Buck Knives: edge retention test

cb, Glad you took the time to conduct this test we may both learn something . What steel does your knife hold ? DM
 
This has been a very interesting read. Thank all of you guys for the testing!

For my use, mostly cutting cardboard, a rather toothy edge has always seemed to hold up longer than a highly polished edge. By toothy, I mean the edge resulting from sharpening on lansky ceramic croc sticks (grey and white.) Most often, the knife I use at work is sharpened at 40* inclusive with 8cr13mov blade steel (SRM 710.) It shaves easily when freshly sharpened, then keeps cutting well for up to about two weeks of my typical use. Not scientific, but my limited experience.
 
Yes, its obvious you've not done any test like this because if you had you would have stated several items in the parameters up front . Instead you went on for paragraphs not telling what I did ? Now, if you really want to make a point that compares with my findings you'd take that same knife and sharpen it using a coarse grit of 280 then start cutting more sisal rope . For an accurate comparison !! DM
 
cbwx34 said:
I've worked on a few ideas of why fine edges 'fail' (discussed below), but hadn't tested them in this manner.

...

I think alot of times, people that find a coarse edge better, or that a fine edge fails or doesn't cut at all, is because it was improperly sharpened. For me, one of the biggest points is that a fine edge doesn't equal a smooth or rounded edge. It will still have "bite" and will penetrate to cut. But it's at a very refined level. You also have to insure that you don't leave a burr or w
wire edge... which is easier to do at this level.

...

Ultimately I know that it's your knife... sharpen and use it how you see fit.

cbw
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I also wonder how much 'failure' depends on 1) how hard or abrasive the cutting medium is, and 2)the standard for the loss of sharpness.

I used a very fine edge to try to cut through a tire bead, just to see what would happen, and I ripped a chunk of the edge out. If the edge hadn't been as fine, there is a good chance it would have done less damage. Is that a failure of the edge or a failure of the operator?

If one person uses a knife that cuts rope at 3lbs of pressure with a fine edge, and then sharpens it again when it cuts at 6lbs, how does that compare with a coarser edge that may cut at 8lbs and then slowly dulls to 12lbs? One could say that the coarser edge only lost 50% of its sharpness, while another could claim that even when the fine edge is dull it cuts better than the coarse edge... and both could be right.

Like you said,
I know that it's your knife... sharpen and use it how you see fit.
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:)
 
David Martin said:
Yes, its obvious you've not done any test like this because if you had you would have stated several items in the parameters up front . Instead you went on for paragraphs not telling what I did ? Now, if you really want to make a point that compares with my findings you'd take that same knife and sharpen it using a coarse grit of 280 then start cutting more sisal rope . For an accurate comparison !! DM
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Do you mean to reference what I did? If so I'm not picking up what you're puttin' down. :)

Edit- Never mind, I guess you are referring to cbw's test. Out of interest, to what variables would you attribute the discrepancy between cbw's results of 400 cuts with no demonstrable deformation, and your results of 4 cuts with obvious burrs?
 
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David, The steel in the knife (it's a Kersahw w/ a 4/08 date) should be 13C26. As for your other post, I guess you just don't get it. Oh well.

Any Cal. said:
Out of interest, to what variables would you attribute the discrepancy between cbw's results of 400 cuts with no demonstrable deformation, and your results of 4 cuts with obvious burrs?
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Any Cal, I'll answer your question, just to reiterate my point. From this testing, you can't attribute the discrepancy to anything, becasue it could be anything or a combination of things. Bad steel in one knife, improperly sharpened, difference in cutting technique, difference in steels, difference in rope, etc. etc. It's why drawing conclusions in sharpening can be so difficult. You can over time draw conclusions based on multiple tests, or by eliminating factors, but not just based on this small sample.

cbw
 
cbwx34 said:
Any Cal, I'll answer your question, just to reiterate my point. From this testing, you can't attribute the discrepancy to anything, becasue it could be anything or a combination of things.
cbw
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I understand that, but I was interested as to DM's opinion as well. Even with different steels, geometries, testing standards, and conditions, it is surprising to have a 100x difference in results (4 cuts vs 400 cuts.)
 
Yes thats a big variance and I'll look into that but that was not what the test was about . In the mean time unless someone sharpens that knife steel at a coarse level and conducts the same test cb's results are at best lacking/incomplete . Different steels are capable of holding a finer/polished edge better than others but thats not getting at this point . Perhaps yours . What I sharpened on was what a normal household may have available to sharpen knives on . Taking it to that high a polished level most households won't have anything near that available . DM
 
David Martin said:
Yes thats a big variance and I'll look into that but that was not what the test was about . In the mean time unless someone sharpens that knife steel at a coarse level and conducts the same test cb's results are at best lacking/incomplete . Different steels are capable of holding a finer/polished edge better than others but thats not getting at this point . Perhaps yours . What I sharpened on was what a normal household may have available to sharpen knives on . Taking it to that high a polished level most households won't have anything near that available . DM
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OMG Yes!!! :) That's exactly what I've been saying all along. You cannot take a test, even yours with 3 knives, and extrapolate out that it solves 99% of cutting needs, and/or the other conclusions that you made. (Funny how quickly you saw this in my test). There's still many variables to address. Based on one test, yours / mine whatever, you simply cannot make conclusions... just provide the results. Testing good... conclusions... not.

I won't even mention that regardless of what you think, Juranitch doesn't support your position at all. (Oh darn, I said it). But the Talmadges/Swaim study appears to.

Your post was good... just hope you really get it!! :thumbup:

cbw
 
cbw if I am understanding what you are trying to say, is the information was good, but the conclushion of it being 99percent of your cutting needs was wrong? What could have been stated is that a corse edge would work for most of your cutting needs, especially out in the field where wieght might be an issue for sharppening stones. I use to put a polish edge on my knives, and still do on some, I like how they cut certain materials. My main carry knife is sharppened simi corse, around 600 grit. I think that is one reason why in the past people liked knives like a stockman, or congress patern, different blades for different purpose, with different edges on them. just my .02 cents. HL
 
Buck_110 said:
It doesn't matter if published materials support his results. That doesn't amount to a hill of beans! What if you were to state that Dave's results do not support Juranitch's position?

Only knowledge can be gained via reading, NOT experience. A very knowledgeable person with little to no experience can merely say, and not do.
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You're right, except for the fact that he claims that it does support his position. That's what makes the difference.

cbw
 
Ok, I resharpened the same 1991, 110 blade on the hard Arkansas and this time was very careful to remove all burrs and had my wife dig out her microscope to examine it at 100X making sure there were none . Then began cutting more sisal rope: the results are, at 100 cuts it began skating, at 150 cuts it began requiring 2 stokes per cut on some . At 170 it was noticably worse . I pressed it to 200 cuts and stopped . By this time it was requiring 3 slices per cut on most of the attempts . The edge would still shave some arm hair with razor burn . I examined the edge with 15X and many burrs were formed and present . Just 'feeling' of the edge it felt sharp . The quote I used in John's book on pg. 57 does support my claim of 400 g for a great edge . I never read in his book where he took a blade to 10K grit like you . DM
 
After rereading your and my quotes it looks as if John Juranitch contridicts himself so, I'll not quote him any more . DM
 
Even with the bobble and redo the tests are consistent within . I don't mind redoing a test numerous times as I'm learning and clear results will surface . Like a more coarse sharpened knife will cut more rope and other mediums too . Such as cardboard, hide in skinning, meat, leather, cord, ect.. Things that allow less refinement in the blade . Which is most of our cutting . Cutting where a refined edge should be used(1K grit) is shaving, operations w/scalpel use, ect. which is fairly specialized cutting . Realize, the higher grit used during sharpening reduces edge retention . Its up to the individual as to how much edge retention matters over edge refinement . So, weigh out your knife needs carefully . These tests are ongoing and updates will be periodically given . DM
 
I like that conclusion considerably more than your first one. :D

I would have to add that steel types could have a HUGE effect on whether that continued to hold true as well... I think. cbw's 13c26 is noted for its fine edge stability, while I haven't heard of many noting s30v's ability to keep a fine edge, rather many mention that for them, it tends to degrade quickly to a point, and then stay there. It could be that for s30v, the coarse edge could be considerably better, while for 13c26, the fine edge could excel. One wouldn't know without trying both ways on the same knife, on the materials they typically cut.

Also that ease of cutting would be a personal preference to balance as well, which I was trying to point out with my test. Some will prefer to have a greater ease of cutting, others will prefer to go longer between sharpenings, though I would imagine that on some media and steel types, the two are not mutually exclusive.

I am in no way arguing with your results David, just attempting to voice the things that I consider when looking at some of this testing. I do thank you for making me look harder at why I choose to do certain things the way I do, and giving me a reason to try something different. :)
 
As I stated these test are preliminary/'ongoing' as some developments are in the wing and I'll bring those forth when testing narrows down . Also, I've e-mailed Mr. Jerker Andersson VP of Sanvik steel and he's conveyed to me that his steel takes well to a fine edge . Still, I'm leaving no stone unturned on this, I'm not going to complain about doing this test and I buy sisal rope by the case . I'll arrive at a soft or firm conclusion eventually . Stay tuned . DM
 
Jerker used to post here. He was active when Kershaw started switching over to 13c26 a couple/few years ago. You might find quite a bit of info if you searched around for his stuff in the Kershaw subforum. I think he posted under razorsharp44 or something similiar, unless he did something really off the wall like post under his name. :D
 
I've finished two more cutting test and the data: The first I sharpened was the one just sharpened on the hard Arkansas . Took it up to the Spyderco X-fine ceramic stone a 2000 grit stone . After stropping and certain there were no burrs I began cutting sisal rope . This blade began skating at 300 cuts, more a 350 and much more at 375 . I stopped at 400 . The edge still had good refinement and could shave arm hair with razor burn . I examined the edge at 20X and noticed many needle point burrs perhaps 20-30% . The results of this really threw us a curve . So, we put our heads together and came up with some possibilities . I reread Mr. Sal Glasser's post discussing this stone in 2008 and he stated it contained sapphires in the matrix/ binder . As we know binders are very important and sapphires are very close to the hardness of diamond (9-9.5 Mohs) . Its possible this imparts some bite to the edge even though its very fine it has effects .
The edge was 'bitey' and very sharp a quick cutter . Yet, appeared fragile . I wouldn't want to torque it/ lateral force as in disjointing a elk's leg . As the edge may slough or break from this force . Just my observation . Whereas the Arkansas stone lacks this type grain structure . Nor is it as hard a stone (only 7 Mohs)as the ceramic . More on this later . Then I thought since I went to that extreme on one end I should go the opposite direction as well . So, I sharpened the blade that originally was sharpened to 280grit taking it down to 100grit . Then began cutting rope . It didn't cut as quick but cut cleanly as the ends of the rope were even not jagged . It started to skate alittle at 950 cuts, then some what more at 1025-1050 cuts . I stopped at 1100 cuts and examined . The burrs were larger than the aforementioned blade but were approximately the same percent . Both these blades were still cutting but I was trying to pay careful attention to equal effort/ cut and note wear and skates expressed . In all fairness . This coarsely sharpened blade required less time on the stone . HA, just one grit . But much more time on the strop to rid it of pesky burrs . They were close to equal sharpening time required . The 100 and 280grits were the Norton JUM-3 SiC. The 600grit was a NOrton fine AO . The Arkansas was a ? old one which I lapped . So, very fine in grain structure and the ceramic was perviously stated . In light of the ceramic and its matrix (questions on how it cut)I should for the sake of accuracy of the test . Sharpen one of the same blades on the same grit changing the type of grit to diamond and see if this imparts a more 'bitey' quality to the blade . A better quality or a better shearing effect on the steel . Then return and cut some rope . Just not tonight, after all this I feel as if I wrestled a gorilla . DM
 
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