as you continually sharpen the blade.
Now, imagine a line drawn through the center of the blade from the edge through the spine. The angle at which the secondary bevel face meets the stone is the angle at which you are sharpening your knife. 20 degrees, 15, 17, etc... are all fairly common, but the angle choice ultimately ends up being up to you. The bigger the number, the bigger and more robust of an edge you are going to have. More material equals more stronger and thicker edge angles make for more material. However, too thick means they don't get as sharp, and in turn do not cut as well.
So given everything we have shown thus far, for a v-grind style of edge, the only thing you have to do is to refine the faces of the secondary bevel. That's it. This is achieved by running that face along a sharpening stone of some sort. You can go crazy with it, going through grits until you get a ridiculously sharp surface, or even a mirror polished surface, but ultimately all you are doing is refining the face against a solid surface until the apex between sides is sharp enough for what you want. This means that if you find something flat, and hard enough to abrade the steel you have in your knife, you can sharpen your knife on it. If it has a flat plane in at least one direction, it will work. This is how people are able to sharpen a knife on the bottom of a coffee mug, or the edge of a car window, or a rock they find in the woods.
Sharpening systems take variables out of the equation, so what you end up with is a fairly rock solid and reliable method to ensure you are getting the same results each time, but ultimately all you really need is a flat rock and a knife and you can get your knife sharp.
Moving on, now we tackle my preferred style and that is the mythical "convex".
Convexing a knife refers to relieving the transition between the primary and secondary grind or the "shoulder". (At least in terms of Becker knives. You could take convex to the extreme and convex it completely, but that is beyond what most of us really want or need in a production knife, and as such while it is possible, it is not done that often, and almost never without the benefit of a belt grinder.)
Convexing is vastly different than from sharpening a v-grind because it is even more variables. You have a curve, and a curve is not an easily measurable thing in the edge of a knife. Mostly though, convexing is in many ways an art rather than a science.
The benefits of this method are that it is very forgiving as all that it requires is smoothing that transition. Getting a Becker knife to this point is simple, and requires very little in the way of tools or equipment. I personally use a cheap nail file to remove this bevel, as shown in this thread here: http://www.bladeforums.com/forums/s...tory-edge-to-convex-with-the-BK2-(and-others)
Using the method shown in that thread will remove the shoulder but it does not get us any closer to "sharp" except in that we now have less material to deal with near the apex, which is the edge. Because we have a curve, the only parts we need concern ourselves with now after having removed the shoulder is the very edge, and this is easily done with a strop.
Again, I don't spend a lot of money, and make my own strops out of old belts (sometimes new ones, although any leather of a decent thickness should work) and wooden paint stir sticks (large sized ones) from Lowes. With some rubber cement it is fairly easy to whip up a strop on the cheap. See this thread here: http://www.bladeforums.com/forums/showthread.php/1120793-Make-a-strop-Part-1 (There is some great info in there about sharpening as well.)
A leather strop works because while it is fairly stiff, it has a definite give to it. Barber strops were not backed with wood, but for my purposes, I do just fine with a strop as shown in that thread (more accurately several).
My strops then have the face coated with a polishing compound, although there are again a plethora of options out there ranging from pastes to increments of fractions of a micron in diamond sprays, and anything inbetween. For typical use though, most of what you want to achieve can be done with easily purchased compounds. Typically they are available at sears or any other place that sells power tools, check near the bench grinders. You are looking for buffing compound, polishing compound, etc...
The compounds are color coded, and here is a fairly basic color chart, starting with coarsest to finest in terms of grit:
By their nature, strops have give. Any material that has a give can be used as a strop, so you will see some strops made out of cardboard, or leather, or even rubber padding. We will look at some alternatives later but for the purposes of this thread right now we are going to look at leather strops. Because a strop has give, the face will contour to your knife edge, and this makes it in my opinion the reason why it is so much more forgiving when sharpening a knife on one.
It is possible to hold your knife at the wrong angle, use too much pressure, and at the end completely screw up your knife. This will happen at some point. However, there are a lot of things you can do to alleviate these issues. First, take a sharpie marker to the edge of your knife. Not right on the edge, what you want to do is color the face of your convexed edge so that it is coated with marker. Then, after stropping a couple of passes, check to see that the strop is hitting the edge. Use a magnifying glass if you have access to one, as you can get really close to the edge without actually hitting the edge, and end up with a not very sharp knife without any real idea why.
So how does one strop a knife? Well first you pull the edge away from the strop, like so:
As you pull away, the strop material will abrade the curved face, towards the apex, and thus a sharp knife is created. By going through multiple levels of stropping, you will refine that edge further and further, getting you closer to what you will consider "sharp enough".
Sharpening does some interesting things to the edge of your knife though. By default, most Becker knives come with a 180 grit edge on them, and that is pretty rough, although definitely useable. As you progress in sharpening you will take it through higher and higher grits, thus refining the edge, but also refining the "teeth" that are formed as material is removed.
As shown in the image above, you will have something like the black lines with a rougher grit, and something like the red lines with a finer grit. This varies in shape and size a little bit but the illustration shows what is happening as you refine that edge on a microscopic level. Thus when you hear people refer to an edge as "toothy" you can imagine that it has longer teeth, which in turn is less refined than a smoother edge. For some, a toothy edge given from a strop with black compound is more than enough to do whatever they need to do with it. FOr others, they want the edge as refined as possible, and end up with super mirror polished edges. Whatever you choose, keep in mind there is no right or wrong end result in terms of grit, shininess, or anything else.
Let's look at the physical act of stropping the knife. The teeth shown above are formed when you pull the knife edge along the strop, and you have to be careful to align those teeth in a certain way to generate an edge that will cut the way you want. I like the middle ground, I want my knife to work well in a push cut or a pull cut, so I alternate my stropping to achieve these.
My strops are about an inch and a quarter wide by around eighteen inches long. This gives me a long slender strop that will work with larger recurve knives, or smaller knives, but not small recurve knives. I strop by starting at the ricasso, then moving towards the tip. Flip, repeat.
Then I start at the tip, move towards the ricasso, flip, repeat.
Alternating each time. If I wanted a knife specifically good at only pull cuts. I would only strop from tip to ricasso, and vice versa for a knife better at push cuts. I alternate though because I like a knife to work well for everything rather than be a master of one thing.
Aside from using sharpie to see where the marker is removed and seeing whether or not you are hitting the edge, you can also listen to the sound the knife makes as you move it down the strop. When you are hitting it at the right angle, you are going to hear a different sound than if you are just hitting the secondary bevel without hitting the edge. Pressure and angle are all that is needed to be modified to adjust this, and getting those two things down are the hardest part of stropping a convex knife.
So, what is the right angle for stropping? Well, that depends. I would get into it, but thankfully someone else here on the forums already covered it pretty well: http://www.bladeforums.com/forums/showthread.php/750008-Stropping-angle-plus-pressure
Keep in mind, while they are using a v-grind edge for demonstration, a convexed edge would work just the same.
That's it. Sharpening a knife is as easy as, well, all that, and to be honest it isn't the easiest thing in the world. It isn't the hardest though. A multitude of options exist, from expensive systems like the KME sharpener, to super cheap strops made out of free paint stir sticks and an old belt. They all work. So let's see some alternatives.
Tradewater showed us awhile back the method of using a drywall sander pad as a backing, then using automotive wet/dry sandpaper for the abrasive.
It has a hard flat backing, a foam pad to create give, and you can attach as fine a grit of wet/dry sandpaper as you want to pick your grit. Works great, costs very little, and is fairly safe given that it has a handle on the backside.
Nail files work too, as they are a known grit of sandpaper attached to a foam core with plastic backing. Cheap too. Great as field "strops" and easily replaced, and very easy to get ahold of.
You can convex on a waterstone, as shown in this video here:
http://www.youtube.com/watch?v=9z878bK-Xfc
Here is a thread dedicated to the perfect strop:
http://www.bladeforums.com/forums/showthread.php/1036649-A-balanced-strop
KME thread by Moose:
http://www.bladeforums.com/forums/showthread.php/971376-KME-and-BKT-s-A-sharpening-tutorial
Anyways, hope this thread helps, and if you guys have any questions, suggestions, different ways of doing things, etc... feel free to post them up, we are all here to learn and have a good time!
First, you decide what you want. A flat V edge, or a rounded Convex edge.
In the picture below, you have three typical grinds. The first is a v type of grind in that the edgemost portion looks like a "V". Knives that just have the vertical flats and a large v grind are "scandi" knives. We don't really deal with those much in terms of Becker knives, but it is useful to know they exist.
The middle design has a double bevel, so a flat vertical portion, then a long primary grind, then a short secondary grind. The transition between the primary and the secondary bevels is known as the shoulder. This comes into play here because most of the Becker knives have this style of grind, which, if you look at the edgemost portion, is also a v-grind.
The right shows a convexed shoulder, or what you can turn the middle one into with a little bit of work removing the sharp transition between the primary and secondary grinds. A full convex would be a smooth continuous curve from edge to spine that would mimic the shapes shown in an abstract way, but as it is incredibly difficult to manage to do with a Becker knife since we already have a flat then other bevels ground into the blade, we primarily concern ourselves with the middle or right designs as they are both easily achieved and maintained on a Becker knife.
So, the first question is, which do you want? The middle, or the right? Ffor most of us, it will be a choice between the middle, or the right.
I have more experience with the right, but the middle option is fairly easy so we will cover that first.
With any type of v-grind edge, your goal is to refine the secondary bevel to an apex between each side, typically at an angle such that it is "sharp". This is done by refining the faces of the secondary bevel, usually on a stone or other flat surface (ceramic plate, diamond plate, etc...).
To sharpen this, we mate the flat part of the secondary bevel to the stone.
These parts meeting up will refine the face of the secondary bevel, and as you alternate between sides, will refine the apex, or very tip where the faces meet, thus creating a sharp edge.
When sharpening on a stone I find it easier to cut into the stone as this leaves less chance for a "burr" to form, and also leaves only one direction of scratches to remove as you continually sharpen the blade.
Now, imagine a line drawn through the center of the blade from the edge through the spine. The angle at which the secondary bevel face meets the stone is the angle at which you are sharpening your knife. 20 degrees, 15, 17, etc... are all fairly common, but the angle choice ultimately ends up being up to you. The bigger the number, the bigger and more robust of an edge you are going to have. More material equals more stronger and thicker edge angles make for more material. However, too thick means they don't get as sharp, and in turn do not cut as well.
So given everything we have shown thus far, for a v-grind style of edge, the only thing you have to do is to refine the faces of the secondary bevel. That's it. This is achieved by running that face along a sharpening stone of some sort. You can go crazy with it, going through grits until you get a ridiculously sharp surface, or even a mirror polished surface, but ultimately all you are doing is refining the face against a solid surface until the apex between sides is sharp enough for what you want. This means that if you find something flat, and hard enough to abrade the steel you have in your knife, you can sharpen your knife on it. If it has a flat plane in at least one direction, it will work. This is how people are able to sharpen a knife on the bottom of a coffee mug, or the edge of a car window, or a rock they find in the woods.
Sharpening systems take variables out of the equation, so what you end up with is a fairly rock solid and reliable method to ensure you are getting the same results each time, but ultimately all you really need is a flat rock and a knife and you can get your knife sharp.
Moving on, now we tackle my preferred style and that is the mythical "convex".
Convexing a knife refers to relieving the transition between the primary and secondary grind or the "shoulder". (At least in terms of Becker knives. You could take convex to the extreme and convex it completely, but that is beyond what most of us really want or need in a production knife, and as such while it is possible, it is not done that often, and almost never without the benefit of a belt grinder.)
Convexing is vastly different than from sharpening a v-grind because it is even more variables. You have a curve, and a curve is not an easily measurable thing in the edge of a knife. Mostly though, convexing is in many ways an art rather than a science.
The benefits of this method are that it is very forgiving as all that it requires is smoothing that transition. Getting a Becker knife to this point is simple, and requires very little in the way of tools or equipment. I personally use a cheap nail file to remove this bevel, as shown in this thread here: http://www.bladeforums.com/forums/s...tory-edge-to-convex-with-the-BK2-(and-others)
Using the method shown in that thread will remove the shoulder but it does not get us any closer to "sharp" except in that we now have less material to deal with near the apex, which is the edge. Because we have a curve, the only parts we need concern ourselves with now after having removed the shoulder is the very edge, and this is easily done with a strop.
Again, I don't spend a lot of money, and make my own strops out of old belts (sometimes new ones, although any leather of a decent thickness should work) and wooden paint stir sticks (large sized ones) from Lowes. With some rubber cement it is fairly easy to whip up a strop on the cheap. See this thread here: http://www.bladeforums.com/forums/showthread.php/1120793-Make-a-strop-Part-1 (There is some great info in there about sharpening as well.)
A leather strop works because while it is fairly stiff, it has a definite give to it. Barber strops were not backed with wood, but for my purposes, I do just fine with a strop as shown in that thread (more accurately several).
My strops then have the face coated with a polishing compound, although there are again a plethora of options out there ranging from pastes to increments of fractions of a micron in diamond sprays, and anything inbetween. For typical use though, most of what you want to achieve can be done with easily purchased compounds. Typically they are available at sears or any other place that sells power tools, check near the bench grinders. You are looking for buffing compound, polishing compound, etc...
The compounds are color coded, and here is a fairly basic color chart, starting with coarsest to finest in terms of grit:
By their nature, strops have give. Any material that has a give can be used as a strop, so you will see some strops made out of cardboard, or leather, or even rubber padding. We will look at some alternatives later but for the purposes of this thread right now we are going to look at leather strops. Because a strop has give, the face will contour to your knife edge, and this makes it in my opinion the reason why it is so much more forgiving when sharpening a knife on one.
It is possible to hold your knife at the wrong angle, use too much pressure, and at the end completely screw up your knife. This will happen at some point. However, there are a lot of things you can do to alleviate these issues. First, take a sharpie marker to the edge of your knife. Not right on the edge, what you want to do is color the face of your convexed edge so that it is coated with marker. Then, after stropping a couple of passes, check to see that the strop is hitting the edge. Use a magnifying glass if you have access to one, as you can get really close to the edge without actually hitting the edge, and end up with a not very sharp knife without any real idea why.
So how does one strop a knife? Well first you pull the edge away from the strop, like so:
As you pull away, the strop material will abrade the curved face, towards the apex, and thus a sharp knife is created. By going through multiple levels of stropping, you will refine that edge further and further, getting you closer to what you will consider "sharp enough".
Sharpening does some interesting things to the edge of your knife though. By default, most Becker knives come with a 180 grit edge on them, and that is pretty rough, although definitely useable. As you progress in sharpening you will take it through higher and higher grits, thus refining the edge, but also refining the "teeth" that are formed as material is removed.
As shown in the image above, you will have something like the black lines with a rougher grit, and something like the red lines with a finer grit. This varies in shape and size a little bit but the illustration shows what is happening as you refine that edge on a microscopic level. Thus when you hear people refer to an edge as "toothy" you can imagine that it has longer teeth, which in turn is less refined than a smoother edge. For some, a toothy edge given from a strop with black compound is more than enough to do whatever they need to do with it. FOr others, they want the edge as refined as possible, and end up with super mirror polished edges. Whatever you choose, keep in mind there is no right or wrong end result in terms of grit, shininess, or anything else.
Let's look at the physical act of stropping the knife. The teeth shown above are formed when you pull the knife edge along the strop, and you have to be careful to align those teeth in a certain way to generate an edge that will cut the way you want. I like the middle ground, I want my knife to work well in a push cut or a pull cut, so I alternate my stropping to achieve these.
My strops are about an inch and a quarter wide by around eighteen inches long. This gives me a long slender strop that will work with larger recurve knives, or smaller knives, but not small recurve knives. I strop by starting at the ricasso, then moving towards the tip. Flip, repeat.
Then I start at the tip, move towards the ricasso, flip, repeat.
Alternating each time. If I wanted a knife specifically good at only pull cuts. I would only strop from tip to ricasso, and vice versa for a knife better at push cuts. I alternate though because I like a knife to work well for everything rather than be a master of one thing.
Aside from using sharpie to see where the marker is removed and seeing whether or not you are hitting the edge, you can also listen to the sound the knife makes as you move it down the strop. When you are hitting it at the right angle, you are going to hear a different sound than if you are just hitting the secondary bevel without hitting the edge. Pressure and angle are all that is needed to be modified to adjust this, and getting those two things down are the hardest part of stropping a convex knife.
So, what is the right angle for stropping? Well, that depends. I would get into it, but thankfully someone else here on the forums already covered it pretty well: http://www.bladeforums.com/forums/showthread.php/750008-Stropping-angle-plus-pressure
Keep in mind, while they are using a v-grind edge for demonstration, a convexed edge would work just the same.
That's it. Sharpening a knife is as easy as, well, all that, and to be honest it isn't the easiest thing in the world. It isn't the hardest though. A multitude of options exist, from expensive systems like the KME sharpener, to super cheap strops made out of free paint stir sticks and an old belt. They all work. So let's see some alternatives.
Tradewater showed us awhile back the method of using a drywall sander pad as a backing, then using automotive wet/dry sandpaper for the abrasive.
It has a hard flat backing, a foam pad to create give, and you can attach as fine a grit of wet/dry sandpaper as you want to pick your grit. Works great, costs very little, and is fairly safe given that it has a handle on the backside.
Nail files work too, as they are a known grit of sandpaper attached to a foam core with plastic backing. Cheap too. Great as field "strops" and easily replaced, and very easy to get ahold of.
You can convex on a waterstone, as shown in this video here:
http://www.youtube.com/watch?v=9z878bK-Xfc
Here is a thread dedicated to the perfect strop:
http://www.bladeforums.com/forums/showthread.php/1036649-A-balanced-strop
KME thread by Moose:
http://www.bladeforums.com/forums/showthread.php/971376-KME-and-BKT-s-A-sharpening-tutorial
Anyways, hope this thread helps, and if you guys have any questions, suggestions, different ways of doing things, etc... feel free to post them up, we are all here to learn and have a good time!
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