You bring up a lot of good points (for instance, 10dps is not needed for shaving...that's very true) and a lot of things I need to look into further. My final thoughts on all of this though:
1. Increasing the apex angle too much on a thin edge can transfer torque into the primary I believe, and thus put it at significant risk...however I don't know how much of this is dependent on a true secondary vs a microbevel.
2. I would suspect that a lot of Verhoeven's problems may have come from the stropping and the issues it presents, but that's not another can of worms I don't care to open in this thread.
3. Acting like 10dps is only acceptable for shaving or eye surgery is a bit dramatic. Ever measured the edge angle on a factory Mora (which come in one of two high edge stability steels [12c27 or 1095] that are far from optimally heat treated? Common measurements seem to range from 20 to 25 inclusive . I just measured the two I own,
Standard .100 stock is at 23inclusive
Robust .128 stock (a relatively new product for Mora) is at 27ish inclusive.
While there are issues with Moras (as would be expected considering the mass heat treat to less than ideal conditions for the steel) 1000's of moras have survived cutting on a much rougher order than you are describing. My own .100 stock, 22 degrees inclusive edge, has done just fine cutting hard seasoned wood and doing light batonning.
Along those same lines wood chisels often come in less than 25 degree angle edges and they obviously survive cutting the wood just fine.
1. Any torque is present already at the apex, you WANT to transfer that to the metal behind it to
prevent twisting/fracturing out the apex.
2. Verhoeven's experiments on sharpening are available online, just google "verhoeven knife edge". STEELING was a problem, as were motorized sharpeners, as both of these put too much stress on the apex, and even sharpening by hand without good wrist control to keep the angle consistent (the second most common problem when sharpening, first being sharpening at the actual apex). Stropping he noted to be the BEST technique to refine a poor edge. He knew what he was doing
3. Yes, it is a bit dramatic, but I keep reading people criticize 15-dps as obtuse when it is an angle at which you can accomplish EVERYTHING from chopping to shaving and not encounter issues with edge-fragility in use or in sharpening, it is the
recommended angle for cutting implements whether they be made of 52100 or S110V. If you have to put the bevel below 15-dps and bring the hardness over 61 Rc in order to give 52100 an edge over S110V in a cutting task, it seems that you are limiting the scope of BOTH steels. If you are optimizing for a
very particular task, GREAT! But for general utility....
The same would be true in reverse. If you need to bring the hardness below 59 Rc and the angle >25-dps (and thicker than 0.010") to give S90V the edge over 52100 in some cutting task, WTF?
Regarding the Mora's or Opinels for that matter, I have worked with both and other "zero-edge" knives and quickly found that for my 'general utility' purposes they lose their apices quite quickly. Mora's are 12-15 DPS from the factory and are soft. I can carve soft wood with them, cut soft flesh with them, open letters... But in seasoned oak, the edge rolls; cutting cardboard and carpet, the edge is either squashing or rolling or wearing away. So what? Just put a true 15-dps microbevel on it and keep going. The steel is soft and not very wear-resistant so while it doesn't hold up all that well, it re-sharpens easily with a few swipes. If it were harder, it wouldn't squash or roll (a strength issue) but it might fracture out... unless it were thicker, where again 15-DPS might make all the difference. Batonning, as long as the apex doesn't experience too much twisting in the wood then stock-thickness gives the strength, hence axes being that same 15-DPS but maintain that angle further back from the apex, thickening to provide support. Wood chisels are similar - you can get chisels at lower angles than 30 degrees but need to be more aware of their limitations.
All this talk of edge-angles and performance cutting makes me appreciate thin knives all the more - be they high or low carbide, they are easy to adapt at the apex for whatever purpose you need them (provided you don't need the strength of a thick spine).
I really look forward to reading Landes' work because I'd like to see where these superiorities really fall. Previous work suggests that 60Rc knives should be 15-DPS. If Landes criticizes high-carbide steels at angles below that but sees no disadvantage above it, well then they must be REALLY bad at very low thickness because previous work criticized LOW carbide steels there. But if Landes is simply showing that for highly specialized cutlery where 15-dps is obtuse or 0.005" is too thick, tasks where edge-twisting is minimized/eliminated, where abrasion is unlikely but hard impact is very likely (?), where a highly-polished fine edge is key... What are all the qualifications to make these high-carbide steels poor performers?
In general utility, how important is edge-strength from Rc hardness vs edge toughness? Wear-resistance vs apex brittleness (as that is the assumed issue with high-carbide steels)?
If 52100 is made hard enough to prevent deformation but also brittle failure of the apex, the question should be, "How thin can we make it before such failures occur?" Make it that thin, then test it for wear-resistance.
If your 52100 blade wears too quickly, what can be done to improve that? Harder won't give it vanadium carbides and might make it too brittle... more brittle than the vanadium carbides?
If the higher carbide 52100 is less brittle than the harder 52100 (i.e. harder than necessary to prevent deformation) and can reach the same thin geometry needed to provide strength to the apex, it is superior. If it needs to be thicker, how much thicker? How much performance is lost in exchange for increased wear-resistance? Can that be mitigated by a coarser finish (i.e. performance of slightly thicker high-carbide blade is higher than performance of low-carbide blade at fine finish)? What about the thinner low-carbide blade at coarse finish - better or worse than high carbide blade?
So many questions, so many mitigating factors. What I really challenge is the assertion that high-carbide steels are so limited in their superiority with regard to application, especially when the most common applications being discussed go well beyond shaving your face. Now whether or not they are worth the price increase for the supposed performance increase is entirely separate. Who cares?? This is about innovation. Are they or are they not helpful innovations for a wide variety of tasks? If not, drop them and go back to 52100 (Bussekin have stuck with SR101 and INFI in blades of all size, only dabbling in other steels). BUT IF they retain strength and toughness while adding wear-resistance for general use applications and beyond :thumbup: Again, whether we want razor-blades with longer wear-life or high-wear blades with lower fragility at thin cross-sections, powder-metallurgy is working in our favor. The narrower we need to make the qualifications that keep PM steels inferior, the better off we all are with the continued innovation.
