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Thread: What exactly is 70/30

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    Senior Member turbochef422's Avatar
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    What exactly is 70/30

    I know I can see that some blades are different but I don't exactly know what I'm looking at. My misono was different. I sharpen all of my knives 50/50 or the same to both sides and get them insanely sharp and I take pride in keeping sure sharp knives. But what is 70/30 or 60/40 and how do you maintain that. Is is more sharpening on one side or different angles and what are the benefits. Sorry if I'm boring with a basic question but maybe I'm missing out on something really cool. Thanks in advance. Nick

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    Senior Member Crothcipt's Avatar
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    http://www.kitchenknifeforums.com/sh...ll=1#post93152

    here is a pic. in a great thread. You should read it, it explains many questions that pop up when trying to understand this. Not sure how to sharpen this way, but would love to learn.
    Chewie's the man.

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    Senior Member eto's Avatar
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    Quote Originally Posted by turbochef422 View Post
    I know I can see that some blades are different but I don't exactly know what I'm looking at. My misono was different. I sharpen all of my knives 50/50 or the same to both sides and get them insanely sharp and I take pride in keeping sure sharp knives. But what is 70/30 or 60/40 and how do you maintain that. Is is more sharpening on one side or different angles and what are the benefits. Sorry if I'm boring with a basic question but maybe I'm missing out on something really cool. Thanks in advance. Nick
    You pretty much answered your own question. 70/30 - what have you 60-40 is basically the manufacture bevels they set.
    You can change the bevel like you have been doing or keep it factory. If you want to maintain 70/30 ratio basically you sharpen the wider bevel (front side) at a lower angle , and sharpen the back side at a bit higher angle. Supposedly the purpose to these type of knives was to mimic a single edge , say yanagi knife, but to be more multi functional. There so thin to begin with I don't Think there is any true advantage here. Others may differ though.

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    Senior Member Benuser's Avatar
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    The 70/30 edge of the Misono is a part of its overall geometry. Would you just put a 50/50 edge on it, after a few months you will have a crazy sharp knife that is perfectly unusable in the kitchen because of wedging and steering issues.
    You may rebuild the entire blade to make it suitable for a 50/50 edge, but that is huge operation involving grinders no one will want to perform on a new knife.
    You better stick with the original geometry and corresponding edge.
    Just to give an idea: most Misonos will be fine with a 10-12 degree right bevel, 15 degree left bevel, where the right bevel is 2-3 times larger than the left one. With a brand new knife these figures are hard to see because Misono strongly convex their out of the box edges.

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    Senior Member Benuser's Avatar
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    To me it isn't clear whether you asked for advice before applying a symmetric edge with the Misono, or you already did so, as one of the posters understood.
    In the latter case: no real harm is done yet.
    It is relatively easy to restore gradually the original configuration by only abrading from the right bevel, and only deburring / stropping the other side. So you will move the center of the edge back to its original position. Within a few sharpenings that will be done.

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    Senior Member turbochef422's Avatar
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    The misono has been sharpened 50/50 for about 5 years. And now it's at a point where after thinning I still can't get it really sharp like I used to. It saw every day work for a few years and then here and there stuff after that. So I guess I'm asking about knives I'm gonna get. I try to follow the factory lines I just thought maybe there was a method behind it. Thanks for the answers.

  7. #7
    Sounds like your current blade may just need a spa treatment...
    once in a while you get shown the light, in the strangest of places if you look at it right

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    Senior Member turbochef422's Avatar
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    I mostly want to sharpen future blades the way they were intended. I get a knife real sharp. But like I read I can get a knife to shave my arm but I want it to cut well. I'm on Long Island and I'll check out korin but I need a class where I can see exactly what's going on an I need it before I go to the next level of knives. If anyone knows where there is such a thing please let me know. Thanks

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    Senior Member Benuser's Avatar
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    I'm sure Dave Martell, Eamon Burke, Jon Broida or Korin's may save your Misono. For heavy thinning and other geometry changes both a grinder and a lot of experience are needed.

    PS Sorry guys, hadn't seen the last posts!

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    Senior Member zitangy's Avatar
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    One possibility is that the the blade has worn off and has receeded upwards (towards the spine) and thus is thick. Look at the choil area and compare the edge thickness to your otehr performing knives

    Options
    a) thin out the whole blade on sand paper, stone or a belt grinder. I do mine on sandpaper and thru the various grits, 240, 600 and 1000
    b_ Thin out the edge and you need a lower angle as the edge by now shld be thick. Basically you need a bigger bevel

    IN the final analysis, it's not the sharpening angle alone that determines the cutting performance.. the thiness of the edge does matter

    Have fun and stay sharp..
    rgds
    D



    Quote Originally Posted by turbochef422 View Post
    The misono has been sharpened 50/50 for about 5 years. And now it's at a point where after thinning I still can't get it really sharp like I used to. It saw every day work for a few years and then here and there stuff after that. So I guess I'm asking about knives I'm gonna get. I try to follow the factory lines I just thought maybe there was a method behind it. Thanks for the answers.

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