For a shaving edge in situations like cardboard cutting, you need very high hardness and good toughness. Nothing works as good as M2 at 64+ HRc that I have tried. I have not tried zdp 189 or M4. M2 has excellent wear resistance, takes a shaving sharp edge easily, and has remarkable toughness at that hardness. This is the hardness gained from tempering for normal industrial uses, so, as a high speed steel, it also has resistance to softening up to ~1000 deg. F. I have a knife I made from a power hacksaw blade that has a 10 degree per side bevel on 0.055" thick stock. The bevel is about 1/4" wide and slighly convex. This is the one that cut about 45 feet of cardboard with the same 1" of blade and would still shave easily. See my thread on testing some cheap kitchen knives for exact details. Its a couple years old in the testing and review forum. If you want to try this blade, drop an email and I can send it as soon as I get the handle back on it. I took the old one off for a better attempt. It looks like fido's ass, but it will cut longer than any knife I've tried.
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CPM S30V - Where is my wear resistance?
- Thread starter sircantaloupe
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I had a knife in Aus-8 that could cut almost 100ft of cardboard and still shave pretty well. Then again, it was overhardened to about 64RC and got a fair number of micro chips just from the cardboard.
Possibly, but that still doesn't explain it cutting longer than ZDP-189.
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Increased cutting performance by 10% maybe possible, I don't really know. But tenfold improvement? Unless it has been re-heat treated or re-profiled then I'd say that there is no way aged S30V could be anywhere near 10x better than when it was new S30V.
Jason B.
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Buck figured it out some time ago, the grind of a knife will be a larger factor in cutting performance than the properties of the steel. A flat ground VG10 blade will probably always out perform a saber ground ZDP blade simply because of the grind.
The steel aging thing with a new steel like S30V I would bet money to say that, that person just got better at sharpening.
The steel aging thing with a new steel like S30V I would bet money to say that, that person just got better at sharpening.
In terms of ease of slicing I can understand, but FFG VG-10 cutting longer than saber-ground ZDP-189... Not to mention that the FFG VG-10 at a thin angle is outcutting the FFG VG-10 at a more obtuse angle.
The whole thing is just whack.
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To offer a different opinion, my thinned and polished (by hand so convexed) S30v mili is one of my favorite users. I think S30V performs great when polished. I appreciate how easy it is to keep very sharp. Here it is cutting a tube of telephone book paper.
Both exactly right. The geometry does the cutting, the steel allows the maker to optimize the geometry. Take the BG 42 and reprofile it like the 420 HC blade, and it will do better yet. Take M2 HSS at 64 HRC and do the same thing, and you will be truly astounded by the results. But you can still get very good results with a "non-super" steel at very reasonable prices.
I've got a couple just like this!
I get the same results.In fairness to S30V, though, I have a knife in CPM 10V that is similar to what Me2 and others have described. It never gets as "push shaving sharp" as some of my other knives, but it dulls much, much slower, especially if you measure sharpness with a slicing cut, such as measuring how much thread it takes for you to cut through the thread.
David Martin
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Both exactly right. The geometry does the cutting, the steel allows the maker to optimize the geometry. Take the BG 42 and reprofile it like the 420 HC blade, and it will do better yet. Take M2 HSS at 64 HRC and do the same thing, and you will be truly astounded by the results. But you can still get very good results with a "non-super" steel at very reasonable prices.
I've got a couple just like this!
In fairness to S30V, though, I have a knife in CPM 10V that is similar to what Me2 and others have described. It never gets as "push shaving sharp" as some of my other knives, but it dulls much, much slower, especially if you measure sharpness with a slicing cut, such as measuring how much thread it takes for you to cut through the thread.
Yes-I agree ! DM :thumbup:
WRT the D4 mystery, I suggest that the thicker blade profile of the "failed" Delicas actually contributed to their lower edge retention. The thicker blade means more resistance while cutting, therefore more abrasion against cardboard-hence the quicker dulling. With the saber-ground ZDP blade, this would probably be even more drastic thanks to the thicker primary grind.
I also suggest that the way the blade is ground affects the wearing. Let's say we have two triangles of the same height-one more acute at the tip and one less.
If we remove the same height from the tip of each triangle, you get a (really) skinny trapezium, but the more-acute triangle is still thinner at the top than the less-acute one. So the more acute blade will remain sharper even after the same exposure to dulling. (Then again, there is more material to remove from the fat blade...but that would have been accomplished by the more-thickness-equals-more-dulling hypothesis.)
I got the top idea from one of the sharpening guides-I believe it's here somewhere- which phrased it a lot better. The second one is just idle speculation.
I also suggest that the way the blade is ground affects the wearing. Let's say we have two triangles of the same height-one more acute at the tip and one less.
If we remove the same height from the tip of each triangle, you get a (really) skinny trapezium, but the more-acute triangle is still thinner at the top than the less-acute one. So the more acute blade will remain sharper even after the same exposure to dulling. (Then again, there is more material to remove from the fat blade...but that would have been accomplished by the more-thickness-equals-more-dulling hypothesis.)
I got the top idea from one of the sharpening guides-I believe it's here somewhere- which phrased it a lot better. The second one is just idle speculation.
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I'm reminded of the importance of edge geometry every time I use a utility knife/box cutter. Inexpensive steel, very thin blade, acute edge grind. For cutting cardboard especially, it still does that job better than any other knife I've ever tried.
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Well, I'm trading my Military in for a Gayle Bradley. We'll see if it fits my needs.
I think what I've learned from this thread is that I was mistaking toughness for wear resistance. S30V is a great steel but I'm not using it hard enough to see it really perform.
I think what I've learned from this thread is that I was mistaking toughness for wear resistance. S30V is a great steel but I'm not using it hard enough to see it really perform.
Hmm... As for cardboard, it seems that thinner blades keep cutting longer and longer. I have a new Kershaw Needs Work whose edge is thinner than even my FFG Delicas. I just did an extreme box-cutting session today, and it cut like a champ the whole way through. It still cuts paper with a snag at one part of the edge.
So maybe you don't need a super steel! (Unless 13C26 is a super steel and I didn't know).
So maybe you don't need a super steel! (Unless 13C26 is a super steel and I didn't know).
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Ok, cardboard was probably a bad example. In reality I'm cutting lots of other things, cardboard is just one of them.
I think my gripe was just about my Military not retaining a shaving edge very long. Being able to cut miles of rope and drywall are just not on my to do list. I just want a knife that's going to stay really sharp throughout lots of small daily chores and be able to handle big chores if they show up.
I think my gripe was just about my Military not retaining a shaving edge very long. Being able to cut miles of rope and drywall are just not on my to do list. I just want a knife that's going to stay really sharp throughout lots of small daily chores and be able to handle big chores if they show up.
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I disagree or might agree, depending on what you mean by edge retention or dulling.
A larger angle on the edge actually will help the edge stay sharper longer, though it might require more force to make the same cut throughout the testing. The larger angle could actually remove some of the stress from the very edge sooner in the cut than a smaller angle edge, or possibly the larger angle edge would create tension in the material being cut, making the materail cut easier. And an edge with more material behind it is stronger and better able to resist failure due to the compressive strength of the steel being locally exceeded by the extremely high pressure of a cut at the very edge. I have a suspicion that much of the dulling experienced at high levels of sharpness is from this type of failure.
This is why you see industrial cutters with 60 degree edge angles (force is not as big a consideration as other factors, and the edge stays sharper longer and in service longer than a cutter with a thinner angle).
If the force required to cut is not a consideration (ie. a sharpness based test is done, and there is no consideration of force to cut), then the thicker edge will probably show better edge retention (though it will require more force to make the cut versus a thinner edge).
This is I think one of the weaknesses of some thread cutting testing done. Because it is not giving consideration to the goal I try to reach with my sharpening - making cuts with less force using sharpness and thinner geometry.