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Chef Knife edge

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Bob Duguay, Aug 19, 2019.

  1. Bob Duguay

    Bob Duguay

    102
    Aug 28, 2017
    just finished my first Chef knife and now need to sharpen. What angle degree should I sharpen it to?
    Thanks
     
  2. Cushing H.

    Cushing H. Gold Member Gold Member

    436
    Jun 3, 2019
    Depends on your user and intended usage. “Typical” for a european style knife, originally designed for general purpose use, and to be usd somewhat “roughly” is something like 20-25 degrees per side (the less acute angle protects the edge more from damage.

    If the intended use / user is kinder and gentler to the knife edge, and does more slicing than chopping, then 15 degrees per side would be more typical, and would give a easier cleaner slicing action. Note, a shallower angle (like the 15 degrees per side) would require a harder rockwell rating (say, 60 min, better 62 or better) to achieve and maintain that edge).
     
  3. weo

    weo KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 21, 2014
    Hi Bob. That's going to depend on a number of things: who you ask; what type of chef's knife; how long you want the edge to last; single vs double bevel; to last to name a few. A common response will be somewhere between 15-17 degrees.

    Have you checked out the Bladforums custom search engine for an answer?
    https://www.bladeforums.com/threads/bladeforums-custom-search-engine.1313722/
     
  4. Bob Duguay

    Bob Duguay

    102
    Aug 28, 2017
    Ok I will check it out.
    Maybe this will help.
    Blade is 15n20 60rockwell.
     
  5. Cushing H.

    Cushing H. Gold Member Gold Member

    436
    Jun 3, 2019
    You might have trouble achieving, and especially maintaining 15 degrees per side. You might be better off with 20 - especially if the blade will be used hard and often....
     
  6. samuraistuart

    samuraistuart KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 21, 2006
    15n20 is extremely tough. Especially at 60HRC. You certainly shouldn't have an issue "achieving or maintaining" a 15° per side edge in the kitchen. Just make sure common sense practices are used....like wooden cutting boards instead of glass/ceramic/plates. But I agree that higher rockwell (62+) would be better.
     
  7. Bob Duguay

    Bob Duguay

    102
    Aug 28, 2017
    I am giving 15 a try. I got the edge pretty thin on the grinder. But not thin enough lol. Taking forever to get it sharp.
     
  8. Cushing H.

    Cushing H. Gold Member Gold Member

    436
    Jun 3, 2019
    Good to hear that is the case with 15n20. I got burned once with an older knife ... not sure what the rockwell is, but clearly on the softer side. Could not even raise a burr on it at 25 degrees, much less 15. Ever since i have been cautious about the relationship between rockwell, and the ability to take a blade to lower edge angles...
     
  9. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Most I do are in the 15-17 degree per side range.

    The biggest factor is wheat the edge thickness is before sharpening. I take mine to a near zero edge.
     
  10. Bob Duguay

    Bob Duguay

    102
    Aug 28, 2017
    Yeah Stacy I know it was not thin enough. Did a lot of work with 100 diamond stone and could not get a good burr at 17 degrees.
     
  11. weo

    weo KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 21, 2014
    Don't be afraid to grind it thinner.
     
  12. Storm W

    Storm W

    266
    Feb 19, 2019
    What are your knives that have formed your experience? Its amazing how much performance is left behind. I have had a couple of 15n20 blades Rc checked at 62. The were ground to maybe 2 or 3 thousandths before sharpening. Everyone who has tried them has been disappointed because they are not stainless and the when I talk to them a couple of months later I am informed that I will not get my test knives back from the wives. They will let me sharpen after 6 months to a year. That anecdote is just to say that even though I find 15n20 to not hold a edge next to S35VN or M2 at 66Rc there is a lot of performance to be had. I have be spatchcocking chickens with mine with no issues such as chipping. This makes me wonder why my 59Rc Shun is nearly serated from chips. If you want to explore 15n20 join the KITH. I can send you a blade if you like.
     
  13. Cushing H.

    Cushing H. Gold Member Gold Member

    436
    Jun 3, 2019
    Storm W - lots here to try to respond to..... will try to make it reasonably short (but you DID ask :) ). Way back when (in 1977) I happened to spot and pick up the first edition of Boye's book on knifemaking. It was enough for me to say "someday I want to do that" ... but especially introduced me to the concept of knives (and steels) better than the extremely inexpensive stuff my parents had around the house ... and given the steels (and their properties) discussed, convinced me then and there that non-stainless high carbon blades were for me (mostly because I always had enjoyed a good sharp knife, and the somewhat softer steel made sharpening on stones easier). In 1981 I bought my first Sabatier's high carbon blades (though I still have no idea just what alloy they are made from):
    upload_2019-8-20_12-26-24.png
    These blades are all pushing 35 years old or so - so from that hopefully you see that the non-stainless issue with 15n20 is not an issue to me (Stacy once asked me if my knives went into the dishwasher - oh. my. no. way :) ).... these blades were (or have been) enough for me to appreciate the influence of use-condition versus appropriate edge angle. For example, the boning knife is 25 dps, the "utility" in the center is 20 dps (because I use it to take pits out of avocados) and the chef's knife and slicer are actually at 15 dps (because I use them mostly for kindler-and-gentler slicing motions). The shallower angles also taught me just how fast a "sharp" knife can dull (even when treated nicely).

    somewhere along the way I got introduced to the restaurant-style plastic handled knives from Victorinox and Henkels:
    upload_2019-8-20_12-35-21.png
    These are stainless, and appear to be a somewhat harder steel than the Sabatier's (sorry, I do not have a rockwell meter...). I also got my first belt sander, and figured I would try "sharpening" using belts on these relatively inexpensive (i.e. replaceable) knives. Especially the top one became one I really experimented on - and have even taken that edge to 5 dps (it is truly scary sharp - the edge holds up somewhat, but I would not call it "robust" against usage). For yucks, I tried to do this shallow angle on the Sabatier "utility" knife ... but it just was not having it... This was my first real introduction to the relationship between steel hardness and the ability to achieve (and maintain) a small edge angle. (I actually still really like these knives for their performance and utility - and regularly recommend them to family and friends who are looking for something better than what they have sitting dull.)

    THEN I got introduced to the japanese high-carbon, high-rockwell knives:
    upload_2019-8-20_12-43-24.png
    These introduced me to what a high-rockwell steel with a well developed (low edge angle) blade can be - and how that edge can truly hold up against use. Per warnings (but I had to try also....) it also reinforced how difficult they can be to sharpen on a whet (not "water") Arkansas stone, and how disastrous it is to take them anywhere near a steel, or a sanding belt (at least at high speed) (leaves a very "toothmarked" edge - I believe due to both brittleness and carbide tear out). These knives (and a few others) are what finally drove me to the T-8 sharpening system - even then, that system leaves a slightly ragged edge. After reading that the Japanese makers grind, then always finish the blade on a waterstone - I discovered that just a few strokes on a waterstone after sharpening on the T-8 cleans up the edge and makes all the difference in the world. The Santoku in the middle I have taken to 10dps - and it is a wonder to use (and holds the edge pretty well also...).

    (I have a number of other japanese knives in stainless steels, including cobalt-vanadium (a Shun), VG-10, and a newer powder steel called "R2", and these have raised the bar even higher on edge properties - but I am still feeling a little like a "traitor" against my long-held bias for high-carbon steels..... :) (the R2 especially is incredible - sometime I will start a thread on that subject....)

    Ok - finally to the point that really started this: A while ago I obtained this knife from my Grandmother:
    upload_2019-8-20_12-56-2.png
    It is clearly not stainless - but I have absolutely no idea what the alloy is. It is also pushing something like 100 years old - so I really do not want to do anything with it other than to look at it, and occasionally use it as a reminder to me of my grandmother. But here is the thing: by the way it has always reacted to stones, it has been clear that the steel is pretty soft. Also, the edge does not hold up worth anything (again, because it is soft. Even at 25 dps the edge does not hold up, and I have never been able to raise a burr on the thing (even on the Tormek T-8) - apparently the edge just kind of rolls over and never breaks off. The only thing that makes it somewhat useful is if I take it to a steel and produce a sawtooth edge using that - and even that does not hold up. More reinforcement for me of the relationship between steel hardness and the ability to reach and hold low edge angles. I know there are other factors (grain structure, carbide content, etc - which might help explain your experience with your Shun blade...), but I think (believe??) that one of the biggest factors is hardness (and hence why I made that comment earlier in the thread).

    I also strongly believe that (per what I said above) that edge angle is not a one-thing fits all - hence my boning knife is at 25 dps, whereas the knives I use more for slicing are at a smaller edge angle (slight aside: western tradition, via Escoffier, have held the chef knife to be a general-purpose tool, whereas the Japanese tradition holds the knives to be single-purpose tools. My own direction has taken me very close to the Japanese tradition - where I will reach for a specific knife for a specific task, even in the middle of prepping a single dish. Anyway - you asked what experience I was coming from in my comment - so there is is (besides, I love to talk knives!) :).

    Re the KITH - I am not at all hesitant about the 15n20 (for all I know that is what the Sabatiers and Nogents are made of....) - I would love to try 15n20 for a kitchen blade, and thank you very much for the offer - but I know I have some rather extensive travel coming up, and no way would I be able to finish the blade within the timeframe of the KITH, and it would not be fair of me to be so late to the game :-( . I do look forward to seeing what others do with it though!!!
     
    Last edited: Aug 20, 2019

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