Kershaw Composite Blade Leek

[UnknownVT]

I'll say straight away this is simply a WoW! knife for me.

The Kershaw Ken Onion Leek is one of my all time favorite knives -
this CB (Composite Blade) version - just takes the prize as my absolute favorite Leek.

Comes in a much larger box than normal -

that's because the 1660CB Leek comes with a pouch -

Compared to the regular Leek(s) -

Silly comparison pic closed -

if I didn't label the knives - I wouldn't have known which was which.

That is the beauty of this knife - it is subtle and understated - just like the regular Leek -
that is until one opens the blade - then WoW! -

Notice the copper colored accent between the two toned steels.

The upper part (back) of the blade is Sandvik 13C26 - actually a stainless steel that I like a lot, but here it is only doing support duty - the cutting edge part of the blade is CPM-D2 - the chromium content is 12% which is just below the 13% required to be called stainless - so it's kind of "semi-stainless" (note: not an official term). But reputable maker like Bob Dozier uses this steel quite extensively.

I love the way the composite is done on this blade - I reminds me strongly of the differential tempered hamon of Japanese swords - I think this blade is a beaut - and very functional too - a kind of marriage of a sort of traditional look with modern materials and funtionality - don't want to gush too much.......

Slightly more enlarged details of the markings on the knives -

The all steel Leeks are Frame-Locks -

This CB sample is almost ideal - covering just more than 50% - slightly more than my other frame-lock Leeks.

As I said the Kershaw/Ken Onion Leek is one of my favorite knives - it probably can start to be considered a classic of sorts -
I like them enough that I now have 6 of them -
alright, 6 different versions - previous reviews -

Kershaw/Ken Onion LEEK (pics)

Kershaw Rainbow Leek - a pictorial review

Black "boron" Leek

polished G10 S30V Leek

G-10 S30V Leek (matte version)

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[Vivi]

I would be interested to hear how the CPM-D2 model holds an edge compared to the 13C26 and 440 Leeks.

 

[ckerwin]

Have you seen the new damascus Leek?:thumbup:

 

[Dog of War]

Thanks, UVT. From other pics I thought this one unusually good looking Leek, and I see now that it's not only the very striking composite pattern on the blade, but the blade grind. Kershaw should consider grinding all Leeks this way.

I'll be waiting for some cutting tests, too ... would like to see some side-by-side with 13C26 and other steels to compare how the CPM-D2 holds an edge.

 

[UnknownVT]

the blade grind. Kershaw should consider grinding all Leeks this way.
I'll be waiting for some cutting tests, too ... would like to see some side-by-side with 13C26 and other steels to compare how the CPM-D2 holds an edge.

My apologies but I can't/don't do edge retention tests -
However FWIW - much less meaningful -
here is an ad-hoc cardboard cutting comparison -

there simply isn't much in it - probably within my inconsistency in cutting.

However there is a slight comment I'd like to make -
the CB Leek blade (although flat ground, vs. hollow) feels about the same when pinched and pulled toward the edge as the 440A Leek (the much older one) - ie: I think the thickness near the edge bevel is about the same. Whereas the one sample of 13C26 Leek seems to feel noticably thinner toward the edge - although it still does the widening toward the edge - it feels less pronounced.

I do not have a suitable micrometer to give measurements - but our feel - although sounds very unscientific and subjective, is actually very sensitive and one can easily detect differences when compared side-by-side as if it were.

FWIW - although this is barely reflected in my ad-hoc cardboard cuts - but the 13C26 Leek did cut deeper, just, and I had to kind of pull my stroke to prevent cutting all the way through.......

I am not an expert on steels - but like any knife knut I am always reading about them - to me Sandvik 13C26 and D2 seem to have opposite qualities. 13C26 has high edge stability which means one can get the blades very sharp without edge defects - whereas D2 is very wear resistant - but has large chromium carbide crystals which kind of goes against having very fine edges - so it can have good longer lasting edges, but not the high edge stability of 13C26.

I tend to favor steels with high edge stability -
eg: I EDC a Victorinox SAK - not known for having a hard steel - but the blade can be sharpened up very well........

But for me almost any well known modern steel works fine for me -
I even been known to use knives with 420J2.

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[UnknownVT]

From other pics I thought this one unusually good looking Leek, and I see now that it's not only the very striking composite pattern on the blade, but the blade grind. Kershaw should consider grinding all Leeks this way.

It appears that the grind has been evolving -

some early photos -

crop from the Kershaw 1660CB brochure -

crop from Kershaw released photo -

Here's a great photo by kneedeep showing his with BoD (Born on Date) of Feb 08 - from the thread -

New 1660CB Composite Blade Leek pictures (with 3D bonus!))

I resized it only -

and finally mine with BoD Mar 08

The Feb and Mar 08 are flat ground
vs. the regular Leeks (and the earlier photos) that have hollow ground

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[Dog of War]

I am not an expert on steels - but like any knife knut I am always reading about them - to me Sandvik 13C26 and D2 seem to have opposite qualities. 13C26 has high edge stability which means one can get the blades very sharp without edge defects - whereas D2 is very wear resistant - but has large chromium carbide crystals which kind of goes against having very fine edges - so it can have good longer lasting edges, but not the high edge stability of 13C26.

Appreciate your observations and comments, UVT. I'm definitely a high edge stability guy myself, love the Sandviks. But the CPM-D2 interests me, with hopefully finer grain and smaller aggregates than regular D2 it could strike a nice balance.

.

 

[UnknownVT]

I'm definitely a high edge stability guy myself, love the Sandviks. But the CPM-D2 interests me, with hopefully finer grain and smaller aggregates than regular D2 it could strike a nice balance.

OK - since I am not a steel expert - I'll quote from other sources -

First CPM = Crucible Particle Metallurgy
so it appears that "CPM"-D2 maybe a misnomer -

Please see Post #6 (link) in this thread in the Spyderco Forum

" References to "CPM D2" or "CPM 154 CM" are misguided, however, as neither of these steels is produced using particle metallurgy. "

Here's a comparison cutting test between CPM-D2 and regular (non-CPM) D2 (pdf)

Using Cliff Stamp's page on knife blade materials -

from his description of D2 -

" D2 has a coarse carbide structures, the primary chromium carbides which can be up to 50 microns in length, the fracture grain size is 7.5. It is commonly used in industry for punches, dies and various types of knives. "

That does not sound very conducive to fine edges.

In contrast from his description of 13C26 -

" Summary : 13C26 is a natural upgrade to 12C27 where a higher hardness and wear resistance are required and the higher corrosion resistance and toughness of 12C27 isn't needed. As 13C26 is designed as a razor blade steel it sets a high standard for edge stability and is thus an ideal stainless steel for those who desire a high initial sharpness and keep their blades very sharp. "

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[Dog of War]

Interesting. Other than that thread you linked, I've never seen it questioned that CPM-D2 uses Crucible's particle metallurgy technology.

.

 

[UnknownVT]

Interesting. Other than that thread you linked, I've never seen it questioned that CPM-D2 uses Crucible's particle metallurgy technology.

I was dubious as well -
but a kind of a "negative vet" confirmation is Crucible's own page on their steel datasheets -
there are 2 instances of D2 - neither is prefixed with CPM (neither is 154 CM) -
whereas there are plenty of other steels that are specifically prefixed with CPM.

The pdf data sheet for Airdi 150 (D2) does not mention anything to do with CPM.

The other pdf on D2 upgrades for rollforming rolls is not on specs on D2 at all,
BUT interestingly gives the known problems of D2 -
" When your D2 rolls...
. chip or break
. deform
. wear too fast "

Of course if anyone is really interested they can write to Crucible for a more definitive answer.

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[Dog of War]

After doing some research of my own with no clarification, I've posted a link to this thread on the Kershaw forum. Hopefully the good folks at Kershaw can give us the whole story on this steel.

 

[rbmcmjr]

Interesting. Other than that thread you linked, I've never seen it questioned that CPM-D2 uses Crucible's particle metallurgy technology.

.

I believe the person quoted was talking out his butt. The CPM process is what is supposed to make CPMD2 such a great blade steel, primarily through smaller carbides and uniform distribution thereof. This allows it to take a finer edge and have greater strength than the regular D2.

Scott Devanna, the Crucible guy, made this comment about a year ago (January 2007) on a different forum:

Alot of very good steels out there and D2 is one of my favorites - afterall I have been selling it for over 30 years now! I am very interested to see how CPMD2 will perform and if it will be an actual improvement over good ol' AISI D2. The good part is we all have our own preferences and thanks to interested specialty steel companies we have quite a few good choices out there.

Very clearly, he is noting a difference between the two steels. Later in the thread, he stated that CPM D2 was expected to be released for use in late February.

 

[UnknownVT]

The CPM process is what is supposed to make CPMD2 such a great blade steel, primarily through smaller carbides and uniform distribution thereof. This allows it to take a finer edge and have greater strength than the regular D2.
Scott Devanna, the Crucible guy, made this comment about a year ago (January 2007) on a different forum:
Very clearly, he is noting a difference between the two steels. Later in the thread, he stated that CPM D2 was expected to be released for use in late February.

Just to help corroborate this - that pdf review of CPM-D2 vs.D2 was found via this thread -

Phorum :: Preliminary Trials :: CPM D2 vs. D2

All the discussion there clearly distinguishes CPM-D2 from plain D2.

However the results did not find significant difference between CPM-D2 and D2 - although it should be noted two different knives were used.

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[Broos]

Thanks for the review - That's a sharp looking version of the Leek!

 

[UnknownVT]

Have you seen the new damascus Leek?:thumbup:

Yes, I have and very pretty blade(s) too.

However there is this thing about damascus - it's kind of like wood-grain to me - they are all very pretty - but it's hard to find exceptional ones - so for me I have to see them in the flesh as if it were - I did a search for images of the Damascus Leek on the web and found these images and I put together a composite of 3 blades -

as one can see the patterns are all good but different. I like them all - but for me none are exceptional -

Whereas this blade from this Browning Double Edged Damacus Hunter is what I like -

detail of blade -

it was the hamon (differential tempering)-like edge with the contour line layering that makes the Browning Damascus, for me -
that's why I like this Compsite Blade Leek so much, and probably over the Damascus Leek - unless I see an exceptional one - (of course I would not say "no" to a Damacus Leek either ) -
we are only talking about looks for now.

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[UnknownVT]

The Composite Blade Leek is flat ground (the regular Leeks are hollow ground) on my sample of one the blade is rather thick toward the bevel/cutting edge.

So I decided to put convexed edge on the blade - by honing away the distinctive step/corner between the blade face and the edge bevel.

Please see -

Convexed Edge

where I put this edge on a SAK.

I used an EZE Lap fine diamond hone to work the bevel, concentrating mainly on getting rid of the step/corner to the edge bevel.

Because one of the main attractions of this CB Leek is its looks - I protected the face of the blade with some Scotch tape - exposing ahout 1/8" at the edge.

As the edge part of the composite blade is CPM-D2 - and D2 is a hard tool steel I was expecting a bit of work - but was very surprised by how quickly I was able to cut in the new convexed bevel.

I was able to feel the burr on the edge - and went to finish the blade on a pair of fine ceramic crock sticks for the final micro bevel edge. The blade certainly felt sharp on slicing paper.

On examining the blade edge under a 30x illuminated microscope I found that on one side of the blade I had retained most of the original bevel really only removing the step/corner to that bevel - and to my surprise I saw fold-over at some parts of the edge - surprised because D2 is supposed to be pretty crisp when hard and resists fold-overs.

I worked more on that side of the blade and honed more away - so that under magnification almost all the bevel is now newly honed. Again finishing with crock sticks for the final micro bevel edge - this time under the microscope I did not see any fold-over.

the legend side was where I initially only partially put a convexed edge on the blade leaving some of the original bevel - and perhaps that was some of the reason why there was some fold-over after using the crock sticks.

this is the current state of the edge after I worked more to fully hone the bevel to a convexed one.

this side is neater since it was the easier side for me being right-handed. But one can see that some of the original bevel remains toward the heel of the blade.

Pinching the blade and pulling toward the edge the step/corner to the bevel is now more or less seamless the transition is now very smooth and I can feel that the bevel is now convex (apple seed shaped cross-section).

The blade now cuts through better having much less resistance at the bevel transition to the face.

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[Vivi]

UnknownVT, it looks like there is some of the original bevel below where you were grinding. Is that how you intend to leave it or have you considered grinding away the whole edge at the more acute angle?

Also looks like you're missing some tip there.

When I got to try out some CPMD2 Military's I was also surprised at how quick they sharpened.

 

[UnknownVT]

UnknownVT, it looks like there is some of the original bevel below where you were grinding. Is that how you intend to leave it or have you considered grinding away the whole edge at the more acute angle?
Also looks like you're missing some tip there.
When I got to try out some CPMD2 Military's I was also surprised at how quick they sharpened.

I think you're looking at the cruder tip (second) photo?

That's the problem with photos - they can only show one viewpoint/angle - I tried to take a photo that emphasised the convex curve - so there are other aspects of the blade edge that did not show as well.

Using different angle of lighting - first let me show you where I did leave some original bevel - near the heel -

it's fairly easy to see, as the grind/hone lines are perpendicular to the edge.

Here's a photo of the same tip using different lighting - this does not show the convex curve that well, but shows that the whole bevel has been honed - and the tip especially - since the thickness extended to there too -

what looks like a "ooops" bit of honing that extends a bit more into the face - I think (not too sure though) the blade actually feels thicker there - so the grinding on the flat hone took more away on the thicker (raised) part.

I did think of thinning more - but that would mean a lot more work and the bevel would be much, much wider - which probably will spoil the looks - so my convexed edge is a sort of a compromise - where I think I have gained quite a bit, for fairly quick and minimal work - the ease of honing the CPM-D2 was a surprise ......

Before-After comparison (using a composite photo) showing the bevel has extended quite a bit more -

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[Vivi]

Thanks for all the photos. I think it might just be the lighting but in that last picture the top blade looks like it was ground more acute than the factory bevel, taking off the shoulders, but not going to the very edge except for the last 1/2 inch or so at the tip. Probably looks that way because of the nature of convex edges and trying to light them for photos.

Either way I'm curious what a Kershaw composite blade would look like after being ground flat to the stone. If I had a larger disposable income I'd try myself.

 

[UnknownVT]

I think it might just be the lighting but in that last picture the top blade looks like it was ground more acute than the factory bevel, taking off the shoulders, but not going to the very edge except for the last 1/2 inch or so at the tip. Probably looks that way because of the nature of convex edges and trying to light them for photos.

I do want a more acute/smaller angle so that the blade is thinner leading up to the final edge.

However I actually said in my first quick attempt I did manage leave some areas unhoned -
but once I saw that under magnification I corrected it, that's why that side looks cruder.

However here is another photo - actually taken a few minutes before the one you commented on so it is exactly the same unchanged hone -
with different lighting which does not show the convex shape that well - BUT does show the entire length of the blade has been honed -

Either way I'm curious what a Kershaw composite blade would look like after being ground flat to the stone. If I had a larger disposable income I'd try myself.

The CPM-D2 part of the blade looks as if it is treated chemically (etched) to be darker - so grinding the face would remove the darker contrast part of the blade.

As mentioned the blade is already FLAT ground so any gain would be either thinning the blade further (which it could do with for optimal sharpness) or being thick'ish may suit a full convex ground.
Either way it would remove the darker finish of the blade and therefore its looks for me -

Like I said, this is about as far as I am willing to go - I have gained a lot for pretty minimal work - because I feel the blade is substantially sharper for cutting through things than before.

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