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The "ideal" angle.

Discussion in 'Becker Knife & Tool' started by Critikill, Jul 9, 2012.

  1. Critikill

    Critikill

    150
    Jun 19, 2012
    Pretty new here still and I'm trying to soak up as much information as I can. I've been working on my BK16 recently and I've gotten it hair popping sharp with shallow convex grind (maybe 10-15 degrees a side) using sandpaper, a mousepad, and a strope I made out of leather from a local shoe repair shop (guy gave me some compound for it too!)

    I've been watching some videos online to improve my techniques and I found this one.

    When I look up edge geometry, I find a lot of basic information but not many specifics. From what I've been reading, and correct me if I'm wrong, a more shallow grind will slice better, but will also retain an edge for a shorter time?

    I plan on using my BK16 for bushcraft and food prep, not too much batoning (I have a hatchet for that). Have I made my edge to shallow?

    What would be the best angle for general wood work? Is there a "best" angle?

    For future reference, how can I figure out the "best" angle for a given knife? Is it based on the slope of the blade face? The thickness of the blade right before the edge? Or is the angle based only on the work I plan to do with the knife?

    BTW: still loving the BK16 and can't wait to take it camping in the next couple months (one it cools down a bit... not trying to fry).

    PS: My left arm and legs are missing large patches of hair. It looks like I have leprosy now.
     
  2. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    I been using a 40 degree inclusive edge on mine. I prefer a V edge over a convex, but that is each persons choice to make.

    Thin cuts. It doesn't take to over the top hard use though. The "wider" the edge, the more surface area you have dragging on the media you are cutting, thus, wearing more of the metal, but with a thinner edge, you also get less separation of the material, i.e. "wedge" so you might feel more drag.

    I personally like the thinner edge on cutting knives, and a thicker on on the beaters.

    A 30 degree inclusive edge on a crafter and food prepper should be awesome. Just be careful, thinner edges roll a little more often.

    Moose
     
  3. Critikill

    Critikill

    150
    Jun 19, 2012
    So you'd say the angle is based more on the work the knife will be put up to than the rest of the knife's geometry?
     
  4. parbajtor

    parbajtor

    Nov 24, 2010
    The angle should be matched to the type of work, but there are also physical limitations imposed by the type of steel and the hardness of the blade.
    Woodworking/whittling knives usually have harder steel and shallower angles, but you might need a different slightly wider angle for a knife used on hard or seasoned woods compared to soft or green woods.
    Japanese kitchen knives tend to be harder steels and shallower angles which suits slicing rather than chopping when it comes to food prep. You probably need to experiment to find the shallowest angle where the edge chips/rolls with woodworking chores and then widen it by a degree.
     
  5. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    Somewhat. Thicker grinds with thinner edges, put alot of "meat" behind a thinner edge, giving the appearance of a "tough" blade, but will roll or chip easy. Thinner grinds with thin edges, are gonna be a slicing beast.

    On my BK16, I went with 20 degrees on both sides, I still baton, beat and work it like I would any other knife of its size. My BK9 has a 25 degrees angle and still works just fine.

    My daughters Izula, sharpened at a 25 degree angle, just wouldn't work well for her. SO, I dropped it down, and thinned that edge out, and she can use it much more effectively now. Remember, she's not strong, and can't power through like a grown man can, so the thinner edge helps her out.

    Moose
     
  6. Critikill

    Critikill

    150
    Jun 19, 2012
    Is there any mathematical way to do this based off blade hardness, thickness, and type of work or is it simple a play by ear and correct as you go type of thing? I feel like finding the idea edge may lose me quite a bit of steal off my knife if I can't find a "formula."
     
  7. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    The thickness of the primary grind before the edge bevel was applied matters too - if the grind leaves a lot of meat at the edge you may want a shallower angle if finer cutting ability is your goal. This will make the edge bevel 'taller'.

    Soo... all of the geometry matters to some degree. The thickness of the original stock along with the height of the blade and the angle of the primary bevel determines how much meat there is at that edge, and how quickly it tapers...
     
  8. Critikill

    Critikill

    150
    Jun 19, 2012
    Can I ask why? From what I've been reading, it seems like a convex edge would be superior in most ways as long as you can learn to sharpen it properly in the field.


    So it sounds like this is something I will have to learn from trial, error, and experience more than something I can read and learn. I can understand that, I just worry it will be an expensive set of "lessons."
     
  9. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    This is my opinion and only my opinion, take as just that.

    Sharp is all determined by symmetry, always has been. Its difficult to get a perfect convex on both sides, since there is no point of reference to begin with. I'm sure someone can make a jig, or some folks can make a symmetric convex, I ain't one of them.

    And for me, field sharpening can be an issue, unless you have the skill to sharpen a knife on feral stone and get your convex right on the money.

    A V edge is a little more forgiving, IMO.

    Plus, if you look at the profile, a v edge will cut the media, then force it apart at the shoulders, creating separation on the shoulder. A convex, will cause the media to follow the edge and up the steel. Jerry Fisk explained the use of the swedge on a BK5 once, and it makes perfect sense. What dulls a blade, is media wearing the edge, and there is just more surface area on a convex edge than a v edge,

    [​IMG]

    These are just my thought, and the reason why I prefer it, easier to sharpen, stays sharper longer, and can be made symmetric and repeated.

    But a knife edge is as individual as the person wielding it.

    Moose
     
  10. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    Yes, it takes some experience and some mental visualization to get to the point where you have reached your own ideal - and that's the thing, there is no 'THE' ideal, just yours. Several of the variables depend on how YOU will use the knife.

    I like a V-edge because it's easier to tell what's going on, but I strop my v-edges. Stropping is essentially a convex sharpening technique, but when used with only very very fine grits, it just polishes the edge (and shoulder), rather than noticeably removing material.
     
  11. parbajtor

    parbajtor

    Nov 24, 2010
    Bevels for bushcrafters usually range from 18 degrees through to 25 on each side, depending on the range of likely tasks.
    If you're not likely to baton with it, 18 or 19 degrees is a good slightly slicey angle to start with.
    As you've already sharpened it to around 15 degrees, I'd put it through it's paces doing some feathersticks and trigger making etc.
    on some dry wood and then inspect the edge for chipping or rolling.
     
  12. Critikill

    Critikill

    150
    Jun 19, 2012
    From what I've read, a convex blade "stays sharper longer." The theory is that there is more "meat" directly behind the finest part of the edge. Also, even if a convex gets a little dull, the geometry is supposed to allow for easier slicing on convex.

    Source

    This is again, just one of the many posts I've read, and not something I've had a lot of personal experience with however. I would love to do a side-by-side comparison of the same knife with different edges some day and determine which I like better.

    Thanks for the advice from those that gave it. The answers make sense, even if they aren't the answers I want:

    I wish there was a more simple "sharpen it to XX degrees and enjoy your new lightsaber." That would let me know I reached "perfection."

    On the plus side, this makes it more of a hobby and I get to try out lots of knives, grinds, metals, shapes, handles, etc. :rolleyes:

    Take pitty on my wallet...
     
  13. Critikill

    Critikill

    150
    Jun 19, 2012
    Can you recommend a good way to do this?
     
  14. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    That hasn't been my experience. I've tried to like a convex edge for years, it just ain't happening. I've got a few custom knives, that sport the convex edge, even one that Jerry Fisk put an edge on for me, I can make a V edge scary sharp, everytime.

    Most of the convex edges I've felt, don't come close. Not to say there isn't any good sharp convex edges out there, they seem to to take too long to make and maintain.

    Moose
     
  15. Critikill

    Critikill

    150
    Jun 19, 2012
    Well maybe if I get the edge right you could field test it against a BK16 with a V edge of your angle choice? I'd love to see the results if you'd be willing to write up a comparison Moose.
     
  16. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    Either that, or I could send you my BK16, and you could. Either way, if you want to, it can be done.

    Moose
     
  17. Critikill

    Critikill

    150
    Jun 19, 2012
    I'd be fine with that too. I figured 1) you may know a bit more about field testing than I do and 2) you probably have more experience/knowledge at determining what makes a good edge and 3)you may not trust the new guy (me). I've been reading enough of this forum to see that there are a lot of guys here that hold you in pretty high regards Moose so I think I could trust you to give my knife back when you're done... thought I could be reading them wrong :p

    Of course this will have to be after I figure out the angle I really like convexed!
     
  18. Moosez45

    Moosez45 Custom Antlers, Factory Knives... Moderator

    Jul 14, 2010
    I'm just a knife user. Use it, if it works, it works, if it don't, it don't.

    Anybody holding me in high regard will get tired fast. I ain't no light weight. :D

    The offer stands, and I'll be honest, I'm a little behind on my knife testing, soccer has been taking much of my time lately. :D

    Moose
     
  19. parbajtor

    parbajtor

    Nov 24, 2010
    The feathersticks or inspecting the edge? ;)

    These days I need reading glasses and I have a pair of 3x magnification clip ons that I use.
    A jewellers loupe or a fabric tester can also be useful. If you have good eyes, you should be able to angle the blade so the edge reflects light.
    This will show any imperfections that you might have added during cutting.
    It doesnt for me because the edge stays out of focus at that distance, hence the need for magnification. I still use the light reflecting off the edge.
    It should be a very thin straight unbroken line (thinner than a hair). Chips will show as sparkles or a raggedy edge, rolls will show as a kink in the line. It's useful to know which part of the edge did the cutting to avoid having to inspect the entire length.

    PS: I prefer convex because all you need in the field is a strop. Rehoning can be done at home, afterwards.
     
  20. Critikill

    Critikill

    150
    Jun 19, 2012
    Lol. I appreciate it. Let me get my knife to where I want it, then we can figure out if you and/or I should do a write up on it, or if we should possibly find a trustworthy 3ed party to do it for us. Again, I'm pretty new on the forums so I don't know who would be trustworthy/capable of doing a good comparison between the different grinds on the BK16s.
     

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