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Thread: Mamma mia!

  1. #21
    Quote Originally Posted by Dave Martell View Post
    On the heel, you can also go one step further and make a bevel on the backside (for real heavy use) on the first 1" or so, see the below diagram...

    Quote Originally Posted by mhlee View Post
    Given that Dave's diagram is in Japanese, I am assuming that this is something that is done, but in my experience, putting a microbevel on the back side edge of the blade doesn't seem to lend itself well to uraoshi sharpening. In order to then be able to take off the burr, you would have to lift up the knife (spine side up) and push, which would further establish the microbevel. This experience is based on what I did to my Kanehisa yanagiba based on what I read back in the day - pre-internet - and I still haven't been able to remedy that.

    I still can't deburr the knife without changing the angle. I only do a little uraoshi sharpening on the back side, then deburr on felt or paper because i can't hit the burr without raising the spine.


    Thanks for making me think more on my statements I made Michael, you made me realize that I should add a warning to what I said above regarding adding a backside bevel on the heel. I don't want everyone running out and doing this to their knives.

    I want to make it clear that this is for a deba ONLY and it is IMO a last resort.

    I feel that the user needs to look at their technique and possibly add a front side micro-bevel (heel or full length) to the knife before ever thinking about using the back side heel bevel thing I showed in the above diagram.

  2. #22
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    Great post Jon.

    @mhlee, you can try the method Jon described in this video for making deba micro bevel: high angle micro bevel for one third along the front side, and the back side. This wouldn't get in a way of uraoshi, very handy method. There are some handy tips about using debas too.


  3. #23
    Quote Originally Posted by tk59 View Post
    Tests are funny things. They are arbitrary and have different significance to different people. You may be right, for all I know but personally, I'd hesitate to criticize the product of someone who by any measure is a master at his craft. I'd also hesitate to imply that every blade, regardless of steel, intended use and blade design should be hardened to 61-62 hrc.
    There was no criticism coming from me toward anybody, just a general observation - hardness and sharpness have been characteristics of Japanese knives for as long as I know it.

    I do post on subjects that I have studied and have first-hand experience with and have discussed these topics with people who have a lot of experience in area of metallurgy and heat-treatment, so some of the information is derived this way.

    Yes, there might not be such a thing as 'optimum hardness' for everybody, but it is a fact that it's much harder to break (destruction test) 61-62RC hardened steel than 63RC (and higher) all other things being equal (similar grain size).

    M


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

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  4. #24
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    Marko-
    Not all knives require the same degree or hardness so that kind of testing is not necessarily applicable. The kind of heat treatment required for each particular type of knife, and even within that, the difference between beginner knives and advanced knives, will differ greatly with some being much more brittle than others.

    I do happen to believe that its arrogant to think ones knowledge of the knives, steel, and how they are used trumps years of experience and real life testing and use. Whether its you or Devin or someone else, I cant think of anyone here that has the experience to make comments like this. This doesn’t mean that I think you (or devin for that matter) have a poor understanding of heat treatments. I just think that the scope of that understanding and experience doesn’t include the types of knives you are talking about here. Likewise, I think when making judgments on knives, its important to consider the knife as a whole (including the design features, intended use, intended user, etc) as that maker thought of, as opposed to imposing your own understanding/opinions of the design features, intended use, intended user, etc. onto that knife/system of thinking.

    In general its a very limited view you have on this and until you really and truly understand the knife, how to use it, and why it is the way it is (and the design and heat treatment ARE intentionally that way), it will be very difficult for you (or anyone else) to make judgement like this.

  5. #25
    I guess, my answer to this will to make knives that will hold longer edge, won't chip or roll, will have an excellent grind, fit and finish, will come with top notch handle and sayas work - all this without years and years of experience. Enough said.

    M


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

    If my KKF Inbox is full (or not), please contact me via Email: anvlts@gmail.com

  6. #26
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    please and by all means... i always enjoy seeing your work... i guess my point is you dont know what you dont know (not just you, but as a general statement) and if it were me in your shoes i would think twice before making adjustments to others work without understanding why things are the way they are first.

    If this was a problem i was having, my first question would be to myself of what i am doing wrong and how i can improve... not immediately assuming the problem is with the knife.

  7. #27
    Jon, is there any insight you can offer regarding what the positive qualities are that this less rugged heat treatment offers?

  8. #28
    I like how we can have an in depth discussion like this and not blow our stacks. We all have lots that we can learn from each other.

  9. #29
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    I remember reading somewhere that some knives are prone to chippiness initially but after the first few sharpenings they settle down. Remember reading something on the old forum about instructions being sent out from kikuichi(?) that mentioned this.
    Given the lack of accuracy of home ovens vs PID HT ovens anyone considering tempering should use a separate thermometer IMO, but this would be last resort

  10. #30
    Senior Member Crothcipt's Avatar
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    I know my 2 Tanaka's have higher hrc ratings (63-65). I pretty much took the otb edge off with a honing rod, on my sankto knife. I had a hard time putting a new edge on it until I went and reread the hrc levels (I since have bought some stones that this isn't a problem). I would never even think about taking the hrc lvl down, but I am not a knife maker either. After reading this I want to now.(trash knife that is). Man I learn so much stuff here.

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