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Thread: Trouble sharpening the curves of knives

  1. #1
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    Trouble sharpening the curves of knives

    I tried once again this weekend to sharpen my knives (worked on Forschner 8 in chef's as a practice and Miyabi Kaizen 8 in gyuto, which is what I use the majority of the time) and can get a serviceable edge on the flat parts. Not great, but serviceable. It bites into my thumb nail when I'm done that I can be satisfied. However, as soon as the blade curves, there is a noticeable drop in cutting performance.

    I have taken a magic marker and colored the bevel. I know I'm hitting the bevel, but it seems to be spotty that I'm hitting the whole thing with a full stroke. I have watched Jon's video on sharpening knife tips to no avail.

    Basically I am trying two things. One is Jon's way, of rotating from the spine to the edge with the knife almost parallel to the stone. The other is just trying to adjust the knife to the stone where the bevel is consistently hit and I am failing in both. Help!

    Oh and the stones I'm using is a Beston 1000 and Norton 4000/8000 combo.

  2. #2
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    Are you using at least a 10x loupe to check if you are actually getting to the edge? Can you feel a burr on the curve?

  3. #3
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    I have a loupe, but at the risk of sounding like an idiot, I'm not sure what I'm supposed to be looking for. I have used it and don't seem to gather any useful data.

    The burr on the curve is not consistent on the whole thing, and while it does feel like something is raised, it isn't as pronounced on the straights of the knife.

  4. #4
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    If it looks like you are hitting the entire bevel but you are not sharpening the edge, it isn't usually a big deal. Stock bevels are not always perfect and they will change to suit your stroke over time, regardless. I would just continue a little more until you get a burr and call it good. If you clearly are not hitting the entire bevel, then you will need to adjust your angle either by raising the handle relative to the tip a bit in the curved areas or raising the spine slightly on that part of your stroke. Try watching the edge on a clean stone and make sure it hits the stone. You should also be able to hear the difference. Slow down and listen. As you go from hitting the edge to not hitting the edge, the sound will change. Adjust to keep the sound consistent.

  5. #5
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    Quote Originally Posted by adletson View Post
    I have a loupe, but at the risk of sounding like an idiot, I'm not sure what I'm supposed to be looking for. I have used it and don't seem to gather any useful data.

    The burr on the curve is not consistent on the whole thing, and while it does feel like something is raised, it isn't as pronounced on the straights of the knife.
    Using the loupe allows you to see that you are sharpening to the edge by letting you see that there isn't a hairline of marker left on the bevel, indicating that you haven't hit the edge. Without magnification, it's possible to miss seeing it. You should see shiny metal all the way to the edge. Tilt the knife one way and the other so that the light reflections can help you see if it is.

    That the burr isn't well-formed is also another clue that you need to do more work with your 1000 grit stone.

    When sharpening the curved part of the blade near the tip, raising the handle of the knife slightly while keeping the edge tangent to the direction of sharpening will help. This is where using the marker will help a lot in refining your technique. Make a few passes, evaluate what you've done, renew the marker and repeat. If your bevel toward the tip is wider than the bevel at the heel, you need to raise the angle that you are using to sharpen the tip. This is one of the tricky parts of freehanding, because the angle you hold the knife at is not the same for all parts of the blade.

    Rick

  6. #6
    Quote Originally Posted by tk59 View Post
    If you clearly are not hitting the entire bevel, then you will need to adjust your angle either by raising the handle relative to the tip a bit in the curved areas or raising the spine slightly on that part of your stroke. Try watching the edge on a clean stone and make sure it hits the stone.
    Instead of raising the handle or spine, you might check out Jon Broida's tip-sharpening technique, here: https://www.youtube.com/watch?v=tmBTO0cA_qw

  7. #7
    actually, i agree with tinh in this case... but i also probably need to reshoot my tip video

  8. #8
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    Keep practising - good luck!

  9. #9
    To get precision tip sharpening better grab the knife from the blade using a towel or cotton cloth (so you will not cut yourself), not the handle. You'll get much better and controllable results.

  10. #10
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    Quote Originally Posted by wsfarrell View Post
    Instead of raising the handle or spine, you might check out Jon Broida's tip-sharpening technique, here: https://www.youtube.com/watch?v=tmBTO0cA_qw
    Look closer. Raising the spine rather than the handle IS the tip sharpening technique Jon demonstrated in his vid. You can't change the angle you're working at without doing one or the other.

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