Sharpening ZDP-189

Discussion in 'Maintenance, Tinkering & Embellishment' started by Eli Chaps, Jan 9, 2020.

  1. Eli Chaps

    Eli Chaps Basic Member Basic Member

    Apr 20, 2018
    I suck at sharpening this steel. Plain and simple. I don't know why, I just know I do.

    There is a thread in the general forum on this steel ( ) and it just got me thinking about it again.

    I only have one example and that is a Delica that came from the factory with a terrible grind. I can grind the steel but I can never seem to get the apex right.

    I've used my KME and free hand. Diamond, SiC, or AlO, I just don't seem to get it. I can sharpen the popular "S" series of steels but this one eludes me.

    I've always thought that maybe it is because I'm so heavily reliant on burr feel and I really never feel one on this knife. But I don't know if I believe that or I just need something to tell myself. :D I mean, S90V doesn't exactly burr up like 440A! So yeah, I don't know...

    I know people say it is so easy to sharpen but man it sure has kicked my backside.

    What say you all? Do you struggle with it? How do you like to sharpen it?
  2. Bill3152


    Nov 27, 2018
    Mine is a snap. I don't use the bur method. I just go by feel. At first I put a 325 dmt edge on and some stropping. But have since taken that edge up to eef DMT. The strop really gets that steel very keen. I use 1 micron cbn on balsa. Then a few light laps on leather glued to balsa with .25 diamond spray.
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  3. I only have two (edit: actually three) knives in ZDP-189. My best effort with ZDP-189 (Kershaw Leek), in terms of the edge produced, came in using a DMT Aligner guide with a Coarse/Fine 8" DMT Duo-Sharp hone. As you mentioned, feeling a burr or even seeing one, with this steel, I think is unlikely. The steel is usually heat-treated so hard, into low/mid-60s HRC, I think the edge basically crumbles away at a thinness that would otherwise produce a burr in other steels of more typical hardness.

    I used the Aligner & DMT hone to reprofile the Leek to something around 30° inclusive. But immediately after finishing that and being impressed with the result, a portion of the tip, 2mm or so, snapped off when it dug into a strop. I learned a hard lesson about ZDP-189 in seeing that. I think it's just too hard and too brittle to hold an edge as thin as I usually prefer. I reground a pointy tip on that blade (grinding the spine to meet the cutting edge), using a 21-inch alumina-zirconia belt (120-grit or so) cut and glued flat on a board. Again, the result was impressive, looking as if it never broke in the first place. But I don't trust the steel to be tough anymore, being so hard & brittle if it's thinned near the edge or tip.

    The steel is easy to grind, in terms of abrasives used. Almost all of the carbide content is chromium carbide (and there's a ton of it in this steel). That doesn't present much of an obstacle to abrasives at/beyond the hardness of aluminum oxide. But the hard part is refining it, once it's apexed, because the lack of a discernible burr makes it difficult to gauge progress toward an apex. I used cutting tests in paper to gauge that, as I reprofiled that Leek.

    The other two knives I have in ZDP are another identical Kershaw Leek and an older-generation Spyderco 'Calypso' in burgundy/purple FRN handle. I've never touched those two with a stone or hone of any kind, and likely won't at this rate. I just don't care for the steel and it's limitations anymore.
    Last edited: Jan 9, 2020
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  4. Eli Chaps

    Eli Chaps Basic Member Basic Member

    Apr 20, 2018
    That's my thing, I just can't seem to refine the apex. I either "over" sharpening it or don't get it refined enough.
  5. BruceMack

    BruceMack Basic Member Basic Member

    May 20, 2015
    Confession - I threw away my Endura ZDP in anger after failing to achieve a decent edge. Several months ago I bought a new Delica ZDP as well as KME glass plates and diamond film. I haven't sharpened it or used it yet. Having had some life scares and also a great personal revelation I promise to do my best in 2020. That includes sharpening this blade.
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  6. tiguy7

    tiguy7 Gold Member Gold Member

    Jun 25, 2008
    I have only ever had to touch up my William Henry ZDP-189 on either a Spyderco Sharpmaker or Shapton Glass stones. On the S/M, I use med, fine , and x fine. I go by the smoothness of the stroke on the med. Once I feel no “hitches” on either bevel, I move to the finer stones to polish the bevels usually counting 10-20 strokes per side on each stone.
    On S/G stones, I use 500, 1000, and 2000 in the same fashion as above.
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  7. bgentry


    Aug 3, 2009
    I have a Delica in ZDP-189 that I've dropped the primary bevel down to ~11-13 dps. I did all this work with a DMT XXC over the course of about 3 or 4 sessions as I dropped it further each time.

    At one time my progression on that blade was: DMT XXC, C, EF, Spyderco UF. At DMT EF it was extremely sharp and a fantastic utility blade. The thin edge probably helped a lot. After I got the Spyderco UF 8x2 stone, I polished up the edge and it produced a near mirror bevel on the fairly wide primary (cutting) bevel. The resulting edge was pretty incredible by my standards. It would push cut phonebook paper with essentially no effort to start the cut. A lot of my blades take just a bit of force to begin the cut into phonebook. With this blade just a touch would begin the cut.

    I'm going to guess that some combination of the relatively thin geometry of this blade (from the factory) and the diamond plates made my job much easier. I'm not sure what factors might be contributing to making other ZDP blades so problematic. Unless you are working with obtuse edges and/or stones that don't cut hard steel well.

    I wish you good luck.

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  8. samuraistuart

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

    Dec 21, 2006
    Interesting timing on this thread for me. I just resharpened a Miyabi Santoku in MC66 (What Henkels/Miyabi call ZDP-189, "Micro Carbide 66HRC"). The factory edge was sharp and the geometry is fairly thin, but I wanted it sharper and a little more acute after using it the past year. In reality it wasn't much of a change. Maybe 15° factory edge down to 14° per side (guided sharpening). I thought the Suehiro Chemical 320 stone would cut that steel easily, but it was taking a long time with scrubbing strokes to get anywhere. I was able to watch the abrasion taking place on the shoulder of the factory edge, and marked the edge bevel with sharpie as well. On simple carbon steels the Chemical 320 will chew through them like butter. I pulled out the Atoma 400 and had no problem, and decided to just stick with the diamond plates, 600, 1200, then the DMT 3 micron. It is extremely sharp after that progression, and with bite as well!
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  9. chiral.grolim

    chiral.grolim Universal Kydex Sheath Extension Knifemaker / Craftsman / Service Provider

    Dec 2, 2008
    Exactly the opposite - the steel is so hard that it doesn't bend/fold as readily as softer materials - you can get it very VERY very thin/keen and it will still hold its shape. It will take a keener edge than steels in more typical hardness and will only form the minutest of burrs at a thinness below when softer material will burr and then will, as you suggest, crack away readily. Typical steels form burrs on the order of a few microns broad (sometimes more, able to be seen by microscope), steels at >63 Rc typically form burrs <0.5 microns broad, ~10X smaller (with an apex 10X finer, if done right). :thumbsup:
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  10. Eli Chaps

    Eli Chaps Basic Member Basic Member

    Apr 20, 2018
    So for those of you who are adept at sharpening this steel, how do you gauge the apex? As I said, I'm a burr sharpener so not having even a hint of that messes me up. I don't know when to flip sides, I get unsure and undoubtedly make mistakes.

    Also, do you make a lot of single side strokes (stroke, flip, stroke, etc.) to refine the edge?

    Very interested in your techniques.
    Last edited: Jan 11, 2020
  11. Bill3152


    Nov 27, 2018
    I do lots of one sided strokes to start in the 325 range. Then I start alternating. I test the edge with my thumbnail. At this stage you can strop it and it will easily shave arm hair. Or you can continue your progression up to whatever stone you want to stop at. The strop really makes any edge imo. On these hard steels I tend to refresh my strop with whatever I'm using. Usually 1 micron cbn on balsa and then .25 diamond on leather.
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  12. wade7575


    Apr 3, 2013
    I use the Venev OCB stones and they seem to work really good on my Sukenari made with ZDP-189,I asked Konstantin from gritomatic and right now all he has is the Venev Legacy resin which is the old resin for the KME but he is getting the Venev stone's for the KME in OCB resin,I would try the OCB they seem to work really good on ZDP-189.
  13. jpm2


    Nov 19, 2014
    It's been a while so I sharpened a zdp caly3 and dragonfly today. They were already sharp so it didn't take but a couple strokes on the fine side of a norton jb8 to raise a small burr on each side. I worked it back down with a few very light strokes then moved to the brown sharpmaker triangles and did a repeat. On to the white triangles then a few strokes on bare denim and done.

    When the burr is too small to feel, I use my thumbnail.
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  14. bgentry


    Aug 3, 2009
    There's a strong case to be made for "no burr sharpening". I have only done it myself a few times. The one I am thinking of, on a Spyderco Yojimbo 2 in S30V came out pretty incredible! The method I used, which is copied from a sharpening guy who's last name sounds like he was born in a post office, goes something like this:

    1. Lightly cut the edge of the blade into a stone. Do this 2 or 3 times *lightly*. Yes, you are trying to remove the edge. This will do it. When you look down at this edge, under medium to bright light, you should easily see a reflection indicating that the edge is "wide" and flat and reflecting light.
    2. Sharpen as you normally would, doing some number of strokes, or some amount of time on each side, changing sides as you progress. I recommend no more than about 90 to 120 seconds per side.
    3. As you progress, keep doing the light reflection check. The reflection should get more and more narrow as you go.
    4. At some point, the reflection will disappear entirely. At this point the edge is very close to apexing. I think I remember reading that the edge should be in the neighborhood of 10 microns wide when the reflection is gone.
    5. Now do alternating strokes, 1 or 2 per side.
    6. Keep going until the edge is clearly sharp, as indicated by cut tests: BESS tester (which I do not own yet!), phonebook paper, arm hair, etc.

    As I said, I was quite impressed with the edge I produced this way on the Yojimbo 2.

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  15. Bill3152


    Nov 27, 2018
    Today I needed a touchup. For the heck of it I used my paper wheel with white compound. Boom! 30 seconds and it was wicked sharp again. For those that have issues with some steels a paper wheel is fail proof imo once you get accustomed to it.


    Jul 14, 2017

    I don't sharpen a lot of zdp-189 however I recently sharpened a stretch 2 and the edge came out fairly well. Used Spyderco med, UF stones and finished on Dan's black Arkansas that was finished/lapped up to 2k using wet/dry sic sandpaper.

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