Exactly. IMO, different approaches to sharpening are a key differentiator between the farming/backpacking use case, in which the user will want to sharpen a blade in the field using small, portable hand held tools like a small diamond stone...
Again, I'm not taking issue with Jim's testing method. I questioning it's applicability in a thread about a knife like an Opinel (or Buck Vantage or Case Sodbuster or Mora, for that matter). Ease of sharpening in the field and the ability to easily achieve a fine edge are design goals for knives of that sort, which seems to me rule out PM steels from the get go regardless of cost issues.
No, diamond cannot tell the difference between PM and non-PM steels
I freehand with a DMT perforated diamond plate from my aligner-kit, but you could use a DiaFold - light-weight, compact, very effective. It sharpens ZDP-189 as easily as AEB-L (skip to ~18:45)
[video=youtube;rEIX7pMSTHo]https://www.youtube.com/watch?v=rEIX7pMSTHo[/video]
I think to get a PM steel to a "very fine edge", several things have to happen. You have to use abrasives capable of cutting through the embedded carbides while concurrently not honing away any of the surrounding matrix so as to expose those carbides. So, while I grant you this may be possible, I think it's also happening in the realm of the highly skilled.
I do not consider myself to be a highly skilled knife-sharpener, and using nothing more than as seen above i can achieve a face shaving-edge on 64Rc ZDP-189, on 60Rc 154CM, on 60Rc M390, and I have no doubt i could achieve it on S110V as well. Again, it is a matter of the tools at hand. Of the steels mentioned, only 154CM has carbides of significant size on matrix-density to present much challenge if they aggregate. The PM steels tend to have carbides <10 um and the volume is sufficiently low that the surrounding matrix provides sufficient support to prevent tear-out while sharpening either by hand or machine, provided that the geometry is sufficient to support the apex (e.g. 15-dps). Keep in mind that the matrix is on the same plane as the carbides, you can only dislodge the carbides if you use an abrasive that fails to cut them as it gouges away the plane.
For most knife-tasks, DMT's 600 grit is perfectly suitable if not advantageous for slicing, producing a 25-micron finish, a 'toothy' edge. If carbide tear-out is likely to occur, it should occur THEN, resulting in an increased apex-diameter and cutting performance over time (i.e. lower wear-resistance), especially on hard or abrasive media. Yet that is demonstrably not the case.
For carving tasks, a finer 1200+ grit is desired, producing a <10-micron finish for shorter and therefore stouter teeth that can penetrate but better resist lateral stress. Edge-stability is strongly dependent on apex geometry and from what i understand from Landes' posts (haven't read his book as it isn't available in English yet), you need to go below 15-DPS and use careful application of lateral force and minute-precision measurements to be able to discern superior edge-stability in the Sandvik steels over PM, not really applicable to everyday knife use where too low of an apex angle simply results in edge-rolling or chipping which in either case
increases apex diameter and so reduces cutting performance... Unless you are only cutting soft unabrasive materials, in which case such stability is hardly worth discussing as the blade would have to be
extremely fragile to evince a problem with one over another.
Having very fine carbides simply makes it easier to sharpen a blade to a very fine edge, i.e. one can use a variety of abrasives.
Keep in mind that the finest razor-blades with these steels achieve an apex-diameter of ~0.5um and are intended for light use like shaving and surgery. The FINEST knife-edges are ~0.005um (100X thinner) from PURE carbide (i.e. obsidian and diamond diatome blades) and those are even more specialized. You do not need, and indeed probably do not ever have, such a fine edge in every day knife use as achieving such an edge on ANY steel is, again, a matter of equipment and skill. A 1200-grit 9um diamond hone gives the same edge-finish regardless of the steel selected.
Yes, Sandvik is
very biased. Their summary chart pretends that 13C26 has the same toughness (ranked "excellent") as 1075 tool steel, but data to support that claim? Most stainless knife steels achieve only 20 - 40J impact toughness via Charpy. D2 achieves ~31J @60Rc, S90V gets 26J @58Rc, CPM-3V gets
95J @60Rc, L6-tool steel gets
92J @57Rc. If they can really achieve impact toughness ~90J at high hardness with 13C26, I'd like to see it! Folk would flock to the steel! Or perhaps they rank "Poor - Average - Excellent" all within that 20-40J range, i.e. hardly discernible in everyday (non-specialized) knife use.
Becker, ESEE, Tops, Buck (with their Ron Hood line), Busse and many others are quite happy to sell expensive knives with carbon steel or small carbide steel. Their customers seem quite happy to pay a lot for them and I don't think that is all just the knife maker building a fat profit margin into the product. It's about use cases that demand the ability to have a tough edge that resists chipping and can easily take a keen edge when sharpened in the field.
Marketing and lack of sharpening skill on the part of some customers, though there are other elements as well, e.g. cost of HT and grinding and handle-materials and blade-coating and sheaths, etc. People will pay what they will pay for what they perceive as sufficiently high quality. 1095 & 5160 are extremely inexpensive, i have no idea what INFI costs to produce. How many Beckers and Bucks are sold for every Busse that costs ~3X more? And how many China-made Gerbers for every Becker? *shrug*
It is not universally true that the upgrade provide a meaningful or desired gain in improvement ... There are use cases where the properties of PM steels not only aren't needed but are specifically not wanted.
Again, that is
subjective not objective. You don't
need the upgrade and so are unwilling to pay for it, but it is still an upgrade
if it improves performance. If it were the same price as the non-upgrade vehicle, would you deliberately reject it? No, you just wouldn't care. What if it were even less expensive? You'd buy the less expensive vehicle because again, you just don't care about that specific attribute. Now if it were somehow detrimental to performance, THEN it would not be an "upgrade".
Again, I don't have an issue with Jim's tests, per se. My issue is their relevance in assessing the value/performance of a farming/backpacking knife, which is a use case that places a high priority on easily achieving a keen edge in the field. ... Abrasion resistance is interesting but not the most important quality being looked for and, as it relates to sharpening ease, is actually a negative (especially if it also comes at the cost of additional brittleness).
I agree, I think it folly to pay a lot of money for an attribute that isn't important to your use of the knife, especially if a corollary of that attribute is a detriment to another attribute that IS important to your use of the knife :thumbup:
A knife like this, it may be an important attribute that it be cheap, i.e. disposable, as it may be lost or used abusively. Also it should be easy to keep sharp or at least very thin as the user may be poorly skilled at sharpening.
When i bought that #6 Opinel, the advantages I saw where 1) low-cost 2) good geometry, and it was the size I wanted. However that low-cost turned out to be detrimental to a number of other aspects that were more important to me. *shrug*
Why are you asking for a quantitative assessment?
Objectivity and comparability. Note the Sandvik chart's "poor - good - excellent" without reference to any measured values. If you compared all of their steel-classes to obsidian for sharpness or edge-stability, would there be a discernible difference? What if you compared them all to S7 shock steel for toughness? What is the range of performance being measured, what are the parameters? The attributes of performance in a knife-blade are objective & measurable. This is science, not philosophy.
Can you give me a quantitative test for determining the best base structure for a ski given temperature, snow age and humidity?
I'm no expert, but I'd guess one could quantify how those attributes affect the ability of a ski (of a given design under and average skiers body-mass) to grip the snow for sufficient agility while maintaining the lowest friction.
Can you give me a quantitative test for determining the best stiffness/flex of a bicycle frame to give the best speed on a road course?
Again, not an expert, but I'd assume one desires maximum velocity to be maintained in a single direction, so the frame must be sufficiently flexible to absorb irregularities in the road and the cyclists movements that might alter that velocity, while sufficiently stiff to transfer all peddling-effort in the correct direction.
Can you give me a quantitative test for determining the best type of bicycle tire for road race? For the Paris-Roubaix race? For a time trial?
Run some tests on different tire-designs and compare times (a quanitity).
I suspect that your challenge to me on this is similar to Rhino's.
Not at all, please feel free to challenge his assessments, just back it up with data, doesn't have to be your own. What makes you think the PM-steels are so brittle? In what use would they perform worse than the Opinels?
There's a lot going in "performance". Better I think to tease out the various performance characteristics for the different use cases and then simply look at the recipes that seem to "win" among the leaders of the field.
...maybe their all cheap skates unwilling to pay for "better" materials. Or just maybe, they've collectively figured out that fine grained steels work better for their usage.
Yes, lots going on in performance, just not PRICE. I've not read any evidence that the PM steels have any less fine "grain" than non-PM knife-steels, carbide content and size are discussed. I've not read any way in which an Opinel is
superior with a more basic steel than it would be if made with a harder or more advanced steel (or alternate handle-material, etc.) other than PRICE. Please offer something, I'd be happy to read :thumbup:
