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Back to absolute basics in sharpening

Discussion in 'Maintenance, Tinkering & Embellishment' started by awestib, Jul 1, 2012.

  1. awestib

    awestib Gold Member Gold Member

    Dec 29, 2008
    I have been thinking lately how kinfe users many years ago or in very remote areas maintained their edges. They may not have had a belt sander, nor diamond stones, nor multiple choices of strops, no Sharpmaker, no Edgepro, no wicked edge ..., you see where I am going.

    I like the idea of having no sharpening tool at all so you would have to find something to maintain your edge that nature provides. Now I think I have to step back here a bit and start with the question, which one would be the best suited knife for this, and I am not talking "one can do all" here, or "what knife survives the apocalypse" etc. I am talking about the grind and edge of a knife that is likely to be the easiest to maintain, and this possibly for years, outdoors, no tools!

    So, we would not only have to sharpen the cutting edge regularly but would also have to maintain the secondary edge constantly to keep the knifes performance. Ever since I saw Murray Carters knife sharpening video, and I am actually not doing it his way, I learned a lot about the secondary edge and it makes so much sense to me. Once I have found a knife that performes well for lets say bushcraft tasks, if I don't grind the secondary edge regularly, I will end up with something similiar to a scandi grind. The primary edge stays at the same angle but the edge thickness goes up "as we move towards the spine". Of course, that is over years of sharpening.

    Although I don't rely on a knife during my routine days and I don't even use a knife that often, I like to try them out, like to improve my sharpening skills and think about a knife as a tool. So, which knife would make sense? a full flat, flat saber grind (or as Talfuchre would call it a "double bevel non-scandi" knife) a scandi or a hollow ground knife? Convex?

    Remember, You likely end up with a natural stone of some sort (that is opefully rather flat), maybe a dirt incrusted wood and animal skin (leather) to maintain your sharp tool. No fast cutting diamond stone, no jigs etc.

    I'd love to hear you thoughts!
  2. Komitadjie


    May 31, 2011
    Convex, for sure. Given that pretty much every edge ends up with SOME degree of convexity with freehanding, may as well start out with something that already has a proper curve to guide you. That would become even more apparent when super-flat stones are no longer available.
  3. Jason B.

    Jason B. KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 13, 2007
    The easiest knife to maintain is the thinnest while being the strongest. Typically the thicker the steel at the shoulders of the bevel the harder it will be to sharpen regardless of steel type.
  4. awestib

    awestib Gold Member Gold Member

    Dec 29, 2008
    Good point Komitadjie! Knifenut, exactly what I think. Whenever the edge is too thick "before sharpening", I get in trouble maintain, follow, improve that edge.
  5. HeavyHanded

    HeavyHanded KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 4, 2010
    Very thin convex grind with steel in the 56 RC range. I've seen primitive sharpening vids where the edge was stropped on a bare calf (leg) with cold ashes from the fire pit. Sprinkling fine sand on a board or taught textile and stropping would seem to be the most simple method. Not a very sophisticated method but effective.
  6. Komitadjie


    May 31, 2011
    Stropping on a bare calf... Yeah, I know it works, but the mental images would make me laugh too hard to hold a consistent angle, I think.

    "Mooo, dammit!"
  7. gomipile


    Apr 17, 2010
    Calfskin wouldn't have enough silica anyway....
  8. KennyB


    Jan 19, 2010
    I saw one episode of Mountain Men that reminded me of something people use to do ( or apparently still do in this case ): Use the edges of two knives to sharpen one another. Use to see this mimicked a lot in cartoons and stuff, but never really used a lot realistically, but this Tom Oar(sp?) guy on the show seems to do a pretty good job making use of it. The last episode they showed him skin a deer.

    I think that the idea of sharpening on a rock or something like that isn't really too outlandish theoretically, but practically speaking you have to find a rock that is the right type of abrasive, flatness, and hard enough to sharpen steel. On the other hand if you can find a small rock that is hard enough, and your blade isn't too messed up, you can sharpen by simply drawing the blade across one small, flat spot that's suitable.

    You just got me thinking... It would be kind of strange to relate the fact to someone who might have actually had to use such sharpening techniques, that now days cement, pavement, cinder blocks, and bricks are so common place that to find a suitable abrasive to "improvise" an edge can be as simple as looking under your feet. I don't really think that rings true for ever environment you will find yourself in, so I would bet that to have some kind of "sharpening stone" that they knew worked for the purpose and took along with them was probably common practice. I mean, just because there's a lack of technology doesn't mean there should be a lack of preparedness.

    As far as the question of what type of blade grind. I personally think that a full flat grind or a scandi would be the best. High sabre grind would also be good, but basically anything with a very acute relief angle. One can then also put on a relatively acute edge grind on to this, and I think the icing on the cake is that when a good relief angle, followed with a good narrow edge angle, if you're really in a pinch to get your edge nice and sharp enough, just knocking the angle up a little bit will "microbevel" it and make you good to go in a heartbeat.

    I don't see anything wrong with convex, I just don't see a huge advantage to it unless you're going to be doing work that needs that type of edge. Filleting fish comes to mind, chopping wood is a second guess. Otherwise I don't really find that a convex edge is that much better, or easier to maintain. On the other hand, I do think that compared to hollow ground blades, flat grinds ( scandi, ffg, sabre grinds, etc. ) and convex grinds are all better at cutting through deep material like this. With a hollow ground blade, the radius starts to thicken back out after a certain point, and material will bind and drag against this gradual upward radius to a more significant degree than on a flat ground blade. The extra concavity just gives the material more space to sink try to fill and there winds up being a lot of pressure on where the shoulder of the hollow grind meets the rest of the blade grind.

    Past that, as you were mentioning earlier about continually grinding on the same angle... I think that becomes a bigger problem on hollow ground blades and it's harder to grind in new relief angles.
  9. awestib

    awestib Gold Member Gold Member

    Dec 29, 2008
    Good thoughts KennyB!!
  10. sir_mike

    sir_mike Gold Member Gold Member

    Jul 5, 2011
    I agree that if I had found a rock that worked, I would keep it with me as part of being prepared. It wouldn't make sense to pitch the rock and hope I find another one later.

    I don't know which grind would be best but I think it would depend on what you wanted to do with it. Back in the day, many years ago my father had some fixed blades that we camped with but 30+ years ago, I dont know what the grind on them were and he kept them sharp with a small file that I believe was pretty fine.
  11. ConBon


    Jan 17, 2012
    I was at a friend's cabin on the little Manistee River this past week, and had my machete on me when we were wading in the shallow, slow part. I apparently snuck up on a water snake, and it came at me. Nothing big, but the bites are still unpleasant. I chopped the snake almost in half, but hit some rocks on the bottom. Anyways, too touch up the machete, I found two semi-flat river stones, rubbed them together too make a flat area, and used it to sharpen a nice and clean edge. Took five minutes total.
  12. Komitadjie


    May 31, 2011
    Bear in mind there that the average machete is a lot softer than your average knife for additional robustness. If it was knife-hard, that edge wouldn't hold up to the pounding a machete takes so well. That likely influences the ease of sharpening with a river rock, though, given that adding another ten rockwell points might well take the knife steel to a point harder than a lot of natural rocks.
  13. gomipile


    Apr 17, 2010
    In most locales, it's pretty easy to find rocks which contain silica, which has a hardness comparable to 69 Rc. That will let you sharpen any low alloy steel that doesn't have a lot of vanadium carbides, niobium carbides, etc.
  14. cpurcell


    May 9, 2012
    I'd suggest the convex edge. Ideally people strop with compounds and what not these days, but a nice leather belt can work great, and if you're like me, you always wear a leather belt. So, since I'll be sitting anyhow, I can use my belt as a strop instead of holding up my pants, and unless I've chipped or rolled the edge, I should be able to get it back to hair popping sharp with stropping!

    Just my $.02
  15. jackknife

    jackknife Gold Member Gold Member

    Oct 2, 2004
    I think sharpening is like a lot of things, we get carried away with it. When I was stationed overseas, I saw the housewives come out about 4 o'clock in the afternoon and strop their kitchen knives on the back steps before starting to prepare dinner. In Italy, these steps were stone, worn smooth over a couple hundred years of use. I've done it and it works. For years now, if I'm just touching up a blade, I'll strop it on the unglazed ring on the bottom of a coffee mug. Works great. In the city, the side of a brick wall works well.

    You don't need a over priced and over hyped sharpening system to sharpen your knife.
  16. mtangent


    Dec 6, 2011
    I think it's a good question, & the first step in my mind is steel. The old guys used carbon steel, not a super hard alloy.
    The second thing is blade thickness. THIN. So thin, it doesn't matter whether its scandi or convex.

    Knives like this would be easy to sharpen, no matter how you decided to do it.
  17. zuluninja

    zuluninja boricua grinder Knifemaker / Craftsman / Service Provider

    Aug 25, 2009
    lol jackknife, my grandma still strops her knives against the top curve edge of the kitchen sink!

    I would go with convex. A piece of leather should be easy to get, and if it gets really bad you can grind against a semi flat stone and then strop on the leather. You can even get more creative and create your own compounds mixing grease, oils, fine sand etc.
  18. ConBon


    Jan 17, 2012
    True. But it is easy to find rocks that are suitable for touchups and such. If you have a knife with carbides (which is something I don't see as being very advantageous), then it would be harder to find a suitable stone. You could always use sand on an oak board though.

    There is a link to a great article in one of the forums here about old time sharpening methods with in depth explainations, tests, comparisons, etc. It is by a Belgian who traveled around Europe to research old methods. He covers stones, where they were quarried, how, and when; sand, ashes, brick and clay dust, etc. on an oak board, and more.
  19. Komitadjie


    May 31, 2011

    Good point, and I suppose it really doesn't cost anything but time to just start testing rocks. Find a likely looking one, give it a try, and if it doesn't work pitch it and pick another one. That would be a very interesting article to read, I think.
  20. Think I know what you're referring to. Haven't tracked down that thread with the links yet (still looking), but was able to glean website info from the copy of the article I saved. The article is in two parts, both pretty large files (~ 15 MBytes in total), and the site itself ( http://bosq.home.xs4all.nl/ ) is in another language, perhaps Dutch(?). I used Google Translate to view the site, but the article itself is written in English. Here are links to the two parts:

    http://bosq.home.xs4all.nl/info 20m/grinding_and_honing_part_1.pdf
    http://bosq.home.xs4all.nl/info 20m/grinding_and_honing_part_2.pdf

    Edit: Found the thread where I originally saw the linked article, posted by member 'J D Wijbenga' in posts #10 and #14 in this thread:
    Last edited: Jul 3, 2012

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