Thinning, Grinds, and Food Release

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Blank Blades.

Blank Blades.

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So a recent thread got me thinking about food release a bit. What would the optimal grind to go for when thinning be? Convexed on both sides? Convexed on the right face flat on the left? Both flat? How convexed, if so? What difference does any of it make?

I have heard convexity aids in food release, while I would imagine the flat grind will help you slide through ingredients with ease. So that brings me to the topic.

What should a person go for if they want the best of both worlds?
 
depends on the rest of the knife.

in general convexity helps with release, yes. that said, my personal preference is for a knife to have some sort of concavity above the main flats, which I can then grind pretty much dead flat. I dont personally like maintaining or polishing heavily convexed knives, and my personal experience (and, I suppose, diet) allow for this.

I do not like the true lazer style full flat ground knives at all. maybe it's my imagination but I imagine the shinogi, whether it's really a hard one or just where you run into the Kurouchi finish, gives you enough help to let you grind the rest of the knife in a way I personally enjoy.
 
I prefer Yoshikane's style - reasonably thick spine, aggressive high grind with very thin convex. Food release in most situations is good. Can occasionally create suction, but I'll take that given the superb performance.

If maintenance is not a concern, double or triple hollow grind can be the best for both performance and food release.
 
Just based on food release as far as I know an s-grind is the most effective and what to aspire to(depending on the knife).
 
Flat grinds don't always reduce friction either. They can have a suction cup effect at worst. A gentle convex/hamaguri grind can help wide bevels as well. There are shades of difference between full flat and full convex too. Those are some of my favorites.
 
Stef said:
Just based on food release as far as I know an s-grind is the most effective
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Gotta put as many curves and ridges on the surface as possible!
EvsbU.gif
 
Kawa said:
This, and that other topic got me thinking about assymetry aswell...

I'd like to show a link. Please take a look at the choil shot.

https://www.japanny.com/products/ku...chef-knife-180mm?_pos=18&_sid=a078f9352&_ss=r
Does this make it a lefty knife?
Since if I turn it around and start cutting with my right hand, the flatter side is on the right/release side?
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Huh, it does look like the opposite of what I would be expecting for a right handed knife. Maybe it's the way it's being held that makes it seem to be more convexed on the left face.
 
jwthaparc said:
Huh, it does look like the opposite of what I would be expecting for a right handed knife. Maybe it's the way it's being held that makes it seem to be more convexed on the left face.
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Yeah, I thought of 'perspective' myself, but
The left side in the picure (or release side when cutting as righty) also seem to have a longer/higher flat.

Maybe someone knows this knife in real life?
 
I went ahead and increased the convexity of my tojiro 210 shiro gyuto to an asymmetric convexed edge. It's a bit hard to tell because it does get quite thin just behind the edge.
20210121_220341.jpg


Here is the right face before polishing. I will add another pic to show the finished product.
 

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And here it is off the kitayama, ready to go on the naturals.
20210121_232228.jpg

Here it is after the uchigumori, it was a bit of a rushed job, but good enough. I will likely touch it back up later, or move to my tenjyou suita.
20210121_233450.jpg
 
so I know I dont get the kudos of the full convex gang, but I do want to reiterate how great (relatively, I mean Im not sharpening on diamond plates here) flat bevels with concave flats can be. Im not going to say it's better, but if you've never tried it maybe take a look at the stuff coming out of Sanjo.

ease of maintenance doesnt hurt, either.
 
tcmx3 said:
so I know I dont get the kudos of the full convex gang, but I do want to reiterate how great (relatively, I mean Im not sharpening on diamond plates here) flat bevels with concave flats can be. Im not going to say it's better, but if you've never tried it maybe take a look at the stuff coming out of Sanjo.

ease of maintenance doesnt hurt, either.
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I'm just trying out what is available to me atm. I'm going to see how this full assymetrical convex goes. If I don't really like it, I can eventually back off the convexity.

I wish I had enough cash to try a lot of the knives I see here. I dont know how expensive the knives you are recommending are though. I guess what I'm trying to say, is one day I will give those knives a try. It just might not be anytime soon.
 
tcmx3 said:
so I know I dont get the kudos of the full convex gang, but I do want to reiterate how great (relatively, I mean Im not sharpening on diamond plates here) flat bevels with concave flats can be. Im not going to say it's better, but if you've never tried it maybe take a look at the stuff coming out of Sanjo.

ease of maintenance doesnt hurt, either.
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What do you do to make the flats concave?
 
JDC said:
What do you do to make the flats concave?
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well personally I dont.

the maker can though. several Sanjo area knives I own are like this; Mazaki, Hinoura, etc. even a cheap little Murata Funayuki I paid under 100 bucks for
 
If there's a line of knives and they all have hollow grinds, it's pretty safe to assume it's designed that way. if there's a line of knives that only one or two or few are known to having hollow grinds and the rest don't have it, it's probably safe to assume it's by accident.

If some part of the shaping of the knife is done with a grinder by the maker, it can easily leave some concave shape by accident. Mostly though I believe it's there by design.

I really enjoy the concave/hollow grind when it's well done.
 
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How do you guys see the term S-grind?

In conversations I see it's used in the same context as hollow/concave grinds quite a lot. And it does kinda fit as it kinda does make the S shape and maybe that's even an accurate assessment. but to me S-grind would be more like what Dalman does, when a hollow/concave part starts after the "primary" edge grind and that makes the S Shape in the grind. If that makes sense.

Also does it matter if the initial grind behind the edge is hollow or flat or convex. If after that there's a concave grind (Dalman style). Would it still be an S-grind?
 
JaVa said:
How do you guys see the term S-grind?

In conversations I see it's used in the same context as hollow/concave grinds quite a lot. And it does kinda fit as it kinda does make the S shape and maybe that's even an accurate assessment. but to me S-grind would be more like what Dalman does, when a hollow/concave part starts after the "primary" edge grind and that makes the S Shape in the grind. If that makes sense.

Also does it matter if the initial grind behind the edge is hollow or flat or convex. If after that there's a concave grind (Dalman style). Would it still be an S-grind?
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To me where to put the hollow and how many hollows to put is the question. I don't think the convex part in an S-grind is necessary from a purely performance point of view. Dalman did replace the convex grind behind the edge with concave grind on some of his knives. This dramatically increases the laserish cutting feel while the food release can be as good, if not better.

The problem is maintenance: how do you thin the knife? how much food release is left after consecutive thinning? Seems to be a dilemma.
 
Yeah, one thing I remember Carter saying makes a good knife is the ability for it to be maintained by the user. He made that statement arguing against serated knives (in most cases), but I can see it fitting here.
 
tcmx3 said:
well personally I dont.

the maker can though. several Sanjo area knives I own are like this; Mazaki, Hinoura, etc. even a cheap little Murata Funayuki I paid under 100 bucks for
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Hmmmm... Concave grind I don't see with Mazaki, nor Hinoura. Murata those I saw were heavily asymmetrical wide bevels, Hinoura does wide bevels, Mazaki is pretty convexed/shoulders rounded but still mostly a wide bevel - can distinctively see the planes in a choil shot. Some level of asymmetry for those two as well but nothing like that of Murata. Sanjo are not really known for doing concave, but for doing thick at the spine convex grinds.

Those who affectionate a good deal of concavity I know of offhand are Y. Kato and Kurosaki - most grinds I've seen.
 
ModRQC said:
Hmmmm... Concave grind I don't see with Mazaki, nor Hinoura. Murata those I saw were heavily asymmetrical wide bevels, Hinoura does wide bevels, Mazaki is pretty convexed/shoulders rounded but still mostly a wide bevel - can distinctively see the planes in a choil shot. Some level of asymmetry for those two as well but nothing like that of Murata. Sanjo are not really known for doing concave, but for doing thick at the spine convex grinds.

Those who affectionate a good deal of concavity I know of offhand are Y. Kato and Kurosaki - most grinds I've seen.
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I dunno what to say man. If I go pick up either my own Mazaki or Hinoura the flats above the bevels are distinctly not flat, but concave. On the Hinoura especially it's so noticeable as to be visible.

actually my Hinoura has some concavity on one of the bevels too but that appears to be more of a rushed grinding job than intentional lmao. not that it matters to me for <250 dollars

I should note for clarity Im talking about this bit here
1611345221611.png
 
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