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Thread: Asymmetry – The REAL DEAL

  1. #41
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    Okay. So essentially when we sharpen a knife that is asymmetrical, we are replicating the edge that was ground into the knife by the maker of the knife? Clayton's illustration shows that an asymmetric grind can be produced by:
    1. Grinding less on the "10 ground" side of the knife than on the "90 ground" side of the knife or
    2. Sharpening at a more obtuse angel on the "90 ground" side and a more acute angle on the "10 ground" side.
    So the maker can achieve the "90/10" edge (or the edge at the 9th place holder) by either method he prefers and it is our job to find which method is used and replicate. Am I right?

  2. #42
    Quote Originally Posted by adletson View Post
    Okay. So essentially when we sharpen a knife that is asymmetrical, we are replicating the edge that was ground into the knife by the maker of the knife?
    Maybe. You can use the maker's edge bevel IF you believe that it replicates the asymmetry of the blade and then once you do this you find that the knife cuts straight. There is no rule to follow here.


    Quote Originally Posted by adletson View Post
    Clayton's illustration shows that an asymmetric grind can be produced by:
    1. Grinding less on the "10 ground" side of the knife than on the "90 ground" side of the knife or
    2. Sharpening at a more obtuse angel on the "90 ground" side and a more acute angle on the "10 ground" side.
    So the maker can achieve the "90/10" edge (or the edge at the 9th place holder) by either method he prefers and it is our job to find which method is used and replicate. Am I right?

    Wrong. I see gaps in both directions that if followed will lead you down the wrong path. You need to evaluate each and every knife and each and every edge bevel and adjust as necessary - this is the only correct answer.

  3. #43
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    So long story short, practice, practice, practice?

  4. #44
    I acutally have a Hiromoto AS and I thinned it down a little, the sides are still assymetric, less than in new knife though.

    I sharpen edge 50/50, and do little convexing - maybe 4 or 5 angles togehter.

    I can promise this knife cuts twice as good now as when it was new.

    I sharpen left side of knife with left hand, its possible that my angle is different, but I think they are both pretty similar.
    I read once on JCK that Hiromoto has two altering angles and the difference was 3 degrees between sides!! Good joke
    I will never get to that kind of skill ever. No point trying.

  5. #45
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    Quote Originally Posted by heirkb View Post
    Really? With the spine up, edge down, tip facing away from you, the bevel is farther on the right side than on the left side? This doesn't make sense to me considering that on a right-handed single beveled knife, the edge will be at 0.
    do you mean higher up the blade?

  6. #46
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    A few questions:

    1. When a knife is asymmetric, is it asymmetric from the spine down or just at the bevels? Or reworded, is it ground at dfferent angles the entire width of the blade from the spine down or is it just the bevel that is ground asymmetrically?

    2. While I can see that the generalizing I made in my previous post is at fault, is the basic premise not correct? That in order to get an asymmetric result, you have to do different things to the two sides of the blade, either to grind less at the same angle as the matching side or to grind at a different angle than the matching side?

    3. Continuing with my number line picture (1-2-3-4-5-6-7-8-9-10), on a "90/10 right hand ground" asymmetric knife, with the spine up, edge down, tip facing away from you, would the knife edge be at 2 or 9?

  7. #47
    Quote Originally Posted by El Pescador View Post
    do you mean higher up the blade?
    No, I mean where the actual edge is relative to the spine. That is, where do the two bevels meet? My guess was 1, not 9.

  8. #48
    Quote Originally Posted by Dave Martell View Post
    If you want to play it safe (while freehanding) a new knife with less than clear factory bevels then I'd suggest starting on the right side (if it's a righty knife) and once I've figured out the appropriate angle for this side I'd flip the knife over to the left side and sharpen at the same angle. If you've done things correctly then these edge bevels should match up to the blade asymmetry pretty closely. If you've got it wrong you might not notice straight away, it might take a few more sharpening sessions for the blade to start twisting while cutting and if that happens you then adjust by grinding more on one side or the other.
    So I have a few other questions here. What do you do to figure out the angle on that first side? I realize that practice is big, but I don't even know where to start, lol. You get the angle, flip the knife, and sharpen till burr? That will itself lead to asymmetric bevels (bigger on the right)?

    And if you feel the blade twisting...let's say it twists towards the left while cutting on a right handed knife. The post above says you adjust by grinding more on one side or the other. So what side would you be grinding more on/making angle adjustments on if the knife steers a bit too much? That is, what type of improper sharpening does the steering suggest?

  9. #49
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    Quote Originally Posted by heirkb View Post
    So I have a few other questions here. What do you do to figure out the angle on that first side? I realize that practice is big, but I don't even know where to start, lol. You get the angle, flip the knife, and sharpen till burr? That will itself lead to asymmetric bevels (bigger on the right)?

    And if you feel the blade twisting...let's say it twists towards the left while cutting on a right handed knife. The post above says you adjust by grinding more on one side or the other. So what side would you be grinding more on/making angle adjustments on if the knife steers a bit too much? That is, what type of improper sharpening does the steering suggest?
    If you are right handed and the knife pulls toward your left hand when cutting you can either: grind more on the left hand side to even it up and bring it closer to 50/50. Or you can relax your grip some and not try to make the knife go somewhere but rather let the edge do the cutting for you. Either way you'll find that steering decreases

  10. #50
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    Originally Posted by adletson

    So am I correct in saying that when a knife is described as being "90/10 right hand ground" that it means that the cutting edge is 90% offset to the right side? Like if you had a number line (1-2-3-4-5-6-7-8-9-10) that represented the total width of the spine of the knife, the cutting edge is sitting on the 9th place holder?
    yup

    I think its the opposite???

    My reasoning tells me that the offset is to the left as the right side has a higher bevel.. meaning that it has been sharpened at a lower angle. IF the the Left side is sharpened at Zero.. it is a single bevel. Since the left bevel is so small, it would mean that it it sharpened between 10 to 15degrees.. thus form the top of spine position it is anywhere between NO 2 or 3 as per your example

    I suppose there should be a sharpening angle on the left side that makes it dead center of the spine. IF the total angle left and right is say 40 degrees.. close to the german sharpening way but with teh thinner bevel on the right side.. a thinner blade on the edge..

    Just my thoughts...

    rgds

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