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How to sharpen a knife

Discussion in 'Knives' started by LinuxHack3r, Dec 22, 2010.

  1. LinuxHack3r

    LinuxHack3r Empty Pockets

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    I remember as a kid I was really good at sharpening a Buck 110. That's the only knife I've really been able to put an edge on. Now I get confused with concave, convex, and hollow ground and however many more there may be. I need some sort of literature I suppose to read. I have a few knives that came razor sharp from the factory, and would like to return them to that. I probably will need some sort of sharpening gear, and I'm not afraid to spend a few bucks if need be. So....please...enlighten me to this world...

    Sent from my Droid using Tapatalk
     
  2. avgeekjlb

    avgeekjlb Empty Pockets

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    IMHO you can't go wrong with a lansky sharpening kit. They hold your knife and the stones at the proper angle. Start with the medium coarse and work down to extra fine. I use a lansky kit with my kershaw and the edge lasts for months nicely...

    avgeekjlb
     
  3. DaPro

    DaPro Loaded Pockets

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    I have been doing my knives with a 1"x30" belt grinder, then to a strop....I normally do a convex edge...but I have been looking into a different setup

    Spyderco Sharpmaker or DMT stone set

    More so leaning towards the sharpmaker

    :shrug:
     
  4. sonny

    sonny Empty Pockets

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    There may be many fancy blade grinds, but you only have to sharpen the edge end.
    For curvy edge like recurve, I carry an rat-tail diamond stick for field sharpening.
    It works for straight and serrated edge as well.
     
  5. CDR_Glock

    CDR_Glock Loaded Pockets

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    That is what I use. I can make a blade razor sharp.
     
  6. fire65

    fire65 Loaded Pockets

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    I have to agree with the Lansky, especially for beginners. I love mine and I have been sharpening for years. It really helps when resetting the angle. Also rub the edge with a magic marker so you can see what you are removing.
     
  7. iacchus

    iacchus Loaded Pockets

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    Doesn't schrade make an edgepro knockoff? Looks to be a great alternative for someone who doesn't want to spend the money on the real thing.
    I don't reccomend them for general upkeep, it is sorta overkill for that (really, IMO so is the lansky), but makes reprofiling a breeze.

    Once a good edge is on it, a crock stick or pasted strop can keep it tuned up for months, depending on how hard you are on your blades, of course.

    Sent from my A854
     
  8. Mad_Maxx

    Mad_Maxx Loaded Pockets

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    make your self a strop
    take some leather or foam, a wood block and some sand paper

    my setup (from my convex guide on another italian forum)

    some foam (1/2mm thick if I recall) on a woodblock that holds the sandpaper firm
    [​IMG]

    [​IMG]

    other strops and papers (3/3,5 veg tan)
    [​IMG]

    color the edge
    [​IMG]

    lay flat and rise a bit
    [​IMG]

    [​IMG]

    check edge and angle

    [​IMG]

    [​IMG]

    sand, strop and you get this
    [​IMG]

    [​IMG]

    also see the BRK convex guide
    http://www.barkriverknives.com/convex.htm

    this is the knife
    Denis Mura backup in A2
    [​IMG]

    cheers
    Maxx
     
  9. iacchus

    iacchus Loaded Pockets

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    Too true. My favorite "system" is the edge-pro, and I use it when I do not want to spend the time w/ bench stones. Even it takes patience and time to get good with. I have seen people buy one, use it once and proclaim it is crap. I guess they thought it would magically sharpen the knife for them.
    There is no super quick way, besides paying an expert. Any system worth its salt will take some time for you to get comfortable with and produce results you are happy with. Hell, benchstones are a "system", just less complex than most.

    As for angle of the bevel, this is something one should keep in mind. My "dress knives" get a thinner bevel than my "work knives". The dress knives will rarely cut more than packages and string, light duty...maybe some food. The work knives will cut shingles, door frames, tar, you name it. I need them to stand up to more, and sacrifice some of the slicing to get the endurance. The intended use of the knife is an important consideration before deciding on re-profiling the edge to a different angle.


    **Edit**

    I just want to add, I think it is great that we have a resource here to post sharpening questions to (and GHawks for crafts, and the other professionals we get to hang out with here).
    I get by with my blades, mainly because I cant afford to have all my blades sharpened by professionals (I learned that after starting to use a straight razor, it gets expensive when hired out), so I took the time to learn how to do it myself. I get better as time goes on, but it takes years and years and thousands of blades sharpened to be really good at it. Words of advice and encouragement from folks who have been doing it so much longer than me has helped me tremendously. I would have never caught on to the intricacies of straight razor sharpening without advice from Lynn Abrams at SRP.

    My point being, I suppose, that Jon has a place that attracts some really skilled and knowledgeable people, and I am very happy to be able to glean some knowledge from those here who so freely share it.
     
  10. LinuxHack3r

    LinuxHack3r Empty Pockets

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    I understand that one cannot simply "but equipment" to make a knife sharp, but I need equipment to start, I believe! Is this the edge pro you speak of, basically a very nice version of the Lansky?
    http://www.edgeproinc.com/
     
  11. iacchus

    iacchus Loaded Pockets

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    That is the one.
    It is a lot more expensive than the Lansky or Smith's versions, but I much prefer it. The main thing is that the edgepro does not use a clamp to hold the knife in place.
    A lot of people like the Lansky, though. I only tried it once, so I cannot say too much about it. I think DMT makes a version as well.

    There is always the Spyderco sharpmaker, as well. I have an interesting relationship with the sharpmaker. I like it, but rarely use it. I have bought it and sold it twice. Bought another one yesterday, and will just keep it this time. Hell, I might even use it now and again.

    Sent from my A854
     
  12. DaPro

    DaPro Loaded Pockets

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    I just ordered a sharpmaker myself....kinda want to try something different, I do everything convex at the moment.

    Here is a bad pic of a CRKT Ryan 7 I received today, sharpened it with my lansky kit

    [​IMG]
     
  13. tower
    • In Omnia Paratus

    tower Loaded Pockets

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    I've had my eye on the Apex4 Edge Pro for some time now. Maybe Santa knows this. I'd like it mostly for my kitchen knives, some of which are even chipped. I want to get a strop for my Fallkniven (convex edge). As Maxx said, the trend these days is to use ultrafine grit wet/dry sandpaper over a mousepad, or the like, so that the abrasive conforms to the blade shape. This is only for covex edges or knives you wish to reprofile to convexity. But mostly, I think I'd like a strop to touch up. Most of my knives don't get that bad.
     
  14. tower
    • In Omnia Paratus

    tower Loaded Pockets

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    All very true, which is why I'm leaning more & more toward convex profiling.
     
  15. iacchus

    iacchus Loaded Pockets

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    Convexing dfinately has its place. The edge will perform a little differently, and some prefer the ease of sharpening using the sanpaper/mouse pad technique.
    I have always preferred a standard primary/secondary bevel on most of my knives, but it is really just a matter of preference. I like stones and ceramics for my sharpening, If only because I feel that I am working towards a skill with each sharpening session.
    Maybe one day I will bite the bullet and invest in some Japanese waterstones like Tourist has. They aren't cheap...but from all reports are worth the money.
    As it is now, I would feel like the guy who just started learning to play guitar and buys a '69 Les Paul. Until I get the muscle memory and technique I want, Arkansas stones, ceramics, and DMT products will have to do.

    Sent from my A854
     
  16. JonSidneyB
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    JonSidneyB Uber Prepared
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    Wait, that is going to totally dependent on what you plan on doing with the knife in the wilds. The wilds are not a once size fit's all answer. It it also well known that harder typlical gets you brittle but there are many applications harder is better as well as softer is better so long as it is not too maleable. The super thick knives being common is a relatively resent thing but they have a place and are very good thing for something but remember, the mountainmen and people that make their living away from civilization typically used relatively thin blades, Green River comes to mind. Now they were fully capable of making thick blades as they did have axes. This is going to depend on what you plan on doing out there and conditions.

    I have all the respect in the world for good soldiers but this is not a valid arguement on the efficacy of one grind over another. If we are talking grind alone and everything else is caeteris paribus and the grind was even somewhat suitable to the job at hand I would not be expecting any failures resultant to the grind unless it was hollow ground. The fact that they had no failures or convex edges does not put things to the test.

    The traditionsl Japanese blades tend to be convex ground, sometimes similar to a Moran convex grind. I think Moran might not deserve having a grind related to him.

    The basic grinds.

    Hollow, from a mass production standpoint cheap to make, from an individual standpoint, if you have a wheel and guide it is quick and easy.
    These edges can be super sharp. These edges are also weaker. Weak edges are not bad for some things but they are weaker than the other grinds all else being equal. You can get them super sharp. Stright razors where not always hollow ground, the flat grind was once the common grind on these. Convex also appeard on straight razors. There are many people very anti hollow ground, I am not anti hollow ground as long as it is used for something it is suitable for. I would dare say most hollow ground knives in use are a forum of a compound grind.

    A flat ground blade gives up some edge strength, it involves more grinding. It is not to say it is weak, it just gives up some edge strength but not like a hollow grind does. Flat ground blades can still be terrific slicers.

    A saber grind is not as good of a slicer but can be good enough. It is stronger than a flat ground blade all else being equal. There are compromises in everything. If I want to favor cutting power comparing a saber grind to a flat ground blade I would go with a flat grind, if I wanted to favor edge strength I would go with a saber grind. Pick which is most important to you. We could break this down to a high flat or low flat saber grind. A low flat is commonly used as a wood cutting knife and is easy to maintain.

    A compoiund grind is quite common, many of you put a compound bevel on your knives by simply sharpening it. Actually I would guess this is the most common we see out there after we sharpen it with a flat object. Many come this way.

    A convex ground, It does put more metal behind the edge all else being equal. It is the strongest edge all else being equal. Some will argue that it cannot be taken to the extremes of sharpness but it can be sharp enough to make a fuzz stick out of a single human hair, that is pretty sharp by most standards. The convex grind became rare as it took more time for a factory to put the edge in place. I am not going to say it is the best for everything. I can say it takes more time using modern manufacturing methods.

    The convex was used in amputation equipment in the past, it was used in the Roman Gladius, it was used on the Katana. It is a very old grind but it not as industrial age friendly to produce.
     
  17. JonSidneyB
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    Now to sharpening.

    There is not much magic about sharpening but there is skill involved if doing it by hand.

    The secret to sharpening with a flat stone is consistency of the angle and not using excessive pressure.

    Lansky tools allow you to sharpen with a relatively consistent angle. The reason I saw relatively consistent is there is play in it, the clamp system does have some flex to it and the further you get from 90 degrees the steeper the angle. The longer the distance from the knife edge to the guide for the rod the less the variance will be but it is still there.

    Using a guide is better than most people can hold with their bare hands. Now just because you use a knife a little bit does not always mean it needs to be resharpened, quick work on a steel, ceramic, or strop can bring the cutting abilty back often times without taking off a bunch of metal.

    You do need to determine what grin you are using and what angles you want.

    Polishing the edge can make it sharper. The sharpest edge I have ever done myself is with some Flitz, a home made guide, a soft cotton polishing wheel and a dremel tool. I made a block to hold the knife and a guide to keep the dremel tool the parallel to the surface and to stay the same elevation. I let the edge go towards the edge rather than away from it and gently polished the edge till it looked like a mirror. I could easily cut cig paper held supported by one corner with it and have shaved a beard with it. Other people produce sharper edges but that has been good enough for me.

    A convex edge is a bit different but there are tons of videos on how to do that.

    There is no magic to this, it does take skill if done by hand but aids will help make things as sharp as most people will really need.

    I am going to go get some pictures of hair whittling.
     
  18. JonSidneyB
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    Here is what TwinBlade is able to do with a slack belt. the top one was done with a huge Hudson Bay camp knife and the lower one done with an Escort, both convex ground. Is this the sharpest out there. Nope but sharper than most and more than sharp enough for most tasks. It is hard to make fuzz sticks from a hair with a larger knife.

    [​IMG]

    [​IMG]
     
  19. JonSidneyB
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    JonSidneyB Uber Prepared
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    Now some caveats. There are a lot of guys that can do this in these forums. There are some debates on what is the absolute best but if you just want a sharp knife there is no mystery, either tools or some skill to do it freehand.

    One the grinds. We can take extreme examples and nullify much of what I posted on grind lines.

    Lets say we take a 2x2x10 block of steel to grind into a knife. If we use a flat grind we don't have much of a taper. Now if we took a sheet 12 inches wide and 1/8 inch thick we have a very acute angle. It is possible to have a saber grind with a more accute angle than a flat grind if the metal is of different thicknesses and the distance from the spine to the edge is wider.

    All the statements about grinds is assuming all else is equal. As we start changing dimentions other things change as suitability is concerned.

    We can have any of the grinds be a very good slicer if the blade is thin enough though some grinds will still have an advantage.

    Now a very poor lathe cutting steel to a knife carving wood analogy (because it really does not work exactly this way). We can turn steel such that we get red hot long ribbons of steel that looks like we could use it as razor wire fencing or we can have relatively cool chips breaking off by how the cutting operation is done. With a knife we can cut in a manner that cutting and prying apart are happening at the same time. We can also have it slicing off long thing slivers.

    We can shave with an angle that does not look like it can cut butter if the edge is adequately polished but it is not ideal. There are some things that are obviously sharper than others and some things that are debatable. Just because something can shave easily does not mean it is suitable for all cutting tasks. We can have a very thick knife that can shave very very easily but is not a great slicer. It can certainly cut well but going deep into a slice is harder.

    That is why I have problems with some edge tests, it can tell part of the story but it is too incomplete. While it is fun showing pictures of the whittled hair, to shave a beard with a knife, and to cut free hanging cig paper it is incomplete. It shows it is sharp. Now knife users can usually fill in the details quite well as they understand these things if they can see the knife or know the the grind and all the dimensions. It does not tell other qualities like toughness or edge retention.

    Other knife qualities. It is possible to have a knife steel of some type at some hardness and it works just fine in a short bladed thick knife with a thicker grind but when we make it a long knife with a more acute edge we can get into trouble. We can take that same hard short knife and go with a very thin grind and we can get blade chipping that didn't happen before.

    Really long knives like a machete, some are very specialized. Some make good choppers, these often do not work so well on tall grass and light undergrowth. The machete that works great on tall grass and light undergrowth can stick if you try and chop with it. First swing, stuck, second swing at the right angle and a chip comes off, third swing, stuck. Makes of an unpleasant chopping experiance.
     
  20. tower
    • In Omnia Paratus

    tower Loaded Pockets

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    OMG, Jon, you never cease to amaze me.

    All I want to toss into the ongoing discussion is that today's laminate blades throw another layer (pun intended) into the mix (e.g. Cold Steel San Mai III, Fallkniven, etc.).

    If anyone is interested, KSF has a great series on sharpening convex blades.

    http://www.knivesshipfree.com/pages/Sharpening-Videos