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Thread: Mamma mia!

  1. #11
    Thanks for all the response.

    Now. My best bet is just simply users technique is not existant. But its quite weird spot for chips.

    I will sharpen the blade and check next time vs tuna.
    If it happens again, then I have a problem.

    Altough its new knife, not every buyer is knife sharpener and not every can microbevel own knives. It shouldnt happen OOTB.
    Back is honed. The line is perfect and thin, but its there.

    I chopped some heavy bones with my yoshihiro and didnt have that problem once.

  2. #12
    I asked Shigefusa ones and he told me he make edges on them very thin, to thin, so user can easier adjust then to him self.
    It depends what bones you cutting, big or small.
    Deba is special knife and not everybody have them in they kitchen. So i will expect to adjust it to my self when i buy one.
    I definitely dont think that it was overhardness, but just not adjusted for your use

  3. #13
    From a practical standpoint I'd suggest making the heel (maybe 1" or so) more obtuse than the rest of the edge and use this section for heavy work. Even then though I think it's best to lean on the knife versus whack on the knife when doing bone sectioning. I've seen a lot of deba repair work over the years and once a knife (and it's user) is adjusted this way chipping problems seem (for the most part) to disappear. I'm not an expert in the use of these knives so please understand that when taking my suggestions here, I offer only what I know from working with people who use these knives themselves and have had problems.

    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...
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  4. #14
    Beiniek, i will also PM you privately about this to explain more about this and how best to handle it but i wanted to make a few public statements as i feel they will be of help to many others around here. Also, @Marko, i hope you do not take what i am about to say as a personal attack... that is not my intention. Please dont mistake my forwardness as trying to be an ass... that is not my intention at all.

    Ok... here we go.

    One of the first things I tell people when we talk about knives is this-
    As a general rule, the more money you are spending on something, the more that will be required of you skill-wise, experience-wise, and technique-wise to be able to use and care for that effectively.

    This is absolutely true when it comes to kitchen knives… and especially Japanese kitchen knives. That’s why there are beginner knives, like the yoshihiro, which are softer, easier to use, easier to sharpen, and easier to care for… and higher end knives like the Gesshin Hide, which are harder and require more skill to use effectively. If there wasn’t so much of a difference between the two, I would imagine that very few people in Japan would buy these kinds of knives… and for those who did, I would imagine they would see just as serious chipping issues as you are seeing here. However, that is not the case among professional chefs in Japan (and please understand that these knives are all intended for professional use).

    Learning about how to sharpen and care for these knives is very important, and here are a few things that should have been done. First, when using knives like this, you need to do final sharpening (even if the knives come sharp out of the box). This includes uraoshi sharpening, which strengthens the blade. This also may include microbeveling the knife (either at the heel, or along the entire blade, based on your personal preference, technique, and what you plan on doing with the knife). If these techniques are not possible for you, I would recommend sticking to a beginner blade like the yoshihiro and practicing/learning until this makes sense and is possible.

    Likewise, skill in using the knife is paramount. Chips like what you are showing here occur out of misuse more than anything else. Make sure you are using the knife correctly before anything else. It looks like you either cut bones in the wrong place, had an unsteady hand while doing so, and/or did so at the wrong angle. That, in combination with a lack of proper sharpening, could easily cause the problems you are seeing here.

    Re-tempering a blade should never be on your list of things to do. Not only does it take away what makes the blade what it is, but it also shows a lot of arrogance thinking that the problem lies in the blade rather than your technique. I don’t think anyone here on these forums has the experience to say what an appropriate heat treatment is for knives like this… and I say this for the following reasons (I am including normal end users, vendors, knife makers, etc. in the following statements)-
    *very few, if any, users here have serious and significant experience using these knives as intended in a professional environment
    *very few, if any, users here have learned proper technique from qualified and experienced users of these knives
    *most users experience with these knives is limited to just a couple of years (and when I say this, I mean significant experience where the knife is being used, cared for, and sharpened correctly)
    *very few, if any users here have spent significant time with Japanese blade smiths learning about the construction, making, heat treatment, etc. involved in making these blades
    *very few, if any users here have spent significant time with Japanese professional sharpeners learning about how these blades are sharpened and cared for

    Most of us (myself included) began learning by just trying things out ourselves. We had some limited videos, books, and a ton or hearsay to go on, but that was about it. Its been more of a trial and error process than anything else and there has been a significant lack of understanding of why thing are they way they are, how things are intended to be used, and the subtle nuances therein. Until recently, I was in the same boat… I now have the opportunity to spend time with sharpeners, blacksmiths, and chefs in Japan and constantly use them as a resource when I have questions about why and/or how things are done.

    To Bieneik, please feel free to use me as a resource as you go about fixing your knife and learning how to use it properly… that is exactly what I am here for. I’ll shoot you a PM in a bit.

  5. #15
    Great post, Jon.

  6. #16
    Senior Member mpukas's Avatar
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    well said, Jon.
    Shibui - simplicity devoid of unnecessary elements

  7. #17
    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.
    Michael
    "Don't you know who he is?"

  8. #18
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    Great information as always Jon, my favourite thing in his post,while it came as no surprise was how you continue to pursue information and knowledge from the craftsmen, sharpeners and chefs. I would also say you didn't come across as an ass at all.

  9. #19
    I don't think what I posted was arrogant, but let me explain and hopefully demystify some things.

    There is an easy test to check whether an edge is chipping or rolling (too hard or too soft). It involves rolling a thinly sharpened edge with a moderate pressure on a brass rod. If it chips, a maker has to temper more, if it rolls, the edge is over-tempered. Some makers here in the US spend a great effort coming up with a 'sweet spot' for astenitizing and tempering temperatures, where the resulting edge is nether rolling nor chipping at 62-63RC hardness.

    The knife I re-tempered was clearly over-hardened, (you don't often see chunks of edge falling out during thinning on Beston 500) and the chipping stopped after 1 hr tempering session.

    Thickness of the edge matters when it comes to edge deformation, but generally, a hard edge will chip while a soft will roll. From the picture it looks more like chipping rather than rolling (but I am not 100% sure without seeing it upclose), so that makes me think that the edge is overly hard. I have owned a deba and garasuki and seen some chipping (sustained after cutting through bones), but nothing like that.

    The "proper" sharpening technique would involve putting a bevel, to increase a cross-seciton of the edge as everybody else has mentioned.

    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

  10. #20
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    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.

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