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Help with knife repair!

I have an old moritaka petty that has an issue with blade geometry I'd like to fix. I think that I damaged the knife while learning how to properly use the edgepro a year or so ago and would like to try to fix the situation now, but Im still relatively new to sharpening and dont know the best method to fix my mistake.

The problem is that the cutting edge is not completely straight, when the knife is placed cutting edge down on the board a small amount of light can be seen coming from underneath the middle of the blade meaning the entire edge is not able to contact the board. What is the best method for everning out the edge with my edgepro? Is there a trick to it or do I just have to eyeball it and hope for the best as I grind away at the two ends?

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  1. <an old moritaka petty that has an issue with blade geometry I'd like to fix>
    <the problem is that the cutting edge is not completely straight>

    Are you sure it is your fault and not the knife itself?
    http://img.photobucket.com/albums/v43...
    Moritaka has a QC issue for some time. Some very good and inexpensive knives are produced by the Moritaka smiths, but some knives have issues of overgrinding. That being said and all I don't know if it is your fault or Moritaka's fault until I get to see your knife in person. I don’t think a photo can capture the details.
    Assuming it is your fault, then it is likely we can fix. There are many ways to fix it. I believe cowboyardee and I have different ways approach this. What I like to do is the following

    1) Straighten the edge by sharpening on the stone. Hit the knife edge 90o (perpendicular) to the stone and get the knife profile you want.
    2) Then sharpen it as always.

    If it is Moritaka’s fault, then it may still be fixed. I was luck able to handle the overgrind issue for my Tanaka knife, but it is more involving.

    7 Replies
    1. re: Chemicalkinetics

      These illustrations are what I meant by grinding the knife until you get the profile you want.

       
      1. re: Chemicalkinetics

        "Straighten the edge by sharpening on the stone. Hit the knife edge 90o (perpendicular) to the stone and get the knife profile you want"

        Can't believe I didnt think of that ><

        As to the question of whether its my fault or not, Im aware of the issues with the moritakas, Ive seen it on a few forums, but since I had no idea what I was doing and used the 120 stone on iy, Im pretty sure its my fault!

        Thanks so much for your help!~

        1. re: twyst

          Your welcome.

          Even though the Moritaka has some grinding issues, my guess is that it does not happen to most of its knives. So hopefully, your knife is fine. You will find out pretty quickly if it is Moritaka's fault or not. If it is Moritaka's fault, then you will run into the same problem very quickly.

          By the way, I understand that you have an EdgePro system. Do you have a regular flat stone? It is much easier to grind out the overall knife profile with a regular stone. Good luck.

        2. re: Chemicalkinetics

          "1) Straighten the edge by sharpening on the stone. Hit the knife edge 90o (perpendicular) to the stone and get the knife profile you want.
          2) Then sharpen it as always."
          _________
          Chem's advice is good, as always, but I want to point out one possible stumbling point: when you grind perpendicular to the stone to flatten the profile, you'll get the profile you want, but parts of the 'edge' (now not sharp at all) will be thicker than others. The part of the edge that had been recessed will be thin and not too far from sharp, while the parts of the edge that had to be ground more will be thick and very dull.

          The problem comes when you 'sharpen as always' because if the way you always sharpen is either in sections or even with sweeping strokes moving across the stone, then you're going to slowly cut a new regrind (or recessed section) into the edge as the thinner parts of the edge sharpen away more quickly before your bevels meet on the thicker parts. This also applies to the edgepro, unfortunately - sweeping strokes after fixing the profile will cause parts of the edge to retreat again.

          The easiest fix: instead of sharpening as always after setting the profile, place the knife lengthwise on the stone so that most of the edge is touching the stone at any given time. This is harder to explain than to just show you, so here is a video (it's a bad sharpening video, but it illustrates the basic technique I'm talking about):
          http://www.youtube.com/watch?v=ttdTCJ...

          If you're dead set on using an edgepro for this kind of repair, you can still manage it. You'll just have to check your work often, taking off a little bit here and there until it looks right, not unlike sculpting.

          1. re: cowboyardee

            <when you grind perpendicular to the stone to flatten the profile, you'll get the profile you want, but parts of the 'edge' (now not sharp at all) will be thicker than others>

            True.

            <The problem comes when you 'sharpen as always' because if the way you always sharpen is either in sections or even with sweeping strokes moving across the stone, then you're going to slowly cut a new regrind>

            Good observation, and the same problem may very well come back.

            <This also applies to the edgepro>

            Probably worse for EdgePro comes to think of it.

            <so here is a video >

            Here is another. Not exactly what I mean, but close enough (watch 15 seconds should get the point across).

            http://youtu.be/jIycmyzrcF0?t=1m27s

            <f you're dead set on using an edgepro....>

            Sound rather difficult to me actually

            1. re: Chemicalkinetics

              "Probably worse for EdgePro comes to think of it."
              "[Using the edgepro] Sound rather difficult to me actually"
              ______
              It is. Not impossible, but definitely tricky. I'd think that the best bet (if one MUST use an EP) would be to flatten the profile by hand as you suggested (or else grind in a very obtuse edge as I did in the thread I linked to below), and then use the EP VERY CAREFULLY to grind in new bevels, grinding each portion of the edge ONLY until you form a burr, switching sides often, and avoiding the usual sweeping strokes you'd do with the edge pro. Then a 'clean-up' sharpening as normal once you basically have a working edge and a good profile.

              But if you have even modest skills hand sharpening, that would be a better way to go.

              Of course, this kind of repair, especially if the regrind is deep, is always a little tricky. Doing it by hand can be a fairly big job, with a few pitfalls to avoid. Using an edgepro has even more pitfalls. Using a belt sander is much quicker but risks overheating and/or mis-grinding the blade if you lose focus. And frankly, it's not a job for a pro who does hack-ish work either (meanwhile, other pros will charge a good chunk of change for this kind of repair, with good reason).

              On the upside, it's a great learning experience. And if you're careful and patient and follow decent advice, you'll get there eventually (note - I'm perhaps foolishly assuming that the problem isn't the infamous Moritaka core misgrinding).

              1. re: cowboyardee

                <it's a great learning experience>

                Agree. I think my overground (slightly) Tanaka nakiri taught me much for exactly the reason you have written.

        3. Chem's advice is good. I made a thread once about fixing a knife that had a big section of the edge recessed from years of sloppy sharpening. A few pics included. Here is the thread, if you're interested:
          http://chowhound.chow.com/topics/808731

          This kind of repair is actually easier by hand than it is with an edgepro, incidentally.

          3 Replies
          1. re: cowboyardee

            Any serious cook should know how to properly steel their knife before use, and even to occasionally touch up the blade on one of several available sharpening systems. But for issues of serious blade damage or blade geometry I whole-heartedly recommend seeking out a knife sharpening professional. There is definitely a point where a cook's ability (and responsibility) to basically maintain a blade ends, and where a professional's knowledge, skill and experience takes over.

            Knife sharpening might not exactly be rocket science, but there is more than a little science in knife sharpening, which involves everything from blade geometry to crystalline structure of the steel. But even more than science, knife sharpening is an art that (like any art) requires daily practice to master and to retain.

            Professionals have the correct tools, they have the experience, they have the instinct, and they have the art. There is nothing shameful about seeking out professional help when we reach the limits of our own abilities, and the limits of what we should reasonably be expected to know how to do for ourselves.

            I promise that you will not be disappointed. You might think that you do a pretty good job of sharpening your knives. But I bet when your knife comes back from the pro you will have to say "Wow!!!" when you experience the difference between your edge and the professional's edge.

            All of the best chef's maintain their own knives. I guarantee that every one of those chefs also periodically send their knives out for professional maintenance. I suggest that you bite the bullet, swallow your pride, and do the same.

            1. re: Habanero

              I'm guessing you meant to respond to the OP, and not to my post?

              Anyway, there's no shame in seeking out a professional sharpener.

              But it's simply not true that a non-professional can't possibly hope to learn to sharpen just as well as a pro if they were so inclined, willing to practice, and just a little bit talented. There are quite a few self-taught sharpeners out there who do top-notch work. True, most people won't get good at sharpening without practicing it, but if a person is down with practicing and studying up - there are worse hobbies to have.

              Twyst is a smart guy. If he feels up to learning to reprofile a blade, he's probably up to it. Again though, no shame in seeking out a pro for anyone who isn't.

              "I guarantee that every one of those chefs also periodically send their knives out for professional maintenance."
              ________
              There are plenty of cooks, professional or otherwise, who don't. Take a look over at kitchenknifeforums.

              1. re: Habanero

                I guarantee that every one of those chefs also periodically send their knives out for professional maintenance.
                --------------------------------------------------------------------------------------------------------------------

                Nonsense.
                That still shouldn't ever stop some one from sending a knife out to a professional when a problem like this comes in to play. The Op has been given some great advice but it would probably take as much of an investment in new stones to attempt the repair as sending the knife out.
                There also remains a possibility that since we are talking about a Moritaka that this is a defect and the simple truth is that many of those just can't be repaired. You can make the knife usable but the problem will rear it's ugly ahead again.
                Since the knife is already damaged either way I would take this opportunity to buy stones and learn to sharpen free hand. Not only will you be able to repair your tools in the future I think you will find that while the edge pro works you probably were missing out on all the fun and even sharper knives.
                BTW A serious cooks know better than to put a good edge on a steel.....EVER!
                Hone maybe.

                TJ

                TJ

            2. Just an update, I used the method chemical prescribed (I used my dmt ><) and was able to fix the blade geometry in less than 15 minutes (I didnt have to remove much of the edge at all, the knife wasnt in horrible shape, just a little uneven).

              I then decided to break out my new chosera edgepro stones and went to town, then even stropped on the edgepro.

              The knife is now better than it was straight from the factory!

              Thanks so much for your help everyone, I knew you guys would be able to point me in the right direction!

              4 Replies
              1. re: twyst

                <I then decided to break out my new chosera edgepro stones and went to town, then even stropped on the edgepro.>

                Oh good. I was a bit concern after cowboy pointed out a very real problem of my advise. He is actually absolutely correct. I think the reason it works out for you is that your problem is very minor, as you said in your original post: <a small amount of light can be seen coming from underneath the middle of the blade>

                Thank you so much for updating us on your situation. It is always good to know if our advises have resolved a problem. If not, we usually like to refine our advises to further target the problem. Sometime the first advise is to very general and can only reduce the problem, but not entirely fix the problem.

                Just curious, when you wrote <was able to fix the blade geometry in less than 15 minutes>
                Did you mean the entire process or only just the DMT part? 15 min on DMT seems long, but that 15 minutes total for all steps seem a bit short. As TradeJoe said, it may not be a bad idea to invest just one inexpensive flat stone like a 800 or 1000 grit stone. A flat waterstone is very helpful in term of fixing these kind of problem. You can probably get one for $20-30. -- it does not have to be super expensive.

                1. re: twyst

                  Glad to hear it worked out. Thanks for the followup post.

                  1. re: twyst

                    Hi, twyst:

                    Good on you. Easy to overthink these things. Did you measure how much height you lost?

                    Aloha,
                    Kaleo

                    1. re: kaleokahu

                      I did not measure, but Id guess about 1/8th of an inch at most. It was a minor repair!

                  2. Since Ive already got most of the voices here I listen to when it comes to all things knife Ill just ask this unrelated question here rather than starting an entirely new thread. Im about to buy my first gyuto. I have narrowed my choices to the Masamoto KS Wa-Gyuto and the Konosuke HD. I am leaning towards the masamoto because as fun as the HD sounds Im not really sure if its suited to be a workhorse knife and feel the masamoto may be better suited for heavy use.

                    You guys have any opinion on which way I should lean? It will see use in a professional kitchen.

                    19 Replies
                    1. re: twyst

                      The Masamoto is an awesome blade but depending on where you work it could draw unwanted attention. Then again the Kono isn't exactly cheap. I wouldn't want a laser for my primary knife but I wouldn't want to be with out one either. If you haven't handled the Masamoto KS WA it has a thin tip.
                      Either of these would be a fine first choice depending on what you want out of the blade. If you don't have to worry about theft the Masamoto would get my vote.

                      TJ

                      1. re: twyst

                        No first hand experience with the Masamoto KS. It is generally said to be a thin knife, but not quite as thin as a 'laser' like the konosuke. In spite of this, I'm thinking there are relatively few things you can't do with a Konosuke that you could do with a Masamoto. That said, those few things do come up in a professional kitchen, and the Massamoto may be better suited as your primary knife than a konosuke.

                        A few other concerns:
                        - The price difference, but that's obvious.
                        - The white steel in the masamoto is arguably a negative in a professional environment. It's on the more reactive side. But that's also obvious. You know better than I do whether you can maintain a carbon steel knife in your working environment.
                        - The profile of the masamoto is the most intriguing thing about that knife, to me at least. It's not very tall at all. It looks like it has a very long straight section of edge extending from the heel past the midway point of the knife. Should be good for slicing and straight-up-and-down chopping.

                        I'm sure both are good knives. Neither is completely worry-free for a pro kitchen. Especially f you go with the masamoto, I hope you'll review it here.

                        1. re: cowboyardee

                          The Masamoto is not highly reactive so that's a plus. You can always force a patina.
                          Once you carbon you may be hooked. (Fair warning!)
                          Neither would be my first pick for work unless theft probability is almost nill.
                          The downside to the Kono HD is the low profile which is not that unlike a Miroshi style or maybe a Carter.
                          Both killer choices either way.

                          TJ

                        2. re: twyst

                          <Ill just ask this unrelated question here rather than starting an entirely new thread. Im about to buy my first gyuto. I have narrowed my choices to the Masamoto KS Wa-Gyuto and the Konosuke HD>

                          You should treat my following with grain of salt because I don't work in a professional kitchen.

                          What I do know is that petek works in a professional kitchen for a long time and is still working in one. He has no problem at all with his Konosuke HD and loves his Konosuke more than any of his other knives. cowboyardee, despite does not work in a professional kitchen, is probably as knowledgeable as most chefs (if not more) in this particular area because of his competition experience.

                          Both knives in theory can work in a professional kitchen, and both knives have something against the rough professional settings. Let's start with square one and establishes the very first point.

                          1) Both knives have been routinely used in professional kitchens, so they can definitely do it.

                          2a) Konosuke HD is thinner, but is essentially very close to being stainless
                          2b) Masamoto KS is thicker, but is a real carbon steel by all accounts.

                          So it is really up to you in this regard.

                          Do you think it is more difficult to handle a thin blade (which require slightly better knife handling)? Or do you think it is more difficult to care for a real carbon steel knife (which requires more wiping and drying).

                          1. re: Chemicalkinetics

                            Fair points and its a tough call. Ive decided to go with....
                            .
                            .
                            .
                            .
                            .
                            .
                            Both! :P

                            I just ordered, they should be here tuesday :D

                            1. re: twyst

                              <Both! :P>

                              Ha ha ha. I know both are going to be good, but now you have two, so one will eventually be your main knife. Man, I must say I (and many others) will be very interested in your review for these two knives. Please take time and write a review. Even if you don't have time please write a short 2-3 sentences one.

                              The reason is that I am interested what is more preferable in a professional kitchen. Would it be the thicker but more reactive knife or would it be the thinner but more inert knife? I suppose it is a personal preference, but we will all be interested to know.

                              My guess is that if it is me, then I would probably slightly prefer the more inert (Konosuke HD) knife.

                              1. re: Chemicalkinetics

                                I will definitely post a review after Ive given them both a fair shot. Ill try them for a week or so each then report back.

                                I do plan on forcing a patina on the masamoto right away with the mustard trick, so hopefully that makes the upkeep manageable.

                                1. re: twyst

                                  <I do plan on forcing a patina on the masamoto right away with the mustard trick, so hopefully that makes the upkeep manageable.>

                                  Before you do that. I like to raise a point here for others.

                                  Do any of you know if the value of a knife will go down due to forced patina?

                                  In other words, would the forced patina (as opposed natural patina) negatively impact its value if twyst decides to sell the knife at a later time,

                                  1. re: Chemicalkinetics

                                    Do any of you know if the value of a knife will go down due to forced patina?
                                    ------------------------------------------------------------------------------------------------
                                    Of course not. Patina is patina. You don't have to keep it and there's no difference if it's forced aside from controlling the color to some degree. Blood gives a nice blue patina.
                                    I Think you will find more in a professional setting will prefer the Masamoto because it's carbon and that's where the heart lies of many knife nutz that haven come too close to the rabbit hole.
                                    Lasers are nice, I'd never be with out one in my roll but the Masamoto is more versatile (IMO).
                                    twyst is going to be a happy camper.

                                    1. re: Chemicalkinetics

                                      Ill start a new thread for a real review in a few weeks after I get some real quality time with these blades, but my initial reaction is OMG, why did I wait this long to get some J steel! I was a bit surprised with how sharp the masamoto was out of the box, I had heard its often not that sharp when it arrives, but this one was definitely RAZOR sharp and could push cut paper from miles away with just a minor stropping.

                                      1. re: twyst

                                        <Ill start a new thread for a real review in a few weeks after I get some real quality time with these blades>

                                        Oh, you got the knife already? Congratulation. This is really fast. Did you buy yours from Chefknivestogo because I know Mark sells both Masamoto KS and Konosuke HD. Thanks for the heads-up, twyst.

                                        1. re: Chemicalkinetics

                                          Yeah, I got them from CKTG and had them shipped overnight. Not my first purchase from them and I can't recommend them highly enough, their service has always been impeccable.

                                          1. re: twyst

                                            JCK has the Masamoto as well for a slightly better price and I usually get my orders just as fast as from CKTG. Can't go wrong with either one.
                                            Any new stones?

                                            TJ

                                            1. re: TraderJoe

                                              "Any new stones? "

                                              Got some chosera stones for my edgepro about 2 weeks ago.
                                              Chosera 400x
                                              Chosera 600X
                                              Chosera 800x
                                              Chosera 1000x
                                              Chosera 2000x
                                              Chosera 3000x
                                              Chosera 5000x
                                              Chosera 10000x
                                              and a leather strop and some paste

                                              I think you guys are turning me to the dark side, Im starting to get obsessed with knives, already looking at honesukis now ><

                                              1. re: twyst

                                                <I think you guys are turning me to the dark side>

                                                You have surpassed us in your knowledge of the Chosera stones, my master.

                                                1. re: twyst

                                                  Chosera stones are awesome. I wish I had more of them but at finer grits the SS's win out for me just on a cost basis.

                                                  TJ

                                              2. re: twyst

                                                <had them shipped overnight>

                                                Wow, you really cannot wait, can't you? :)

                                                I agree with TraderJoe that I have excellent experience with JapaneseChefsKnife as well. JCK is so fast that it is not slower than any other US based stores.

                                    2. re: twyst

                                      <Both! :P

                                      I just ordered, they should be here tuesday :D>

                                      Nice!! you're gonna rock the kitchen with those 2 beauties..congrats and please give us a review when you can.
                                      (so jealous right now)

                                  2. re: twyst

                                    I said Id chime in with a brief review after some time with both knives (Masamoto ks wa gyuto and konosuke hd wa gyuto both 240).

                                    The masamoto takes and holds a fantastic edge, feels sturdy enough to do almost any work you might want to do with a chefs knife, and has a pretty flat profile that makes it a fantastic shape for many of the knife strokes most commonly associated with j knives. I loathe the handle shape on the knife and will be sending it off to be rehandled soon. With the cost of the knife added to the cost of rehandling its going to have run me almost $500 to get this knife set up the way I want it.

                                    The konosuke is light as a feather, I like the handle, and it holds an edge for almost as long as the masamoto it seems. The HD steel is also so much more worry free in a pro kitchen, perhaps I babied the masamoto a bit to much, but the kono is truly pretty much a worry free blade during my shift. The profile of the kono also seems to have a bit more belly which makes it much more suited for rock chopping herbs etc. The kono set me back $200.

                                    The kono is the clear winner for me, I absolutely LOVE the knife and recommend it without hesitation to anyone looking for a new gyuto.

                                  3. Hi, twyst:

                                    I've waited to weigh in until now. Everyone's given good advice. I've rehabbed a good number of these swayback edges and IMO largely the same issues arise here as arise with chips and dings, even broken tips. As CBAD has described, simply reprofiling opens a can of worms. Without getting too wonky, you can limit the number of worms, but there's a price to be paid for that, too.

                                    Before you do *anything*, accept that you will not get your knife "fixed"--it will never be quite the same. The very best--theoretical, professional, perfection--result you can hope for is a downsized facsimile with approximate, proportional bevels. Think (a) overall height reduced by the height of the swale, all along the entire blade edge (which would come closest to retaining your starting profile); or (b) "blending" from the start of the swale either toward the tip or the heel (which would dramatically shorten the OAL or spine-to-heel).

                                    Frankly, while CBAD is technically correct, I would recommend that (after your acceptance of reality) you follow Chem's advice (reprofile), put an edge on it, and *ignore* all the other worms in the can. Your edge *bevels* will just have some minor whoop-d-do's in them wherever the blade goes from thin to thick, is all. IMO, better to have these *lateral* irregularities than either an entirely changed profile or what you're starting with. This will save you days if not weeks at the stone, and the suicidal/homicidal urges you will feel if you mess up and make matters worse.

                                    So if you want your knife rehabbed, it can be done, but it won't be perfect even if *you* are. If you want your knife fixed, retire it and get another. Or both.

                                    I'll leave you with a thought: Do you think Euro slicers, "utilities", and the J's that resemble them sprang forth into existence from some brilliant cutler's mind? I don't. I think that form took its profiles from years of sharpenings and "fixes". I have some fine old Sabbatiers that are in mid-metamorphosis from chef to slicer.

                                    Aloha,
                                    Kaleo

                                    2 Replies
                                    1. re: kaleokahu

                                      "Frankly, while CBAD is technically correct, I would recommend that (after your acceptance of reality) you follow Chem's advice (reprofile), put an edge on it, and *ignore* all the other worms in the can."
                                      ________
                                      I suspect the degree to which you can get away with ignoring the other worms in the can is inversely proportional to how big of a regrind you're trying to fix. The smaller the regrind, the more my above posts overcomplicate things. A big deep regrind on a long, thick knife - a job that will take a long time even in the best of circumstances - it would be pretty frustrating and probably a little confusing to spend a good while straightening the profile only to see the regrind reappear as you grind in the bevels.

                                      1. re: cowboyardee

                                        Hi, CBAD:

                                        Yep, agree. But your use of "get away with" covers a lot of subjective ground. I'm more in the school of "If the edge passes cleanly through the food, I'm getting away with it." I suspect for you and many others here, who can--blindfolded, one hand behind your back, and not knowing what is being cut--detect sub-millimeter thickness irregularities with one pushcut, "get away with" has a much different meaning, investment and motive force.

                                        Aloha,
                                        Kaleo