Probably the best value for a good sharpening stone right now⬇ amzn.to/3fUilj5 Or my website www.outdoors55.com/shop where I go over knife sharpening stones / equipment, knives, and knife making equipment I have personally used and reviewed. As an Amazon associate I earn from qualifying purchases.
Yes, Unfortunately the only thing i can do is block them but then 3 more appear. Sorry I dont do giveaways. You can pretty much count on the fact that no RUclipsr is doing giveaways in the comments. Thats not how anyone would contact you for a giveaway. I would think 99.99% of people would know this by now.
I would like to see a real time - no cuts sharpening video. Your videos always get a like from me. Thanks for breaking this down into crayons for me & anyone else that watches.
I can see why the explaining of that felt odd but I think you hit the nail right on the head. The big takeaway is that there is a geometry for each use case. Cutting soft veggies - a thin thin edge has a load of benefits. On the other extreme is the battoning you mentioned and that definitely requires a heavy edge if you want the blade to survive. We need more of these education videos in the community, thanks.
@@redrustyhill2I get what you’re saying which is why I’ve always used a hatchet. My guess is that when people baton with a knife is because they don’t want to carry around a hatchet when out bushcrafting 🤷♂️
@taylorbrandon86 any real "bushcrafter" will have the proper tools for the job. This whole "survival" nonsense stems from these stupid reality "survival" shows, thinking they will build a shelter and traps with nothing but a belt knife.
True of s110v. Heat treat and steel selection could also help limit chipping in that situation. But still holds true what you've demonstrated, just takes more force. Thats why when we buy thin knives we should know how to use them. Thats why some makers talk to customers to make sure they understand this and to not cut any hard materials with the super thin geometry. I have a playl-ist section on my page for geometry for more on the subject, I think I'll add this one to the mix. Check out the others too.
This may be the first time in a couple of years of delving into this stuff that I'm hearing a person say there was a potential price to be paid in thinning a knife. Yes, it's often said you don't want to have an edge angle so acute the metal can't support it. But thinning behind the edge? No warnings ever that I can recall. So this is next-level understanding, as usual. Thanks and keep it coming.
I'm a mechanical engineer. My intuition is that your explanation is correct. You also briefly mentioned stress risers, and I think that is also relevant. It would be interesting to model a few knife edges and do finite element analysis to try to backup or disprove these ideas.
I'd etch it and micrograph it at the chip site and along the now stressed edge. I'm thinking it's grain and grain support failure in this specific failure mode.
The fundamental factor at play here is anisotropy. In the thicker blade more of the material immediately adjoining the break site is being supported along stronger axes. You could go more into depth in terms of crystal structure/boundaries, but it all boils down to the same thing.
I have many different knives and they all have a specific purpose. They're all sharp and do whatever they were created for very well. Not to say that I've never chopped onions with my pocket knife because I have. My dad was a butcher and he had knives for everything and they were good knives. He died when I was 18 years old in 1971 but he told my mother to be sure that I got them. I cherish them and still remember how he showed me to clean them, store them and to keep an edge on them. I think some sharpening techniques I've learned from you and others are better techniques (Sorry Pop!) and the stones we have available today are certainly better than was available to him! But he told me something one time that I've never forgotten. He said: "Son, it's just as easy to carry a sharp knife as it is a dull knife". My pocket knife back when I was a kid was normally dull, very dull. But when you're a kid you're busy playing and I used that poor knife for every kind of tool when I was working on my bike or something else. He always gave me a hard time about not keeping it sharp. I keep it sharp now and never use it for a pry bar! When I think back on my life back then I feel kind of cheated that I didn't get to spend more years with him. After all of these years I still miss the hell out of him. Anyway, enough sadness. I'm happy to see that you're back and posting on a kind of regular basis again. You're my favorite knife channel and hopefully with more room now you may even build another knife from time to time. Thanks for the video!
I noticed the strokes weren't very smooth. I figured it was dull, but when you rubbed your hand on the blade, I was genuinely confused. I didn't think it was THAT dull.
In solid mechanics, a stress concentration (also called a stress raiser or a stress riser) is a location in an object where the stress is significantly greater than the surrounding region. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. Wondering if you can round the part where the edge and the blade meet.
That's how I sharpen my chisels. Can't say with any scientific certainty but it does feel resiliant and stronger edit: and very seldom get chips in the blades.
This is the correct explanation as far as I'm aware as material scientist. At the same time the procedure of thinning the blade without proper heat treatments in between and at the end could have weakened the steel a lot (initiation and lengthening of cracks). Grinding the steel puts a lot of plastic deformation in the steel which needs to be removed regularly.
As someone who has basically no real experience or knowledge regarding knives or steels in general I suspect the blade would just chip at a more random spot along the curve.
In my experience, stress concentrators mostly occur if the sharp corner is to the inside of the part, like a scratch(or a bigger similar geometry). Rounding the part where the blade meeds the edge might still help with the resistance by making the whole area more elastic.
Great video. Shows well pros and cons of a thin geometry. AEB-L probably would not chip with the same thin geometry. Clean carbides, high hardness potential and high toughness. That's why I think AEB-L is such a good steel. Cheap to make and outperforms several super steels in many tasks. To cut highly abrasive materials powder metallurgy still shines.
@@NSW15355 True. If you want to optimize for slicing AEB-L has higher toughness on 64 HRC than 1.4116 on 57HRC. If you want to optimize for toughness it gets four times tougher than 1095 on same hardness while also being stainless. It's a freaking beast but unfortunately it doesn't get top grade heat treatment from pretty much any of the large companies.
@@thiago.assumpcao aebl has history too. I think it was deployed in the 1950s as a razor blade steel for shaving. I was always drawn to it's ability to remain stable with a thin cross section and fine grain. And being stainless is nice
Hollow grinding has been the industry standard for most knives for a long time, except for the Nordic countries where we use "Scandi grind" (although I think it's a bad term since Finland is not in Scandinavia, and is a very important country in Nordic knife culture). Scandi grind leaves more material behind the apex, while keeping the blade thin.
Love this video. Kind of a surprise attack, I thought you were gonna recommend we all grind to .008" behind the blade. And then you gave us the, "But wait, there's more." The ideal behind-the-blade thickness is probably (entirely) task oriented. In kitchen knives, for example, guess I'd love to have a whole block of chef's knives with slots marked, .008 (maybe for sushi fish), .016 (boneless steaks), .024 (soft vegetables), .030 (carrots and potatoes). Chuckling...thanks for passing along your experiences and research.
Your demonstration with the cardboard cutouts was ingenious in its simplicity!!! ...who didn't understand that should stick to spoons rather than knives.
For metal stability, it helps to draw in the force lines. This tells us, that rounding the edges between the triangle and the parallel surfaces can help to reduce the stress in the edges
I have 2 SAK knives with 2 different blade thicknesses. One is an officer model with a master blade for an 84 mm knife and the second is a 93 mm blade that is thicker. I like to get them to shave arm hair without pulling. The smaller knife achieves this much easier and quicker than the larger knife meant for heavier work. This video confirms why some knives have always been harder to achieve this level of sharpness as well. I have had several knives in the past from major manufactures, where certain knives sharpened easier and better than others of the same make or model. I always thought it was my inability but now I think it had to do with geometry too. Thank you for this great informative video! Jeff
This video came at the perfect moment: Just had chipping issue with one of my whittling knives which I thinned down. Thought it would cut wood like butter, but ended up chipping and making ugly scratches in the wood. Thanks for explaining. I’m working on restoring it now. Gently, because the blade of a detail whittling knife is not very high. Keep up the good work 😀👍🏻
Excellent job explaining and showing why the chipping occurred. Great job! Been a sub for a few years and your video style as well as all the info you give is why I still watch. Education and information 👊🏽
So something you should try doing is create a micro bevel with the 8 thou blade and compare it to something similar with a 30 thou blade and no microbevel. that would be interesting to see. keep it up!
Definitely a great video. That's one thing that definitely matters a lot. Also like you said at the end, the task the knife is intended for, the hardness, the carbide volume (also carbide size to some degree), all matter a lot too. Especially when getting down to those thinness'. Something that's able to maintain good toughness, high hardness, while having just the right volume of small carbides, tends to do very well with thin grinds. Though even low toughness, higher hardness, and higher carbide steels can Excell, if the tasks theyre used for, don't involve impacts, or torquing the edge.
I had a benchmade that I ground out to a long secondary bevel and a thinner primary. The steel was S30V. The edge literally flaked and crumbed from skinning some electrical wire for a splice. Prior to the sharpening, I could nearly baton the blade through a bundle of wire with no discernible damage. Great video and explanation. I’m wondering if steel type matters here as well? I’ve heard S30V is prone to flaking.
Nice Video very informative especially the demo about the knife geometry /angle when you showed the wood triangle comparison very impressive your'e the only person who showed something like that ..Thank you for sharing .👏👍🏼
What about a video where you improve the geometry of kitchen knives? What are some tools that you can use at homes? Maybe a deep dive into products on the market which have better geometry than the rest?
Excellent, as usual. I doubt that many people have the power tools to reshape the primary bevel. I think that I will concentrate on my basic technique.
I'm convinced (science, it's like magic,but it's REAL). Finally, someone who knows what makes a good blade. I'm gonna be a loyal subscriber, keep it up.
It has to do with hardness and flex. Your blade is a material that has a higher hardness value but you thinned the blade to the point where there's not enough supporting material to resist the edge from flexing beyond the fail point and the hardness alone isn't enough to prevent the edge from flexing during normal operation.
8:19 I could be wrong but i don't think it's really the size behind the sharp edge that make the apex strong. What i think happen is as you put your blade deeper into any item, the sides help cut by spreading out whatever items you are cutting through, therefor reducing the load on the tips. (It could also be a mix of what i just said and what you said at :19.. :) ) When you use an axe to chop in half a log, the sharp edge beging the work, and the thicker sides continue the harder work. You would not be able to split a log in half with only the thickness of the sharp axe edge using the same amount of force and head weight.
You should try sharpening at a more acute angle since the blade is now thinner, it sounds counterintuitive but it absolutely *could* be the reason for the chippiness Fantastic video btw!
A lot of people might not realise this, but the ideal culinary knife geometry for chopping is actually thicker but sharp. You want a thicker primary bevel to separate the chopped part of the food away as you cut. Ultra thin knives may feel impressive and sharpen quickly, but they are sticky, and really best for cutting thin slivers rather than chopping. Asymmetrical grinds are designed to do this, but a fat cleaver sharpened like a shaving razor will do that job better, IMO. A one-sided knife obviously has great separation, but it’s hardly ideal for repeated straight cuts. It’s a great demo at the beginning, made the point well. People become obsessed with thinness and “demonstration sharpness”. But that crunching sound… indicative of a knife that will pound a tomato, not slice it. A great knife should be almost silent. Really enjoyed this video, the demonstration of the structural weakness of over-thinned blades was great. The longer secondary bevel of a thicker knife clearly spreads the stress along a greater length than the shorter bevel of a thin knife.
Always look forward to and enjoy your videos. Thanks for the time you put into this. There isn't a ton of RUclips videos focusing on geometry, toughness, and heat treating so that information is much appreciated.
Well done and very informative. I now have two related questions: 1) is there an optimal blade thickness for a given secondary bevel angle? and 2) is your Manix blade now ruined? How would you fix that?
No, it would depend on the end use of the knife. The manix ist ruined at all. Its thinner but I brought the bevel back and that added a couple thousands. Im working on a video showing me fix it.👍
Very nice simplification in my mind. It is good enough to be useful. And I think it holds up in predictions well enough compared to going much further -- like thinking about why the "all this supporting material" is supporting in the first place.
Really enjoyed the video, yet I believe you missed something: steels like s110v have an high volume of carbides, those can be either alone but are usually distributed in relatively small clusters, sized if I remember correctly in the range of 10 to 20 microns, those groups of carbides in very thin edge configurations may not be properly supported by the steel matrix, causing small edge blowouts. Finer grained, less carbide heavy steels may perform better: my spyderco chaparral right now is 7-10 tho bte, yet shows no significant chipping, even in rough cutting like chest-lever cuts on branches and whatnot Something like for example your 1084 should have nicer properties for that kind of edge imo Keep up with content, your channel is great!
Im not sure thats the case here due to where the chips propagated, which was right at the corner of the secondary bevel. Id lean more towards carbide if it was more towards the apex. Very good thought 👍
This problem and explanation of the chipping is interesting. Metals in general form crystalline organization pattern of the atoms. No matter how well you make the metal there are imperfections in the crystalline structure. Fracture or chips or cracks form usually on these imperfections, and then propagate through the material. The more distance the crack has to propagate through the more time it takes, and more force will be required to start the process. Once the crack starts less material is supporting and thus the crack propagates through till it chips out. When you sharpen the knife any angular changes in geometry leave micro cracks or imperfections starting the cracks (from grinding), and that would explain why chipping would start at the change in angle of the appex. Grinding will always leave behind micro cracks. If you could form a thin sheet of metal without grinding the chance of chipping should go down.
10:20 the force is actually along the entirety of the side of the primary bevel, except in cases where you are purposefully pushing the blade in sideways. It’s just that the pressure is too large for even that area. If it was only on that point, then it would deform first (flattening out) becoming a new secondary bevel which would then break off. While the model is somewhat rudimentary and can’t completely describe the nuances of metallic deformation, it’s pretty close if you only consider the sides of the triangle instead of that point.
i love the beard and also welcome back and thanks for the video i learned alot i hope you talk more about carbides i read so many articles on knife steel nerds
One of the best knife sharpeners ive ever come across had a surprising source. It was the arc tube out of a bad sodium vapor lamp. It would put a super sharp edge on almost anything 🤓😁❤
This reminds me so much of those scored "snap" utility blades, where you just break off the section that becomes dull. Its a common occurence to experience chipping like this in my profession (mechanic, we use razors all the time) and razors chip right at the very apex often, but we also break them regularly because they are flimsy little pieces of metal (so is a bullet, but thats a different topic lol🤣).
I think you should consider how the chipping occurs. Presuming it's side load, leverage consideration explains how with similar twisting forces from your hand produce different forces on the apex. With thicker blade, secondary bevel is large lever and thus resulting force is smaller. However with thinner blade, secondary bevels forming apex make a much shorter lever, thus force on the apex is multiplied more and twisting motion of the blade in the cut leads to chipping. Edge between primary and secondary bevel would not usually be a stress concentration, but it is the pivot around which twisting forces occur.
I have been wondering for the last week: Why can't I get a cheap chef knife with super steel as a backup survival knife? Well, 11:19 was what I needed. ;) I should have known this since I grew up in the house of a knifemaker, but It never made sense until this video. Thank you for sharing your knowledge.
great vid! you may even say steel typeband heat treat are serve to allow a specific geometry. Usage dictates geometry and thus dictates steel typeand heat treat
I have a some sort of japanese titanium kitchen knife with very rounded, sharp tipped edge that is a thin blade. I find it really nice knife, but really difficult to sharpen successfully, it's basically cutting with the geometry since day one. Like to be able to follow the curve is so difficult and trying to finish by making the burr disappear is just never ending thing, feels like even when you manage to do that, it still won't cut paper like butter. I suppose the edge material is also more difficult to sharpen. So in a sense, a point for your average cheap kitchen knife just for the sake of shape and material making it easy to repeatedly make sharp again. Then I remembered your tips about stropping and realized I have a strop belt for shaving razor blade and alas, few passes and the performance increased by factors. Thanks! I'm thinking looking at FEM simulation or just structural integrity calculations/graphs for shear forces and tensions, you would find the breaks often if not always occur at those transitional planes (unless it's like pitting or some other form of surface wear). They are usually the places where the supporting forces and stressing forces peak and/or change sides causing the high shear forces. The strength/resistance against tensions is also defined per the perpendicular section area. This from the top of memory so details and some terms might not be accurate, and I don't think this is very coherent, but I believe this to explain some of it.
Geometry definitely cuts. I bought a Robert Herder paring knife and it was 2-3 thou tops(it's pretty much a zero ffg grind with a microbevel put on) and 44 thou blade stock and even it was dull from factory it cut cardboard almost as well as my razor sharp pm2 regrind to 0.005. After I actually sharpened it is the best light to medium duty cutter I've experienced. Not every knife needs to be 5-10 thou bte but for certain ones it is really nice.
Would you try a convex edge on your .008“ Manix? I think it would eliminate the chipping because it’s more „natural“ ( less hard edges ) edge. Nice video! Take care!
Real life geometry story: I once built a balsa wood model airplane. My sharpest knife could not cut a balsa wood stick without crushing it. On the other hand, a single edged razor blade worked perfectly. The razor's thin blade made all the difference.
I have this 3.5 euros chinese "knife" (a chinese cleaver) which is literalliy a stamped steel handle welded on piece of sheet metal with a very narrow andgle towards the edge. I keep it well sharpened but it works much better than the much more expensive chef knives I have if you want to chop up stuff.
I suspect it has more to do with the change in angle at the bottom of the apex causing a stress concentration at that point, making it the point most vulnerable to chipping... which is why it tends to break there and not above or below. It's just that a full thickness blade has enough material at this vulnerable spot to prevent this failure mode under reasonable/normal use.
I feel the discussion of geometry is important. However not every geometry is welcome in every day use. I love my spedco’s but as a daily use or medium use knife I’ve seen far to much flex in the blades because of full flat grinds an thin geometry. I would rather have to spend more time sharpening an have more confidence in the longevity of the blade. I have thick blades an thin blades . I’ve even made some knives . My preferred grind is a high hollow grind with a convex edge. It leaves enough meat to brevet flex an the problems you encounter here. Steel choice an it’s treatment is as important. A softer steel will flex an bend rather chip or crack . Cool vid
Probably the best value for a good sharpening stone right now⬇
amzn.to/3fUilj5
Or my website www.outdoors55.com/shop where I go over knife sharpening stones / equipment, knives, and knife making equipment I have personally used and reviewed.
As an Amazon associate I earn from qualifying purchases.
Hey there is a scammer in the comment section! Be aware!
@@lionknives3 I was wondering what that was all about.
@@flyfishbrad that happened many times on many channels.
Yes, Unfortunately the only thing i can do is block them but then 3 more appear. Sorry I dont do giveaways. You can pretty much count on the fact that no RUclipsr is doing giveaways in the comments. Thats not how anyone would contact you for a giveaway. I would think 99.99% of people would know this by now.
What would happen if the corners in the transition from the .008 to the edge were rounded instead of being such sharp transitions?
I would like to see a real time - no cuts sharpening video. Your videos always get a like from me. Thanks for breaking this down into crayons for me & anyone else that watches.
Me too
👍
I don't really see the point of a real time no cuts sharpening video unless you enjoy the asmr aspect. there isn't a whole lot to see generally.
"no cuts"
"sharpening"
heh
I can see why the explaining of that felt odd but I think you hit the nail right on the head. The big takeaway is that there is a geometry for each use case. Cutting soft veggies - a thin thin edge has a load of benefits. On the other extreme is the battoning you mentioned and that definitely requires a heavy edge if you want the blade to survive. We need more of these education videos in the community, thanks.
What we need is more people who aren't afraid to say batoning is a stupid use for a knife, for the same reason you don't fillet fish with an axe.
@@redrustyhill2I get what you’re saying which is why I’ve always used a hatchet. My guess is that when people baton with a knife is because they don’t want to carry around a hatchet when out bushcrafting 🤷♂️
@taylorbrandon86 any real "bushcrafter" will have the proper tools for the job. This whole "survival" nonsense stems from these stupid reality "survival" shows, thinking they will build a shelter and traps with nothing but a belt knife.
True of s110v. Heat treat and steel selection could also help limit chipping in that situation. But still holds true what you've demonstrated, just takes more force. Thats why when we buy thin knives we should know how to use them. Thats why some makers talk to customers to make sure they understand this and to not cut any hard materials with the super thin geometry.
I have a playl-ist section on my page for geometry for more on the subject, I think I'll add this one to the mix. Check out the others too.
This may be the first time in a couple of years of delving into this stuff that I'm hearing a person say there was a potential price to be paid in thinning a knife. Yes, it's often said you don't want to have an edge angle so acute the metal can't support it. But thinning behind the edge? No warnings ever that I can recall. So this is next-level understanding, as usual. Thanks and keep it coming.
I'm a mechanical engineer. My intuition is that your explanation is correct. You also briefly mentioned stress risers, and I think that is also relevant. It would be interesting to model a few knife edges and do finite element analysis to try to backup or disprove these ideas.
He also isn't considering Hertz contact stresses. The max shear stress plain is larger with the thicker blade and thus the shear stresses are less.
I'd etch it and micrograph it at the chip site and along the now stressed edge. I'm thinking it's grain and grain support failure in this specific failure mode.
The fundamental factor at play here is anisotropy. In the thicker blade more of the material immediately adjoining the break site is being supported along stronger axes.
You could go more into depth in terms of crystal structure/boundaries, but it all boils down to the same thing.
I have many different knives and they all have a specific purpose. They're all sharp and do whatever they were created for very well. Not to say that I've never chopped onions with my pocket knife because I have. My dad was a butcher and he had knives for everything and they were good knives. He died when I was 18 years old in 1971 but he told my mother to be sure that I got them. I cherish them and still remember how he showed me to clean them, store them and to keep an edge on them. I think some sharpening techniques I've learned from you and others are better techniques (Sorry Pop!) and the stones we have available today are certainly better than was available to him! But he told me something one time that I've never forgotten. He said: "Son, it's just as easy to carry a sharp knife as it is a dull knife". My pocket knife back when I was a kid was normally dull, very dull. But when you're a kid you're busy playing and I used that poor knife for every kind of tool when I was working on my bike or something else. He always gave me a hard time about not keeping it sharp. I keep it sharp now and never use it for a pry bar! When I think back on my life back then I feel kind of cheated that I didn't get to spend more years with him. After all of these years I still miss the hell out of him.
Anyway, enough sadness. I'm happy to see that you're back and posting on a kind of regular basis again. You're my favorite knife channel and hopefully with more room now you may even build another knife from time to time. Thanks for the video!
What a beautiful comment
I noticed the strokes weren't very smooth. I figured it was dull, but when you rubbed your hand on the blade, I was genuinely confused. I didn't think it was THAT dull.
In solid mechanics, a stress concentration (also called a stress raiser or a stress riser) is a location in an object where the stress is significantly greater than the surrounding region. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. Wondering if you can round the part where the edge and the blade meet.
That's how I sharpen my chisels. Can't say with any scientific certainty but it does feel resiliant and stronger edit: and very seldom get chips in the blades.
This is the correct explanation as far as I'm aware as material scientist. At the same time the procedure of thinning the blade without proper heat treatments in between and at the end could have weakened the steel a lot (initiation and lengthening of cracks). Grinding the steel puts a lot of plastic deformation in the steel which needs to be removed regularly.
As someone who has basically no real experience or knowledge regarding knives or steels in general I suspect the blade would just chip at a more random spot along the curve.
My thoughts exactly
In my experience, stress concentrators mostly occur if the sharp corner is to the inside of the part, like a scratch(or a bigger similar geometry). Rounding the part where the blade meeds the edge might still help with the resistance by making the whole area more elastic.
Great video. Shows well pros and cons of a thin geometry.
AEB-L probably would not chip with the same thin geometry. Clean carbides, high hardness potential and high toughness. That's why I think AEB-L is such a good steel. Cheap to make and outperforms several super steels in many tasks.
To cut highly abrasive materials powder metallurgy still shines.
Aebl is slept on but it's so good for so many reasons
@@NSW15355 True.
If you want to optimize for slicing AEB-L has higher toughness on 64 HRC than 1.4116 on 57HRC.
If you want to optimize for toughness it gets four times tougher than 1095 on same hardness while also being stainless.
It's a freaking beast but unfortunately it doesn't get top grade heat treatment from pretty much any of the large companies.
@@thiago.assumpcao aebl has history too. I think it was deployed in the 1950s as a razor blade steel for shaving. I was always drawn to it's ability to remain stable with a thin cross section and fine grain. And being stainless is nice
Hollow grinding has been the industry standard for most knives for a long time, except for the Nordic countries where we use "Scandi grind" (although I think it's a bad term since Finland is not in Scandinavia, and is a very important country in Nordic knife culture). Scandi grind leaves more material behind the apex, while keeping the blade thin.
Love this video. Kind of a surprise attack, I thought you were gonna recommend we all grind to .008" behind the blade. And then you gave us the, "But wait, there's more." The ideal behind-the-blade thickness is probably (entirely) task oriented. In kitchen knives, for example, guess I'd love to have a whole block of chef's knives with slots marked, .008 (maybe for sushi fish), .016 (boneless steaks), .024 (soft vegetables), .030 (carrots and potatoes). Chuckling...thanks for passing along your experiences and research.
That actually made sense! You baffled me with the same angle but then it all came together with the thickness behind the Apex. Cheers mate!
To reduce the stress riser you might roll the blade side into the apex angle instead of a sharp division.
Your demonstration with the cardboard cutouts was ingenious in its simplicity!!!
...who didn't understand that should stick to spoons rather than knives.
I think the explanation was perfect and in fact, i’ve read and heard that is the main reasons why convex edges are so strong.
For metal stability, it helps to draw in the force lines. This tells us, that rounding the edges between the triangle and the parallel surfaces can help to reduce the stress in the edges
edit your OP with a picture like that shows?...wait no i think YT deletes links now. fuck YT
I have 2 SAK knives with 2 different blade thicknesses. One is an officer model with a master blade for an 84 mm knife and the second is a 93 mm blade that is thicker. I like to get them to shave arm hair without pulling. The smaller knife achieves this much easier and quicker than the larger knife meant for heavier work. This video confirms why some knives have always been harder to achieve this level of sharpness as well. I have had several knives in the past from major manufactures, where certain knives sharpened easier and better than others of the same make or model. I always thought it was my inability but now I think it had to do with geometry too. Thank you for this great informative video! Jeff
this remmember me of the katana, perfect o cut joints, but so thin, it can break with easy in no trained hands!
the explaination got to me at the end of when you were explaining it, as a foreigner i think your explaination was as clear as water
This video came at the perfect moment: Just had chipping issue with one of my whittling knives which I thinned down. Thought it would cut wood like butter, but ended up chipping and making ugly scratches in the wood. Thanks for explaining. I’m working on restoring it now. Gently, because the blade of a detail whittling knife is not very high. Keep up the good work 😀👍🏻
Excellent job explaining and showing why the chipping occurred. Great job! Been a sub for a few years and your video style as well as all the info you give is why I still watch. Education and information 👊🏽
Keep going budro! You are making people rethink "truths" about blades and sharpening
So something you should try doing is create a micro bevel with the 8 thou blade and compare it to something similar with a 30 thou blade and no microbevel. that would be interesting to see. keep it up!
Good to see you back doing what no one else seems to be able to cover
I always learn and enjoy your videos. Thanks for your time !
This is one of the most interesting videos I have seen in awhile, and I really learned a lot; thank you good sir
That must be why my s110v Native that is now almost a scandi grind seems to hold up so well. The consistent great videos is astounding 👏🙏
Very educative and enlightening! You're very good!
I never ever seen anyone go in depth about knives like this, w find.
Definitely a great video.
That's one thing that definitely matters a lot. Also like you said at the end, the task the knife is intended for, the hardness, the carbide volume (also carbide size to some degree), all matter a lot too. Especially when getting down to those thinness'.
Something that's able to maintain good toughness, high hardness, while having just the right volume of small carbides, tends to do very well with thin grinds. Though even low toughness, higher hardness, and higher carbide steels can Excell, if the tasks theyre used for, don't involve impacts, or torquing the edge.
Make a sharpening asmr video then do cut test the same way as the blade dulls and the pitch decreases. Love your in depth videos. 😍
Actually, the explanation was very clear and easy to understand, thanks you so much 👌🏻
Your explanations are very good. As always. Anyone with common sense must understand these!
Love your humor!
Greetings from Germany💚🤘
perhaps that is why so many luv a convex grind, a radius removes the weak point, and has some material behind it. that would make a great vid.
Wow!! The amount of effort and knowledge that you put into your videos is impressive!!
Perfectly explained!
I had a benchmade that I ground out to a long secondary bevel and a thinner primary. The steel was S30V. The edge literally flaked and crumbed from skinning some electrical wire for a splice. Prior to the sharpening, I could nearly baton the blade through a bundle of wire with no discernible damage. Great video and explanation. I’m wondering if steel type matters here as well? I’ve heard S30V is prone to flaking.
0:12 this moment got me in tears 😭
very dramatic 😭😭 those poor onions :< even i got tears
That’s wild you got the blade so thin . ❤ them Spyderco knives .
Nice Video very informative especially the demo about the knife geometry /angle when you showed the wood triangle comparison very impressive your'e the only person who showed something like that ..Thank you for sharing .👏👍🏼
Makes perfect sense & your videos & editing I envy.
What about a video where you improve the geometry of kitchen knives? What are some tools that you can use at homes? Maybe a deep dive into products on the market which have better geometry than the rest?
Excellent, as usual. I doubt that many people have the power tools to reshape the primary bevel. I think that I will concentrate on my basic technique.
once again, very well demonstrated.
I'm convinced (science, it's like magic,but it's REAL). Finally, someone who knows what makes a good blade. I'm gonna be a loyal subscriber, keep it up.
It has to do with hardness and flex. Your blade is a material that has a higher hardness value but you thinned the blade to the point where there's not enough supporting material to resist the edge from flexing beyond the fail point and the hardness alone isn't enough to prevent the edge from flexing during normal operation.
So, when my mom said "You ain't the sharpest knife in the drawer,"
she was actually giving me a compliment?
8:19 I could be wrong but i don't think it's really the size behind the sharp edge that make the apex strong. What i think happen is as you put your blade deeper into any item, the sides help cut by spreading out whatever items you are cutting through, therefor reducing the load on the tips. (It could also be a mix of what i just said and what you said at :19.. :) )
When you use an axe to chop in half a log, the sharp edge beging the work, and the thicker sides continue the harder work. You would not be able to split a log in half with only the thickness of the sharp axe edge using the same amount of force and head weight.
Nice. Love the contrast of that project compared to the axe grinding video. Kind of both ends of the spectrum.
I had no idea about this so it was very valuable info. That you for the good quality video!! And, thank you for your good sense of hummer!!!
I is ve learned a lot from you my friend. I’ve ruined so many moras and my favorite knife the Ontario 1 folder. This helped me out a lot on sharpening
@UC8QKxrtolxCCaTrHv5VPGQg Thank you O55
That was a really good explanation
I understood it by the end
You should try sharpening at a more acute angle since the blade is now thinner, it sounds counterintuitive but it absolutely *could* be the reason for the chippiness
Fantastic video btw!
I’d always like another sharpening video.👍🏻
A lot of people might not realise this, but the ideal culinary knife geometry for chopping is actually thicker but sharp. You want a thicker primary bevel to separate the chopped part of the food away as you cut. Ultra thin knives may feel impressive and sharpen quickly, but they are sticky, and really best for cutting thin slivers rather than chopping.
Asymmetrical grinds are designed to do this, but a fat cleaver sharpened like a shaving razor will do that job better, IMO. A one-sided knife obviously has great separation, but it’s hardly ideal for repeated straight cuts.
It’s a great demo at the beginning, made the point well. People become obsessed with thinness and “demonstration sharpness”. But that crunching sound… indicative of a knife that will pound a tomato, not slice it. A great knife should be almost silent.
Really enjoyed this video, the demonstration of the structural weakness of over-thinned blades was great. The longer secondary bevel of a thicker knife clearly spreads the stress along a greater length than the shorter bevel of a thin knife.
Always look forward to and enjoy your videos. Thanks for the time you put into this. There isn't a ton of RUclips videos focusing on geometry, toughness, and heat treating so that information is much appreciated.
Well done and very informative. I now have two related questions: 1) is there an optimal blade thickness for a given secondary bevel angle? and 2) is your Manix blade now ruined? How would you fix that?
No, it would depend on the end use of the knife. The manix ist ruined at all. Its thinner but I brought the bevel back and that added a couple thousands. Im working on a video showing me fix it.👍
@@OUTDOORS55 Thank you, Sir! Your videos are interesting and helpful.
Very nice simplification in my mind. It is good enough to be useful. And I think it holds up in predictions well enough compared to going much further -- like thinking about why the "all this supporting material" is supporting in the first place.
Really enjoyed the video, yet I believe you missed something: steels like s110v have an high volume of carbides, those can be either alone but are usually distributed in relatively small clusters, sized if I remember correctly in the range of 10 to 20 microns, those groups of carbides in very thin edge configurations may not be properly supported by the steel matrix, causing small edge blowouts.
Finer grained, less carbide heavy steels may perform better: my spyderco chaparral right now is 7-10 tho bte, yet shows no significant chipping, even in rough cutting like chest-lever cuts on branches and whatnot
Something like for example your 1084 should have nicer properties for that kind of edge imo
Keep up with content, your channel is great!
Im not sure thats the case here due to where the chips propagated, which was right at the corner of the secondary bevel. Id lean more towards carbide if it was more towards the apex. Very good thought 👍
This problem and explanation of the chipping is interesting. Metals in general form crystalline organization pattern of the atoms. No matter how well you make the metal there are imperfections in the crystalline structure. Fracture or chips or cracks form usually on these imperfections, and then propagate through the material. The more distance the crack has to propagate through the more time it takes, and more force will be required to start the process. Once the crack starts less material is supporting and thus the crack propagates through till it chips out. When you sharpen the knife any angular changes in geometry leave micro cracks or imperfections starting the cracks (from grinding), and that would explain why chipping would start at the change in angle of the appex. Grinding will always leave behind micro cracks. If you could form a thin sheet of metal without grinding the chance of chipping should go down.
10:20 the force is actually along the entirety of the side of the primary bevel, except in cases where you are purposefully pushing the blade in sideways. It’s just that the pressure is too large for even that area. If it was only on that point, then it would deform first (flattening out) becoming a new secondary bevel which would then break off. While the model is somewhat rudimentary and can’t completely describe the nuances of metallic deformation, it’s pretty close if you only consider the sides of the triangle instead of that point.
Brilliant mate, knew about it but could never figure out exactly why. Thanks 👍
Wow - GREAT video. Excellent explanation.
i love the beard
and also welcome back and thanks for the video i learned alot
i hope you talk more about carbides i read so many articles on knife steel nerds
One of the best knife sharpeners ive ever come across had a surprising source. It was the arc tube out of a bad sodium vapor lamp. It would put a super sharp edge on almost anything 🤓😁❤
This reminds me so much of those scored "snap" utility blades, where you just break off the section that becomes dull.
Its a common occurence to experience chipping like this in my profession (mechanic, we use razors all the time) and razors chip right at the very apex often, but we also break them regularly because they are flimsy little pieces of metal (so is a bullet, but thats a different topic lol🤣).
That was actually a great explanation man.
The way you cut that onion made me so anxious
I think you should consider how the chipping occurs. Presuming it's side load, leverage consideration explains how with similar twisting forces from your hand produce different forces on the apex. With thicker blade, secondary bevel is large lever and thus resulting force is smaller. However with thinner blade, secondary bevels forming apex make a much shorter lever, thus force on the apex is multiplied more and twisting motion of the blade in the cut leads to chipping. Edge between primary and secondary bevel would not usually be a stress concentration, but it is the pivot around which twisting forces occur.
I have been wondering for the last week: Why can't I get a cheap chef knife with super steel as a backup survival knife? Well, 11:19 was what I needed. ;) I should have known this since I grew up in the house of a knifemaker, but It never made sense until this video. Thank you for sharing your knowledge.
Thanks for sharing. I always enjoy your videos.
Realy enjoying your video's.
I have learned to sharpening my knives by watching your video's 👍🏼. Thank you 👍🏼
Your manix is almost a Warnie Manix! Well loved and used.
great vid!
you may even say steel typeband heat treat are serve to allow a specific geometry. Usage dictates geometry and thus dictates steel typeand heat treat
You explained it perfectly
I watched this with my daughter, we like the models!
I have a some sort of japanese titanium kitchen knife with very rounded, sharp tipped edge that is a thin blade. I find it really nice knife, but really difficult to sharpen successfully, it's basically cutting with the geometry since day one. Like to be able to follow the curve is so difficult and trying to finish by making the burr disappear is just never ending thing, feels like even when you manage to do that, it still won't cut paper like butter. I suppose the edge material is also more difficult to sharpen. So in a sense, a point for your average cheap kitchen knife just for the sake of shape and material making it easy to repeatedly make sharp again.
Then I remembered your tips about stropping and realized I have a strop belt for shaving razor blade and alas, few passes and the performance increased by factors. Thanks!
I'm thinking looking at FEM simulation or just structural integrity calculations/graphs for shear forces and tensions, you would find the breaks often if not always occur at those transitional planes (unless it's like pitting or some other form of surface wear). They are usually the places where the supporting forces and stressing forces peak and/or change sides causing the high shear forces. The strength/resistance against tensions is also defined per the perpendicular section area. This from the top of memory so details and some terms might not be accurate, and I don't think this is very coherent, but I believe this to explain some of it.
So what do you do now? Widen the apex?
Banger as always
It was not terrible it was a great explanation. Prisms are strong geometries as are pyramids. Makes sense.
Geometry definitely cuts. I bought a Robert Herder paring knife and it was 2-3 thou tops(it's pretty much a zero ffg grind with a microbevel put on) and 44 thou blade stock and even it was dull from factory it cut cardboard almost as well as my razor sharp pm2 regrind to 0.005. After I actually sharpened it is the best light to medium duty cutter I've experienced. Not every knife needs to be 5-10 thou bte but for certain ones it is really nice.
Great info, well presented. Thank you!
I really think it was a great explanation 👍
Great explanation. As always.
Beautiful work!
Thanks for this. Good information here for sure!!
I used to use a liquid cooled surface grinder at a machine shop I worked at. I bet that would be ideal for this process.
Would you try a convex edge on your .008“ Manix? I think it would eliminate the chipping because it’s more „natural“ ( less hard edges ) edge.
Nice video! Take care!
Real life geometry story: I once built a balsa wood model airplane. My sharpest knife could not cut a balsa wood stick without crushing it. On the other hand, a single edged razor blade worked perfectly. The razor's thin blade made all the difference.
Good video , thanks for sharing , God bless !
Great explanation. Thanks for sharing
Enjoyed the video, and it made me think of the benefits of convex grinds as well
I have this 3.5 euros chinese "knife" (a chinese cleaver) which is literalliy a stamped steel handle welded on piece of sheet metal with a very narrow andgle towards the edge. I keep it well sharpened but it works much better than the much more expensive chef knives I have if you want to chop up stuff.
I suspect it has more to do with the change in angle at the bottom of the apex causing a stress concentration at that point, making it the point most vulnerable to chipping... which is why it tends to break there and not above or below. It's just that a full thickness blade has enough material at this vulnerable spot to prevent this failure mode under reasonable/normal use.
I feel the discussion of geometry is important. However not every geometry is welcome in every day use. I love my spedco’s but as a daily use or medium use knife I’ve seen far to much flex in the blades because of full flat grinds an thin geometry. I would rather have to spend more time sharpening an have more confidence in the longevity of the blade. I have thick blades an thin blades . I’ve even made some knives . My preferred grind is a high hollow grind with a convex edge. It leaves enough meat to brevet flex an the problems you encounter here. Steel choice an it’s treatment is as important. A softer steel will flex an bend rather chip or crack . Cool vid
i have a knife thats 0,40mm/0,015" behind the edge and i was supriced how good it cuts compared to my other knifes.
Food for thought...... I hadn't realized how much the geometry affected the strength.
The wood visual made a perfect example