Durability test of the sharpness of D2 knives, compared to two SG2 knives.

[bill_zeng]

These past few days, I have seen some discussions about D2 (SKD11, SLD) and SG2. SG2 and D2 are the steels I use most frequently in my knives. I have some different views. I use a pressure measurement test while cutting tomatoes to compare the differences between the two.

The testing equipment is very simple: an electronic scale, some cardboard, and three knives. They are:

• SG2 by TOJIRO HRC62+
• SG2 by Sakai Takayuki HRC62+
• D2 made by me HRC60

All blades are standardized to 15°-16° edge angles and a cutting distance of 210mm (Sakai Takayuki's is 240mm, so I used tape to cover 30mm).

Testing Process:

1. Each knife was first tested on tomatoes to measure the pressure needed to cut through, ensuring they all had very similar sharpness. The initial sharpness of the D2 knife was slightly less.
2. Each knife then made 20 cuts on cardboard to dull them quickly.
3. The pressure required to cut the tomatoes was tested again on the same tomato. The maximum pressure to break the skin increased, but the pressure data was not significantly different among the knives.
4. Each knife then made 5 more cuts on cardboard.
5. The cutting pressure was tested again, with little difference in the data (Sakai Takayuki's was slightly duller).
6. To strengthen the test, each knife then made 10 additional cuts on longer cardboard.
7. The final test results showed that on the same tomato, the D2 had the least pressure needed to break the skin, followed by TOJIRO's SG2, and Sakai Takayuki's SG2 required the most pressure.

I have uploaded the test video on youtube . It’s a simple test that anyone can replicate. My testing method is a very practical and close-to-real-life cutting approach.

 

[blokey]

Thanks for another test, tho this time I think the relative pressure on tomato skin may have more to do with edge aggression than edge sharpness, D2 have larger carbides and will have more micro serrated like edge, it’s a topic that’s not well explored yet, but there’s some test being done
https://www.kitchenknifeforums.com/threads/the-effect-of-“edge-aggression”-between-steels.68718

 

[bill_zeng]

I hope everyone seriously considers a question: Are some durability charts really applicable to kitchen knives? After all, doing a test yourself only takes half an hour. It's very simple and not troublesome at all.

 

[bill_zeng]

Thanks for another test, tho this time I think the relative pressure on tomato skin may have more to do with edge aggression than edge sharpness, D2 have larger carbides and will have more micro serrated like edge, it’s a topic that’s not well explored yet, but there’s some test being done
https://www.kitchenknifeforums.com/threads/the-effect-of-“edge-aggression”-between-steels.68718

So I don't call this edge retention or edge wear resistance. I call it a sharpness durability test.
For kitchen knives, this more directly affects cutting performance.

 

[blokey]

So I don't call this edge retention or edge wear resistance. I call it a sharpness durability test.
For kitchen knives, this more directly affects cutting performance.

Yeah it’s kind a phenomenal that presents itself in different steels, people call it bity edge, some steel just dull in a way that’s turns to be more rounded and smoothed out, which are still sharp but struggle against waxy stuff like tomato or pepper skins, while some steel keep a good bite in rest of the edge life, very interesting stuff and it’s what kept me trying out different steels

 

[bill_zeng]

Yeah it’s kind a phenomenal that presents itself in different steels, people call it bity edge, some steel just dull in a way that’s turns to be more rounded and smoothed out, which are still sharp but struggle against waxy stuff like tomato or pepper skins, while some steel keep a good bite in rest of the edge life, very interesting stuff and it’s what kept me trying out different steels

The knives I use myself are made from CPM-3V material. The edge is very sharp and works great for cutting some flexible foods. It has good impact resistance, allowing me to grind it very thin with very little cutting resistance. It also has some rust resistance. However, I can't solve the cost issue to make them into cheap products. Recently, I bought some MagnaCut material with Bos heat treatment and plan to make some new toys for myself.

 

[blokey]

The knives I use myself are made from CPM-3V material. The edge is very sharp and works great for cutting some flexible foods. It has good impact resistance, allowing me to grind it very thin with very little cutting resistance. It also has some rust resistance. However, I can't solve the cost issue to make them into cheap products. Recently, I bought some MagnaCut material with Bos heat treatment and plan to make some new toys for myself.

You won’t be disappointed, if you can contact 新国 he’s doing his own heat treatment in house now and it is more on kitchen knife side of treatment, very good edge feeling, I’ve also got some K890 knives from 陈高志，that steel is also really tough but can be made quite hard and sharp, I think you would like it too

 

[bill_zeng]

You won’t be disappointed, if you can contact 新国 he’s doing his own heat treatment in house now and it is more on kitchen knife side of treatment, very good edge feeling, I’ve also got some K890 knives from 陈高志，that steel is also really tough but can be made quite hard and sharp, I think you would like it too

The knives from 新国 are very well made. However, I've already purchased a large piece of material with Bos heat treatment. I plan to make some small toys myself. I haven't worked with 陈高志 yet, but I would like to try it if I get the chance.


In recent years, I've mainly been using semi-stainless steel. I had enough of the slippery cutting feel of stainless steel before.

 

[Matt Jacobs]

I hope everyone seriously considers a question: Are some durability charts really applicable to kitchen knives? After all, doing a test yourself only takes half an hour. It's very simple and not troublesome at all.

I definitely think about this when I see tests. We don't cut paper with our kitchen knives (short of testing a fresh edge) and more importantly we never look at how things like acidity affect the edge of knives. For example during tomato season my AEB-L knives far outlast some of my carbons for a toothy edge. I like this test you did.

 

[azn_knives_4l]

I hope everyone seriously considers a question: Are some durability charts really applicable to kitchen knives? After all, doing a test yourself only takes half an hour. It's very simple and not troublesome at all.

Charts really don't mean much, unfortunately, due to vagaries of heat treatment and geometry. Larrin Thomas's tests are performed with 'optimum' heat treatment against his own knife-making philosophies so get really wonky outside of that in tests that *aren't* CATRA. He's reviewed the work from other 'real world' rope-cutting experiments and found peak R^2 at 66%, iirc, and this lends credibility to his work. That said, 34% or more of variation is simply unaccounted for and that's enough to flip the conclusions for pretty much any steel in his charts.

Another confounding factor to the test you present here is geometry of the primary grind (above the edge bevels) as it relates to the ease of cutting through the cardboard and pressure/related dulling. You were able to control with the chicken wing experiment but could be a big source of variation here.

Edit: I actually deal with this kind of variability as a function of my day to day. There are ways around it but those 'ways' are tons and tons of repetitions to achieve convergence in the sample to the 'true' empirical distributions against known and otherwise uncontrollable randomness.

 

[Redwax]

I hope everyone seriously considers a question: Are some durability charts really applicable to kitchen knives? After all, doing a test yourself only takes half an hour. It's very simple and not troublesome at all.

Cutting cardboard with a kitchen knife is a questionable way to test it's ability in the kitchen though, no? Also you are comparing three specific knives with a lot of potential variables in geometry, effectiveness of how each was sharpened etc. which makes it arguably irrelevant to anyone looking for information about the attributes of those steels in any other knives.

I mean I get it, you are just trying to sell your knives and they look great. I actually like both steels.

 

[bill_zeng]

1）The purpose of cutting cardboard is simply to dull them quickly within a controllable number of cuts.
Cutting cardboard is no different from cutting anything else. Cardboard isn't even as hard as a kitchen cutting board.
Moreover, this is not about averaging the performance of cutting cardboard.
The real test is the tomato cut.

2）The cardboard I tested is very clean, with no other impurities causing excessive wear on the blade. In the middle of the test, I conducted a paper cutting test, which proved that cutting the cardboard did not cause excessive damage.

3）Using edge angles or those little cheating tricks to alter test results is just too lowbrow. That's why I say this is a very simple test. Anyone can easily replicate it. If someone doesn't trust me, they can do the test themselves. It only takes a little time, a tomato, and some cardboard.

4）Of course, I want to sell more of my work. However, I must emphasize that this is not about money. I work for the world's wealthiest gaming company and am a core member. I make knives during holidays, not for the pursuit of money.The modest income from knife sales is likely less than any of my financial investments.I might sell knives for a year and still not make as much as one of my financial investments does in a single morning.
I also posted part of today's financial income this morning. It's much more than what I earn from making small knives during holidays, working hard for several days in a hot forging workshop
What I hope for is to discuss the actual performance of the knives.
I have already posted the pure gold medal I received for my contributions to the COD Mobile team. It weighs approximately 30 grams.
You can search the internet for information about us. Our company's average annual salary exceeds $200,000, while the studio I work in exceeds $400,000.
This is all public information.
I have lived in Canada for a long period of time. During that time, I worked as an aerospace engineer.
I can understand some subtle biases.
Saying this, I'm not trying to prove how wealthy I am. I feel that some people might think I'm just a cunning businessman looking to make a quick buck on KKF.
I am here out of my love for knives.

 

[bill_zeng]

Charts really don't mean much, unfortunately, due to vagaries of heat treatment and geometry. Larrin Thomas's tests are performed with 'optimum' heat treatment against his own knife-making philosophies so get really wonky outside of that in tests that *aren't* CATRA. He's reviewed the work from other 'real world' rope-cutting experiments and found peak R^2 at 66%, iirc, and this lends credibility to his work. That said, 34% or more of variation is simply unaccounted for and that's enough to flip the conclusions for pretty much any steel in his charts.

Another confounding factor to the test you present here is geometry of the primary grind (above the edge bevels) as it relates to the ease of cutting through the cardboard and pressure/related dulling. You were able to control with the chicken wing experiment but could be a big source of variation here.

Edit: I actually deal with this kind of variability as a function of my day to day. There are ways around it but those 'ways' are tons and tons of repetitions to achieve convergence in the sample to the 'true' empirical distributions against known and otherwise uncontrollable randomness.

I know this experiment has many uncontrollable factors. Some people might even think I could cheat a little. So, I conduct this experiment to promote a way of thinking: those edge retention charts do not truly reflect actual cutting performance. I try to use a method that anyone can replicate to test, so that more people can test for themselves and believe in their own results.
Over the years, in the EDC community and the kitchen knife community, I have debated more than once about the reference value of those charts for actual use. Many people are not even willing to spend 15 minutes to test it themselves.

 

[jedy617]

Just an fyi, cutting cardboard degrades edges VERY fast all things considered.

Would be cool to see this test with 2 knives that were as close as possible in geometry

 

[Redwax]

@bill_zeng

Sorry if I offended you, that wasn't my intention nor was I trying to imply that you are here just to make money.

I was replying to your assertion that "some durability charts" are not relevant because of how they were tested in regards to kitchen tasks. Your test seems to me to be just as irrelevant. The point is that you can see a lot of different people testing knife steels through different methods and getting wildly variable results; often contradicting each other. Yours is just another test, no better or worse than most others, and as I said there are way too many variables for me to take much anything from your test.

This is just my opinion, so please don't take it personally. I'm sure many people will agree with you.

 

[bill_zeng]

Just an fyi, cutting cardboard degrades edges VERY fast all things considered.

Would be cool to see this test with 2 knives that were as close as possible in geometry

Yes, that's why I advocate for everyone to do their own testing.

 

[jedy617]

Yes, that's why I advocate for everyone to do their own testing.

It's hard because I'm not sure if any knife company that makes an r2 and d2 knife in the exact same geometry, might have to be made in a factory as well for more consistent grind.

Interesting test, thanks for sharing.

Also 3v is cool, you should make some kitchen knives with it!

 

[bill_zeng]

@bill_zeng

Sorry if I offended you, that wasn't my intention nor was I trying to imply that you are here just to make money.

I was replying to your assertion that "some durability charts" are not relevant because of how they were tested in regards to kitchen tasks. Your test seems to me to be just as irrelevant. The point is that you can see a lot of different people testing knife steels through different methods and getting wildly variable results; often contradicting each other. Yours is just another test, no better or worse than most others, and as I said there are way too many variables for me to take much anything from your test.

This is just my opinion, so please don't take it personally. I'm sure many people will agree with you.

I used to firmly believe in some of those charts. However, after actually testing many knives, I found that the charts often deviate significantly from real-world use. I want to thank Spyderco because, thanks to their company, I was able to purchase knives made from various rare steels
Of course, I do acknowledge that the chart accurately represents wear resistance. However, many people use that chart as a basis for actual cutting ability, which I strongly disagree with.
For a kitchen knife or an outdoor knife, actual cutting performance is crucial, even more so than wear resistance. The edge retention shown in those charts is meaningful for tools like industrial paper cutting machines.

 

[Redwax]

I used to firmly believe in some of those charts. However, after actually testing many knives, I found that the charts often deviate significantly from real-world use. I want to thank Spyderco because, thanks to their company, I was able to purchase knives made from various rare steels
Of course, I do acknowledge that the chart accurately represents wear resistance. However, many people use that chart as a basis for actual cutting ability, which I strongly disagree with.
For a kitchen knife or an outdoor knife, actual cutting performance is crucial, even more so than wear resistance. The edge retention shown in those charts is meaningful for tools like industrial paper cutting machines.

I agree with you. Wear resistance is not the only thing or even most important thing for various types of knives for edge or sharpness retention.

Most people wouldn't be able to tell the difference between steels that are as evenly matched as D2 and SG2 and most would probably not care about a few percent difference in edge retention or toughness anyway.

 

[azn_knives_4l]

I know this experiment has many uncontrollable factors. Some people might even think I could cheat a little. So, I conduct this experiment to promote a way of thinking: those edge retention charts do not truly reflect actual cutting performance. I try to use a method that anyone can replicate to test, so that more people can test for themselves and believe in their own results.
Over the years, in the EDC community and the kitchen knife community, I have debated more than once about the reference value of those charts for actual use. Many people are not even willing to spend 15 minutes to test it themselves.

Yeh, there are many intractable ideas flying around. Big Brown Bear, author of the linked 'toothiness' experiment above, at one point posted on Instagram his belief in the importance of super abrasives for edge quality and edge retention in the sharpening of vanadium carbide steels and showed the toothy edge produced by SiC abrasive as his evidence. Ofc, that idea is entirely contradictory to this more recent writeup.

It's as bad or worse than the science regarding modern diets and related recommendations. At least traditional is more or less a known quantity even if observational so we can always fall back on that when things get too weird. Thanks for sharing.

 

[bill_zeng]

Yeh, there are many intractable ideas flying around. Big Brown Bear, author of the linked 'toothiness' experiment above, at one point posted on Instagram his belief in the importance of super abrasives for edge quality and edge retention in the sharpening of vanadium carbide steels and showed the toothy edge produced by SiC abrasive as his evidence. Ofc, that idea is entirely contradictory to this more recent writeup.

It's as bad or worse than the science regarding modern diets and related recommendations. At least traditional is more or less a known quantity even if observational so we can always fall back on that when things get too weird. Thanks for sharing.

That's quite a coincidence. Recently, I've been testing S110V, a super wear-resistant high vanadium material, and have gained some related experience. The pronounced cutting performance of the micro-serrations is indeed noticeable, but not everyone likes it. Some prefer a delicate cutting feel, while others prefer a rougher one. If we were to delve deeper, it would be quite an extensive discussion. One of the tools I've been testing recently is the SPYDERCO S110V C81 folding knife, which I showcased in my testing video.

 

[jedy617]

That's quite a coincidence. Recently, I've been testing S110V, a super wear-resistant high vanadium material, and have gained some related experience. The pronounced cutting performance of the micro-serrations is indeed noticeable, but not everyone likes it. Some prefer a delicate cutting feel, while others prefer a rougher one. If we were to delve deeper, it would be quite an extensive discussion. One of the tools I've been testing recently is the SPYDERCO S110V C81 folding knife, which I showcased in my testing video.

One of my favorite EDCs is in s110v. I use a lot of s110v and s125v, they are amazing steels. My favorite for everyday use is s90v or magnacut usually.

 

[M1k3]

Cutting ability is determined by geometry. SLD, SG2, 1045, Damasteel, 125SSC, etc. doesn't matter for cutting ability.

The steels matter in 1) edge retention 2) ease of sharpening 3) stainlessness 4) durability/fragility.

 

[azn_knives_4l]

Cutting ability is determined by geometry. SLD, SG2, 1045, Damasteel, 125SSC, etc. doesn't matter for cutting ability.

The steels matter in 1) edge retention 2) ease of sharpening 3) stainlessness 4) durability/fragility.

I think it's hard to separate sharpenability and steel from cutting ability. It's more or less the premise to BBB's writeup above in the formation of the toothy edge under functionally similar geometries and sharpening routines even with super abrasives.

 

[M1k3]

I think it's hard to separate sharpenability and steel from cutting ability. It's more or less the premise to BBB's writeup above in the formation of the toothy edge under functionally similar geometries and sharpening routines even with super abrasives.

I'd personally say that's both cutting ability and edge retention.

A toothy edge with crap geometry will not cut well.

Thin behind the edge, good convex geometry and toothy edge will be the "bees knees".

 

[bill_zeng]

是的，有很多棘手的想法飞来飞去。上面链接的“齿度”实验的作者 Big Brown Bear 曾一度在 Instagram 上发布了他对超级磨料对磨削碳化钒钢磨削中边缘质量和边缘保持的重要性的信念，并展示了 SiC 磨料产生的齿形边缘作为他的证据。Ofc，这个想法与最近的这篇文章完全矛盾。

它比关于现代饮食和相关建议的科学一样糟糕或更糟。至少传统或多或少是一个已知的数量，即使是观察性的，所以当事情变得太奇怪时，我们总是可以依靠它。感谢分享。

Everyone has different cutting habits. When evaluating materials, I try not to impose my personal cutting style preferences. All I can do is showcase what exists. The cutting performance resulting from the combination of high-hardness alloys and coarse-hardness alloys with low-grit abrasives does exist. However, I personally don't like that friction feeling, especially the obvious friction and grit sensation when cutting paper.

But many people do like it, and that type of edge is very durable. For professional kitchen workers, this is very practical.

Of course, slicing sashimi is an exception. Slicing sashimi requires a very fine edge to achieve a smooth cut.

Many knife enthusiasts do not understand the needs of those who cut vegetables in busy restaurants all day long.

Like me, I sharpen my knives almost every two to three days, and I always use sharpening stones with a grit above 10,000.

However, my social circle has expanded, and I have met many friends who work in the culinary industry—whether in Japanese restaurants, Western restaurants, or Chinese restaurants. There are professional slicers who only handle cutting in large restaurants, and there are slicers in small restaurants who juggle multiple roles.

Everyone's needs and preferences are different, even in the same job position.

Many people only acknowledge their own habits, thinking that only their habits are correct. This is very common.

As a product manager (with a side job developing bicycle products), I need to understand the difference between personal preferences and actual situations.

 

[bill_zeng]

我认为很难将锐化性和钢与切削能力区分开来。这或多或少是 BBB 上面写的前提，即在功能相似的几何形状和锐化程序下形成齿状边缘，即使使用超级磨料也是如此。

In the past few days, I have repeatedly demonstrated the differences between D2 and SG2. Personally, I don't like D2 (SKD11, SLD) material. I prefer the fine cutting feel of SG2. I also don't need the long-lasting cutting ability of D2 because I sharpen my knives frequently. By the time my knife gets dull enough to need that kind of tough cutting performance, I have already resharpened it. I handle my knives carefully, so SG2 won't get damaged. However, I can't ignore the characteristics of D2 material just because of my own usage habits.

 

[azn_knives_4l]

在过去的几天里，我反复展示了 D2 和 SG2 之间的区别。就个人而言，我不喜欢 D2（SKD11、SLD）材料。我更喜欢SG2的细腻切割手感。我也不需要 D2 的持久切割能力，因为我经常磨刀。当我的刀变钝到需要那种坚韧不拔的切割性能时，我已经重新磨了。我小心翼翼地处理我的刀，所以 SG2 不会损坏。但是，我不能仅仅因为我自己的使用习惯而忽视 D2 材料的特性。

Yeh. I tend to use 'fine-grained' steel, both carbon and stainless, for similar reasons. Optimizing to edge retention in the kitchen just isn't valid to my uses.

 

[Barmoley]

Yeh, there are many intractable ideas flying around. Big Brown Bear, author of the linked 'toothiness' experiment above, at one point posted on Instagram his belief in the importance of super abrasives for edge quality and edge retention in the sharpening of vanadium carbide steels and showed the toothy edge produced by SiC abrasive as his evidence. Ofc, that idea is entirely contradictory to this more recent writeup.

It's as bad or worse than the science regarding modern diets and related recommendations. At least traditional is more or less a known quantity even if observational so we can always fall back on that when things get too weird. Thanks for sharing.

I think you missed what Shawn was saying about sharpening vanadium rich steels with SiC. You get a raged edge that is stressed and weakend, so it has nothing to do with toothier edges being better for some applications.

You guys also seem to be making sweeping statements about charts without making it clear what exactly you are talking about. Larrin provided not only wear resistance, but also all the other tests and attributes of steel combinations which determine the edge retention and stability. Noone here is claiming that wear resistance is the only measure, so I am not clear why you keep on harping about this. Your complaints about Larrin's testing is misplaced and misinformed. If you want to compare steels there is no other reliable way to do this. If you want to compare knives, that's different and comparing knives tells you little about the steels these are made out of unless everything else is the same.

 

[azn_knives_4l]

I think you missed what Shawn was saying about sharpening vanadium rich steels with SiC. You get a raged edge that is stressed and weakend, so it has nothing to do with toothier edges being better for some applications.

You guys also seem to be making sweeping statements about charts without making it clear what exactly you are talking about. Larrin provided not only wear resistance, but also all the other tests and attributes of steel combinations which determine the edge retention and stability. Noone here is claiming that wear resistance is the only measure, so I am not clear why you keep on harping about this. Your complaints about Larrin's testing is misplaced and misinformed. If you want to compare steels there is no other reliable way to do this. If you want to compare knives, that's different and comparing knives tells you little about the steels these are made out of unless everything else is the same.

You're reading too much into my statements. Stressed steel is only one tiny part of the equation and is unavoidable in the grinding of steel, in general, and we have no studies on the balance vs. the benefits of toothiness.

There is no sweeping generalization here except to say the same as what you're saying in that the numbers presented in Larrin's charts do not tell the entire story and that making a decision for knives using only the charts on steel is of limited value.

Edit: Words for clarity.