As an aside, I don't worry too much about the steel a knife I buy is made of. What I worry about is the maker being able to tell me how they made (including heat treat process), why they chose to do it that way, what performance I can expect (and not expect) and what testing they have done to know they can give me those parameters of use.
Blade steels - what's wrong with improvement?
- Thread starter Comeuppance
- Start date
If you plunk down your hard earned money on an expensive piece of cutlery, wisdom would dictate that you also know how to maintain
the same. That your knowledge of the steel determines your ability to discern if your investment is working up to its percieved claim.
I suspect that in certain times of comfort with the familar, we are willing to gamble on the promises of others who have reached a little
past the shelf where our trusted possessions lay. This is my first post on this forum , hopefully not the last. I just purchased my first
blade in N695 and confess I have no first hand knowledge of its charateristics but...... I'm willing to learn! I like this place!
the same. That your knowledge of the steel determines your ability to discern if your investment is working up to its percieved claim.
I suspect that in certain times of comfort with the familar, we are willing to gamble on the promises of others who have reached a little
past the shelf where our trusted possessions lay. This is my first post on this forum , hopefully not the last. I just purchased my first
blade in N695 and confess I have no first hand knowledge of its charateristics but...... I'm willing to learn! I like this place!
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Few people seem to address the core issue. Let's assume newer alloys are better than older ones. To what extent are they better? What is the % performance gain for specific applications? You have to optimize the knife for the particular task, which means picking the steel and edge geometry that will yield the most performance for that task.
Since no one answered my specific questions earlier, what new modern alloys are superior to older alloys for cutting soft, non abrasive items like meat (not hitting any bones)? This is one simple example.
By what % are they better at specific tasks with low DPS and low polish? By what % are they better at high dps and high polish? High dps and low polish? Low DPS and high polish?
If modern alloys are vastly superior to old alloys for all tasks then it should be trivial to demonstrate this by experimentation.
Since no one answered my specific questions earlier, what new modern alloys are superior to older alloys for cutting soft, non abrasive items like meat (not hitting any bones)? This is one simple example.
By what % are they better at specific tasks with low DPS and low polish? By what % are they better at high dps and high polish? High dps and low polish? Low DPS and high polish?
If modern alloys are vastly superior to old alloys for all tasks then it should be trivial to demonstrate this by experimentation.
JB in SC
Gold Member
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I like it a lot, and Tom makes a lot of Coverts in various configurations. Pretty low drag..
This simple sentence encapsulates everything that I like about Bladeforums, and hopefully describes this thread and all others like it. Hopefully we assume that we are all intelligent adults and let's just talk about steel.
Certainly heat treat is extremely important. However, the newer, high-performance steels offer incredible advantages. But, yes, you often have to specify exactly what advantages in what circumstances.
But I mostly hear two general objections to "super steels," which isn't even a real term, just a casual reference to newer, high-performance steels: 1) Who cares, I like to sharpen my knives and don't care about wear resistance (or my granddaddy did just fine with old steels); and 2) all super steels come with disadvantages, so you have to specify every possible variable in order to make any statement.
The second objection, which is mostly being discussed here, has a some truth to it (generalities don't apply to all specifics), but ultimately it is meaningless because we can never specify every possible combination of heat treat, blade geometry, hardness, alloy purity, etc.
Ankerson's tests leave out a lot of variables, as he acknowledges, but they offer a good test of actual knives made of different steels. Yes, the blade geometries are different. The heat treats are different. But it's still a good reference, especially as he adds new knives and steels. One person making careful observations under a consistent protocol can yield incredible results. His tests are more than observational, but less than fully rigorous scientific tests. For example, the gold standard for scientific studies is double-blind experiments. Pretty difficult for Ankerson to pull off a double-blind study, and we know that even fully engaged PhD's will allow personal bias to creep into studies that are not double blind.
At the practical level, I know that when I switched from an ordinary machete using 1075 steel to a knife using 3V (15dps), I experienced a huge gain in performance. The edge lasted much longer and cut much better for a much longer time. I don't think S7 could match 3V in this kind of cutting because it lacks 3V's wear resistance.
I also know that my thin, 10V trailing point blade (0.015 inches behind the edge) absolutely blows any of my conventional steel knives out of the water for cutting cardboard and other abrasive material. Would I use it as a pry bar? Nope. But for cutting up stuff, from cardboard to garden pruning, it can't be matched.
You can look at D2 or 154 cm, both well-respected and traditional steels, and see a large improvement in both toughness and wear resistance when made with powder steel technology. CPM D2 is better than D2. CPM 154 is better than 154 cm.
And if you specify almost any particular task, it's almost certain that a super steel will out perform a traditional steel.
But I mostly hear two general objections to "super steels," which isn't even a real term, just a casual reference to newer, high-performance steels: 1) Who cares, I like to sharpen my knives and don't care about wear resistance (or my granddaddy did just fine with old steels); and 2) all super steels come with disadvantages, so you have to specify every possible variable in order to make any statement.
The second objection, which is mostly being discussed here, has a some truth to it (generalities don't apply to all specifics), but ultimately it is meaningless because we can never specify every possible combination of heat treat, blade geometry, hardness, alloy purity, etc.
Ankerson's tests leave out a lot of variables, as he acknowledges, but they offer a good test of actual knives made of different steels. Yes, the blade geometries are different. The heat treats are different. But it's still a good reference, especially as he adds new knives and steels. One person making careful observations under a consistent protocol can yield incredible results. His tests are more than observational, but less than fully rigorous scientific tests. For example, the gold standard for scientific studies is double-blind experiments. Pretty difficult for Ankerson to pull off a double-blind study, and we know that even fully engaged PhD's will allow personal bias to creep into studies that are not double blind.
At the practical level, I know that when I switched from an ordinary machete using 1075 steel to a knife using 3V (15dps), I experienced a huge gain in performance. The edge lasted much longer and cut much better for a much longer time. I don't think S7 could match 3V in this kind of cutting because it lacks 3V's wear resistance.
I also know that my thin, 10V trailing point blade (0.015 inches behind the edge) absolutely blows any of my conventional steel knives out of the water for cutting cardboard and other abrasive material. Would I use it as a pry bar? Nope. But for cutting up stuff, from cardboard to garden pruning, it can't be matched.
You can look at D2 or 154 cm, both well-respected and traditional steels, and see a large improvement in both toughness and wear resistance when made with powder steel technology. CPM D2 is better than D2. CPM 154 is better than 154 cm.
And if you specify almost any particular task, it's almost certain that a super steel will out perform a traditional steel.
There is nothing wrong with improvement. The newer steels all do something the old ones don't. Typically, at least w/r to knives, it's resist wear better by means of higher carbide volume. However, that carbide volume comes at a price. They're more expensive, requiring CPM or similar processes. The extremely high carbide volume steels are not even practical to manufacture without CPM or similar technology. They are more costly to process, using more supplies to shape, polish, sharpen, heat treat, etc. All this means that they do one or 2 things better, at a significant cost increase. The trade offs are not worth it to me.
To the sub-discussion of high edge stability and high carbide/wear, I'll offer this. Lower edge angles cut better for longer. Higher edge stability steels can do the same work with a lower edge angle without taking damage. The rule of thumb for sharpening is to use as low an angle as is consistent with durability. It's only in the last couple of years that I've started using edge angles lower than 15 degrees per side (dps). If the knife is used for cutting, even fairly abusive cutting, they work much better. If you cut soft abrasive material, like fur and such for hunting, this may not be useful information. However, thin down a properly hardened blade of AEB-L, 1095, White #2, etc. and cut some zip ties, wood, or other relatively firm material and see if it works. I was surprised at how easily I could cut caulk from concrete, plastic tubes, cardboard, wood, zip ties, etc with an edge from 7 dps to 12 dps with minimal damage, and resharpen them very quickly.
Here is the reasoning that led me to prefer low carbide steels at low angles. Experienced axe users have written books on sharpening. In the one I'm familiar with (Leonard Lee, The Complete Guide to Sharpening), edge angles are recommended for felling axes in the range of 8 to 12 degrees per side. Granted, these are dedicated felling axes, not used for other tasks. However, I had to wonder, what was the purpose of an angle on a folding knife that was greater than that on a felling axe, in some cases by 2x or more?
To the sub-discussion of high edge stability and high carbide/wear, I'll offer this. Lower edge angles cut better for longer. Higher edge stability steels can do the same work with a lower edge angle without taking damage. The rule of thumb for sharpening is to use as low an angle as is consistent with durability. It's only in the last couple of years that I've started using edge angles lower than 15 degrees per side (dps). If the knife is used for cutting, even fairly abusive cutting, they work much better. If you cut soft abrasive material, like fur and such for hunting, this may not be useful information. However, thin down a properly hardened blade of AEB-L, 1095, White #2, etc. and cut some zip ties, wood, or other relatively firm material and see if it works. I was surprised at how easily I could cut caulk from concrete, plastic tubes, cardboard, wood, zip ties, etc with an edge from 7 dps to 12 dps with minimal damage, and resharpen them very quickly.
Here is the reasoning that led me to prefer low carbide steels at low angles. Experienced axe users have written books on sharpening. In the one I'm familiar with (Leonard Lee, The Complete Guide to Sharpening), edge angles are recommended for felling axes in the range of 8 to 12 degrees per side. Granted, these are dedicated felling axes, not used for other tasks. However, I had to wonder, what was the purpose of an angle on a folding knife that was greater than that on a felling axe, in some cases by 2x or more?
Ankerson
Knife and Computer Geek
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I don't believe anyone ignored the questions.
It just that nobody has the answers, or lets say definite answers.
A lot of different types of knives are used for those tasks in even more different grades of steels all over the world.
That's from home owners to Chefs to people in slaughter houses to Butchers to short order cooks to hunters to guides and the list goes on.
So that a very broad scale of use in talking about meat and that's even getting into fish.
All I can say is get something thin in the type of knife that is needed and work with the knife with different edge finishes until you find what works the best for you.
The best answer I can give is to contact a Custom Knife Maker and let him know what you need and listen to his recommendations.
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Terminology is problematic agreed. Even "carbon" steel isn't accurate, all steels have Carbon by definition. As it is supersteels refer to high speed/high performance alloys, mostly some for of PM, but yeah the same steel can be included or excluded from super category... Also, I mentioned earlier, try CPM 3V at 62-63HRC in a thin knife, at ~10DPS and you will be surprised how well it will hold up. Toughness isn't necessarily about banging your knife iwth a hammer, does have a role in edge stability/holding.
Well, it's been a long time since I've tested something below 63HRC, most of the new stuff I have is 64 and above. I just want maximum cutting efficiency and edge holding.
Very few people make 1095 at 64HRC or above. And even at 10DPS it would have very hard time on abrasive mediums.
Just whatever you have to cut with your pocket folder or small/medium fixed blade outside of the kitchen. I exclude kitchen because majority of the food is soft, and high polish, very thin edges are exceptionally well suited for the kitchen use. Still, Ankerson is quite happy with HVCs in the kitchen, I've tried quite a few myself and they do well, 12-15DPS and slice away. So, what's left would be mundane stuff like cardboard, plastic, rubber, rope, etc.
I don't question that, however as these debates go, "old steel" fans mainly bring up mainstream knives, from Buck to unnamed blades from 20-80 years ago... None of that fits in the category you described above, and Mr. Calton's knives would not work too well for quite a few users, and for cutting abrasive stuff. Paring knife is still a kitchen knife.
I totally agree with you, but you can check how many old steel supporters bring up those insanely thick edges as irrefutable proof that new alloys are BS.
You can call it semantics. Point is, "cleaner" is happening thanks to modern technology, because someone said, "good enough is not good anymore, and went ahead and improved it. This thread was about improvements or not, and my main objection to "old steels are good enough" is just that. If it ain't broken don't fix it doesn't apply to everything universally, and it's the philosophy that does hinder progress and innovation.
Completely new formula or 10x less contaminants, it's still a new product based on the new tech and innovation. Same argument can be applied to Shirogami, saying that it's all BS and there is no improvement, just grind at 25DPS edge and run it at 60HRC...
Price/profit ratio. I suspect they'd run into the same issues knife makers have now. Work on 10xx and make/sell 5 blades fast, or spend 7x time and tool wear to make 1 blade, which probably won't sell for 5x, or will take a lot more time to sell.
Technologically that's simple to achieve without changing other variables. I mean cost won't really go higher because of the extra 2in long super thin strip. Using new alloy would increase cost more significantly.
I can't find that article on Cashen's site anymore, but a while back he did wrote an interesting one about ABS testing methodology and criticized quite a few things, including bending. You can still find his article The Anatomy Of Hype" on web archive though. Does resonate with a lot of what we're discussing here.
I suppose I am not the one to tell the maker what he should or shouldn't do
His work, experience, time invested, etc are the factors. Still, that absolutely doesn't negate the possibility that should he(or any other maker) decide to use a newer/better alloy he'd achieve better results.I am free to choose the maker though, based on materials he works with being one of the factors.
What is given with HCV steels, is aggressive edge, very good wear resistance, and expanding into modern alloys, is higher attainable hardness, finer grain, etc, etc. A lot of those alloys were not even possible 50 years ago, technology wasn't there. If "don't fix it" prevailed back then, we'd never had PM steels at all, forget about PM steels in knife blades. Outside of the kitchen, HCV-s do work better compared to low alloy steels like 10xx, unless we're talking cutting something very fluffy all day long
Contrary to the popular myth, HCV-s are quite easy, (easier in fact) to sharpen compared to good old 10xx, or 44x, especially mainstream variations.
james terrio
Sharpest Knife in the Light Socket
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First off, I should point out that I shave about 6 times a year, so I simply don't know much about disposable razors or the market for them. I'm basing this post entirely on my understanding of basic manufacturing processes and what various steels cost in real terms (including grinding, HT, etc).
My guess is that the increased costs of buying and machining "super steels" for disposable razor blades would be far greater than consumers would be willing to pay. Your theory on that is based on knife knuts like us (a tiny percentage of the market), not the average guy walking down the aisle at WalMart. Joe Schmoe is not going to pay an extra $10 for a razor head that lasts an extra week.
We're talking about a factor of at least 2 or 3 times in raw steel cost alone (assuming someone even convinced a mill to roll out a batch that thin), before even considering machining, HT, etc. As I said before about production knives... that might be "only" a few dollars per blade to you and me, but to the guy counting the beans at a factory, that's going to add up to a great deal of money.
We also need to keep in mind that disposable razor makers probably have no interest at all in their blades staying sharp longer. Selling replacement blades for those cute plastic handles is what makes them profitable. Why on earth would they want to use way more expensive steel, and sell far fewer blades at a much lower margin? That would be a terrible business plan for them... if I walked into the boardroom at Gillette (or wherever) and proposed such a thing, I'm pretty sure they would fire me immediately.
That's all well and good in theory. Edge-holding doesn't matter much if a person doesn't use the knife much, or only opens envelopes with it.
But serious knives are not typically used, or judged, in terms of weeks at a time. Let's take a hunter for example...
In practice, if a knife goes dull in 10 minutes instead of 20 or 60 or 120 minutes of field-dressing game animals... that's a pretty big deal.
Because it really only takes 10 minutes or so to clean out a deer or hog, and if my knife can't stay sharp that long, I'm gonna have some very angry phone calls/emails/forum posts to deal with. If my knife stays sharp for 2 or 3 or 4 deer/hogs/whatever (which might take several weeks or a year to actually get around to), I'm gonna have very happy people falling all over themselves to convince their friends to get a knife like theirs.
I absolutely agree. :thumbup: Geometry cuts, plain and simple. Thin is in. Alloy selection and HT should be matched to what needs to be cut, and how long the knife needs to keep cutting... and whether or not the knife is going to be subjected to a lot of impact ( big choppers, etc.)
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Gator,
Can you please show me an explanation that today's modern alloys have finer grain than say AEB-L or 1095 or 52100?
Does anyone even know why the PM process is used? It's in large part to make high carbide volume steels even viable...otherwise at the extreme end you get such extreme carbide aggregation the extremes of the edge stabilization are ridiculous. The PM process segregates the carbides to a more normal distribution. It does not however create inherently finer grain...that is dependent on many, many other things. Moreover, it does not improve the average edge stability...rather it reduces the range of edge stability failures and keeps them more consistent along the median, bc PM processing does not change the carbide load at all.
With regard to modern alloys simply working better than old alloys (I'm going to specify that my modern I am talking HCV, not the Japanese ones you've mentioned, and old alloys I'm referencing high edge stability) that's simply untrue. The cutting you mentioned is all abrasive soft material, so yes I would expect HCV to work better. Those are hardly the only things cut by people though. If wood work is the primary use, I think people are not going to find the same advantages to the HCV.
And Gator and James,
I feel my posts with regards to the razors were largely ignored.
Why did they move from 2 blades in the early 90s to up to 5 now? Why use more materials, increase the number of shaves from one cartridge, etc? That goes completely against the logic you are using.
Moreover, if HCV are really so good and could perform better, why not go back to 2 blades made from HCV? I'm guessing the increased costs would be offset by halving your production quantity...
Edit: A few more questions about the razor blade steel
I am strictly push cutting through the hair with a razor...I think we can all agree with that...there is no slicing motion
What do I gain by taking a bunch of carbides (essentially microscopic rocks) and inserting them into the edge here? How is that helping my edge retention is this case?
Even if you say they make the edge harder more wear resistant how is that helpful in this case? Considering the matrix holding them is softer it will wear away sooner, and if the carbides don't then fall out, I now have an apex that is jagged with small carbide teeth. How does that help me push cut through the hair? The carbide itself isn't even apexed and sharp (unless of course you cut sharpened it and formed it with <1 micron CBN or diamond abrasives...which of course we didn't in this case) so what is it doing for me on this push cut? Or even on a slice through the small hair follicles? How is that small, unapexed vanadium carbide going to slice through the small hair follicle? How is it helping me get through the hair...or by the extension any sort of push cutting (like wood working, etc).
While the carbides might increase wear resistance on the slice, in this case that is of no benefit to me as far as I can tell. But perhaps there are different answers to these questions. I feel pretty confident saying though that the high edge stability (low carbide) steel is not only ideal for the razor blade but that the HCV offer absolutely no advantage.
What does matter is the thinness and low angle of the edge. The lower and thinner I can get it the longer it will cut in this case.
Can you please show me an explanation that today's modern alloys have finer grain than say AEB-L or 1095 or 52100?
Does anyone even know why the PM process is used? It's in large part to make high carbide volume steels even viable...otherwise at the extreme end you get such extreme carbide aggregation the extremes of the edge stabilization are ridiculous. The PM process segregates the carbides to a more normal distribution. It does not however create inherently finer grain...that is dependent on many, many other things. Moreover, it does not improve the average edge stability...rather it reduces the range of edge stability failures and keeps them more consistent along the median, bc PM processing does not change the carbide load at all.
With regard to modern alloys simply working better than old alloys (I'm going to specify that my modern I am talking HCV, not the Japanese ones you've mentioned, and old alloys I'm referencing high edge stability) that's simply untrue. The cutting you mentioned is all abrasive soft material, so yes I would expect HCV to work better. Those are hardly the only things cut by people though. If wood work is the primary use, I think people are not going to find the same advantages to the HCV.
And Gator and James,
I feel my posts with regards to the razors were largely ignored.
Why did they move from 2 blades in the early 90s to up to 5 now? Why use more materials, increase the number of shaves from one cartridge, etc? That goes completely against the logic you are using.
Moreover, if HCV are really so good and could perform better, why not go back to 2 blades made from HCV? I'm guessing the increased costs would be offset by halving your production quantity...
Edit: A few more questions about the razor blade steel
I am strictly push cutting through the hair with a razor...I think we can all agree with that...there is no slicing motion
What do I gain by taking a bunch of carbides (essentially microscopic rocks) and inserting them into the edge here? How is that helping my edge retention is this case?
Even if you say they make the edge harder more wear resistant how is that helpful in this case? Considering the matrix holding them is softer it will wear away sooner, and if the carbides don't then fall out, I now have an apex that is jagged with small carbide teeth. How does that help me push cut through the hair? The carbide itself isn't even apexed and sharp (unless of course you cut sharpened it and formed it with <1 micron CBN or diamond abrasives...which of course we didn't in this case) so what is it doing for me on this push cut? Or even on a slice through the small hair follicles? How is that small, unapexed vanadium carbide going to slice through the small hair follicle? How is it helping me get through the hair...or by the extension any sort of push cutting (like wood working, etc).
While the carbides might increase wear resistance on the slice, in this case that is of no benefit to me as far as I can tell. But perhaps there are different answers to these questions. I feel pretty confident saying though that the high edge stability (low carbide) steel is not only ideal for the razor blade but that the HCV offer absolutely no advantage.
What does matter is the thinness and low angle of the edge. The lower and thinner I can get it the longer it will cut in this case.
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Good points Terrio. I like the razor blade example. The problem is that few people "know" that the razor blade that costs a lot more per unit actually is much better. They only see the advertising and what is available at the Dollar Store or Walmart. I know people that still use the old blue Gillette blades and are quite comfortable.
Another point made is that few are willing to research the new steels other than to take the word of some knife manufacturer that "they are really good". And when you read something, you really don't know if it is true or just propraganda to sell products. When Mike Stewart says the CPM 3V is very promising, that is all that most knife people need. Most people would never know the difference between their regular A-2 and CPM 3V.
Geometry has always been the key to cutting tools.
chiral.grolim
Universal Kydex Sheath Extension
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- Dec 2, 2008
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- 6,422
You guys are killing me.
Even in Verhoeven's paper on razor-blade sharpening, the recommend edge angle OF RAZOR BLADES (AEB-L and 52100 included) hardened to 60 Rc is 15-dps, no lower.
But shaving is abrasive. For cutting soft vegetables and flesh, he states the 10-dps is acceptable, but below that users begin to experience significant edge degradation, so it is better to leave it higher. Remember, this regards steel specifically for razor-blades and kitchen knives, fine-grained and low carbide, 15-dps. THIS is why 15-dps is the industry standard, because published literature demonstrates that sharpening lower is pointless, pun intended. If you want better cutting performance, you do NOT lower the apex-angle, rather you thin out the bevel BEHIND the apex.
STOP talking about such angles as if they are obtuse. OBTUSE isn't the issue, it is edge THICKNESS.
It was mentioned that axes "used to be" sharpened at 15-dps. Well, mine still are! But the thickness at the bevel is quite high. Whether you are slicing veggies or chopping wood, you are relying on the strength of the steel, and because axes are so think BEHIND the edge, the bevel face takes stress away from the apex and provides the strength necessary to complete the task. Also, degradation at the very apex isn't as important in chopping wood. In slicing soft vegetables, such strength isn't necessary and apex-stability is far more important. Well, to preserve the apex you keep the SAME edge-angle but thin the cross-section substantially. This protects the apex while reducing drag.
Keep in mind that when calculating the forces involved in cuts, if 'angle' fits into the equation, it does so via trigonometry, meaning that you simply aren't converting that angle to what it really measures, i.e. thickness.
When you sharpen a knife to <10dps and then strop the apex, you increase the apex angle with a microbevel. In Verhoeven's experiments, the importance of that microbevel cannot be overestimated - it allows for a much thinner blade with a still stable apex. When y'all are talking about razor-blades sharpened at lower angles than 15-dps, what published experiments are you referring to? Verhoeven's experiments feature high-mag images SHOWING the edge degradation.
So if S90V performs better than 52100 at 15-dps in the task of your choosing, shaving or otherwise, then S90V is superior to 52100.
Can someone please post references to experiments demonstrating that an apex angle <30 inclusive is the way to go for razor-blades? Or are y'alll just talking about the primary bevel and not the actual apex geometry?
Even in Verhoeven's paper on razor-blade sharpening, the recommend edge angle OF RAZOR BLADES (AEB-L and 52100 included) hardened to 60 Rc is 15-dps, no lower.
But shaving is abrasive. For cutting soft vegetables and flesh, he states the 10-dps is acceptable, but below that users begin to experience significant edge degradation, so it is better to leave it higher. Remember, this regards steel specifically for razor-blades and kitchen knives, fine-grained and low carbide, 15-dps. THIS is why 15-dps is the industry standard, because published literature demonstrates that sharpening lower is pointless, pun intended. If you want better cutting performance, you do NOT lower the apex-angle, rather you thin out the bevel BEHIND the apex.
STOP talking about such angles as if they are obtuse. OBTUSE isn't the issue, it is edge THICKNESS.
It was mentioned that axes "used to be" sharpened at 15-dps. Well, mine still are! But the thickness at the bevel is quite high. Whether you are slicing veggies or chopping wood, you are relying on the strength of the steel, and because axes are so think BEHIND the edge, the bevel face takes stress away from the apex and provides the strength necessary to complete the task. Also, degradation at the very apex isn't as important in chopping wood. In slicing soft vegetables, such strength isn't necessary and apex-stability is far more important. Well, to preserve the apex you keep the SAME edge-angle but thin the cross-section substantially. This protects the apex while reducing drag.
Keep in mind that when calculating the forces involved in cuts, if 'angle' fits into the equation, it does so via trigonometry, meaning that you simply aren't converting that angle to what it really measures, i.e. thickness.
When you sharpen a knife to <10dps and then strop the apex, you increase the apex angle with a microbevel. In Verhoeven's experiments, the importance of that microbevel cannot be overestimated - it allows for a much thinner blade with a still stable apex. When y'all are talking about razor-blades sharpened at lower angles than 15-dps, what published experiments are you referring to? Verhoeven's experiments feature high-mag images SHOWING the edge degradation.
So if S90V performs better than 52100 at 15-dps in the task of your choosing, shaving or otherwise, then S90V is superior to 52100.
Can someone please post references to experiments demonstrating that an apex angle <30 inclusive is the way to go for razor-blades? Or are y'alll just talking about the primary bevel and not the actual apex geometry?
With regard to the disposable razor blades, I don't think the CPM etc steels will fit into how they are processed. They use very thin strip, rolled to the thickness, and kept under tension during forming. The higher carbide steels, even if they were better, probably couldn't stand the rolling or would play havoc with the dies used in forming.
This is it. Buck did this back in 2000 with their Edge2000 process. Years ago Tom Krein would do custom regrinds and drastically thin the primary grind out for some of us knuts. The difference in performance is staggering. Check out the bottom knife.
http://i137.photobucket.com/albums/q203/sodak_photos/inventory/p1010010-1.jpg
To go thin, the steel has to be strong enough to support the edge, and that means hardness. The same steel will be much stronger at 64 HRC then at 57 HRC. So you select a steel that can be taken that hard and has the attributes that you want. Geometry cuts. Select the steel that can support that geometry via hardness and heat treat.
You can thin out most knives, but you'll never be able to thin a knife at 57HRC to the extent that you can thin a knife at 62-64HRC. That alone will give you a tremendous performance advantage.
Bingo. The knife pictured above has a micro bevel. My Dovo straight razor has a 14 DPS edge. But it's almost paper thin behind that edge. I did a thread years ago playing around with a FFG D2 hunting knife. Took it way down to 10 DPS, (with a really thin grind) and had horrible chipping. Took out the chips with a microbevel, and the problem went away, and it still cuts like a light saber. You can see the pics in my microbevel sticky.
From Roman Landes, who did his PHD thesis on exactly this subject and is an often invited speaker at the respected Ashokan seminars:
"Landes measured the deformation of edges at the same edge cross section in response to microloading. He classifed steels into three groups, type I, type II, and type III mainly based on carbide volume, 0.5-5%, 5-15%, and greater than 15% respectively. These groups needed different angles to both take and hold a high polished sharpness, 8-12, 12-20, and 20-30 degrees per side respectively. The greater the size and volume of carbide, the greater the angle required to keep the edge stable. "
His book can be purchased in German, or you can register at hypefreeblades and interact with him, or friend him on facebook.
And as i wrote already, edge stability is not necessarily dependent on edge thickness. It is angle dependent as the carbide load increases.
Could you please provide other references that show less than 15dps is useless? Right now we're at a standstill with referenced work.
Moreover, since we're talking about making improvements, explain to me why it is absurd to push for steels than can handle your thin edges but at less than 10dps and remain stable? Why must improvement necessarily be alloy based.
Essentially let me rephrase your question: If 52100 performs better than S90V at 10dps, then 52100 is superior to S90V. (And this happens to be the point I'm trying to make...not that either steel is better but that it's not easy to say one is better than other...it is circumstance dependent.)
Or if your statement is true that "you do NOT lower the apex-angle, rather you thin out the bevel BEHIND the apex", then why even 15dps, why not 20dps or 25 dps?
And moreover, my question still stands...please explain to me how the chemistry of S90V contributes to superior shaving performance and edge holding?
One last question: What if the AEB-L and 52100 had been run harder (which is quite possible...AEB-L can reach 62-63, and so can 52100 as far as I know)....their edge stability would be even higher and so perhaps at those hardness 15dps wouldn't be necessary in Verhoeven's experiements. And in fact we often talk about the "super steels" having peak performance at above 60RC, so why limit the high edge stability steels the same way?
"Landes measured the deformation of edges at the same edge cross section in response to microloading. He classifed steels into three groups, type I, type II, and type III mainly based on carbide volume, 0.5-5%, 5-15%, and greater than 15% respectively. These groups needed different angles to both take and hold a high polished sharpness, 8-12, 12-20, and 20-30 degrees per side respectively. The greater the size and volume of carbide, the greater the angle required to keep the edge stable. "
His book can be purchased in German, or you can register at hypefreeblades and interact with him, or friend him on facebook.
And as i wrote already, edge stability is not necessarily dependent on edge thickness. It is angle dependent as the carbide load increases.
Could you please provide other references that show less than 15dps is useless? Right now we're at a standstill with referenced work.
Moreover, since we're talking about making improvements, explain to me why it is absurd to push for steels than can handle your thin edges but at less than 10dps and remain stable? Why must improvement necessarily be alloy based.
Essentially let me rephrase your question: If 52100 performs better than S90V at 10dps, then 52100 is superior to S90V. (And this happens to be the point I'm trying to make...not that either steel is better but that it's not easy to say one is better than other...it is circumstance dependent.)
Or if your statement is true that "you do NOT lower the apex-angle, rather you thin out the bevel BEHIND the apex", then why even 15dps, why not 20dps or 25 dps?
And moreover, my question still stands...please explain to me how the chemistry of S90V contributes to superior shaving performance and edge holding?
One last question: What if the AEB-L and 52100 had been run harder (which is quite possible...AEB-L can reach 62-63, and so can 52100 as far as I know)....their edge stability would be even higher and so perhaps at those hardness 15dps wouldn't be necessary in Verhoeven's experiements. And in fact we often talk about the "super steels" having peak performance at above 60RC, so why limit the high edge stability steels the same way?
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I think what is being said is that right now, 15 DPS is the benchmark given the steels that we have. My unofficial (and unscientific testing) confirms that in my own mind. If you could find a steel that would take a hardening of 70 HRC you could probably go thinner on the primary and under 15 DPS. The problem is the amount of work to accurately test that, and having a huge budget and the patience of Job. Verhoeven used a lot of expensive equipment with electron microscopes, and defined a sharp edge being less than 0.5 microns wide. He proved it with pictures.
Most of us just don't have access to that type of setup, nor the time.
Most of us just don't have access to that type of setup, nor the time.
And I believe vanadium carbides are on the order of 2-4 microns, so how you plan to fit one of those into an apex 0.5 microns wide? You have to increase the edge angle to stabilize it unless you are somehow shaping the vandium carbide itself and apexing it.
So as in your post about Buck, if the thinner edge performed better, imagine how much better it would perform on the Catra test if the apex angle was also lower (less resistance)...and as seen in Roman's work, some steels can handle less than 15dps. And these steels are also cheap and easily hardenable to above 60 RC.
So as in your post about Buck, if the thinner edge performed better, imagine how much better it would perform on the Catra test if the apex angle was also lower (less resistance)...and as seen in Roman's work, some steels can handle less than 15dps. And these steels are also cheap and easily hardenable to above 60 RC.