ZDP 189 Leek = huge disappointment

I have Kershaw ZDP Leek and pretty happy with it. I got one which was sharp, I resharpen it anyway and this did not take much time - I was surprized after I hear all this cryes about how hard it is. My experience with ZDP was same as with CP154 or BG-42 or CPM S30V. I had no problem at all and it respond to sharpening very well and I was able to get exteremly high edge on it.

I am using it a lot lately for cutting wood (hardwood including), paper and mostly thick leather on the wooden base - my latest hobby leather-crafting. It is very pleasant to have such a sharp knife and have it sharp for so long - I do not worry about its ability to cut, just take it out of my pocket and cut whatever I need. And I am very happy with this tip - it allows to use it for cutting out splinters by gently citting top layer of skin without reaching blood vessels - only two knives are suitable for this ZDP Leek and Microtech Mini SOCOM (absolutely impossible to use delica for this too thick edge).

I am not making holes in soft plastic as well as not wet it in saltwater - I guess my expectation of fine edge is different and I can agreed it may be not a "working knife" mentioned here, but it is what it is - magnificent cutter (which you probably do not need, as I see).

In general I think you should not jugge Ferrari same way you jugge Track or cheap famaly car etc - it is too expencive, take too much gas, can not be used to carry heavy load and can not accomodate famaly of 5... From my point of view you missuse this knife, and your expectation just do not much reality.

Thanks, Vassili.
 
So, harder steel doesn't not correlate with brittleness or torsion rersistance? Why then do diff. HT?
 
its a good question. i think it has something to do with adverse tension/stress in the material, which you can relieve by tempering the steel, i dont think its possible to test untempered steel at 64 hrc compared to tempered steel at 64, its very easy to break untempered steel by bending it
 
robertmegar said:
Why then do diff. HT?
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Generally because those types of knives tend to take a lot of pounding and you want the higher impact toughness. As well because if they are overloaded you are more likely to keep the blade in one piece - but severely bent.

The latter part is what gets people confused. If you take two blades and put them under the same force and then increase it, the blade which is softer actually breaks sooner, a piece of annealed steel will actually tear apart before the hardened steel even takes a set.

However it isn't like you have some kind of internal torque wrench and can stop at exactly 150 ft.lbs so most people stop at angles and not torques and a softer blade will generally bend further but be much easier to get there. You can see this clearly here :

http://www.panix.com/~alvinj/graphA2vsO1.jpg

Note at the high tempers, the A2 blade has a lower maximum torque, so it is weaker, but it has a much higher deformation, so it bends much further before it breaks. This of course is a general behavior of all steels.

If you want to see it first hand then buy one of those cheap $15 khukuris which are just edge quenched. They are basically annealed in the spine and even though they are 3/8" thick they bend extremely easy. You can even twist them like a candy cane.

Now try to do the same thing with just a 1/4" blade which is fully hardened and it won't even bend significantly.

-Cliff
 
So a harder steel bends less under a load, but will shatter when you hit it? (what does a shatter look like?)
 
A delicate thin tip is going to be prone to snaps no matter the steel. When I sharpened some ZDP blades for forum members I didn't think it was any harder to sharpen than D2 or S30V. Maybe even easier than both actually.

As for the factory edge. I guess I'm suprised by that. I've had a Vapor, a Leek, a Storm II, a Scallion, Chive and BlackOut and all came sharp as all get out and ready to go. I can't say I'd discount the whole company based on one experience with one knife.

Kershaw has a lot going on that is very good, Ken Onion for one, their great service dept. for another. I understand the disappointment you must feel when your cheaper Rainbow Leek performed the same tasks flawlessly but you might give some thought to the limited potential that you just got a bad blade.

Talk to Thomas about having them evaluate it for you before jumping to conclusions. He is worth giving the benefit of the doubt to as is Kershaw IMO.

STR
 
STR said:
A delicate thin tip is going to be prone to snaps no matter the steel. When I sharpened some ZDP blades for forum members I didn't think it was any harder to sharpen than D2 or S30V. Maybe even easier than both actually.......

Kershaw has a lot going on that is very good, Ken Onion for one, their great service dept. for another. I understand the disappointment you must feel when your cheaper Rainbow Leek performed the same tasks flawlessly but you might give some thought to the limited potential that you just got a bad blade.

Talk to Thomas about having them evaluate it for you before jumping to conclusions. He is worth giving the benefit of the doubt to as is Kershaw IMO.

STR
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STR....

Your chosen words speak of a depth of experience and understanding.

Derision tossed casually and without thought or truth behind it truly bothers Thomas. Plainly, if he does not believe in the company that he works for, he does not stay there.

It is not simply a passion for Thomas, but a calling. He is compelled to drive the machine to be the best that it can be.

To compare Gerber Knives in the current incarnation to Kershaw Knives shows a true lack of understanding of the knives themselves, and the dynamic driving the company.

Kershaw Knives IS commited to producing a better product for the intended audience. IF ZDP was not the right steel for this knife, the principals involved will work harder than most of us can imagine to make things right.

Best Regards,

STeven Garsson
 
STR said:
A delicate thin tip is going to be prone to snaps no matter the steel.
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When steel gets thinner it can actually bend more before it breaks. This is why for example Wilson can put 90 degree bends in his S90V fillet knives. Thinner tips will of course be weaker however his other Leek didn't get damaged on similar work so properly hardened ZDP-189 would not either.

If you compare a soft stainless and ZDP-189 both reground to thin and acute edges you will note, as expected, that the ZDP-189 edge will deform much less, which would be expected because it is much harder. You can observe this directly under 10X magnification and the same general principles will apply to the tip or the blade bending as a whole.


GarageBoy said:
So a harder steel bends less under a load, but will shatter when you hit it? (what does a shatter look like?)
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In general, very general, steels with a higher hardness tend to have a lower toughness but again this is just a general rule and there are many exceptions. Brittle failures will have no deformation and will usually induce multiple pieces broken which have very sharp edges. If you bend a butter knife for example you will note it will eventually just tear apart but if you try it with a file it will just snap clean. The butter knife has ductile failure and the file brittle.

-Cliff
 
I have a ZDP Caly Jr. My very unscientific opinion is that it (ZDP) is over rated, at least for my purposes.;) :p :p
 
Thomas only said he was worried about the ZDP 189 blade because it was a 'cutting blade' and was only suitable for that. Using it as a prybar or an auger is the 'abuse' he was worried about and the tip breaking off is the consequence. I love my Ti-ZDP but I only use if for cutting and it is a sharp as a razor for that purpose.
 
When steel gets thinner it can actually bend more before it breaks.
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We are talking about 64Rc here, perhaps more. I've fixed dozens of thin tips from blades of S30V, D2 and many others from 420HC, 440C to ATS34 59Rc and above hardness blades for knife owners. Frome my perspective it appears that tips break off quite often. I can only recall one that came into my shop that was bent and the tip broke when it was straightened out. It was an A.G. Russell Woodswalker blade which was very thin. I rarely see a high carbon non stainless blade for breaks though. Most of what I'm referring to above is always stainless. Here in the last year I've had two ZDP189 blades into my shop for this same thing where a small part of the tip broke off. One a Delica solid ZDP and the other a Calypso Jr laminated one..

STR
 
I guess it is possible to break anything with enough effort. Can you give us some statistic about how many tips was broken by different steels or makers? And what is commo reason for this?

Thanks, Vassili.
 
STR said:
We are talking about 64Rc here, perhaps more.
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It isn't the hardness which makes the tips very inflexible as much as the massive amount of carbide in ZDP-189, but yes even then what I noted is a general property of steels. When the cross section is reduced the ability of a steel to bend is increased. The strain that is induced in a given curvature is proportional to the thickness. This is why you can take a 1/16" machete and bend it like a pretzel but a 1/4" blade will crack at a much lower angle.

If you look at the edges of used ZDP-189 blades under magnification you will see the edge is highly deformed. This happens on every steel, even 66 HRC, at really low cross sections the plastic region gets large. Yes as I noted the tip is likely weak because it is thin, however his other Leek didn't get damaged and thus this one should not either because the yield point is higher not lower and it wasn't an impact failure but a tensile failure.

-Cliff
 
I am posting this as a follow up to my ZDP Leek experience.

I broke the tip off of my ZDP Leek while cutting dry wall. I know that many call it "sheet rock", but it is only compressed gypsum and I usually use a utility knife to cut it. I felt that the Leek would do a good job in cutting this material.

This Leek was one of the "not sharp" ones out of the box. I managed to get it very sharp after quite a while in sharpening. Anyway, I was not very happy when the tip broke. I decided to return it to Kershaw. I sent it to them last Wednesday and they returned it to my house with a new blade, today, Tuesday!

Although, I still do not think that the tip should have broken and I believe that it should have also been sharpened correctly in the first place, I want to recognize the outstanding customer service that Kershaw has provided me in resolving this issue.

Kershaw has exceeded my expectations in customer service! Thank you!:thumbup::thumbup:


 
you can flame me if you want, but my zdp leek is one of my "Goin' Out" knives. it gets carried alot but dosent really get much action.

hard work...? thats what my Pikas and Natives are for


who the hell puts on a pair of dress slacks to go lay concrete?

now i realize that sebbies have the whole 'have your cake and eat it too' thing goin on. but really! sometimes you just cant have it all.
 
Hi Vassili. Tips do break a lot. I'm not suggesting that they don't just bend just that I never seem to see those as often.

As for your question. I can't say I do a bunch of that type work to make a real accurate assesment of the steel that is more prone to break over say another. I see knives like Buck 110s and here lately several S30V blades with broken tips. I've fixed Spyderco Dodos, Yojimbos and a couple of Caly Jrs for reprofiles this year and I have seen D2 and AUS steels also though. Mostly the ones I get in that are broken are beater uppers that work hard for a living from the looks of them and they are usually not that expensive. I still get some old Fury cheapy knives and stuff that says "surgical stainless" and stuff like that often enough too.

Some of these good ole boys out here in Oklahoma in the oil fields have and carry knives that you almost want to disinfect before you dare touch them. Pretty scary stuff at times. :D I have seen relatively newer knives that look like they have been carried for many years the way they are all gunked up and beat to hell so I think it is probably more accurate to blame the end line user for tip breaks and blade breaks than to focus on any one steel.

STR
 
I just wanted to caboose my own thread to say that Kershaw went above and beyond in honoring their warranty policy. I finally returned the knife about a month ago. After a few e-mails, they agreed to replace the blade with an S30V blade which would better fit my needs as a user.

It was shipped promptly, it is extraordinarily sharp, and I am a very satisfied customer. Kudos to Kershaw.

Mike
 
William Henry uses ZDP in their knives and they have a series for about $170ish I believe.The handles are carbonfiber ,super light and very durable knife. H300-C is the model and it weighs .9 oz.

MPE
 
MPE said:
William Henry uses ZDP in their knives and they have a series for about $170ish I believe.The handles are carbonfiber ,super light and very durable knife. H300-C is the model and it weighs .9 oz. MPE
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Those knives are friction folders, and do not have an active locking mechanism.

Best Regards,

STeven Garsson
 
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