My takamura migaki

Discussion in 'Cooking Knife Reviews' started by pricey, May 20, 2019.

  1. pricey

    pricey

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    So I purchased this knife I think two years ago and planning on pulling it back out of my bag for some use in the kitchens again, I was having a recurring problem last time , with it being pretty brittle, even with the micro bevel, I was sharpening at a 15 on each side then I think if I remember right my micro bevel was about , 25, on a finishing stone, nothing coarse ofc,

    Using these plastic Board's that all kitchens use these days I put it down to those being harsh on the knife. Perhaps it's just the kind of steel it is, maybe my push cut wasn't great. Any way. Any tips on sharpening angles, I'm pretty sure mine where ok, or micro bevels, or why this micro chipping occurs. I do cut hard veg with it, aswell, and as it is a laser I imagine if probably best get a work horse along side this knife for the harder veg.

    Any way, wish you all the best. Hope your all not working too hard.
     
  2. benuser

    benuser

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    I don't know this very knife, so just a few general observations. I guess it's made of R2/SG-2.
    Most knives come brittle from factory. Has all to do with how sharpening and especially deburring is taking place there, often with buffering. So out of the box the edge is made of fatigued steel. First thing I do with a new knife is getting rid of the original edge, starting at 320 or 400.
    In order to leave the final edge to the customer some factories sharpen at a very low angle, far below what it can actually hold in real life.
    For performance the thickness right behind the edge is far more important than the very edge itself. The same in a strange way with edge retention: a fine edge with thick blade behind it will require more effort to get through the food, and the board contact will be harder as well, than with a more obtuse edge that has a thin back bevel behind.
    When thickness right behind the edge doesn't exceed 0.2 millimetres the angle of the final edge won't make much difference as far as performance is concerned.
    With R2/SG-2 on poly board I would probably make a one-sided micro-bevel of some 35°. So, with a back bevel at the lowest possible angle — say 2° above the blade's inclination — I guess I would aim for a convexed bevel on the right side ending at 12°, on the left side a straight one of 18°, and cut a 35° micro-bevel on the right bevel. That makes a very stout edge within a very thin geometry.
     
  3. pricey

    pricey

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    How do you make a convexed edge, I've probably sharpened mine since I had it, maybe 4 times, it's chipped every time within a month or so of using, so maybe im just not removing enough metal, it is R2 powdered steel , er it is on chefknivestogo if you want to have a look , takamura migaki it is a gyuto

    As for the micro bevel , we always do this in the highest grit possible right, I have a 13000 stone for this purpose alone, I don't polish on this as it takes alot of bite away from my knifes and in hind site it can shave hairs but can't bite through veg .

    I can gauge the angle. More or less , I'm pretty good at that. But by convexed you mean different angles on each side, being right handed does that change your original angles mentioned?
     
  4. benuser

    benuser

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    Convex edge: you start at the lowest possible angle and only little by little the spine. You want the bevel to form one continuous arc towards the edge. Be aware that Japanese knives are asymmetric and have the edge off-centered to the left, which benefits to food release — provided you are right-handed.
     
  5. rick alan

    rick alan

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    My Migaki required quite a few minor sharpenings to get past the "corrupt" factory edge and show less microchipping. I sharpen at 10deg and MB to suite the task, in your case stropping in a 25deg MB is right. I've never touched the edge with anything courser than 1K, and always finish sharpen and MB at 6K. Even with a 25deg MB I can slice onions <1mm, actual precision caliper measure, no board contact of course, but I should think you'd find this edge to cut very slick through a shift. 0.75mm is about the limit with a 6K stone and a shallow MB.

    If you could work out a convenient way to have your own HighSoft rubber board at work that would make a huge difference for the edge. And of course control your force, and always add at least a slight push or pull to your vertical motions.
     
  6. phatch

    phatch Moderator Staff Member

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    There are some other simpler methods but there are trade-offs.

    Slack belt on a belt sander. Not a beginner technique and requires special equipment. Fast and amazing edges though.

    Wet-dry sandpaper techniques on somewhat squishy substrates:

    Strop on the sand paper against a firm mouse pad or leather strop. But you need to use fairly light pressure and the angle you hold is not the angle generated at the edge. The edge is more obstuse than your held angle with this substrate. 13 degrees is close to a 20 degree edge angle generally speaking

    Strop on the sandpaper against balsa works as does clear new growth pine. No knots on the surface you'll use. Your held angle is closer to the actual edge angle this way.

    Practice on lesser blades until you get a feel for how this works. I mostly use a mouse pad.

    You can't easily use a rod on this sort of edge. A similar effect can be had with a piece of non corrugated cardboard (think shoe box) loaded with some stropping paste. Or a leather strop of course.

    Dont let a convex edge go dull. Lots more work to restore than just to maintain.
     
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  7. rick alan

    rick alan

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    You can easily convex your secondary bevel(s) all you want just by varying you angles from high to low as you go. Here I am considering everything behind the MB as a secondary bevel. But your MB is put in straight, just 1-2 degrees difference from your initial sharpening angle.
     
  8. benuser

    benuser

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    By the way, I don't think using a 12k makes much sense with a double-bevelled stainless. R2/SG-2 is relatively coarsely grained, I don't polish it and use medium-fine stones only for very light stropping and deburring. I guess I would use a JIS4000 for both cutting the micro-bevel and deburring.
     
  9. pricey

    pricey

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    Also guys while I have you here, what do you know about blade resetting? Like completely taking off any edge to put a new one in the blade, this isn't for the takamura, just a older global I use for my harder veg pumpkins ect. Never invested in that cleaver like I wanted too .
     
  10. benuser

    benuser

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    Use a really coarse stone, 220 or 320, start by thinning, so begin at the lowest angle. Go on and stay with that angle until you have raised a fat burr, repeat at the other side. The only way to make sure you have removed all fatigued steel. Set your bevels with a medium-coarse, say 400-600, in the case of a Global with very little pressure.
     
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  11. pricey

    pricey

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    Ok cool , thing is as with all knives look after them well enough , and you won't need to spend soo much money. I will at some point want to reinvest in a new set of three or four. And then hopefully not for a long time :) I'm curious so jump into carbon knives at some point . Never used or owned these blue or white steels and will be fun to get to learn about these .

    As for this takamura, benuser said they are a little off set, so do I sharpen let's say 3 strokes on right side 2 on left? How can I make sure I don't mess with the geometry , and if I do, how do I fix it?
     
  12. rick alan

    rick alan

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    I never noticed any offset in my Migaki, and like with all lasers there is not much metal there to offset, but you can sharpen them asymmetrical if you like. On a knife that is symmetrically ground I personally don't see the gain in asymmetrically sharpening a properly thin and properly microbevelled edge.
     
  13. benuser

    benuser

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    Some serious effort is needed to change a blade's geometry!
    If you're fine with the existing one, start sharpening one side, before switching to the other one. You start fairly behind the edge, increasing the angle little by little. Verify your progress by looking at the scratch pattern or use a marker to see where the ink is removed and steel abraded. A loupe is very helpful, think 8X.
    You go on until you've raised a burr on the other side.
    That’s the moment to start on the other side, and do the same.
    No stroke counting, no measurement needed.
     
  14. rick alan

    rick alan

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    SG-2 relatively coarse grained? It's PM steel, and the finest grained stainless I've come across (never used AEB-L). Perhaps you're confusing the fine microchipping for coarse grain?
     
  15. benuser

    benuser

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    No, no confusion here.
    The highly charged PM steels still are much coarsely grained than, indeed, AEB-L or simple molys. The only 'advantage' is in high abrasion resistance. See Roman Landes' Messerklingen und Stahl.
     
  16. rick alan

    rick alan

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    Unfortunately I don't speak German. Carbide size in PM steels is typically a distribution of sizes running from 1-4 microns. It would be surprising if simple molys are better than that. I can say that both srs-15 and r2/sg2 both hold a 6K edge exceptionally well.
     
  17. benuser

    benuser

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    Typical carbide size of PMs are in the 3-8 micron range. To give an idea, AS stays below 1 micron. With the kind of edges we're looking for, a bit problematic. Edge stability suffers. I wouldn't use the finest stones for a full polishing, but only for very light stropping and deburring.
     
  18. rick alan

    rick alan

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    Last edited: May 31, 2019