Knife Sharpening FAQ

Discussion in 'Blades' started by melbo, Dec 8, 2010.

  1. melbo

    melbo Hunter Gatherer Administrator Founding Member

    Here's a great article on sharpening knives. Joe Talmadge lays out a great process to keep and maintain your edge. I spent a few months tracking him down for permission to post this and finally received it tonight.
    by Joe Talmadge

    This FAQ has been improved immeasureably through the tests and discussions on rec.knives. I thank everyone who has engaged in sharpening debates over the years, I've grabbed ideas here and there from many of you.



    II. The Fundamentals of Sharpening - Getting a sharp edge - What angle? - What kind of stone? - Should I use oil or water on my stone? - How fine should my stone be? Important notes on grits! - Stropping - Using a steel

    III. Putting it all together - Freehand tips and tricks - Why does my knife go dull so fast? - Keeping bevels even - Putting it all together

    IV. Sharpening The "Differently-Ground" Blade - Those pesky serrated blades - The Moran (Convex) edge - The chisel-ground edge

    V. Overview of various sharpening systems - Clamp-on sharpening guides (Razor Edge, Buck, etc.) - Guide-and-Rod rigs (Lansky, Frost, etc.) - V-type sharpeners (Spyderco Triangle, etc.) - Other miscellaneous - Freehand sharpening, and its wondrous advantages!

    I. Introduction

    When I started writing this FAQ, I began by writing a detailed treatise on how to sharpen. I soon found that there was no way I could do this in the kind of detail I wanted without ending up with a book-length FAQ. As it turns out, someone has already written a book on sharpening, and done a better job than I could have done. So the most important part of this FAQ, for the beginner, is the following recommendation: the first thing you need to do is buy and read _The Razor Edge Book of Sharpening_ by John Juranitch. No matter what sharpening system you end up using, the fundamentals as laid out by Juranitch remain intact. I don't agree with Juranitch on everything, but the illustrations he gives really help with understanding the principles.

    So this FAQ will discuss the central elements of sharpening, and then go on to more detailed subjects. Sharpening angles, hones, sharpening systems, the latest fads in edges (e.g., chisel grinds), etc. Basically, Juranitch will show you how to get a burr and grind it off to end up with a sharp knife. Hopefully, the FAQ will tell you everything else.

    For many people, when they try to sharpen a knife, the knife actually gets duller! If it's any consolation, I was in the same boat at one time. The best way to start out is to read about the sharpening fundamentals, and then use some kind of sharpening system (discussed below) that pre-sets the angles. That way, you can begin by learning how to raise a burr, feel for the burr, and then grind it away, without having to worry about keeping the angle consistent as well. When you understand how to sharpen, then you can get rid of the rig, buy some flat hones, and learn how to sharpen freehand.

    II. The Fundamentals of Sharpening

    - Getting a Sharp Edge
    Okay I lied about not discussing the sharpening ritual itself. Here's a much-too-short review of the sharpening process, before we get into the rest of the FAQ. If this section is confusing, read _The Razor Edge Book of Sharpening_. Many of the subjects in this section (e.g., stone grits) are explored further elsewhere in the FAQ.

    You grind one edge along the stone edge-first until a burr (aka "wire") is formed on the other side of the edge. You can feel the burr with your thumb, on the side of the edge opposite the stone. The presence of the burr means that the steel is thin enough at the top that it is folding over slightly, because the bevel you've just ground has reached the edge tip. If you stop before the burr is formed, then you have not ground all the way to the edge tip, and your knife will not be as sharp as it should be. The forming of the burr is critically important -- it is the only way to know for sure that you have sharpened far enough on that side. Once the burr is formed on one side, turn the knife over and repeat the process.

    To re-cap, you've sharpened one side only until you felt a burr along the entire length of the opposite side, then you switched sides and repeated the process. I suggest you do not follow the directions that come with many sharpeners, of the form "Do 20 strokes on one side, then 20 strokes on the other". You go one side only until the burr is formed; if that takes 10 strokes or 50 strokes, you keep going until you get a burr, period. Only then do you flip the knife over and do the other side.

    Having raised a burr, our job now is to progress to finer stones, in order to make the edge smoother and remove the burr. So now we run the blade along the stone from end to tip, this time alternating sides with each stroke. Switch to a finer stone, and then do it again.

    Sometimes, the burr is turned directly downwards during sharpening, and since it is very thin and razor sharp, it seems like an incredible edge. This is called a "wire edge". But being fragile, it will break off the very first time you use the knife, leaving you with an extremely dull knife. If you seem to be getting good sharpening results on your knives, but they are getting dull very quickly with little use, you may be ending up with a wire edge. If that's the case, you'll need to be careful and watch out specifically for a wire edge; you should try progressing down to finer stones, try double-grinding the edge, and give the knife a quick stropping once you're finished (all these terms are explained below). If your knife is fading fast as you're sure it's not because you left a wire edge, steeling between uses may be what you need. My last few strokes on the stone become progressively lighter, to avoid collapsing the edge and raising another burr.

    On a badly-worn or damaged edge, I'll typically start with a medium (300-400 grit) stone, then move to a fine (600 grit) stone, and then sometimes I'll finish on an extra-fine (1200 grit) stone if I want a more polished edge. However, once my knife is sharp I try to re-sharpen before it gets too worn down. In that case, I can usually start on the fine stone. But be sure to read the important notes on grits later in the FAQ.

    Lastly, I may use a leather strop on the knife.

    On other sharpening systems, the same fundamentals as laid out above still apply. For example, on a V-type sharpener, I'll start by sharpening one side only against the right-hand stick until a burr forms. Then I switch to the other stick until a burr forms. Only after I've raised a burr from both sides will I follow the manufacturer's directions and alternate from one stick to the other between strokes.

    - What Angle?
    The smaller the angle, the sharper your knife will feel. But the smaller the angle, the less metal that's behind the edge, and thus the weaker the edge. So your sharpening angle will depend on your usage. A surgeon's blade will have a very thin, very low-angle edge. Your axe will have a strong, thick, high-angle edge.

    Something like a razor blade will having an angle of around 12- degrees, and it's chisel-ground so that's 12-degrees total. Utility knives will have angles anywhere between 15- and 24- degrees (30-48 degrees total). An axe will have something around a 30-degree angle.

    For double-ground utility knives, a primary edge of 15-18-degrees, followed by a secondary grind of 21ish-degrees, works well. Don't be obsessed with getting the exact right angle; rather, make sure that at whatever angle you've chosen, concentrate on holding it precisely.

    See also the sections on convex edges and chisel-ground edges.

    - What Kind of Stone?
    Basically, a stone needs to cut metal off the edge. The stones below do this well, and for most of us our time would be better spent actually learning how to sharpen than worrying too much about the minor advantages of one stone vs. another. Get the biggest stones you can afford and have room for. Big stones make the job much much easier.

    The time-honored stone is the arkansas stone. Soft arkansas stones provide the coarser grits, with harder stones providing finer grits. Many people use oil on these stones, ostensibly to float the steel particles and keep them from clogging the stone. John Juranitch has popularized the notion that oil should absolutely not be used when sharpening, and indeed results from people using arkansas stones without oil have been very positive. However, if you have ever used oil on your arkansas stone, you need to continue using it, or it will clog. If you never put oil on your arkansas stone, you will never need to.

    Synthetic stones are very hard, and won't wear like natural stones (a natural stone may get a valley scooped out of it over time). They clean well with detergent-charged steel wool, I use SOS detergent pads, they clean very very fast and very well. I know you're thinking that cleaning with steel wool will cause the stone to shear off the steel wool and fill up the stone even worse! But I assure you that is not the case, for whatever reason SOS pads clean synthetic stones, they do not make the stones dirtier. Spyderco and Lansky are some manufacturers who sell synthetic stones.

    Stones with diamond dust embedded in them cut aggressively. You can remove metal very quickly if you need to, but be careful lest you remove too much too fast! DMT, Eze-Lap, and Lansky are some manufacturers who sell diamond-based hones. Some diamond stones have the problem that the diamond dust wears off quickly, leaving you with a useless stone. I have experience with the DMT stones, and can say that they do not have this problem.

    Japanese water stones come in some very high grits -- I've seen all the way up to 8000! These stones are very expensive. The stones sit in a water bath, and a slush forms on top that helps the final polish. Don't know any manufacturers, but Bob Engnath and Gorilla & Sons both sell Japanese water stones.

    Both Japanese water stones and natural stones will eventually dish out in the center with use. To flatten them back out, put some sandpaper on a flat surface and rub the stone top on it. Wet/dry 400 grit sandpaper mounted on a table top or glass is reputed to work well.

    - Should I Use Water or Oil on My Stone
    John Juranitch has popularized the notion that no liquid should be used on the sharpening stone. Since oil has been used for many years on stones, this leads to some confusion.

    Basically, the purpose of the stone is to rub against the blade and remove metal. Slippery liquids, like water and especially oil, make the rubbing slicker, causing less metal to be removed, causing sharpening to take longer. On top of that, Juranitch claims that as your edge is being sharpened on the stone, the oil-suspended metal particles are washing over the edge and dulling it again.

    On an arkansas stone, the oil is supposedly needed to float metal particles away from the stone surface, lest the stone clog and stop cutting. Some people on this group have used their arkansas stones without oil or water, and have reported good results. However, if you've already used oil on your arkansas stone, you'll probably need to keep using oil forever on it, because an already-oiled stone will clog up if not kept oiled. If you have a fresh arkansas stone, go ahead and use it without the oil, and things should be okay.

    I've used diamond and synthetic stones without liquid, and they worked just fine.

    Japanese water stones are the one type of stone that need water. The stones are designed to work with water, and as you sharpen a small amount of the stone's material breaks off and forms an abrasive slurry along the top.

    In any case, the bottom line is: use liquid or don't. Using the liquid will make the sharpening process slower and messier, but if you insist on using liquid and are willing to spend more time, that's your call. If you don't have the skill to hold a consistent angle, it's all moot anyway!

    - How Fine Should My Stone Be? Important notes on grits!
    The finer the stone, the more polished your edge will become. The rougher the stone, the more the scratches in the edge function as "micro-serrations" (see also the serrated vs. plain edge FAQ). Though the actual ontological status of the micro-serrations is debatable (Juranitch says there's no such thing, having looked under a microscope), the serrated effect of the coarser grind is undoubtably there.

    The more polished the edge, the better your edge will work for doing push-cut applications like shaving, whittling, peeling an apple, skinning a deer. Also, your cut will be more clean and precise with the polished edge.

    A rougher, more micro-serrated edge will work better for slicing-type applications like cutting through coarse rope, wood, etc. The serrations present more edge surface area, and tend to "bite" into the thing being cut.

    It is possible to get an edge that will shave hair with a medium (300-400 grit) stone, with practice [I specifically mention stone grits because many manufacturers call the 300-400 grit stones "coarse" rather than "medium"]. The medium stone will have pretty big micro-serrations. In previous version of the FAQ I stated that I find this too rough a finish for my general utility edge. However, I've since found this to be a really nice edge finish for utility work -- it won't shave great, but it does a really nice job on cutting coarse materials.

    Anyone should be able to get an edge that shaves hair easily with a fine (600 grit) stone. I find this to be a pretty useful finishing stone, leaving enough micro-serrations for general utility work but still being hair-shaving sharp.

    An extra fine stone (1200 grit) should start polishing the edge, and you should end up with a hair-popping sharp edge. This is also a good choice for a general utility finish, especially on a partially-serrated blade, where the serrations can be used when the slightly-polished main part of the blade becomes less effective.

    One can buy Japanese water stones with grits up to 8000, which leaves a polished edge that's so sharp, your hairs will jump off your arm when they see the edge coming. I would question this finish on an everyday utility knife which might be called upon to cut through a thick rope or what have you, but it is a finish that works well when a polished edge is called for.

    ************* IMPORTANT TIP ****************
    - Stropping
    Stropping consists of running the edge along a piece of leather charged with some kind of abrasive like stropping paste or green chromium oxide (I had previously said jeweler's rouge is okay, but have since heard that a more aggressive cutter is needed). It is done for a short time to finish off the burr, or for a long time to give the edge a final polish. Stropping is an easy-to-use finishing step (as opposed to the difficulty in keeping a consistent angle on a stone).

    Before you strop, remember to wash and dry your newly-sharpened knife. If you don't, you might grind leftover metal particles into the strop itself. If you need to charge your strop, put a little paste on your fingers and rub it into the leather.

    To strop, you run the edge along the leather with the blade positioned spine first and the edge trailing (opposite way from sharpening on a stone). With a thin straight razor, the spine of the razor is always kept on the strop, and direction is switched by flipping the razor over along its spine. In my experience, this isn't necessary with a utility knife. You can strop with the blade spine raised above the leather (don't lift too high -- if the edge bites into the leather, that's too high), and change directions by lifting the entire knife up, turning it over, and placing it back down.

    If you've never stropped your knife before, give it a try. It will come out very sharp, but of course polished and so optimized for push-type shaving cuts. The strop to some extent can make up for less-than-perfect sharpening technique -- a sharp knife can be made extra sharp on the easy-to-use strop. However, I always tell people that they should be able to get their knife scary sharp without the strop; don't let the strop keep you from recognizing weaknesses and improving your technique on the hone!

    In the absence of a strop (say, out in the field), many people use their jeans and then their palm as a strop. There's probably no need to point out the danger in this practice, so don't do it. That said, I must admit to having done this myself on numerous occasions, and having gotten good results.

    A safer and more effective trick is to use cardboard (say, the cardboard back of a standard notepad). You can optionally charge the cardboard with metal polish, just rub it in with your fingers. Then strop as above. Even without the polish, the cardboard will strop acceptably. Stropping with cardboard has become a de-facto standard last step for sharpening chisel-ground (single-side ground) knives these days, for burr removal purposes.

    - Using a Steel
    The sharpening steel should be an important part of your knife maintenance strategy, and is maybe the most mis-understood part.

    When you use a knife for a while, especially a knife with a soft, thin edge like that found on a kitchen knife, the edge tends to turn a bit and come out of alignment. Note that the edge is still reasonably sharp, but it won't feel or act very sharp because the edge may not point straight down anymore! At this point, many people sharpen their knives, but sharpening is not necessary and of course decreases the life of the knife as you sharpen the knife away. It's also akin to putting in a thumbtack with a sledgehammer.

    The steel is used to re-align the edge on the knife. Read that last sentence again. Re-aligning the edge is all the steel needs to do. It does not need to remove any metal. Since the steel's only function is to re-align, the sharpening steel can be perfectly smooth and still do its job. You'll see many bumpy steels on the market, but this is almost certainly because consumers think that steels must have bumps to work. The bumps can actually mess up the edge, and make the work of steeling more difficult.

    There are two schools of thought on steels. Some people use grooved steels, which align the edge more aggressively but are harder on the edge. I use a smooth steel, which is easy on the edge but may align the edge more slowly.

    To use the steel, run the knife along the steel on one side using light pressure -- no more pressure than the actual weight of the knife is required! Then switch to the other side and do it again. Repeat a number of times until your edge feels sharp and nice again. I hold the steel in my left hand, the blade in my right, and lightly run the blade along the steel while keeping the steel stationary, but it's perfectly fine to move both steel and knife past each other at the same time, or whatever works for you.

    Most people run the knife down the steel edge first, the same direction you use when sharpening. This yields good results. However, theoretically going edge-first along the steel could bite into the edge while straigtening it, and so many people like to go spine-first (like when stropping) instead. This method also works well, and I personally have begun to feel that steeling in this direction gets my edge the tiniest bit sharper. It is more awkward to go spine-first, so if you have any trouble with it switch to edge-first, and your edge will end up just fine.

    If you steel your knife every time you use it, you will significantly lengthen the time between sharpenings. I've found steeling to be critical on kitchen knives, but it's an incredible help even on ultra-hard ATS-34.

    III. Putting it all together

    - Some tips and tricks
    If you want to determine if you are sharpening at the same angle that the blade already has, try this easy trick. Mark the edge bevel with a magic marker. Then go ahead and do a stroke or two on the stone (or take a stroke with your Lansky, or whatever). Now pick the knife up and look at the edge. If you have matched the edge angle exactly, the magic marker will be scraped off along the entire edge bevel. If your angle is too high, only the marker near the very very tip will be gone. If your angle is too low, only the marker near where the edge bevel meets the primary bevel will be gone.

    Another trick is to use light and shadow to get the edge precisely. Using strong directly light, lay the edge down on the stone and watch the shadow below. As you tilt the spine up, the edge contacts more of the stone and the shadow disappears. As the shadow just disappears and the edge just touches the stone, that's your angle. If you go higher than that, you should be able to see the edge tilting over onto the stone.

    One trick to freehand sharpening is to use your thumb as a guide. I'll place the spine of the blade against my thumb pad, and rest my thumb on the stone. That way, I can feel the angle between the knife and stone, and make sure that it is consistent. Typically, the hardest part to freehand sharpen is the curving belly of the blade, as keeping a consistent angle here is more difficult.

    I use all these tricks extensively when sharpening freehand, and use the marker trick even when I'm using a sharpening rig.

    One thing to keep in mind is that there's no reason you need to keep the factory edge. If you're happy with that edge, great. However, many factory edges are too thick to really cut well. If you're unhappy with the cutting ability of your knife, don't be afraid to try lowering the angle a bit.

    - Why does my knife go dull so fast?
    A frequent complaint I hear is, "I sharpened my knife and did a good job, it was really sharp. But then after just a few uses it went dull." Why does this happen?

    One of the following factors -- and many times a combination of those factors -- is at play:

    1. Wire edge If the burr is not properly ground off, but is instead turned downwards, your knife will feel razor sharp. However, the burr quickly turns or snaps off, leaving you with a very dull-feeling knife. Be sure to use a light touch at the end of the sharpening process and make sure the burr is gone.

    2. Thin, weak edge If the bevel angle you chose for your knife is too thin for your usage, the edge can chip and get really wavy. Try using a larger edge angle, or at least double-grinding the edge.

    3. Edge turning In regular use, all edges turn to some extent. If your edge is much too thin, it will be damaged as above in #2. If it's only slightly too thin, it will quickly turn out. As long as the the edge is not being damaged, but simply turning, you don't necessarily need to re-grind a thicker edge. Instead, see if frequent steeling will give you the performance you need, it can really work wonders. Keep in mind it's difficult to see a turned-out edge by eyeball -- only using the steel will tell you conclusively if this is your problem.

    4. Thick edge A thin edge will feel sharper than a thick edge. If your edge is too thick, when it starts to dull even the slightest bit it may no longer feel so sharp anymore. Consider using a lower angle and seeing if that helps. Of course, your thinner edge will be more fragile than the thicker edge, so you may end up chipping the edge out, and the thinner edge may not be feasible. I personally feel that this is rarely the real problem, so be sure to try the other solutions first.

    5. Soft steel Occasionally, a manufacturer or maker will make a mistake while heat treating, and the steel in the blade will end up too soft. No matter how well you sharpen, your blade will still go dull quickly. Often, soft steel is the first thing people point at when their edges dull quicker than expected. But this problem really is relatively rare; in the vast majority of cases, it is one of the above reasons rather than soft steel that's the problem. So if your edge dulls too fast, don't blame the steel until you've exhausted the above options. If it's still dulling quickly, contact the manufacturer, they are often interested in testing to see if they made a mistake.

    - Keeping bevels even
    With the burr method of sharpening, one side of the knife can end up with more metal taken off it than the other side. This forces the edge to be not-quite-centered. This normally doesn't affect performance, but aesthetically it doesn't look quite right. This happens because as you grind the one side to create the bevel, it has to go far (that is, lots of metal has to be removed) to create the bevel on the other side. When you flip to the other side, the edge is already thin, so very little metal has to be removed to flop the burr back over. There are a few ways to avoid this.

    First, you can just switch which side you start sharpening on. If you start with the edge that's on the right side of the blade, that edge bevel will be a little bigger than the one on the left side. So next time you sharpen, start off on the left side. You can pick which side to start your sharpening on by just using whatever side seems to have a smaller edge.

    The method I use is to switch sides while trying to get the initial burr. If I start on the right side, I'll sharpen for 20 seconds or so and then check for a burr. If no burr is found, I switch to the left side and repeat. I keep doing this -- sharpening one side for a time, then the other side -- until I finally start to feel a burr. Then I just follow the normal directions: I keep sharpening that side until the burr goes the entire length of the edge, then flip and get a burr along the entire length of *that* edge. The fact that I'm flipping the knife keeps the edge bevels even.

    - Putting it all together
    As you use your knives, you may see your sharpening strategies change. Many of us seem to be homing in on the philosophy that you should choose the thinnest, coarsest edge possible that can do your job without the edge being damaged, especially in the context of general usage.

    Thin blades and low-angle edges seem to cut better than thick ones. They slide through the material being cut with less effort. Which makes sense -- the wider the V that your edge forms, the more metal you're pushing into the material. However, go too thin and your edge can chip out. So go as thin as you can without damaging your edge, and use a steel often to touch it up. Obviously, what "thin" means depends on usage. "Thin" means one thing when the job is slicing soft materials, something else entirely when chopping hard materials. Lightly double-grinding a shallower bevel on a thin edge may help give you the best of both worlds. If your first bevel is a thin 15-degrees (say), try doing a few light finishing strokes at a stouter 24-degress.

    Coarser edges slice better than polished ones, but a polished edge will laterally push-cut (e.g., shave) better. If you find yourself doing a lot of lateral push cuts, then you'll obviously want to polish your edge more. However, most people do much more slicing than push cutting, and as a result end up with a much more polished edge than optimal. You should play around with coarser grits. The edge won't do as well shaving hair, but unless this particular knife is a razor blade, who cares? You may find the knife cutting through other materials much better than usual.

    Lastly, I have become something of a steel fanatic. Steeling your knife frequently -- even if the blade is of really high-hardness steel -- works wonders on the edge. It also allows you to have a slightly thinner (and hence better-cutting) edge, because if you steel frequently you'll keep the edge aligned. If you don't steel at all, you'll have to use an edge that's thick enough not to turn, and that may negatively affect sharpness and cutting power. Remember to steel frequently, because if your edge's shape gets too bad, the steel won't work and you'll have to go back and sharpen.

    IV. Sharpening The "Differently-Ground" Blade

    - Those Pesky Serrated Blades

    It is not that difficult to sharpen the Spyderco-type serrations, or the typical serrations on a bread knife. Both the Lansky rig and Spyderco's Triangle-Angle Sharpmaker have special hones meant to sharpen serrated blades. A triangle-shaped hone rides along the grooves. Although I can't quite get my serrated knives as sharp as they come from Spyderco's factory, I do get them extremely sharp, and am satisfied with the results. Don't let fear of sharpening scare you away from serrated blades.

    I have not tried it, but the above systems supposedly work for Benchmade-type reverse serrations. Cold Steel's tighter serrations would seem to present more of a problem. Cold Steel sells Spyderco's Tri-angle Sharpmaker as the solution to sharpen their serrations, so this would seem the logical system to try.

    Others claim to get excellent results from the tapered diamond-coated rods that are being sold to sharpen serrated knives. The disadvantage of these is that you have to sharpen each serration separately.

    For those curious about how a custom maker might serrate an edge, here's a quote from A.T. Barr:

    When I make a serrated blade, I first grind the cutting edge down to approximately .020. I then use two files. A 1/8" round file and a 3/16" chain saw file. I then use a course DMT diamond rod that is tapered from about 1/16" to 1/4". I use that to put the final edge on before heat treating. After heat treating I again use the same DMT rod to clean up the scale. I put the blade (if a folder) or wrap the handle (if a sheath knife) in a vise in a horizontal position. You're right, it is not easy, but you can do it.

    - The Moran (Convex) Edge
    Named after Bill Moran and featured on many of Blackjack's knives, the Moran edge (aka convex edge) is, well, convex. Usually, an edge is a straight bevel over the last millimeter or two of the knife. With a convex edge, the edge continuously curves towards the very point. The advantage is that there's more metal behind the edge, so you end up with a very sharp but strong edge, which needs to be felt to be believed. Knifemakers typically create this edge with a slack belt, which leads us to the disadvantage: if you don't have a slack belt grinder and the know-how, you'll need to return your knife to the maker for sharpening periodically.

    If you buy an unfinished tanto blade from Bob Engnath, you'll see that edge consists of 3 distinct straight grinds, each more acute than the one before. When hand-finishing the tanto, the junctures between the grind angles disappear, and you end up with a convex edge.

    Some people simulate a convex edge by double- or triple-grinding the edge. That is, after they've ground the edge, they change the bevel angle and grind a bit more. This is easy to do with Lansky-type rigs and the Razor Edge type clamps. It results in a superb edge. But it is not quite the same thing as a convex edge.

    Some people use the term "rolled edge" to mean a convex edge. As such, a "rolled edge" is a good thing. But most people use the term "rolled edge" to mean a wire edge -- that is, an edge that is not an edge at all, but a burr that's been turned down. A wire edge will be razor sharp, but will break off and leave your knife dull the first time you use it. When used this way, "rolled edge" is a bad thing. So when you hear the words "rolled edge", you'll need to listen carefully to the context. If the speaker is using the term approvingly, a convex edge is meant; if the speaker is using the term disapprovingly, a wire edge is meant.

    - The Chisel-ground Edge
    Phil Hartsfield has for years been making tantos with a chisel grind, but Ernest Emerson's CQC-6 design and Benchmade's Emerson-designed 970 have really popularized the grind. Typically, the blade is an Americanized tanto format that's ground on one side only (the other side comes straight down). An edge bevel is ground from the middle of the blade and goes all the way through the edge. It is extremely sharp.

    The chisel ground edge owes it sharpness to the fact that the edge bevel is typically ground at around 30 degrees. Since the opposite side of the blade is essentially at 0 degrees (it comes straight down with no bevel), that's a total of 30 degrees + 0 degrees = 30 degrees edge angle. With a more traditional edge, you'll typically have each bevel being ground at around 20 degrees, so that's 20 degrees + 20 degrees = 40 degrees total edge angle.

    To sharpen the chisel-ground edge, you'll place the entire edge bevel on the stone and grind it until a burr is formed. Many people then strop the edge on a piece of cardboard on the other side, to remove the burr. Optionally, you can lay the flat side *flat* on a fine stone and do a little grinding from that side as well (something guaranteed to mar the finish). If you can't bear to mar the finish that way, lay the flat side as flat as you can -- maybe 5-degrees off the stone at most. What is critically important is to not grind a big second angle into the back (flat side) of the blade. The chisel grind's sharpness arises from the acute angle formed between the front bevel and the flat back. You can then try to use decreasing pressure to grind off the burr, and finishing with a steel provides really nice results.

    Hartsfield and many other believe that for a right-handed user, the edge bevel should be on the right side of the knife (that is, the side that faces you when the knife tip is pointing to the right). Following Emerson's lead, most makers are grinding the left side of the knife instead, apparently because that's where the maker's stamp is traditionally positioned, and advertisements look better if the stamp and edge are on the same side.

    To see why the grind should be on the right side for a righty, think about trying to make a precise cut in, say, a carrot, or a piece of material, or whatever. If you're like most righties, you want to hold the work in your left hand and cut with your right hand. If the knife is ground on the right side, then the flat part of the blade is the part you can see, and you can make sure the flat part of the blade is exactly along the line you want to cut. If the grind is on the left side, the material is diving underneath the bevel, and it's difficult to eyeball whether or not you're cutting in the right place. This adds to the chisel-ground tanto format's existing problems: 1) no belly, and as such not the best general utility format, and 2) unsymmetrical grind, making precise cutting difficult.

    The most popular chisel-ground folder, the Benchmade 97x series, uses a 30-degree secondary grind to form the edge [Note: Benchmade uses a secondary bevel; most custom makers bring the primary bevel all the way down to the edge]. The Lansky system includes a 30-degree position, but for some reason most users have found that the angle is not quite right (it's unclear at this time whether it's Lansky or Benchmade whose angle is not precisely 30 degress). Some Lansky users on rec.knives has fashioned an extension to the Lansky system to get the proper grind angle for the 97x, by extending the post using plastic from a milk carton. The Edge Pro, a similar but much more expensive system, will get the 97x's angle properly.

    V. Overview of Sharpening Systems
    The first three systems discussed below all give outstanding results, if the enthusiasm of rec.knives people is any indication. Some other methods of sharpening are discussed in the miscellaneous section. The last section discusses the advantages of freehand sharpening, and why it's worth attaining this skill even if you're happy with whatever system you have.

    - Clamp-on sharpening guides (Razor Edge, Buck, etc.)
    The clamp-on guide fastens to knife blade itself. It is used in conjunction with a standard stone (arkansas stone, diamond stone, synthetic stone, etc.). It is used with the exact same techniques as you would use to sharpen freehand, the guide making sure that all your angles are held perfectly. If the blade has a belly, the guide should be positioned in the right place in order to keep a consistent angle through the entire edge grind; the instruction booklet should illustrate that.

    The most popular clamp-on guide is the Razor Edge guide. I've already told you that the Razor Edge sharpening book is indispensible, but it's especially important if you decide to use this system. Actually, on top of that, buy the Razor Edge video as well. It is a huge advantage to actually see someone on video applying the techniques, and I can't recommend the video highly enough.

    An advantage of this system is that because you are using the exact same motions as you would during freehand sharpening, proper motion is put into muscle memory. After several months of using this system, I found that even the mechanically-inept (like myself) could do a good job sharpening freehand. See below for the advantages of freehand sharpening.

    The disadvantage of this system is that one never knows at what angle they are sharpening. For most of us, knowing the exact sharpening angle probably isn't an issue.

    - Guide-and-Rod rigs (Lansky, Gatco, DMT, etc.)
    Very popular are the Lansky-type clamp-and-rod rigs. The knife is held in a clamp, and the back of the clamp protrudes upwards and has a number of holes in it. The hone is attached to a rod. By putting the rod through one of the holes in the clamp, you can control the sharpening angle you're using. Most of these systems have around 5 holes, corresponding to 5 different grind angles. Double-grinding your edge should be very easy with this system.

    One thing to watch out for is that simple geometry will tell you that as you sharpen parts of the knife that are further from the clamping point, the angle of sharpening will change. To sharpen a very long knife, you may need to unclamp it and move it several times during sharpening. The system works extremely well for short knives, however.

    A number of hones are supplied, corresponding to different grits. Flat hones are used for plain blades. Some rigs have a triangular hone available to sharpen serrated blades.

    The Edge Pro Apex system is roughly this type of system, but is of higher quality and price (retailing around $125). It also provides greater angle granularity than the rest. Although the price seems high, you should seriously consider this system. By all reports, the quality of the system is up to the price, it is very accurate, no multiple re-clampings need to be done.

    - V-type sharpeners (Spyderco Triangle, etc.)
    Typically the V-type sharpeners have ceramic sticks stuck into a plastic base at a preset angle. The knife is held perpendicular to the ground (a position which most people seem to be able to do easily), and ground down the side of the sharpener. The system is easy to use, but obviously the angle is preset. If you want to use a different angle, you're out of luck. If your knife's edge has been ground at a different angle than the V, the first time you sharpen it the new angle will be ground in.

    Different ceramic sticks are supplied corresponding to different grits. One Spyderco Tri-angle sharpmaker model also has diamond sleeves that fit over the sticks and function as a coarser hone.

    - Other miscellaneous
    A number of ceramic or diamond-coated sticks are available. They are often marketed as steels, but since they remove metal they do not actually function anything like a proper steel, and should be considered sharpeners instead. Since there's obviously no angle guide of any kind, some skill is needed to keep the angle consistent. If you've got the skill, these sticks work just fine.

    There are a number of gadgets with pre-positioned round "hones" (like Accusharp) that meet to form a V. You draw the knife straight through the sharpening mechanism. Your knife will come out sharper, but some believe that repeated use of these products will harm the edge, as they often work by chipping out the edge. If that's true, your knife will be hurt in the long run. In addition, because no relief is ground into the blade each time, it will gradually become harder and harder to sharpen your edge with these gadgets, until finally you must spend some time on a benchstone thinning the edge back out properly.

    The are electric sharpening machines that have rotating stones, sometimes in a water bath. They supposedly work fine. Be *very* careful, however. With some steels, it is very easy to heat up the steel and ruin the temper of the blade on these electric machines, even in the cold water bath. Pull the blade off the machine and check it for warmth frequently. In addition, these machines can remove metal very fast. It's easy to sharpen your knife away.

    - Freehand sharpening, and its wondrous advantages!
    Sharpening freehand has some advantages to it, provided you have the skill to actually get a satisfactory edge. Perhaps the best advantage is that you don't have to go hunting around for hex keys, screws, nuts, or any other little thing that might get lost from of your sharpening rig. Nor do you need to waste time clamping, screwing, and bolting your knife into various rigs. If your knife just needs a quick touch up, swipe it on a stone and you're done.

    More importantly, if you're doing something where weight becomes an issue (backpacking, etc.), you probably aren't going to want to lug around your sharpening rig. I go out into the backcountry with my knife and a small lightweight 3"x1" diamond hone, confident that I can use my knife hard and touch it up no problem.

    Lastly, there's a certain satisfaction in attaining the skill to sharpen a knife hair-flinging sharp, especially when previously your sharpening efforts seemed to make the knife duller!

    Happy sharpening!

    Joe can be contacted by PM at the candlepower forums.

    Attached Files:

    Last edited: Feb 1, 2014
    Hanzo and probie like this.
  2. Bear

    Bear Monkey+++ Founding Member Iron Monkey

    Wow!... nice article...
    Still learning to sharpen my knives... someday I'll get it right :0)
  3. Goldwampum

    Goldwampum Monkey+

    Thanks for this article. I have a lansky recently purchased and do some free hand but this is going to help a lot. [winkthumb]
  4. kckndrgn

    kckndrgn Monkey+++ Moderator Emeritus Founding Member

    Very nice, tagged for later reading.
  5. Falcon15

    Falcon15 Falco Peregrinus

    Tagged and printed too! [winkthumb] Adding this to my Preppers Bible.
  6. TXKajun

    TXKajun Monkey+++

    Outstanding article. Well done and thank you.

  7. melbo

    melbo Hunter Gatherer Administrator Founding Member

    Glad you like it. I found it to be very thorough yet easy to read and understand.
  8. Hispeedal2

    Hispeedal2 Nay Sayer

    Truly a lost art. I use water stones and take my time.
    Brokor likes this.
  9. Equilibrium

    Equilibrium Monkey++

    I would prefer purchasing non-electrical tools and appliances when possible. In your opinion, would this product be appropriate for someone who basically has kitchen knives, pocketknives, and a few hand axes to sharpen; Diamond Hone Sharpening System | Smith's - The Edge Experts? I am very open to suggestions. BTW, wonderful tutorial on sharpening knives.
  10. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    The article claims that you must use oil on your whetstone once you start using it. This is not entirely true. In recent years, Smith's has come out with a honing solution (that's what it is called) which will clean your whetstone and condition it, removing any foreign metal particulates. The article also suggests that you should use the Arkansas stones dry. This is not true at all. It will be up to you to decide for yourself, it's your stone and your time. Over time, the stone will wear much faster and can clog up with metal shavings. Because of the Smith's honing solution, I can use water, oil, or honing solution with my Arkansas stones any time now. Traditionally, once you use oil, you want to keep it that way since oil and water don't mix and it will cause the stone to clog up. With the honing solution, however, this is no longer a problem.

    Try it out and see for yourself. Good luck!

    YouTube - Smith's Honing Solution @
  11. Equilibrium

    Equilibrium Monkey++

    The stone I taught myself on was inherited from my brother. He used oil. I remember him using it. I didn't have any oil so I used water. Evidently that was a mistake but.... my kitchen knives are sharper then they were but I'm sure they're not as sharp as they could be. I know I need more than just a coarse stone which is all I have. After getting the "feel" for how to sharpen "experimenting" on my kitchen knives, I'd like to move onto my hand axe which is in sore need of sharpening. Will that Diamond system I found be sufficient to sharpen my hand axe and sport knives and what ever else is laying around here if I use the Smith brand honing formulation you suggested? I did notice the old stone is clogged with metal dust if that's what it's called. I suppose I screwed it up when I tried to get the metal dust out of it with a potato brush.
  12. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    Get some honing fluid (soak the stone with the fluid) and wipe it with a DRY 100% cotton canvas cloth or something similar. Do not rub the stone vigorously. Do that a few times and then soak it in warm, but not terribly hot water. Give the stone a final dousing of fluid to let it soak in, it should be good as new...unless you really screwed it up.

    I do not know what type of diamond sharpening stone you have. It would help if I knew. If it is too small, it will not sharpen as well as a larger sharpener since it will not cover the entire blade of the tool well enough, but with a little ingenuity, just about anything can work in a pinch. Heck, the best whetstones are only -rocks, afterall. It is true their qualities are unique, and only the best are found in Arkansas, but you would be surprised what you can sharpen a blade with. Ebay for an inexpensive stone if you still need one. You would probably want a MEDIUM grit whetstone. I don't suggest investing in anything else until you get accustomed to the medium stone. Besides, the medium stone will do most of your sharpening and suits nearly all your needs anyway. The only reason you will need a more coarse stone is when you are working with a really, really torn up blade with rough edges, we're talking serious deficiency. The fine and extra fine stones are nice to have, but they require more subtle technique and should not be used by the beginner in my opinion due to fact that it's an extra process in sharpening and if you can't get a good edge with the medium, you're only wasting your time and money invested in it.
  13. ghrit

    ghrit Bad company Administrator Founding Member

    ETA: Honing fluids are over the top for roughing edges into decent shape. Honing is a step toward really fine edges, and not usually necessary for kitchen tasks. Now, when you get to razors and your Katana, then fine Arkansas stones or Japanese water stones want something a bit above oils.

    Other than that, Brokor and I are in (amazing!!) agreement.
    Brokor likes this.
  14. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    Forgot to mention that dawn dish detergent works well also to clean a stone.
  15. Equilibrium

    Equilibrium Monkey++

    Ohhh.... thanks you two for so many wonderful tips. I am going to need time to absorb some of this. I definitely need to sharpen my axe... it's seen better days. I whacked into a nail and then some embedded barbed wire when I was girdling some large Norway maples and it did a number on my axe. Broker> "I do not know what type of diamond sharpening stone you have." I don't know either.... it's attached to a piece of wood and it's much coarser than a little tool I have that I've been trying to sharpen an old apple corer/slicer with. My oldest brother died and it was one of the few things I took other than his cats. It reminded me of him and I forgot I had it until some of my knives started getting dull. ghrit> I'm fresh out of "genuine samuri Katana with carborundum" (smile). I'm also fresh out of "High quality blades" All I've got are the run of the mill type knives and such unless my husband or one of the boys has something high-quality. They could... I just don't know.

    adding something.... I might have ONE higher quality blade. I bought a multi-tool Leatherman Surge a coupla days ago.
  16. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    Pretty good multi-tool. It's steel is 420HC, which is an okay hardness, but I can't find any info on whether or not it is heat treated. Depending upon this factor, the edge may hold up adequately but would do far better if heat treated to a Rockwell hardness of around 55-58. In any case, you will just have to try it out. As far as blades are concerned, for the money it's not a high quality one, but I still have my old Leatherman Wave and it will probably keep working for a long time to come. I love the way they are built, but I am not a fan of the steel, especially the edge retention aspects. It's not bad, and our tools could be different even though they are most likely the same steel, so don't be worried it's not good enough. Still, in my opinion, it's better than the S30V Kershaw steels. Now, I had to research for a minute to get the RW hardness info, and I am not sure of the heat treating info with Leatherman multi-tools as I said, but if anybody does know for certain, feel free to chime in.

    If you get a blade with 154CM, that's when you will see a difference because that's the stuff of legend. ;)
  17. Equilibrium

    Equilibrium Monkey++

    There was another multi-tool by Gerber that I had in my hand. It was $40 cheaper. There was a gentleman standing next to me looking at the Leatherman multi-tools too and he told me he'd gone through two Gerbers so far and that the problem with them was losing tips off the needlenose pliers. He said he hadn't had that problem with the Leatherman so he was buying one for his son. I thanked him and put the Gerber back. Another man volunteered that he'd lost the tip off his Gerber too. Hmmm.... two Gerbers at $60 a piece is $120 or one Leatherman at $100. Gosh it's great being female and over 50 sometimes!!! I get all this wonderful unsolicited help when I'm shopping in "manly" places and it saves me $$$ having to make a second trip because I don't have to drive home and "research" before buying. I don't buy much but when I do.... I prefer to get the most "appropriate" tool for me that's going to last. That Leatherman negates the need for me to pack up oodles of tools. The only thing it didn't have was a nail file which I've got on my pocketknife. I looked at the packaging for you and no mention of whether it's heat treated or not.
  18. Hispeedal2

    Hispeedal2 Nay Sayer

    Depending on the blade, I start with an Arkansas type stone set. I estimate the fine grit around 600. I then move to Japanese water stones. I use an 800 and then like a 6000 to hone. I use oil on the Akansas stones and, of course, water on the water stones. I take every knife up to 6000 grit. We use mostly carbon steel knives. I fine honed edge lasts a lot longer than one without. The trade off is the time it takes to sharpen. Our kitchen knives last some 2 months before they need resharpening.

    I would like a water stone between 800 and 6000. Working up with less strokes on a single stone is a lot easier than making large jumps. It's easier on the stones too.

    There are several good sources for water stones. Ebay has a great selection.

    Another method that I am about to try is sand paper. Extremely fine grit sand paper glued to a glass tile. I already bought several grits and some tiles. I will let you guys know how it goes.
    Brokor likes this.
  19. Seacowboys

    Seacowboys Senior Member Founding Member

    I use a 4000 and 8000 grit water stone to sharpen my straight razors. A hollow-ground razor is designed to lay flat on the stone to achieve the proper angle. I use a pyrimid stroke between the stones when sharpening. One stroke on the 4000 grit equils two one the 8000 grit so if a razor is dull, I might start out with five strokes on the 4000, ten on the 800, four one the 4000, eight on the 800, three on the 400 and so on. It is very important to keep the stones wet.
    percival likes this.
  20. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    GAH! You mean 8000 and 4000. A lot of "oopsie" moments there.
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