# Good Scientific Resource?



## Tea_Hills (Jan 13, 2022)

Pretty new to the forums and first post on the sharpening board so hello everyone!

I've been sharpening for a few years now and I can often get an arm hair shaving edge on my good knives freehand but have struggled getting shaving edges on anything from Germany. Also perfect consistency is not easy. Now I know none of this really matters for most kitchen applications but it started me on a journey to understanding what is actually going on during the sharpening process. This led me to discovering Vadim Kraichuk. He seems quite well regarded and has published a number of 'scientific' white papers on sharpening. He also believes that a lot of commonly held community beliefs are false. I was hoping to see if anyone has any trial and observation type of information that runs counter to his findings. Mainly these points:

1. Apex creation on a diamond surface instead of the traditional whetstone compound of Silicon/aluminum oxide allows a properly finished' edge to reach smaller apex edge thickness and consequently a sharper blade.

2. 'Toothy' edges are not preferable to a properly polished edge in terms of edge retention in any way. 

3. Burr creation falls into 2 rough camps in the way they are created. Primarily harder steels create a 'negative' burr upon grinding and softer steels create 'positive' burrs. These need to be deburred in different ways.

4. Deburring by cutting cork or felt leads to a wider apex width and less sharp edge.

5. 'Wear resistant' steels that contain large Vanadium and Chromium carbides (such as D2, R2, etc) absolutely require edge setting and finishing on diamond or CBN based abrasives. This a result of traditional whetstones lacking the required hardness to grind the carbides into a sub micron width. He postulates that a sharp edge can be created with traditional whetstones but as the steel matrix at the edge wears away you have unground large carbides that remain at the edge (with a risk of tear-out) and this results in an edge that loses sharpness much faster than it should.

I gathered a lot of this from his published literature and his book. I don't want to link any of it directly as to not plug his site (and store). I will say that he runs Knife Grinders of Australia if anyone is curious. 

Now I am going to adapt some of his procedures to a home setting (that doesn't have a grinding or felt wheel) and try to post my findings. I can't seem to find much in the way of peer review on any of his findings so really I guess I'm asking if anyone has read his work and seen any counterpoints. 



Thanks!


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## big_adventure (Jan 13, 2022)

You can also check out Science of Sharp and Knife Steel Nerds (callout to @Larrin ) for great information on steels and sharpening them.

Nothing said above is too controversial.

Notably, however, SEM shots of edges shows that the idea that "normal" stones can't cut the carbides in very hard steels is false. They can and do. That said, it'll probably take longer to sharpen and extremely hard-carbide-rich steel on softer stones than harder stones.


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## HumbleHomeCook (Jan 13, 2022)

Welcome and good for you to jump into the sharpening journey.

Now, my day-in and day-out life is immersed in science and while it is no doubt interesting in the sharpening world, I would also readily caution not to get too overly concerned with it all early on. It can seem overwhelming and confusing.

There are some widely held and accepted claims in your post but just about all of them are debated as well. And some things you've presented as absolutes when they aren't.

For example, chromium carbides, in general, are not that hard to cut and most synthetics can handle them just fine. Vanadium carbides are hard to cut but widely accepted as not a big deal until above 4% and at higher grits.

I sharpened my Aogami Super gyuto last night. It is near silently cross-cutting paper towels. That edge has never seen a diamond stone and hopefully never will.

And so on.

Form a burr. Flip the knife. Form a burr. De-burr.

That's the basics of sharpening and it doesn't matter what the steel is. Relax and let the knife tell you what you're doing (right and wrong) and how it is reacting to those inputs.

What are your German knives? You're struggling with them as they are softer stainless and at rather high angles. It isn't uncommon for folks to have the same issues.

Are you using a marker on your edge bevels?


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## ian (Jan 13, 2022)

Tea_Hills said:


> Pretty new to the forums and first post on the sharpening board so hello everyone!
> 
> I've been sharpening for a few years now and I can often get an arm hair shaving edge on my good knives freehand but have struggled getting shaving edges on anything from Germany. Also perfect consistency is not easy. Now I know none of this really matters for most kitchen applications but it started me on a journey to understanding what is actually going on during the sharpening process. This led me to discovering Vadim Kraichuk. He seems quite well regarded and has published a number of 'scientific' white papers on sharpening. He also believes that a lot of commonly held community beliefs are false. I was hoping to see if anyone has any trial and observation type of information that runs counter to his findings. Mainly these points:
> 
> ...



You could totally link to his stuff, imo. Would help us understand which articles you're citing.


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## Tea_Hills (Jan 13, 2022)

HumbleHomeCook said:


> Welcome and good for you to jump into the sharpening journey.
> 
> Now, my day-in and day-out life is immersed in science and while it is no doubt interesting in the sharpening world, I would also readily caution not to get too overly concerned with it all early on. It can seem overwhelming and confusing.
> 
> ...



The 4% Vanadium or so making a difference is interesting. It does make sense that there would be a threshold on Vanadium composition where higher hardness abrasives actually don't make a practical difference. 

I would consider myself an average freehand sharpener in the sense of being able to hold a consistent angle across stones and side flips (certainly used a fair bit of sharpie learning), even pressure, minimizing the burr with decreasing pressure, etc. I get regularly consistent hair shaving results (on harder steels). I like to sharpen for friends and family and found that their $20 knives, maybe not German haha, certainly behaved differently when deburring and required a different technique to get to equal sharpness. 

Now I'm more curious than anything about the techniques people use to get XYZ level of sharpness and different steel types and what is happening at the micron level during the process. I love my loupe but its no SEM!


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## Tea_Hills (Jan 13, 2022)

ian said:


> You could totally link to his stuff, imo. Would help us understand which articles you're citing.



Gotcha, so a lot of the assumptions I mentioned are more clearly outlined in his book but some of the research can be found here Knife Grinders


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## SilverSwarfer (Jan 13, 2022)

HumbleHomeCook said:


> Form a burr. Flip the knife. Form a burr. De-burr.


+1

The best resource I can recommend is an open mind. There are many interpretations and opinions, and enough disagreements over fundamentals to prove to me that the only 'correct' way to sharpen is the way that improves the edge of the tool in your hand to best suit some task(s) at hand.

Sharpening is an ancient, simple maintenance chore that we can make as complicated, involved, expensive, esoteric as we like (_'good enough_' vs '_good enough for me_'). IME the best path to improvement is practice. Study becomes much more relevant/useful after repeated trial-failure. It is easy to become confused and frustrated; especially so if more time is spent with a book/mouse in your hand, rather than with a knife/stone in your hand. Focusing on one thing at a time is important. Isolated variables = easier troubleshooting. It is an ongoing journey: no matter how well-developed our skills, there is always some room for improvement. 

Practice + Persistence + Patience = Progress


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## ian (Jan 13, 2022)

Tea_Hills said:


> Gotcha, so a lot of the assumptions I mentioned are more clearly outlined in his book but some of the research can be found here Knife Grinders



Just ordered the book. Love the technical stuff, even if it's not what you should focus on when you're starting out.


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## Vesteroid (Jan 13, 2022)

I just binge watched all his videos over the holidays. So much so that I bought a torment t8.

I completely buy into the process he outlines in his book and subsequent videos/ articles on his page.

I bought his front stand for the tormek and the jstone To go with the t8. I will hold off on his stones till I see how well I can transition from hand sharpening to the t8. I even got the tester to have some objectivity to my results.
I am going to try and hand sharpen a few of my knives, test them, then do the profile he suggest, then test again. 
We will see


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## Barmoley (Jan 13, 2022)

big_adventure said:


> You can also check out Science of Sharp and Knife Steel Nerds (callout to @Larrin ) for great information on steels and sharpening them.
> 
> Nothing said above is too controversial.
> 
> Notably, however, SEM shots of edges shows that the idea that "normal" stones can't cut the carbides in very hard steels is false. They can and do. That said, it'll probably take longer to sharpen and extremely hard-carbide-rich steel on softer stones than harder stones.



Science of sharp photos confused me when I saw them as it doesn't make sense to me that softer abrasive can cut harder carbide. It is hard to argue with empirical evidence, but I don't understand the mechanism of how it happens. I saw him show this on lower grid stones, have you seen him also show this with higher grit? I also get much better results with diamond stones on high wear resistant steels, but this could just be lack of technique, not enough skill on my part. Since diamond stones cut these steels faster for me, I have less time to screw up the edge.

If we step away from steel for a second and take extreme substances such as tungsten carbide or flexible ceramic blades. These are hard to sharpen even with diamond stones and are just impossible with regular synthetic stones. These are not steels, so I don't know if it is at all relevant, but with these too, harder abrasives are needed to have any success at all.


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## Mr.Wizard (Jan 13, 2022)

Tea_Hills said:


> 2. 'Toothy' edges are not preferable to a properly polished edge in terms of edge retention in any way.



Where does he describe this? Other experiments have found that toothy edges last longer in slicing while polished edges last longer in push cutting.


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## spaceconvoy (Jan 13, 2022)

Glass is harder than iron. And jets of water can cut through steel plate. Hardness is not the only issue at play.


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## Luftmensch (Jan 13, 2022)

HumbleHomeCook said:


> Now, my day-in and day-out life is immersed in science and while it is no doubt interesting in the sharpening world, I would also readily caution not to get too overly concerned with it all early on. It can seem overwhelming and confusing.





SilverSwarfer said:


> +1
> 
> The best resource I can recommend is an open mind. There are many interpretations and opinions, and enough disagreements over fundamentals to prove to me that the only 'correct' way to sharpen is the way that improves the edge of the tool in your hand to best suit some task(s) at hand.
> 
> ...



Such great advice!!



Tea_Hills said:


> I guess I'm asking if anyone has read his work and seen any counterpoints.



I am vaguely aware of his work. I would spend some time reading the articles on Knife Steel Nerds - they may validate or invalidate Kraichuk's work. 

I am wary of treating this as a science. Sure... you can be really methodical about your approach... Understanding the material science behind it can help with your progress and understanding... but the act is really a _craft_.

I am super wary of lionising particular people in the community. There are experts in the community who have a huge amount of experience. You _should_ take these people _seriously_. But I find it frustrating when their advice is viewed as immutable truths that should end a conversation. You may find a different method or perspective works better for *you*.

The other thing I might encourage, is that obsessing over this stuff is somewhat academic. _It is fun_. But ultimately it is unlikely to be practical. A knife is sharp or it isnt. You need to sharpen it or you dont. Whether you have attained that 3% better performance by removing stress concentrators on a microscopic level is not going to have a profound practical effect on carrots. I want to stress that it is very fun to dive deep... but ultimately that is out of curiosity. You'll likely find more use out of setting yourself higher goals: can i make a sharper edge than last time; can I sharpen quicker than last time; can I produce a longer lasting edge than last time... Certainly, better knowledge will help you do that.


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## ian (Jan 13, 2022)

spaceconvoy said:


> And jets of water can cut through steel plate.



Aren’t these jets typically loaded with abrasives? Or am I confused? I fully believe water can “cut” iron at high enough velocity though.


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## spaceconvoy (Jan 13, 2022)

ian said:


> Aren’t these jets typically loaded with abrasives? Or am I confused. I fully believe water can “cut” iron at high enough velocity though.


Both! Abrasive speeds up the process and reduces the amount of pressure needed, but it isn't strictly necessary.


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## daveb (Jan 13, 2022)

Luftmensch said:


> There are experts in the community who have a huge amount of experience. You _should_ take these people _seriously_. But I find it frustrating when their advice is viewed as immutable truths that should end a conversation. You may find a different method or perspective works better for *you*.



I thought we had found some common ground, then I realized I was in the wrong thread.....


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## daveb (Jan 13, 2022)

Something unique about learning sharpening as a skill is the solitary nature of it. If you want to learn to fish you go fishing with a friend. If you want to learn to bake, you find a friend that bakes. And so on.

If you want to learn to rub steel on rocks, you'll likely be the only one in your social circle that does so. You can watch the utubers but there are so many, some good, some bad, some that contradict each other. It's seems more intimidating than it should - though within a short time you should be able to make a knife sharper than it was when you started. 

As you develop proficiency, it's not uncommon to develop bad habits. There's no one to guide you or tell you don't do that. Keep practicing, keep watching utubers, be self-critical.

And then there's the finer points. Removing chips, repairing tips, maintaining the profile, thinning, sharpening tips, polishing out the scuff marks. It's easy to plateau on "proficient". Getting to "good" takes awhile. Jon, from JKI is my mentor of choice (he had no say in the matter), he still goes to Japan to study and he's widely regarded as "expert" in the field.

Do the best you can - and no Cliff.


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## Tea_Hills (Jan 13, 2022)

Mr.Wizard said:


> Where does he describe this? Other experiments have found that toothy edges last longer in slicing while polished edges last longer in push cutting.



Unfortunately it is in his book but the quoted text is:

_The “micro-serrations” concept contributes to the confusion as people tend to mistakenly generalize properties of the serrated edge onto the microscopic level of a ragged coarse edge. The saw teeth and the edge ragged by a coarse abrasive are not the same. This myth about blades having "teeth" formed by the "scratches" on the bevel just won't die. Coarse scratches do not create "teeth" on the apex. In the edge sharpened coarse, the high spots are mostly burrs and the low spots are mostly chips far wider than any given scratch; after deburring you get an irregular apex riddled with flaws. A knife edge sharpened to rougher finishes will have larger scratches than a finely honed edge, and these scratches can be thought of as pre-existing flaws; the sub-surface damage is also more pronounced and extended. A coarser edge does “bite” initially, however the knife dulls faster as the “teeth” get broken off, and as the edge chipping develops along those flaws.

Thoroughly done studies have shown that the coarse finish is associated with increased grip force, cutting effort and cutting time, and worse edge retention. In precise cutting and carving unpolished bevels cause traction in cuts and lower accuracy and quality of cut. _

There are some supporting SEM photos but no link to the studies he mentioned. 

Could you point me in the direction of the experiments you were mentioning? I'd love to take a look. Thanks!


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## Tea_Hills (Jan 13, 2022)

Vesteroid said:


> I just binge watched all his videos over the holidays. So much so that I bought a torment t8.
> 
> I completely buy into the process he outlines in his book and subsequent videos/ articles on his page.
> 
> ...



I'm interested if you can replicate it at home. Please share!


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## Luftmensch (Jan 14, 2022)

daveb said:


> I thought we had found some common ground, then I realized I was in the wrong thread.....



Guy! We were making great progress! We were about to agree that Ryky is the definitive source of knowledge! 



Isnt that the mark of civilised adults? We can have a reasonably polite disagreement on somethings and share common ground on others


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## Luftmensch (Jan 14, 2022)

daveb said:


> Something unique about learning sharpening as a skill is the solitary nature of it.



Thats true isnt it! 

 I dont think I have ever just happened to bump into somebody that was keen on sharpening. Either that tells you something about how social I am.... or something about how common the hobby/skill is! 




daveb said:


> Jon, from JKI is my mentor of choice



Hard to beat for practical knowledge. Korin is good. As is Naoto from Knifewear. The discussion on KKF is great if you are willing to read through the 'back-catalogue'.

I hesitated to mention these because they are more to do with the practice and craft of sharpening... (which I think it more useful/relevant). But since @Tea_Hills wanted 'science'... Larrin is the most obvious recommendation that has leveraged new media to share knowledge.... There are decades of publications and text books on material science and solid mechanics. These arent particularly accessible or geared towards knife use... or as 'fun'. 

I guess it might be worth pointing out the obvious.... Larrin probably doesnt sharpen as well as Jon.... And Jon doesnt know metallurgy or material science as well as Larrin. Neither is 'better'... they are just different!


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## icanhaschzbrgr (Jan 14, 2022)

Tea_Hills said:


> Pretty new to the forums and first post on the sharpening board so hello everyone!
> 
> I've been sharpening for a few years now and I can often get an arm hair shaving edge on my good knives freehand but have struggled getting shaving edges on anything from Germany.


Sorry that I skipped most of your questions, cause I'm not sure if any of them has anything to do with sharpening  
You don't need science in order to get German knives shaving sharp. By German knives I mean something from Zwilling/Wusthof and similar (so I'm not referencing to any of those awesome custom knife makers from Germany).

raise burr on one side. Flip and raise burr on the other side. Move to a finer stone and repeat. Once you hit 2-3k gritnes and debur — knife should shave arm hairs easily. Yes deburring on cork isn't perfect cause you are actually tearing burr away (and it will cause micro damage to the edge) — but that shouldn't really affect arm hair shaving. 

And once you master sharpening your german knives and shave all your arms —return to the books and learn dark depths of sharpening


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## kayman67 (Jan 14, 2022)

From my perspective, most people want some validation that they are doing the best, not because it's the best, but since that's the best they can do, it must be the best [.] 
We, here, are much more prone to develop sideways, but we are a small variety. 
It happens that my experience is somewhat similar to his. Well, to some extent anyway.

Wear resistant structures can be grinded by regular coarse stones, but it's more of a "smash and grab" affair. At higher grits, this won't work and, imho, the true potential of those structures, is wasted. On the other hand, some ways are still better than others, even if not making everything as good as possible. Finding such methods is a good thing.


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## ian (Jan 14, 2022)

I notice you haven't gotten a ton of responses to your actual questions, except for 5. I'll try to respond. Hopefully I can get partial credit for saying "I don't know" on some of them. 



Tea_Hills said:


> Pretty new to the forums and first post on the sharpening board so hello everyone!
> 
> I've been sharpening for a few years now and I can often get an arm hair shaving edge on my good knives freehand but have struggled getting shaving edges on anything from Germany. Also perfect consistency is not easy. Now I know none of this really matters for most kitchen applications but it started me on a journey to understanding what is actually going on during the sharpening process. This led me to discovering Vadim Kraichuk. He seems quite well regarded and has published a number of 'scientific' white papers on sharpening. He also believes that a lot of commonly held community beliefs are false. I was hoping to see if anyone has any trial and observation type of information that runs counter to his findings. Mainly these points:
> 
> 1. Apex creation on a diamond surface instead of the traditional whetstone compound of Silicon/aluminum oxide allows a properly finished' edge to reach smaller apex edge thickness and consequently a sharper blade.



Never used diamonds. I'd believe this, although I'm not sure if it will be a truly noticeable difference on most steels. Maybe, tho.



Tea_Hills said:


> 2. 'Toothy' edges are not preferable to a properly polished edge in terms of edge retention in any way.



Perhaps true to some extent. I do find that a fresh off the stones high grit edge stops cutting tomatoes and peppers sooner than a lower grit edge, though. So maybe there's a distinction between however he's measuring edge retention (e.g. with his Bess or whatever) and perceived edge retention in the kitchen.



Tea_Hills said:


> 3. Burr creation falls into 2 rough camps in the way they are created. Primarily harder steels create a 'negative' burr upon grinding and softer steels create 'positive' burrs. These need to be deburred in different ways.



I guess that's true. Mostly we just think of soft steels as giving more stubborn burrs, so you adopt more aggressive measures to get rid of them, like incrementing your angle a bit. "Need to be deburred in different ways" is a bit strong, though. Pretty much everything will deburr with a slightly higher edge leading stroke. Maybe the distinction is that with brittle steels you can get away with edge trailing, same-angle deburring.



Tea_Hills said:


> 4. Deburring by cutting cork or felt leads to a wider apex width and less sharp edge.



I fully believe that deburring aggressively like this leaves a ragged non-crisp edge. Whenever I use cork to rip off a horrible burr I follow it up with additional sharpening afterwards.



Tea_Hills said:


> 5. 'Wear resistant' steels that contain large Vanadium and Chromium carbides (such as D2, R2, etc) absolutely require edge setting and finishing on diamond or CBN based abrasives. This a result of traditional whetstones lacking the required hardness to grind the carbides into a sub micron width. He postulates that a sharp edge can be created with traditional whetstones but as the steel matrix at the edge wears away you have unground large carbides that remain at the edge (with a risk of tear-out) and this results in an edge that loses sharpness much faster than it should.



Yea, dunno. Never sharpened a fancy steel like that. I'll join everyone in pointing to that Science of Sharp article, but I've been underwhelmed with some of the conclusions drawn on that site from time to time, so I dunno.



Tea_Hills said:


> I can't seem to find much in the way of peer review on any of his findings



If only there were sharpening journals! I mean, there are journals for all sorts of useless sh*t, why not something useful like sharpening?


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## kayman67 (Jan 14, 2022)

The idea behind the sharpness thing is what late Cliff Stamp used to say. The sharper you make them, the longer they stay sharp. I don't know exactly where to find it right now, but polished edges have been proven to last longer even with softer alloys, even slicing various stuff (makes little difference what since it's not ingredients anyway). Problem is, what is a polished edge from this perspective? Would this be a super even apex, glass like mirror? Not really. It never is. It's more of like structures that are closed better, would last longer, but it also takes a more considerable amount of time, effort and skill to make them. I don't think that even here there's much of a debate over this since most of us do something similar in one way or another. Also, this works even better with very thin edges.


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## Luftmensch (Jan 14, 2022)

Tea_Hills said:


> 2. 'Toothy' edges are not preferable to a properly polished edge in terms of edge retention in any way.





ian said:


> Perhaps true to some extent. I do find that a fresh off the stones high grit edge stops cutting tomatoes and peppers sooner than a lower grit edge, though. So maybe there's a distinction between however he's measuring edge retention (e.g. with his Bess or whatever) and perceived edge retention in the kitchen.





kayman67 said:


> The sharper you make them, the longer they stay sharp. I don't know exactly where to find it right now, but polished edges have been proven to last longer even with softer alloys, even slicing various stuff (makes little difference what since it's not ingredients anyway). Problem is, what is a polished edge from this perspective?



To me, the idea of polished edges having greater edge retention is _theoretically_ convincing. Why? Stress concentration. This is a well known concept in engineering. I can imagine a ragged edge will have many more stress risers than the theoretical dead flat edge. Failure points propagate... So from a theoretical perspective, I am comfortable with the assertion that removing stress risers (polishing) creates a more durable edge.

Yet, I havent bothered seeking empirical evidence for it... largely because I am not convinced you get much more performance for your troubles. I'll raise the caveat that I am talking about competent edges vs scifi optimal edges. For instance does the person who spends an extra 15 minutes polishing the blade gain anything meaningful over the person who has a rational but concise finishing routine? An extra week? An extra day? An extra meal? One carrot? I'd wager there are diminishing returns and at best you are buying yourself an extra shift/day.

Of course, no doubt mediocre and terrible edges finishes will have correspondingly mediocre and terrible retention.




Tea_Hills said:


> 4. Deburring by cutting cork or felt leads to a wider apex width and less sharp edge.





ian said:


> I fully believe that deburring aggressively like this leaves a ragged non-crisp edge. Whenever I use cork to rip off a horrible burr I follow it up with additional sharpening afterwards.



I agree with @ian... and again... pulling steel off rather than abrading it will result in stress risers...




Tea_Hills said:


> 5. 'Wear resistant' steels that contain large Vanadium and Chromium carbides (such as D2, R2, etc) absolutely require edge setting and finishing on diamond or CBN based abrasives. This a result of traditional whetstones lacking the required hardness to grind the carbides into a sub micron width. He postulates that a sharp edge can be created with traditional whetstones but as the steel matrix at the edge wears away you have unground large carbides that remain at the edge (with a risk of tear-out) and this results in an edge that loses sharpness much faster than it should.



I think the relevant Science of Sharp article people are referring to is this one. His conclusion is that tear-out is not a thing (at least for Maxamet)... He has a few diamond/carbide posts... so perhaps people are thinking of a different one?

I am not super convinced that 'large' carbides at the edge are meaningfully 'bad'. No doubt, grinding edge carbides into a sub-micron thickness will be 'sharper' than natively shaped 1-2 micron carbides (which is pretty small!). But again... we are scratching around for marginal gains. An exposed sub-micron carbide sounds brittle as hell. It might test well on a BESS tester, but I can also imagine those sub-micron carbide tips shattering early during use and settle on a larger surface area that can support cycling loads (eg hitting a cutting board).


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## HumbleHomeCook (Jan 14, 2022)

Knife Grinders and Todd Simpson (Science of Sharp) both post on Blade Forums. Todd's posts are often abrupt and short but can still have some good info.

I won't have anything to do with BF any more so I can't remember what screen name KG uses but their posts were often lengthy. Sometimes I found them quite interesting and informative. Other times they seemed a bit like pseudo-ads.

Anyway, just sharing that these folks are out there in the broader community to some extent or another if people want to seek out more.


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## ian (Jan 14, 2022)

HumbleHomeCook said:


> I won't have anything to do with BF any more



Why?


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## HumbleHomeCook (Jan 14, 2022)

ian said:


> Why?



I'm no fan of the owner.


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## ian (Jan 14, 2022)

HumbleHomeCook said:


> I'm no fan of the owner.



What? Who? Why?


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## M1k3 (Jan 14, 2022)

Another thing about higher grit edges, the apex gets narrower as the grit rating goes up. Thinner apexes are less stable. Which if there's a lot of board, bone and other assorted hard stuff contact, is going to significantly reduce edge retention.

I think edge retention versus grit rating is dependent on use. A lot of variables regarding "what is best".


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## Barmoley (Jan 14, 2022)

There is a mention of finish effect on edge longevity in this article by @Larrin, just another test to look at. At least in CATRA testing using DMT diamond plates, 600 grit seemed the most optimal. Could be the media, or the DMT plates themselves or something else, but it is interesting to see these results.

I am still not clear of how softer abrasive can cut harder carbides. I don't think the example of water jet cutting is relevant here, totally different mechanism. At hand sharpening speeds and pressures it seems like harder material would wear softer material, but of course hardness of the abrasive is not the whole explanation. Abrasive size, shape and durability plays a role as well. For example for most effective cutting, the abrasive has to break easily enough to expose new sharp edges, but not so fragile that it shatters easily and doesn't cut. All that said it seems like whatever else is in play the abrasive has to be harder than the material it cuts. It definitely works when we are talking about the same material, harder steel cuts softer steel, but I don't know if this extends to situations when different materials are involved, feels like it should.

In my personal experience diamond stones produce longer lasting edges on high wear resistant steels and lower grit edges after a point stay sharper longer in kitchen and utility use.


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## Mr.Wizard (Jan 14, 2022)

Tea_Hills said:


> Could you point me in the direction of the experiments you were mentioning? I'd love to take a look. Thanks!



Thanks for the quote. I believe he may be speaking to his primary market of kitchens, butchers, and meat processing plants, rather than absolute terms to all applications.

Cliff Stamp's rope cutting experiments found a strong trend of coarser edges lasting longer. See the summary as well as the forum thread. Unfortunately the figures were hosted by Photobucket and cannot currently be enlarged, but the incomplete figures in the thread are still easy to read. The page may be on Wayback Machine but that is giving me "503 Service Unavailable" so I cannot check.

There are lots of anechdotal reports that support this; one fresh in my mind from another thread where HeavyHanded on BladeForums wrote:

"In my own experience I witnessed a huge difference in longevity (all else being equal) depending on edge prep. Massive improvement in longevity when using a coarse edge for manually cutting coated papers at work, and likewise a tremendous improvement in edge retention using a polished edge for chopping"


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## Luftmensch (Jan 14, 2022)

Tea_Hills said:


> Primarily harder steels create a 'negative' burr upon grinding and softer steels create 'positive' burrs. These need to be deburred in different ways.




By the way... is this widely shared nomenclature or did Kraichuk invent these terms.... I have no idea what a 'positive' burr is... nor a 'negative' burr. Can somebody explain??


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## HumbleHomeCook (Jan 14, 2022)

Luftmensch said:


> By the way... is this widely shared nomenclature or did Kraichuk invent these terms.... I have no idea what a 'positive' burr is... nor a 'negative' burr. Can somebody explain??



The positive burr thinks the sharpening is half done whereas the negative burr thinks the sharpening is half incomplete.






Okay, I don't know either.


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## Barmoley (Jan 14, 2022)

Luftmensch said:


> By the way... is this widely shared nomenclature or did Kraichuk invent these terms.... I have no idea what a 'positive' burr is... nor a 'negative' burr. Can somebody explain??


He made ithem up.


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## Mr.Wizard (Jan 14, 2022)

Luftmensch said:


> By the way... is this widely shared nomenclature or did Kraichuk invent these terms.... I have no idea what a 'positive' burr is... nor a 'negative' burr. Can somebody explain??



I do not believe it invented these terms. Observe *positive burr* and *negative burr* in this 2014 figure.


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## HumbleHomeCook (Jan 14, 2022)

No practical knife user will ever need that level of detail.


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## Luftmensch (Jan 14, 2022)

Mr.Wizard said:


> I do not believe it invented these terms. Observe *positive burr* and *negative burr* in this 2014 figure.





That figure is about machining.... for instance a face mill. Chip formation is super important in surface finish and tool longevity. I am not sure if it is appropriate to draw a link between machining chips and knife burrs. Mills literally cut chips out of their material. Whetstones abrade....

... I guess the commonality is that more ductile materials (low hardness steels) will 'cling' on to their burrs more stubbornly. I would say most of my knifes are above 60HRC... I dont concern myself with burrs _at all_. I guess you could call these 'negative' burrs....?? But I think this is a strange term! With edge leading strokes, I tend to think you are using too much pressure if you form a burr on hard knives (but that is just *my* opinion).... Because the steel is less ductile, the material is abraded away without deformation (essentially no burr)...


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## Mr.Wizard (Jan 14, 2022)

Luftmensch said:


> That figure is about machining.... for instance a face mill. Chip formation is super important in surface finish and tool longevity. I am not sure if it is appropriate to draw a link between machining chips and knife burrs. Mills literally cut chips out of their material. Whetstones abrade....



The formation of positive or negative burrs is still the same, and grinding _is_ a chip-forming process. Non-ductile steel is prone to break-out just as the figure illustrates. Whether you call that a negative burr or something else it is useful to qualify.


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## Luftmensch (Jan 14, 2022)

Mr.Wizard said:


> and grinding _is_ a chip-forming process



I am uncomfortable with this statement.

I have no qualms admitting my lack of machining knowledge. It isnt even machining 101 level! But it is _something_. So I could be quite wrong. Perhaps somebody in KKF is well versed in this...

Maybe you are right and the difference between chips and abrasion is only a matter of scale. However there is enough practical difference for machinists to consider them different processes. The language used to describe the two reflects this. Milling machines use 'cutters'... Creep-feed grinders using 'grinding' wheels. One has sharp carbide blades. The other has bonded abrassives. The considerations required to properly deploy each are quite different

I dont think you could ever convince me that milling cutters were grinding... but I suppose you could convince me grinders are 'cutting' at a micrometer scale... and that swarf is just a mixture of miniature 'chips' and broken down abrasives...




Mr.Wizard said:


> Whether you call that a negative burr or something else it is useful to qualify.



Only if it actually exists in a meaningful way (for knives)?? Could you draw (even if a 30 second sketch on an envelope) what a positive and negative burr looks like on a knife?

The only way I can practically think of a 'negative' burr... is an edge that has sheared off. Perhaps it is a more ragged edge than is ideal... To me this isnt a burr... a knife burr requires plastic deformation of the ultimate edge... but again... this is all my understanding...


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## Barmoley (Jan 15, 2022)

This is sort of overthinking hand sharpening to the n-th degree. The negative/positive burr makes very little sense in this contexts. We are not talking drastically different materials or drastically different hardness of steel. Most knives are in 58-62 hrc, but majority is even closer, so most will act in a very similar fashion.


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## Tea_Hills (Jan 15, 2022)

Barmoley said:


> This is sort of overthinking hand sharpening to the n-th degree. The negative/positive burr makes very little sense in this contexts. We are not talking drastically different materials or drastically different hardness of steel. Most knives are in 58-62 hrc, but majority is even closer, so most will act in a very similar fashion.



I'm not so sure. I think that a burr on a typical German kitchen knife and a well hardened Japanese knife acts quite different. Positive and negative burrs could explain that difference if Vadmin is correct.


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## Luftmensch (Jan 15, 2022)

Reiterating a previous point, I am weary of experts that accumulate disciples. 

Some are clearly trained and appear quite thorough (Larrin) others are more observational/empirical (Science of Sharp)... Others use pseudoscience-like explanations for their experience (maybe Cliff??). Occasionally bubbles form around these people and they are treated as if they have unlocked some 'secret' knowledge.

KKF members who are interested in material engineering (that is really what steel compositions and heat-treatments are), would do well to read about stress-strain curves. These graphs encapsulate a lot of information about what happens to a material when force is applied. 

The yield point of a material records the amount of strain a material can withstand _before_ plastic deformation. That is, if the material is subject to _less_ strain, it will 'spring' back to its original shape. If subject to _more_ strain a material _may_ begin to elongate. The ultimate tensile strength of a material is the maximum amount of strain it can withstand. Failure/rupture _may_ occur beyond this point

For ductile materials there is often a gap between the yield point and ultimate tensile strength. In this region you will have effects like work hardening. For brittle materials, they may not support plastic deformation. In other words they fail before yielding (e.g. glass).

Applied to knifes? Strain will be applied to the cutting edge during sharpening (abrasion). If the strain is high enough, ductile (soft) steels will allow plastic deformation. This can create a burr at the edge which is work hardened. Stress and strains in the burr causes fractures that makes the burr weak... this is why we want to remove it. Remember... stress and strain can propagate along failure points. Fractures create stress concentrators that promote additional rupture - this is why cracks propagate. 

Harder steels will have a narrower plastic deformation region before failure. It might be so narrow that the steel effectively just fails/ruptures without yielding or work hardening... In these steels there is no point 'chasing a burr', they are unlikely to form. If there is no plastic deformation at the edge, and the steel is rupturing... I still dont think there is any value in calling it a 'negative' burr... but that is just *me*. 

I won't debate the merits of polishing any ragged failure points at the edge. I agree with that.... but still think it is worth keeping diminishing returns in mind. Finishing a kitchen knife at 3000-4000 grit is a pragmatic goal..


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## KilgoreTrout (Jan 15, 2022)

Tea_Hills said:


> Pretty new to the forums and first post on the sharpening board so hello everyone!
> 
> I've been sharpening for a few years now and I can often get an arm hair shaving edge on my good knives freehand but have struggled getting shaving edges on anything from Germany. Also perfect consistency is not easy. Now I know none of this really matters for most kitchen applications but it started me on a journey to understanding what is actually going on during the sharpening process. This led me to discovering Vadim Kraichuk. He seems quite well regarded and has published a number of 'scientific' white papers on sharpening. He also believes that a lot of commonly held community beliefs are false. I was hoping to see if anyone has any trial and observation type of information that runs counter to his findings. Mainly these points:
> 
> ...



So does he give an alternative method to deburring if cork/felt isn’t ideal?


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## kayman67 (Jan 15, 2022)

M1k3 said:


> Another thing about higher grit edges, the apex gets narrower as the grit rating goes up. Thinner apexes are less stable. Which if there's a lot of board, bone and other assorted hard stuff contact, is going to significantly reduce edge retention.
> 
> I think edge retention versus grit rating is dependent on use. A lot of variables regarding "what is best".



Unfortunately, for kitchen knives we have a rather limited range of alloys to play with at a very high level (as opposed to pocket and let's call them hunting knives). Not that there wouldn't be any at all, but they are custom made, rarely done and quite expensive.
Even so, with what we have, we already deal with very thin edges. Some (most?) of us anyway. And at least we were able to see the level of fractures going on at lower grits. From my experience, considering that they will chip away and form some toothy structures for a while, they still don't last the same. Even softer alloys can benefit from a closed structure, but the problem is that softer alloys can't hold a thin edge as it will move entirely to one side or another, even if the apex is just fine - the only way to deal with this was to push them on purpose and keep whatever structure was stable enough.
For me at this point is not a question of what's better (open vs closed and the best way to achieve this for some alloys), but if it's worth the extra hassle. It's not an easy task. Also most would be okay with parts of it as they don't have "super" alloys anyway. If we put the entire effort into getting the best possible edges at lower grits (fast, clean, easy), we still face diamonds starting with the bottom of them all - softer alloys. I admit that I was really amazed by this in the beginning, seeing just how well it works. This is where I agree with him. He says that diamonds would put less stress on the structure while making burrs quite less of an issue. Obviously "diamonds" are tools. No one should expect them to perform by default. Actually I see, often enough, how guys use different abrasive surfaces exactly the same way and expect same results. This is fine if one would search for a stone to fit that usage scenario. Doesn't work when the goal is to find the best performance for each. Hammer and nail approach always has limitations. I agree with him as diamonds have the potential to form quickly good clean structures even at lower grits, even with softer alloys. So they aren't a good option just for a handful of top tier blades.
About the thin aspect of the cutting edge and higher grits, most (if not all) guys I know won't close to a crazy level. I mean we aren't applying for the 600k grit group any time soon. It's around 5k equivalent (but diamonds or cbn would always be more aggressive) with stropping on 1-2 micron diamond/cbn compound. Some things will vary, of course. Let's call the above a middle ground. As far as I was able to see, this translates into a homogeneous fine stria pattern providing most resilient edges that perform very well over a long period of time. Even for something like ZDP-189, that's neither here or there due to the type and structure of carbides, nothing offered a razor like edge to last so long. So while closed, maybe polished is not the word for them? (to the naked eye, they still look mirror like, though)


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## ian (Jan 15, 2022)

KilgoreTrout said:


> So does he give an alternative method to deburring if cork/felt isn’t ideal?



I assume he's recommending that you deburr on the stones themselves, or on pasted leather or something. (I seem to remember seeing vids of him doing that.) That is, abrade off the burr, don't rip it off violently by cutting something like cork or felt.



Tea_Hills said:


> I'm not so sure. I think that a burr on a typical German kitchen knife and a well hardened Japanese knife acts quite different. Positive and negative burrs could explain that difference if Vadmin is correct.



It could just also be explained by the fact that harder steel is more likely to chip than deform. Hard steel will deform less. Hence the burrs (even if they're created using the same mechanical method) are more subtle, and easier to get rid of.




Mr.Wizard said:


> I do not believe it invented these terms. Observe *positive burr* and *negative burr* in this 2014 figure.



What's the real difference between the two cases here? I get that there's a bigger piece broken off on bottom that's not in line with the direction of cutting, but presumably the burr is still created by the same sort of deformation of the steel, it's just that some of it is broken off on the bottom. Is the difference supposed to be that there's no "plastic zone" or "elastic zone" left in a negative burr? I'm confused about what this means, although I'm basically confused by all of this, so yea.


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## Mr.Wizard (Jan 15, 2022)

Luftmensch said:


> I dont think you could ever convince me that milling cutters were grinding... but I suppose you could convince me grinders are 'cutting' at a micrometer scale... and that swarf is just a mixture of miniature 'chips' and broken down abrasives...



That's exactly what it is. I am not an expert either, so I direct you to the material of Dr. Jeffrey A. Badger _The Grinding Doc_ who is an industrial consultant specializing in precision grinding. His presentation _The Great Divide: Grinding in Academia and Production_ begins with this.



> Significant progress has been made in the past 50 years in advancing our understanding
> of the complicated and seemingly random process of grinding, moving it from a sort of
> black art to an understandable *chip-formation process*.



He has a playlist of 92 videos on the subject of grinding. _ Episode 35: A closer look_ has a segment on this starting at 5:29 where he shows electron microscopy of the chips from 60 Rockwell high-speed steel.






Luftmensch said:


> Only if it actually exists in a meaningful way (for knives)?? Could you draw (even if a 30 second sketch on an envelope) what a positive and negative burr looks like on a knife?
> 
> The only way I can practically think of a 'negative' burr... is an edge that has sheared off. Perhaps it is a more ragged edge than is ideal... To me this isnt a burr... a knife burr requires plastic deformation of the ultimate edge... but again... this is all my understanding...



You seem to be hung up on terminology here. Academics have chosen to call break-out "negative burr" and I imagine they have an informed reason for doing so but I am not married to the term and I don't care if you use it. Okay, it isn't a burr—let's move on. The scienceofsharp entry _Sharpening with the King 1k/6k combination stone_ provides electron microscope images of an edge with a burr and an edge with micro-chipping.





Edge-view of a cross-section through the apex following edge-leading strokes on the King 1k stone. The white lines show the native angle of the blade with a burr clearly visible beyond that triangle. Such burrs form when the micro-chipping occurs more slowly than metal removal from the bevel faces.






Edge-view of a cross-section through the apex following edge-leading strokes on the King 6k stone performed under running water. There is no significant reduction in the amount of apex-damage due to micro-chipping.


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## Mr.Wizard (Jan 15, 2022)

ian said:


> What's the real difference between the two cases here? I get that there's a bigger piece broken off on bottom that's not in line with the direction of cutting, but presumably the burr is still created by the same sort of deformation of the steel, it's just that some of it is broken off on the bottom.



In one case you have the target geometry (a triangular apex) plus some unwanted material attached to it that needs to be removed. In the other there is material missing from the target geometry—there is a void at the point of the triangle formed between the two bevel faces. (The while lines overlaid in the first _scienceofsharp_ image above.)


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## ian (Jan 15, 2022)

Mr.Wizard said:


> In one case you have the target geometry (a triangular apex) plus some unwanted material attached to it that needs to be removed. In the other there is material missing from the target geometry—there is a void at the point of the triangle formed between the two bevel faces. (The while lines overlaid in the first _scienceofsharp_ image above.)



Ah, so you think it's just about the location of the burr relative to the apex, not about any intrinsic quality of the burr itself. I suppose if that's the case, maybe it makes sense to try to get rid of such burrs by deburring at the apex angle (like the knife grinder guy says), rather than at a higher angle, since raising the angle will make you more likely to hit the very apex. I'm imagining negative burrs sort of hanging off the side of the bevel at the bottom of a chip. Idk, though.


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## Barmoley (Jan 15, 2022)

To me it sounds like the positive burr is regular burr and negative is the opposite of that so no burr at all but instead material missing from the apex. So a chip on the apex. Could be wrong, but that is how I read it. If so negative burr is totally misleading as it is not a burr at all. I must be misunderstanding this


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## ian (Jan 15, 2022)

I mean, if that's the case then talking about a special technique for negative burr removal is kind of ridiculous. You'd just call it "further sharpening" or something.


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## Luftmensch (Jan 15, 2022)

Mr.Wizard said:


> You seem to be hung up on terminology here. Academics have chosen to call break-out "negative burr" and I imagine they have an informed reason for doing so but I am not married to the term and I don't care if you use it. Okay, it isn't a burr—let's move on.



No dramas Gandalf! A new term was introduced to KKF. It appears to be causing confusion.

I had never heard the term. And thanks to @Tea_Hills and yourself for bringing attention to the term  . Having poked around a bit trying to understand it... I am still uncomfortable assuming a machining term automatically applies to knife sharpening.


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## Luftmensch (Jan 15, 2022)

ian said:


> I suppose if that's the case, maybe it makes sense to try to get rid of such burrs by deburring at the apex angle (like the knife grinder guy says)





ian said:


> You'd just call it "further sharpening" or something.





But this is the part that I find somewhat recursive. If you sharpen and get a negative burr... then you sharpen at the same apex angle to get rid of the burr... which presumably creates another negative burr... that you would remove by sharpening at the same apex angle....


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## ian (Jan 15, 2022)

Luftmensch said:


> But this is the part that I find somewhat recursive. If you sharpen and get a negative burr... then you sharpen at the same apex angle to get rid of the burr... which presumably creates another negative burr... that you would remove by sharpening at the same apex angle....



Hah. I’m imagining you’d increase grit or lighten pressure to make the new breakouts smaller.

Zeno would be great at sharpening.

Edit: btw, I just found myself looking at KKF on my phone while having KKF open on my computer in the background. Anyone else do that?


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## Barmoley (Jan 15, 2022)

ian said:


> I mean, if that's the case then talking about a special technique for negative burr removal is kind of ridiculous. You'd just call it "further sharpening" or something.


Assuming, I understood this correctly

Which is why I said it is not applicable, made up in the scope of hand sharpening knives, and is overthinking of hand sharpening knives. For one you would not be able to tell there is a negative burr unless you used serious magnification. In my, somewhat limited experience all knife steels create a burr, the burr is larger or smaller and more or less difficult to remove, but it appears on every knife I’ve sharpened sooner or later. Removing burr on softer stainless steel knives is more difficult. No burr sharpening as promoted by some also works, but is more difficult for me personally because I can’t tell when I get to the apex, so I use burr as an indicator. This is one of the issues I have with trying to sharpen flexible ceramic knife. It doesn’t create a burr and the material is black, so I can’t really tell if I am hitting the apex.


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## Luftmensch (Jan 15, 2022)

ian said:


> What's the real difference between the two cases here?



I annotated the image with what I think are the significant points...






The most significant difference between the two is that the tool has not finished the cut in the brittle material. The crack has propagated faster than the tool feed rate. This causes the chip to _break off_ rather than being cleanly _sheared off_. As a result some material in the workpiece has been torn off.

While it make sense in machining, this is why i dont think it makes sense in knife sharpening. During sharpening, do the abrasives ever apply forces on the steel that causes breakout rather than a clean cut? Maybe... but I am not convinced yet...

There are also tear burrs. It is a similar concept... rather than cleanly shearing off material, the chip is torn off. Note that some of these terms are tool specific or workpiece specific. For example, break out will happen most commonly at the end of a workpiece as the tool exits the material. Another example, I believe cut-off burrs are specific to lathes... but are another example of burr formation due to the material rupturing before the cut is finished.


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## ian (Jan 15, 2022)

Reading the relevant book. A lot of the stuff in there seems good and inspiring, and conforms to my experience. The positive / negative burr stuff though… idk. It seems like he’s taking this stuff from materials science and just using it as inspiration, and then using positive and negative burrs as code for “more ductile steel” vs “more brittle steel”, rather than talking specifically about eliminating positive burrs or negative burrs as defined above. He kinda acknowledges that here:


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## kayman67 (Jan 15, 2022)

Luftmensch said:


> While it make sense in machining, this is why i dont think it makes sense in knife sharpening. During sharpening, do the abrasives ever apply forces on the steel that causes breakout rather than a clean cut? Maybe... but I am not convinced yet...



Didn't scienceofsharp show that enough force would shatter the structure altogether?


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## Mr.Wizard (Jan 15, 2022)

Luftmensch said:


> While it make sense in machining, this is why i dont think it makes sense in knife sharpening. During sharpening, do the abrasives ever apply forces on the steel that causes breakout rather than a clean cut? Maybe... but I am not convinced yet...



I find this statement baffling. Yes, of course they can, as it easy to create chips along the edge of e.g. Aogami Super using too much force on a coarse stone or a ceramic rod. Do you mean in skilled sharpening perfectly applied?

It doesn't even take something as hard as an abrasive to rip off metal. Yet more images from _scienceofsharp_ showing the plateau after a burr is broken off stropping on newsprint.


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## Luftmensch (Jan 15, 2022)

ian said:


> The positive / negative burr stuff though… idk. It seems like he’s taking this stuff from materials science and just using it as inspiration, and then using positive and negative burrs as code for “more ductile steel” vs “more brittle steel”, rather than talking specifically about eliminating positive burrs or negative burrs as defined above. He kinda acknowledges that here:



When I was googling positive/negative burrs... I came across a similar quote on the Tormek forums:



> Our "Knife Deburring" research discriminates burrs into "positive" that should be honed at a higher angle to get the edge sharper, and "negative" that should not.
> In the context of knife sharpening, the term “negative burr” is an umbrella term, not fully matching the connotations given to it in the metallurgical science.
> There is a branch in cognition science about human thinking based on polarized constructs. We've introduced this "positive-negative" construct to make selection of deburring method easy. This "positive-negative" logical construct helps us to choose the right honing method.


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## ian (Jan 15, 2022)

Luftmensch said:


> While it make sense in machining, this is why i dont think it makes sense in knife sharpening. During sharpening, do the abrasives ever apply forces on the steel that causes breakout rather than a clean cut? Maybe... but I am not convinced yet...



I think the fact that the scratches on the bevel don’t end in teeth, but rather irregular hills and valleys, points to this.


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## Luftmensch (Jan 15, 2022)

kayman67 said:


> Didn't scienceofsharp show that enough force would shatter the structure altogether?





Mr.Wizard said:


> I find this statement baffling. Yes, of course they can, as it easy to create chips along the edge of e.g. Aogami Super using too much force on a coarse stone or a ceramic ro



In the context of what I understand the machine definition of 'break out'... or negative burr to be. I would prefer to use the term tear-burr or tear out if you are talking about chips on the edge... I know it is nitpicking...


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## ian (Jan 15, 2022)

Luftmensch said:


> In the context of what I understand the machine definition of 'break out'... or negative burr to be. I would prefer to use the term tear-burr or tear out if you are talking about chips on the edge... I know it is nitpicking...



Can you explain the difference better?


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## Mr.Wizard (Jan 15, 2022)

Luftmensch said:


> I would prefer to use the term tear-burr or tear out if you are talking about chips on the edge... I know it is nitpicking...



I agree. Tear-out, chip-out, or break-out all make more sense to me. Separate from this is the question of how to identify and deal with it.


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## ian (Jan 15, 2022)

Mr.Wizard said:


> I agree. Tear-out, chip-out, or break-out all make more sense to me. Separate from this is the question of how to identify and deal with it.



I think he’s making a distinction between break out and tear out. I’m just not sure what the difference is to him.


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## Barmoley (Jan 15, 2022)

I tend to agree with @Luftmensch, I am not convinced what happens in machining is what happens when hand sharpening. The cutter usually moves in one direction, is this correct? When hand sharpening most alternate between edge leading to edge following. With edge leading what happens to the apex seems different. The ridges and valleys on the apex might be results of weakend burr breaking off unevenly or even collision with hard abrasive particles.


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## daveb (Jan 15, 2022)

I've got the answer, just not sure if OP is referring to a horizontal negative burr or a vertical one?


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## kayman67 (Jan 16, 2022)

There are some things to consider. First, he does a lot of machine sharpening, but I'm gonna skip that, even if I know some things about it. I will address more the jig and unidirectional sharpening that some guys do (so even with freehand). I know people that with jigs move only one way and never against the edge. Is their experience that this would simply tear the apex of some alloys, never getting a burr. It's not a tear with/of a burr that would pull the entire thing uneven. Note that they use only diamond and/or cbn and also note that in the above mentioned machine sharpening, cbn is common. This being said, it was shown that with enough force, similar behaviour is possible with other abrasives. He does say at some point that there is a difference between how diamond/cbn vs. regular stone abrasives interact with the structures and even when a burr happens, it's of different nature. This is a point where our experience is similar. Again, this is not a given, as force and consistency can change what's happening. And most people here get at least cleaner edges faster with various diamond surfaces (if not better altogether and most say they do) - cbn is less common in usage, as far as I could tell, because it's less available.


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## kayman67 (Jan 16, 2022)

As a side note, the break can happen even if it's not against the edge, but seems to be less frequent.


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## BoSharpens (Jan 16, 2022)

Funny stuff. I've sharpened for decades, get good results, have a microscope to check edges at times to see what I'm getting in. I manage to get rid of burrs with diamond laps and a leather strop. The edges are then very sharp and cut very nicely. That's what I want.

Will discussions of positive and negative burrs make a difference in anyone's technique?


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## Barmoley (Jan 16, 2022)

We discuss stuff that makes no difference all the time. That said can't beat practice when sharpening for sure. Even with jigs and equipment still need practice to build the skills.

The whole negative burr stuff though


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## KilgoreTrout (Jan 16, 2022)

Do you have links to the videos?


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## ian (Jan 16, 2022)

BoSharpens said:


> Funny stuff. I've sharpened for decades, get good results, have a microscope to check edges at times to see what I'm getting in. I manage to get rid of burrs with diamond laps and a leather strop. The edges are then very sharp and cut very nicely. That's what I want.
> 
> Will discussions of positive and negative burrs make a difference in anyone's technique?



You could use the same logic to dismiss any innovation in sharpening, though. It’s great if you’re happy with your technique, but it’s also fine if people want to probe some other avenue, informed by some sort of new understanding of the mechanics of abrasion. That’s what this discussion aspires to be, at least. I’m still not sure if it is that or not. The positive/negative business confuses me. It also seems like the practical recommendations that the people promoting this viewpoint make are essentially what many of us do anyway: raise the angle for stubborn burrs.


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## daveb (Jan 16, 2022)

Didn't know they were tournedos, just grilled and ate them steaks.


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## Luftmensch (Jan 16, 2022)

Caveat emptor... "Vell, Luftmensch's just zis guy, you know?"



ian said:


> Can you explain the difference better?





ian said:


> I’m just not sure what the difference is to him.



I barely know what the difference is to me!

So just to recap. The conversation went down this path and I seem to have backed myself into a corner  'Negative burrs' are a new concept to me. When I asked for an explanation, an example from machining was presented. I have no problems with this definition... I am just uncomfortable applying that example to whetstone sharpening.

As far as I can tell from the figure and some reading, negative burrs occur during break out. In a brittle material, as a cutter approaches the end of the workpiece, less and less material is available to support the cutting forces. Eventually the cutter will reach a distance from the end of the workpiece where deformation between the cutter and the unsupported material will occur. The cutter is pushing material diagonally upwards... away from the stock material and towards the unsupported end. This creates a 'pivot' point in the material. The unsupported end of the pivot is in compression and the interface at the cutter is in tension. The cutter is also spinning and appling a _shear force_ to the material at the interface between the blades and the material. The stress in this region may cause a crack - perhaps around some flaw in the material or an extreme concentration point (maybe chips/swarf that aren't properly cleared away). Once the crack forms it propagates quickly along deformed region which is already under strain. The crack reaches the end of the workpiece before the cutter is able to finish the pass. This causes 'break out' - the chip is broken off rather than being cleanly cut. 

Feed speeds, spindle RPM, depth of cut, number of teeth on the cutting tool... rake angle... etc... these will affect how much break out occurs.

I do not believe it makes sense to apply machining break out to honing. I am not sure what the analogy would look like? I created a figure to _try_ and illustrate break out (top row):









Tear out is very similar (bottom row). Rather than being cut cleanly... unsupported material fails in the direction of the cut. Once abrasion reaches the very edge, there is very little supporting material. A tiny amount of edge material will be placed under tension (as a simplification) from the abrasion. The material is brittle (hard) and resists deformation, so it does not bend out of the way. Eventually stresses in the remaining supporting material exceed the fracture strength... since the material is brittle, this is likely close to the ultimate tensile strength. Brittle fracture occurs. To me this is a more compelling explanation.

In both scenarios, the cut is not finished cleanly. The material fails before the cut can exit the material cleanly. The difference is in how they _fail_:

Break out: cracks form and propagate (not in the direction of travel) to an unsupported face
Tear out: material is subjected to high (tensile) forces in the direction of travel, supporting material at the interface experiences brittle fracture

I don't believe there is a need for the term 'negative burr'... but if there had to be... explaining it with tear out burrs would make more sense to me than break out burrs





Mr.Wizard said:


> how to identify and deal with it.



Identification?? I don't know... you are talking about the limits of human perception (if you don't have fancy equipment). Assuming you don't have a big, flappy, ductile burr... _something_ will be happening at the edge of the steel. Lets say your eyes can resolve objects at 40 micrometers. _Maybe_ you will be able to see something at JIS 400. Perhaps you can use other tricks (reflected light... fingers) to sense higher grits.

But I dont know that you need to identify anything if you _do not_ have a big, flappy, ducticle burr. The recommendation to 'deburr' at the same apex angle just sounds like polishing to me... Dont get me wrong... this is sensible!!! But is it really any different to saying 'polished edges are more durable'? As you progress through your sharpening, finer stones and lighter pressure will help clean up a ragged edge. Your edge will always be ragged and stressed at some level of magnification... just make those regions smaller and smaller until the macro geometry suits your purposes.


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## ian (Jan 16, 2022)

Luftmensch said:


> Caveat emptor... "Vell, Luftmensch's just zis guy, you know?"
> 
> 
> 
> ...



Why do you find break out less likely than tear out when stone sharpening?


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## Luftmensch (Jan 16, 2022)

ian said:


> Why do you find break out less likely than tear out when stone sharpening?



I kind of imagine abrasion is like pulling a rock through sand. The rock will create a groove behind it. It will create berms either side of it as material is pushed aside (its wake if you will). There will also likely be a wave of compressed material accumulating in front of it. If this were on a ledge, once the rock reached the edge, it would push the wave of sand over. If the sand had some cohesion, you would see some tearing effect as the material in berms and beneath the stones attempted to support the wave. As the wave is pushed over the edge it will pull some supporting material with it until the bonds of cohesion fail. You will see raised edges at the berms, a trough from the groove and likely a small amount of drawn out (torn) material... This just seems like a better analogy to me.

Steels are not brittle in the same way that we think of ceramics/glass. Maybe you could cause breakout if you torqued the edge into the stone and applied a lot of force. The edge might just shatter once you reached that point - I doubt it.

But yeah...Tear out... failure in the direction of cutting/abrasion. Break out... failure at an angle to the direction of cutting/abrasion.

I am in the realm of talking out my hoop. It would be easier (for me) if some professor of abrasion came out the woodwork and told me I was wrong and explained why...  Maybe break out and tearout are really the same thing.


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## Mr.Wizard (Jan 16, 2022)

Luftmensch said:


> Maybe you could cause breakout if you torqued the edge into the stone and applied a lot of force. The edge might just shatter once you reached that point - I doubt it.



It is possible with low toughness steel like Aogami Super. I have done it.


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## ian (Jan 16, 2022)

Mr.Wizard said:


> It is possible with low toughness steel like Aogami Super. I have done it.



If I understand @Luftmensch’s distinction correctly, there’s basically no way you’d be able to tell if you had break out or tear out, though, unless you SEM imaged your blade after or something.


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## ian (Jan 16, 2022)

Luftmensch said:


> I kind of imagine abrasion is like pulling a rock through sand. The rock will create a groove behind it. It will create berms either side of it as material is pushed aside (its wake if you will). There will also likely be a wave of compressed material accumulating in front of it. If this were on a ledge, once the rock reached the edge, it would push the wave of sand over. If the sand had some cohesion, you would see some tearing effect as the material in berms and beneath the stones attempted to support the wave. As the wave is pushed over the edge it will pull some supporting material with it until the bonds of cohesion fail. You will see raised edges at the berms, a trough from the groove and likely a small amount of drawn out (torn) material... This just seems like a better analogy to me.
> 
> Steels are not brittle in the same way that we think of ceramics/glass. Maybe you could cause breakout if you torqued the edge into the stone and applied a lot of force. The edge might just shatter once you reached that point - I doubt it.
> 
> ...



The distinction sort of makes sense, although idk why I shouldn’t think of the tear out as a crack happening perpendicular to the cutting direction, which is kinda the same as break out. I’m not sure about the sand analogy though. It’s not so compelling to me when it’s trying to compete against an analogy with milling metal, which I can totally believe is a macro version of sharpening. Maybe macro vs micro makes a difference though.


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## Luftmensch (Jan 17, 2022)

ian said:


> If I understand @Luftmensch’s distinction correctly, there’s basically no way you’d be able to tell if you had break out or tear out, though, unless you SEM imaged your blade after or something.



Definitely... we're talking about micrometers... verging on nanometers. 





Luftmensch said:


> Maybe break out and tearout are really the same thing.





ian said:


> although idk why I shouldn’t think of the tear out as a crack happening perpendicular to the cutting direction, which is kinda the same as break out





Maybe you should! I am just some guy! After all... fracture in brittle materials under tension will likely start at some weak point and rapidly propagate a crack from there. Both failures will be doing that.




ian said:


> I’m not sure about the sand analogy though. It’s not so compelling to me when it’s trying to compete against an analogy with milling metal, which I can totally believe is a macro version of sharpening. Maybe macro vs micro makes a difference though.



I hadn't actually read this Science of Sharp article. He has some images that look very much the analogy! I had thought of the analogy from other SEM images! Check out this image of a hardened carbon steel coupon. It was polished and then lightly abraded with 600 grit sandpaper:





[Image credit: Science of Sharp]

To what we are discussing... what does the silicon carbide grain do if it reaches the end of the hardened carbon steel coupon? Would it push/pull through the edge and leave a messy exit gouge? Or... if the coupon was thin enough and the steel was hard enough... would it punch _through _to the opposite face of the coupon _before_ reaching the edge?



If you forced me to guess I would choose messy exit gouge!


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## kayman67 (Jan 17, 2022)

ian said:


> It also seems like the practical recommendations that the people promoting this viewpoint make are essentially what many of us do anyway: raise the angle for stubborn burrs.



Seems like a lot of people do various things without really knowing the "math" behind them (try everything, keep what solves a problem), but they tend to converge towards common grounds eventually the more we look into it (not that unexpected maybe).


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## ian (Jan 17, 2022)

Luftmensch said:


> Definitely... we're talking about micrometers... verging on nanometers.
> 
> 
> 
> ...



You're right that that picture isn't something you see as much of on the larger cutting scale. Size matters, perhaps.


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## ian (Jan 17, 2022)

kayman67 said:


> Seems like a lot of people do various things without really knowing the "math" behind them (try everything, keep what solves a problem), but they tend to converge towards common grounds eventually the more we look into it (not that unexpected maybe).



Mostly true in general. But I imagine people also do a lot of inefficient things, sometimes for scientifically misinformed reasons and sometimes out of habit. It's easy to develop bad habits when you can't actually see what's happening at the edge, and you haven't sharpened the thousands of blades you'd need to in order to notice differences in methods. The things we do work well enough, but the fact that there's constant discussion about various aspects of sharpening, and disagreement among experts, means that perhaps there's something to be gained from further understanding of what's going on.


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## kayman67 (Jan 17, 2022)

I totally agree with this.


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## Mr.Wizard (Jan 17, 2022)

ian said:


> If I understand @Luftmensch’s distinction correctly, there’s basically no way you’d be able to tell if you had break out or tear out, though, unless you SEM imaged your blade after or something.



I meant at the macroscopic scale. I thought the question was whether or not knife steel was brittle enough to fracture when pressed hard against a stone; I cannot attest that some is, and I know others can too as I've read about it. Perhaps I misunderstand.


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## ian (Jan 17, 2022)

Mr.Wizard said:


> I meant at the macroscopic scale. I thought the question was whether or not knife steel was brittle enough to fracture when pressed hard against a stone; I cannot attest that some is, and I know others can too as I've read about it. Perhaps I misunderstand.



No, everyone agrees that knives can chip. Luftmensch was trying to theorize about *how* microscopic chips occur in the edge when sharpening on stones; whether they occur via "tear out" or "break out", and whether there's even a difference between those things.


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## Tea_Hills (Jan 20, 2022)

KilgoreTrout said:


> So does he give an alternative method to deburring if cork/felt isn’t ideal?


He does. He has different methods for different burr types. For softer steels his method really boils down to:
Creating a burr on a 1000 grit stone at the desired apex angle.
Minimizing the burr size by using a 5 micron or so compound while grinding at the apex angle used on the 1000 grit. 
Removing the burr by grinding at a higher angle (about 2 degrees) than what was used to create the apex. 
This deburring is done on a felt wheel with .80gm/cm3 hardness.
Cleaning the edge up using the apex angle again and honing on a paper wheel loaded a mix of .25 micron diamond compound and Cr2O3 (Green compound). 

For harder steels that would encompass most of the knives we talk about here his process is essentially:
Creating a burr on a 1000 grit stone at the desired apex angle.
Grinding away at the root of the 'negative burr' by using a paper wheel with 5 micron compound at .1 degree lower than the apex angle
Elongating the remaining burr by grinding at apex angle on a .5 micron loaded paper wheel
Removing the final burr by grinding at about a 1 degree higher angle than apex on a paper wheel loaded with 1 micron compound
Cleaning the edge up using the apex angle again and honing on a paper wheel loaded a mix of .25 micron diamond compound and Cr2O3 (Green compound).

When supplies get here I am going to test using a .79gm/cm3 felt strip from durofelt for the felt wheel replacement and a loaded paper strop over the felt block for the paper wheel replacement. 

Again, this is entirely for fun. I am well aware it is overkill and unnecessary but I love a good project and in all it was about 100 dollars for the compounds, felt, and "freehand" jig needed to overcome hand sharpening angle variations. My goal is to create and edge that will cut a free hanging hair, which requires and apex thickness of about .1 micron. Will report my findings!


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## Tea_Hills (Jan 20, 2022)

Luftmensch said:


> I am in the realm of talking out my hoop. It would be easier (for me) if some professor of abrasion came out the woodwork and told me I was wrong and explained why...  Maybe break out and tearout are really the same thing.



As am I during my research! I'm on the hunt for a abrasion wizard  professor and their spells  papers.


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## kayman67 (Jan 22, 2022)

I'm not the best with words in moments like this. Vadim passed recently due to heart failure. I just find out myself.


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## M1k3 (Jan 22, 2022)

kayman67 said:


> I'm not the best with words in moments like this. Vadim passed recently due to heart failure. I just find out myself.


Vadim? Or Valdim? Either way, my condolences.


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## kayman67 (Jan 22, 2022)

Vadim.


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## Luftmensch (Jan 22, 2022)

As in Dr Kraichuk?

That is sad news. I hope his family are doing okay.


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## kayman67 (Jan 22, 2022)

Luftmensch said:


> As in Dr Kraichuk?


Yes...


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## Luftmensch (Jan 22, 2022)

Thats a shame... I think he was only 50? 60?... Pretty young...


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## HumbleHomeCook (Jan 22, 2022)

Oh damn, that is sad news. I interacted with him many times. Very interesting person.


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## Tea_Hills (Jan 22, 2022)

Terrible news but thanks for sharing.


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## HumbleHomeCook (Jan 22, 2022)

kayman67 said:


> I'm not the best with words in moments like this. Vadim passed recently due to heart failure. I just find out myself.



@Deadboxhero posted an excellent thread about the loss on the Spyderco forum:



RIP Dr. Vadim Kraichuk "Knife Grinders" Wootz - Spyderco Forums


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## Luftmensch (Jan 23, 2022)

HumbleHomeCook said:


> @Deadboxhero posted an excellent thread about the loss on the Spyderco forum:
> 
> 
> 
> RIP Dr. Vadim Kraichuk "Knife Grinders" Wootz - Spyderco Forums





@Deadboxhero; nice of you to commemorate his impact on the community!


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## Bico Doce (Jan 24, 2022)

@Tea_Hills thanks for starting this thread. I had never heard of Dr. Vadim until now. I purchased his book and it has been a fantastic read so far. I was pretty lost in this thread with negative burrs but reading about it in his text definitely helped. I find his classification of different burr types and how to address them respectively very refreshing as it demystifies some of the variance that we can experience as sharpeners depending on the knife/steel.


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## Tea_Hills (Jan 26, 2022)

Not a problem! Glad it helped. I learned a lot here as well. In fact the last of my supplies came yesterday for adapting his method to home sharpening. On my first test I was able to get konosuke HD2 steel to an estimated 50 - 100 BESS, which is insane compared to what I was able to do entirely freehand. This was done without using any traditional deburring technique at all. Instead a used -.1 angle grinding. Visual tests and edge degradation tests all indicate there is no feather / wire / foil burr. More tests to come!


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## ian (Jan 26, 2022)

Tea_Hills said:


> Not a problem! Glad it helped. I learned a lot here as well. In fact the last of my supplies came yesterday for adapting his method to home sharpening. On my first test I was able to get konosuke HD2 steel to an estimated 50 - 100 BESS, which is insane compared to what I was able to do entirely freehand. This was done without using any traditional deburring technique at all. Instead a used -.1 angle grinding. Visual tests and edge degradation tests all indicate there is no feather / wire / foil burr. More tests to come!



So you bought a Tormek and a BESS tester?


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## Tea_Hills (Jan 26, 2022)

I did not! My goal was to attempt to replicate the Tormek grinding methods using stones, pastes, and strops as that is what I had and I am not willing to spend 1000$+ for a professional setup meant for volume sharpening. 

I used a hapstone t1 jig for fine angle control. 
I created a small powershell program to help calculate required blade height off the stone to achieve desired angle with the hapstone. 
I have a Venev 1200 / 800 diamond stone I use for apex creation
To achieve Vadim's paperwheel honing I used a piece of printer or notebook paper wrapped around the venev stone and loaded it with required diamond paste. 
Diamond pastes used were from techdiamondtools (50% percent concentrate)
To acheive Vadmin's felt wheel burr removal I used 79gm/cm3 felt strips loaded with 1 micron diamond paste.

To measure blade height off of the stone I used a 20$ amazon caliper I had (precise to one-one hundredth of a millimeter accurate to probably +- .05mm)

BESS estimates were approximated without a proper testing machine. I used this chart http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf

The entirety of the blade length was able to achieve quite smooth against the grain hair shaving. I was able to cut a free hanging hair along portions of the blade . My estimate should probably be revised to a BESS between 50 - 150. I don't have immediate plans to buy a BESS machine so estimates will have to do for now. 

To ensure the absence of a foil / wire/ feather burr pressure was applied, three times, to the entire edge approximate to that of rock chopping herbs. If there was some F/W/F burr I would expect to see a quick dulling of the edge after pressure was added, which I did not see. Edge retention is largely subjective without proper testing equipment or approximation guides so I don't want to comment on that in the future. 

Most of this is to see if Vadim's method work and can be applied to a home environment without much cost. 
I'm not ready to say with certainty if it does as I have only tested his prescribed process for a wear resistant steel (HD2) and that not require the use of higher angle felt deburring. I will say that no traditional deburring (cork, felt, leather, etc.) was required at all. My process for HD2 steel was adapted from his process for D2:

(All edge trailing strokes)
15 degree medium pressure grind on Venev 1200
15 degree light pressure 'grind' on paper loaded with 10 micron diamond paste
14.9 degree light pressure 'grind' on paper loaded with 5 micron diamond paste (angle estimated by putting 2 pieces of paper under stone holder)
15 degree light pressure 'grind' on paper loaded with 1 micron diamond paste
15 degree light pressure 'grind' on paper loaded with 1 micron diamond paste
15 degree light pressure 'grind' on paper loaded with .25 micron diamond paste

I recently received a gesshin uraku from JKI and the resulting edge of the HD2 sharpening subjectively felt just a tad smoother when shaving arm hair but there is no doubt it was at least as sharp. Overall I am very impressed with the results especially with the 15 degree angle (30 inclusive). I have a White#2 Wakui I am going to test next and may used a 12 degree angle.


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## Tea_Hills (Jan 26, 2022)

Here is the script if anyone is interested: 

#This is your desired angle, change as needed
$TargetAngle = 15
$TargetRadians = $TAngle * ([Math]:i / 180)
#This is the 'length' of the blade from the spine to edge at the point you will be measuring the height of the blade off the stone. Change this to the measurement taken after the jig is attached.
$Bladelength = 45.13
$RequiredHeight = [Math]::Sin($TRadians) * $Blength

Write-Output "Blade length : $Bladelength mm`nDesired Angle: $TargetAngle degrees`nNecessary blade height from stone top is $([math]::round($RequiredHeight, 3)) mm"


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## Tea_Hills (Jan 26, 2022)

And here is the output.


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## Tea_Hills (Jan 26, 2022)

This is going to be blasphemy to our skilled free hand folks but using a jig to remove the human element of wobble allows you to focus solely on pressure and vertical height adjustment to compensate for blade belly and I really recommend it. Not perfect for all applications but you can get angle consistency on par with a highly experienced sharpener without spending years training your body into a human jig. Full disclosure I'm not naturally talented at visual angle control.


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## ian (Jan 26, 2022)

Tea_Hills said:


> The entirety of the blade length was able to achieve quite smooth against the grain hair shaving. I was able to cut a free hanging hair along portions of the blade . My estimate should probably be revised to a BESS between 50 - 150. I don't have immediate plans to buy a BESS machine so estimates will have to do for now.



Cool. You might just say what tests you used instead of asserting a BESS score in the future, if you're not using a machine. Most people on here probably don't know what a given BESS score means anyway.



Tea_Hills said:


> Here is the script if anyone is interested:
> 
> #This is your desired angle, change as needed
> $TargetAngle = 15
> ...



 I usually tell people to enter "50 sin(12 degrees)" into google search if they want to get the height of the spine off the stone for a 50mm tall knife and a 12 degree angle.

----

Sounds like fun experimenting.


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## ian (Jan 26, 2022)

Tea_Hills said:


> This is going to be blasphemy to our skilled free hand folks but using a jig to remove the human element of wobble allows you to focus solely on pressure and vertical height adjustment to compensate for blade belly and I really recommend it. Not perfect for all applications but you can get angle consistency on par with a highly experienced sharpener without spending years training your body into a human jig.



Also, idk if anyone thinks it's blasphemy. It's just not so clear that this kind of fine angle control makes a massive difference for kitchen use once you have some experience, and it requires more setup, so it's slower. I think it's cool that you're doing this, though. I'll be reading your results!


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## Tea_Hills (Jan 26, 2022)

ian said:


> I usually tell people to enter "50 sin(12 degrees)" into google search if they want to get the height of the spine off the stone for a 50mm tall knife and a 12 degree angle.



I had no idea that you could type 'degrees' after the angle into google to tell it to not use radians, that would've saved me a few minutes haha.


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## Tea_Hills (Jan 26, 2022)

ian said:


> Also, idk if anyone thinks it's blasphemy. It's just not so clear that this kind of fine angle control makes a massive difference for kitchen use once you have some experience, and it requires more setup, so it's slower. I think it's cool that you're doing this, though. I'll be reading your results!



That is the one downside for sure, it is slower. Take a little bit setting up the jib with the correct angle and all. Total overkill for someone who already has good control. In fact, this is all overkill


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## Barmoley (Jan 26, 2022)

Do you move the jig multiple times as you sharpen in order to keep the same angle as the width of the blade changes toward the tip?


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## Tea_Hills (Jan 26, 2022)

Very glad you asked as I have been meaning to ask for a second set of eyes on my assumptions!

When you say width of the blade do you mean height from spine to edge or thickness change as a result of a distal taper?

I do not compensate for the change in blade thickness. I believe this shouldn't actually change the angle but bevel width will change. Please correct me if I'm wrong on this.

As for compensating for the change in spine to edge thickness, I do that by lifting the blade vertically with respect to the direction of the blade on the axis of the stone. I have heard that people change their angle near the tip but I believe this is in error. From what I can reason, the sharpening angle (pitch axis to use an aviation term) should stay the same but the roll axis should change.

The way that I think of this is to imagine each point on the blade as a triangle (assume a flat ground triangular piece of metal). This quick illustration I made is why I believe that the angle should not actually change just how close you need to move the metal to the stone. I am no expert though so I would love to know if I am incorrect.


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