Ah, the hammered finish is a different story, and the ridges can still be problematic...
Thinning, Grinds, and Food Release
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spaceconvoy
Senior Member
This has become more important to me over the years. You can spend $$$ chasing the perfect grind from a maker, but then what? If you're a home user you can maybe get away with babying it for a year to preserve ootb performance. Seems like a good number of people here will just buy another knife at that point, or well before then - are they really 'bored' with the knife or just noticing the subtleties of degraded geometry?
It's not the optimal geometry for food release, but I prefer a symmetrical convex grind. Combined with a polished blade and self-applied 800 grit sandpaper 'hairline' finish, I can maintain close-to-ideal performance and aesthetics indefinitely. Not worrying about scratches during use or avoiding thinning while sharpening allows me to use the knife as a tool instead of a sacred object.
To achieve the perfect convex grind just buy a knife that's thicker than ideal and regrind it yourself. I've found that Sukenari has what I'm looking for, a nicely convex middleweight that just slightly too wedgy ootb. Spend $5 on a bag of small apples from the grocery store and check the balance between wedginess and food release periodically while thinning. That's how I've found my ideal geometry.
I am still not exactly sure what you all are cutting up that causes you such issues.
In my opinion, if you don't like the way food is releasing from your knife then you have two options.
1. Think about using a different tool to complete the task at hand (a mandoline or food processor attachment is sometimes just the way to go and that is okay)
2. Modify your knife by adding convexity to improve its food release (any knife, not just big tall fat ones)
Here's a video showing what I mean
In my opinion, if you don't like the way food is releasing from your knife then you have two options.
1. Think about using a different tool to complete the task at hand (a mandoline or food processor attachment is sometimes just the way to go and that is okay)
2. Modify your knife by adding convexity to improve its food release (any knife, not just big tall fat ones)
Here's a video showing what I mean
Weird apple indeed.
Man I love this thought. "Goodness over time" is my new goal instead of "perfect today." Well said.
DavidPF
Likes Boring Knives
I've studied the knife I have now, according to what's being said here, and I have a strong feeling that I know exactly how it was made. Except for the edge's curve up to the tip and the spine's curve down to the tip, the entire knife from the bolster forwards appears to be literal straight lines from point to point, programmed into a CNC machine. My knife is a real-life build of an unmodified schematic diagram. The manufacturers never bothered to turn to "Chapter 2: Grinds" in their "How To Knife" textbook, so it's a wedge grind with a wedge-shaped distal taper. I can say it's entertaining to look at, imagining the generations of accumulated knowledge and experience that this blade has nothing whatsoever to do with.
I bought it because I needed a knife.
Now I have it, and I've discovered I still need a knife.
I bought it because I needed a knife.
Now I have it, and I've discovered I still need a knife.
I've studied the knife I have now, according to what's being said here, and I have a strong feeling that I know exactly how it was made. Except for the edge's curve up to the tip and the spine's curve down to the tip, the entire knife from the bolster forwards appears to be literal straight lines from point to point, programmed into a CNC machine. My knife is a real-life build of an unmodified schematic diagram. The manufacturers never bothered to turn to "Chapter 2: Grinds" in their "How To Knife" textbook, so it's a wedge grind with a wedge-shaped distal taper. I can say it's entertaining to look at, imagining the generations of accumulated knowledge and experience that this blade has nothing whatsoever to do with.
I bought it because I needed a knife.
Now I have it, and I've discovered I still need a knife.
You can fix it. There are no perfect knives. You only really need the convexity in the 10mm behind the edge. Start thinning so you are hitting 10mm behind the edge consistently and then gradually move the focus of your finger pressure toward the edge. Deburr at a little higher angle yet. And you will add convexity where the knife really needs it. This also makes sure you get rid of any factory shoulders. All of my knives get this treatment. I never have issues with food release or wedging.
...But but but, I have the perfect knife?
...For me!
Wakui Hairline, It's like it was built for me. Everything about that knife is like someone asked me what I want from a knife and then made it. Profile, grind, weight, balance, f&f, heel hight, tip, thinness behind the edge food release, performance, it all is blends into a perfect knife for me. And for 200€??? You gotta be kidding me!
Except the steel. It's great for White 2 (not my preferred steel), but SKD would be better. But in this thread we're not talking about the steel, we're discussing thinning, grinds and food release and that's where it shines for me.
Edit. Thank you Preizzo!
...For me!
Wakui Hairline, It's like it was built for me. Everything about that knife is like someone asked me what I want from a knife and then made it. Profile, grind, weight, balance, f&f, heel hight, tip, thinness behind the edge food release, performance, it all is blends into a perfect knife for me. And for 200€??? You gotta be kidding me!
Except the steel. It's great for White 2 (not my preferred steel), but SKD would be better. But in this thread we're not talking about the steel, we're discussing thinning, grinds and food release and that's where it shines for me.
Edit. Thank you Preizzo!
Could you still manage to do that you think with a knife that's quite thin behind the edge OOTB, but with a sticky laser-ish V grind? Since you don't have tons of steel to play around, it seems difficult. Not that I'd know of another way for these. I usually worked on knives that needed the thinning to start with. Always used compound bevels as the technique I learned first and know how well, but always wondered with differential pressure points and levels to create convexity on very thin edges... Thanks for any further insight!
I would use a slightly higher grit, so you are removing the metal slower. It will help you make sure you ate doing exactly what you want with the precious little steel you have to mess around with.
That's for sure. Still when already needle like behind the edge there's little room for anything but convexing at the very edge a bit, which I suspect won't make a world of difference if any.
I think it may actually help a bit. It won't make it worse at least.
Nope and interesting to try! I never truly met such a knife - usually those cheap V grinds aren't particularly thin behind. More of a theoretical wonder.
Yes, I believe that a lot of the benefits of convexity don't require a thick blade or extra wide bevels. If you a have laserish knife with a very flat v-grind (I give the Kanehide as an example) you can add convexity to it and improve food release by thinning behind the edge, getting rid of the factory shoulders, convexing the path to the apex, and applying some form of a microbevel/high angle pass/kippington style deburr to finish.
You strop a straight razor to smooth out the teeth, but partly to add some micro-convexity as well. Here the goal isn't food release but the idea of allowing the blade to glide over the skin and cut the hair but not the skin is done through essentially micro-convexing with the strop.
Micro-convexing will not have the same affect as all of the crazy versions of s-grinds and such, but it can really make a difference. And for knives that are chippy because their bevel angle is too small, adding a little micro-convexing can be enough to strengthen the bevel without having to do a full on more traditional micro-bevel.
DavidPF
Likes Boring Knives
I should say (if it wasn't clear) that this is a supermarket knife.
I may just have a poor grasp of what you're saying, because my mind often fails to draw 3D pictures correctly, but I think maybe I do know what you're saying and actually don't get how it could work. If there was a choil shot of this knife (there's a fat bolster in the way), the entire choil shot including the spine would literally be one continuous wedge, a plain unrelieved V - there is no surface at a right angle to the spine anywhere, no concave area, no convex area, just wedge. If I aimed to hit 10 mm above the edge, I would necessarily also hit the spine at the exact same time, and regrind the entire surface.
I theoretically could gouge that 10 mm zone near the edge so that part of the knife becomes a narrower wedge than the rest... ? In my hands, this would just take it from Probably Bad, to Embarrassingly Bad And Ugly Too.
Oftentimes the things necessary to improve performance do not add a whole lot to the aesthetic value of the knife.
tostadas
Hobbyist / Craftsman
I doubt that its a true flat grind from the apex to the spine. If that were the case, then there is not really anything you could do to thin. More likely, its fairly flat until 1-2mm behind the very edge, where you have your primary bevel. I could be wrong, but it would help if you had a photo of the edge.
DavidPF
Likes Boring Knives
My photo skills are terrible, but I just verified that it is lay-a-straightedge-on-it-no-daylight flat. (Until the rolling sharpener's edge kicks in
)Note: I thought "maybe my straightedge wasn't straight", so I found the straightest thing in the house, the edge of a new 50-mm-length Japanese disposable razor blade, and the knife really is flat flat right to the edge.
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tostadas
Hobbyist / Craftsman
My photo skills are terrible, but I just verified that it is lay-a-straightedge-on-it-no-daylight flat. (Until the rolling sharpener's edge kicks in
But like stringer said, there is still a bevel at the very end of the knife. You can create your convex from apex to 10mm, because currently it should not be flat between those two points.
Even if the grind is totally flat, it’s completely possible to add convexity. If you want a lot of it, you can start sharpening with a super low angle, like 1 degree more than flat. That’ll decrease the height of the knife, but it’ll also cut in a new bevel, which will give you some convexity.
But if you want just a bit of convexity, which you probably do, remember that metal is removed primarily where pressure is applied. So if you put the whole flat grind right on the flat stone, it’s true that you’ll scratch up the whole knife, but if you keep your finger pressure near the edge, you’ll remove more material there, slowly converting the flat grind into a convex one.
But if you want just a bit of convexity, which you probably do, remember that metal is removed primarily where pressure is applied. So if you put the whole flat grind right on the flat stone, it’s true that you’ll scratch up the whole knife, but if you keep your finger pressure near the edge, you’ll remove more material there, slowly converting the flat grind into a convex one.
DavidPF
Likes Boring Knives
I'm confused by this - the current non-flat area (bevel) is around 1 mm. It is just like the example pictures given with "don't skip thinning behind the edge, or this is what you'll get".
tostadas
Hobbyist / Craftsman
I assume the black is what your blade looks like. Red is where you can apply a slight convex from apex to 10mm
DavidPF
Likes Boring Knives
This makes sense to me - something like this would be messy and approximate at first, and gradually take better shape. It's asymptotic, or some other related cute term.
Well, a scratched-up but somewhat improved knife will be worth it, and if it ends up scratched-up and also worse, it's no great loss.
DavidPF
Likes Boring Knives
Thank you, you are exactly right and this makes perfect sense.
tostadas
Hobbyist / Craftsman
Just try to do it flat from apex to 10mm. Slight inconsistency from hand sharpening coupled with stones that may not be completely flat will naturally make it convex.
It's really more about finger pressure than angle precision. Here's a thread I did where I show how I approach it.
https://www.kitchenknifeforums.com/threads/sharpening-with-continuously-changing-bevel.45003/
https://www.kitchenknifeforums.com/threads/sharpening-with-continuously-changing-bevel.45003/
DavidPF
Likes Boring Knives
I have enough inconsistency to cause not just convex but pear-shaped.
But I'll try it.
Yes. I've done it on a Takamura.
Lol man exactly the knife I had in mind to buy and try. Thanks!
SeattleB
Well-Known Member
As a newbie, I'm a little unclear on this concept. We start with a 50mm tall knife with a 2mm spine that has a truly flat grind down to the edge. Then we're going to round the last 10mm to get convexity. It seems the amount of convexity will be measured in fractions of a millimeter. After all, how thick is the knife 10mm back from the edge? (Quick check with a calculator shows the knife would be 0.4mm thick). How much convexity can we put in that last 10mm? It would seem to this newbie that the amount of convexity would have to be more than that to affect food release.
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