# ZDP-189 Sharpening is difficult



## deanb (Sep 6, 2012)

A few months ago I bought a 7" Twin Cermax Santoku fom Amazon at a ridiculously low price. I'm not all that wild about santokus but the price was right and I was curious about the steel. I'm assuming that M66 translates into ZDP-189. The OOTB edge wasn't too bad so I just polished a little on a 12K Shapton Pro and stropped it with a CrO2 loaded strop. Yesterday I decided it was time for a little touchup. I ended up thinning the blade and going all the way from a 320 grit stone to a 12K stone. This is without a doubt the most difficult sharpening job that I've ever had. I don't think I'll be getting another ZDP-189 knife. Too darned hard to sharpen


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## bluntcut (Sep 6, 2012)

I agree zdp is more trouble that its worth - for kitchen knives.

I'd thinned a few mono-steel zdp pocket knives, unpleasant experiences even with diamond benchstones. I found the cermax mc66 gyuto (zdp core cladded with stainless) a bit chippy when bevel angle lower than 20* incl.


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## Schtoo (Sep 7, 2012)

Just a tip when Shaptons run out of bite.

Get some slurry worked up on them with a diamond plate, soft steel (mild steel will do) or a scotchbrite pad, make sure the stone is damp and have at it. You should get a lot more bite out them and they'll work (kind of) with the really tough steel alloys.

Because you're pushing the stone waaaay past it's normal operating envelope, expect some random weirdness like clogging, a 'wet' stone that'll need proper drying and a few other things that you'll know when you see it. Not show stoppers, but 'odd'. The balance of wet/dry will be different with a slurried up Shapton, with more of a lean to 'wet'. 

This also works on Choseras, as they too can run out of bite when the steel has a large proportion of chromium, vanadium, tungsten, etc. in it. It's not the hardness of the steel, it's the abrasive resistant components that cause the difficulty and as these hard/tough parts 'blunt' the abrasive, you need to keep fresh stuff coming into play, which is why having some loose particles running around will tend to keep the stone cutting where as a 'normal' stone won't refresh itself fast enough to work properly. 

The mechanics behind why the Chosera runs out of bite is different to the Shapton, but the cure is similar. Again, you'll be pushing the stone beyond it's happy place, but it'll work and it's not like it something you need to do often, because if you need to sharpen these tough alloys often, you need something more capable of sharpening them. 

(It's really odd when you run some steel on a 1K Shapton, and the stone feels like it's greased. Shapton 1K stones _don't do that_...)

Good luck, 

Stu.


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## chuck239 (Sep 7, 2012)

I don't think it is fair to say all zdp-189 is difficult to sharpen. I will say I own a twin cermax zdp knife that is a pain to sharpen. But my other zdp knife isnt that bad.

-Chuck


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## NO ChoP! (Sep 7, 2012)

I found the Cermax more trouble than its worth. It needed thinning. Was a pain to thin. Had soft cladding that scratched easily. Was very chippy. May have had good retention, but lost it's initial edge almost immediately. 

You can get SG2 which is easier to sharpen, gets sharper, has good retention, and is about as chippy.

Or, R2, which is less chippy...

Absolute retention is not _that_ important to me...


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## bkdc (Sep 7, 2012)

If I didn't own an Edge Pro, I would probaby cuss every time I had to sharpen ZDP-189. It would be more trouble than its worth if I had to hand-sharpen it.


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## Cadillac J (Sep 7, 2012)

I have a Spyderco ZDP Endura that seemed fairly easy to sharpen with my regular stone progression: Shapton Pro 220 -- Chosera 600 -- Bester 1200 -- 5K SS (I've also used this for M390 and CPM M4)

But then again, I'm not sure what hardness it is HT'd to or if that even matters at all.


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## Justin0505 (Sep 7, 2012)

bkdc said:


> If I didn't own an Edge Pro, I would probaby cuss every time I had to sharpen ZDP-189. It would be more trouble than its worth if I had to hand-sharpen it.



±1
I for most sharpening the EP is fun, but freehand is more fun. Thats not the case with glass-like pm blades. Even just using the EP to set the inital bevel is a huge help..im also amazed by how well the stock stones cut the really hard / tough stuff.


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## JBroida (Sep 7, 2012)

i dont know... i dont really have trouble with harder/more wear resistant steels on stones either


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## Mingooch (Sep 7, 2012)

I own some ZDP knives and use both Choseras and jnats on them, and I have minimal issues. I really like the ZDP, not as much as R2, but I cant say it is hard to sharpen IMHO.


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## James (Sep 8, 2012)

I have a twin cermax and sharpening isn't too terrible for me. I find that zdp-189 deburrs incredibly easily; thinning is a different issue though...


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## ThEoRy (Sep 8, 2012)

Just sharpened up a twin cermax "petty" or chuto or whatever they call it. No problems sharpening it , however at one point both my gesshin 400 and bester 1200 loaded up and stopped cutting well for a minute till i cleaned them up with the atoma. So no problems with the steel, minor glitch with the stones.


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## Keith Sinclair (Sep 8, 2012)

Cadillac J said:


> I have a Spyderco ZDP Endura that seemed fairly easy to sharpen with my regular stone progression: Shapton Pro 220 -- Chosera 600 -- Bester 1200 -- 5K SS (I've also used this for M390 and CPM M4)
> 
> But then again, I'm not sure what hardness it is HT'd to or if that even matters at all.



How did it go wt. the M390?I have the spyderco,giving it a hard workout & abuse wt. some landscaping work.I was really impressed how it did not even chip,but eventually the edge rounded.That steel is the hardest to sharpen that I have encountered yet.I still don't have an exceptable edge on it yet,find it hard to get a burr going,i think I'm going to the Atoma 140 see if I can kick up a decent burr.Interested to hear others experience wt. this steel & how they sharpened it.


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## bluntcut (Sep 8, 2012)

I've thinned (essentially zero-grind) 5 spyderco zdp-189 knives: cf stretch, delica, dragonfly, 2 ladybugs. Mono vs clad - thinning a ladybug(1.78" blade) was more work than reprofiled (thinning behind the edge) a 8" Twin Cermax MC66. 

Zdp-189 steel matrix at 64-66hrc is much harder than a bastard file(62hrc) - therefore tough on grinding equipment. Zdp predominant(ignoring tiny% of VC) Chromium carbides at ~66hrc are actually not too hard for Alumina/Sic/etc to abrade. To get tree-topping sharpness (for showing off :tooth: hair-popping by float the blade 1/4" along skin) at sub 20* incl took huge effort - microchip with 1 careless stroke or impatience deburr/wire.

Zdp super thin edge is super chippy - clearly visible with naked eyes. This problem get old very quick, so instead of a laser/razor I put a convex edge with angle ~30*. For heavy duty gardening (*slice* palm fronds & small branches) with my cf, I added a 50* micro-bevel.

Zdp worth it? Yes if you know how to sharpen it, otherwise too much trouble. Cf stretch & dragonfly are here to stay, I gave away others. I rather deal with zdp than s30v & d2 but my time better spend on cpm-m4/m390.


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## Keith Sinclair (Sep 8, 2012)

Schtoo said:


> Just a tip when Shaptons run out of bite.
> 
> Get some slurry worked up on them with a diamond plate, soft steel (mild steel will do) or a scotchbrite pad, make sure the stone is damp and have at it. You should get a lot more bite out them and they'll work (kind of) with the really tough steel alloys.
> 
> ...



Thanks Stu thats very informative.Today I finally got a good edge on my Spyderco M-390,thinned it some starting wt.DMT XX coarse,Atoma 140,Atoma 600,Gesshen 2K soaker,Rika 5K,Leather Strop-green oxide


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## Dave Martell (Sep 9, 2012)

Try sharpening some of those Michel Bras knives and you'll be loving that ZDP


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## JBroida (Sep 9, 2012)

its more the shape of the michel bras knives than the steel... uggg


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## Knifefan (Sep 10, 2012)

I haven't got too many problems with a prototype Miyabi that I bought at Henckels' shop sale in Japan. That knife has a ZDP189 core and soft damascus cladding. It takes longer to sharpen, I guess about twice as long than VG10, but still manageable. At acute angles (under 20 deg included, which is what I usually put on those) the edge gets a little chippy, probably due to size and volume of the carbides. Adding a 35 deg microbevel takes care of this. No chipping plus a MUCH longer edge retention with minimal loss of sharpness. ZDPP189 definitely is a steel where microbevels are recommended.

One word to thinning. I also have a Cermax Petty. I thinned both the Miyabi and Cermax. The Miyabi was A LOT easier to thin. Probably the cladding on the Cermax is harder than that of the Miyabi.


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