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How to identify grind issues
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Thread: How to identify grind issues

  1. #1
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    How to identify grind issues

    From what I've read, grind issues are one of the major and common issues with all knives; overground knives can be more flexible than correctly ground knives, can cause a knife to steer because one side of the knife is ground more than the other, and can cause a knife to not cut smoothly, among other things.

    However, I'm not sure what to look for. I have knives that are more flexible than expected, knives where one side of the knife seems to be ground more (the grind seems to go higher than the other side). But, I'm not sure these knives are overground or incorrectly ground.

    What are clear markers or things to look for to identify grind issues?

    Thanks.
    Michael
    "Don't you know who he is?"

  2. #2
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    grind issues:
    Point the knife tip toward a window or something that is going to show straight lines when reflected on a flat surface. Look at the reflected lines on either face of the knife. Convex grinds will show some even curvature in the reflection. Flat grinds will show straight lines. Uneven grinds (those with one or more over/under grinds) will show wavy lines. More grind imperfections means more waves. You will also see bends and twists this way but you cannot differentiate between the three without looking at a couple more things.

    You can run your fingers carefully on both sides of the knife simultaneously and feel for uneven grind.

    You can look at your bevel. If your angle is fairly consistent, an overgrind near the edge will manifest itself as a wave or dip in the bevel. It is common to find overgrinds on the heel of knives, making them appear thinner than they really are.

    Bends:
    Point the tip of the knife toward your eye with the spine up. If the knife is bent, you will see a wave in the spine.

    Twists: Do the same with the edge up. If you see a different bend than the spine, your blade is twisted.

    Keep in mind, all knives have imperfections. In fact, I believe minor grind uneveness would probably decrease "sticktion" and improve performance to an extent. Also, fixing may not be the best thing for a knife. Even in straightening a knife, you will cause other small bends or other deformations. There are also imperfections we can't see in the steel and sometimes fixing the bends leads to pretty severe microscopic cracking or even breakage. For most knives, the question should simply be does the knife work the way it should. When I'm paying big money for a knife, I'd want the grind to be pretty damn good but that's just me. I am a knut, after all.

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    El Pescador's Avatar
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    +1 on the knit Tinh!

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  5. #5
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    I was wondering if you were gonna bring that up somehow.

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    Quote Originally Posted by Dave Martell View Post
    If it says Moritaka on the blade.
    Haaaaaa!
    Too funny.

  7. #7
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    I wonder why this topic comes up today?
    (sorry I could not resist, I tried, but I was overcome)
    Del

    Laminated metals specialist, Kitchen knife and gadget maker
    www.ealyknives.com
    www.mokume-jewelry.net
    "Build a man a fire and he will be warm for a day, set a man on fire and he will be warm for the rest of his life"

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    If you don't have a hole in the edge, you don't have an overgrind problem. Not yet at least.

  9. #9
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    Del:

    It actually has nothing to do with either you or Moritaka knives. I don't own one of your knives or a Moritaka.

    Actually, it's just something I've been thinking about for a while now, and something that I've been very curious about. I exchanged some e-mails with Tinh recently and we briefly discussed this. I just wanted to learn how to identify grind issues on my own.
    Michael
    "Don't you know who he is?"

  10. #10
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    I've been really careful to make sure that the blades on the knives that I have been making have as straight a blade as I can make. Today I looked at the Forschners that I have used for the last 20 years, and they are bent! I don't know what this means as a practical matter, butt I guess sometimes it is better to not look? As long as it keeps cutting, anyway!
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

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