what is your strategy for assymetrical bevel formation? (heavy thinning)

[mikaelsan]

Hello, i have recently gotten a couple of new knives and fixed up some old, with some extensive thinning projects. i generally prefer this grind, as a righty, as flat as i can on the lefthand side preferably a shallow widebevel i am not nitpicky whats so ever so im not trying to be perfect. And as convex on the right as possible while stil being pretty thin on the right side.

What is your general strategy for establishing the convex bevel righthand side? Do you work from spine to tip, from tip to spine or go back and forward randomly till you are somewhat happy with the results? maybe something different. i tend to be left with too much convexing at the last 2-3 mm towards the edge instead of a more continues convex up the blade, and i go back and forward feeling the knife out but generally go from tip towards spine.

 

[panda]

multiple thinning sessions, there is natural wobble while hand 'sharpening' that leads to convexity. but generally after initial wide bevel thinning I then progressively go higher angles. at the end start rounding the shoulders.

 

[stringer]

For really intense stuff I do two minutes on each side with at least a five minute break in between. I always spend more time toward the tip and thin at a sharper angle. I make the heel chunkier. So I guess that is like reverse thinning. Fattening up. I work with the geometry of the knife as best as I can. I try not to fight it. A flat laserish grind I will focus on building microconvexity behind the edge. For something that is wedging, I will reduce convexity. It just depends.

Here's my latest thinning project. A big fat cleaver. It has a lot of forged in convexity that make it a wedge monster. So my goal is mostly in reducing convexity/ thinning behind the edge.

 

[Benuser]

For convexing I use a medium-fine Chosera 2k, looking for friction and correct facetting. From the lowest possible angle, moving the blade edge leading until I feel some resistance. That position gets one pass. Go back to the initial position, and repeat. After a few passes I have a smooth convex bevel, forming a continuous arc with the face.

 

[panda]

notice the lack of responses to this thread in a forum about knives

 

[mikaelsan]

multiple thinning sessions, there is natural wobble while hand 'sharpening' that leads to convexity. but generally after initial wide bevel thinning I then progressively go higher angles. at the end start rounding the shoulders.

Thank you all, this mostly resonates with me for the sessions I have at least. But all makes sense and I will try to digest it next time, I think I finished to my santoku for now think I ended up flattening the righthand side a little too much convex as it may still be. Well see I feel like I usually think I'm done till I have used the knife for a week or two and realise I'm not

Don't think I'm as much into the whole very classic chefs knive thick heel thin tip, but nice work on the cleaver stringer I only thinned two slicing cleavers in my time, and I distinctly remember feeling like I was sharpening a shovel. Oh yeah and 5-10 minutes will do nothing on my stones read a couple of books for my kid while doing a +1 hours session earlier hehe

 

[panda]

Thank you all, this mostly resonates with me for the sessions I have at least. But all makes sense and I will try to digest it next time, I think I finished to my santoku for now think I ended up flattening the righthand side a little too much convex as it may still be. Well see I feel like I usually think I'm done till I have used the knife for a week or two and realise I'm not

Don't think I'm as much into the whole very classic chefs knive thick heel thin tip, but nice work on the cleaver stringer I only thinned two slicing cleavers in my time, and I distinctly remember feeling like I was sharpening a shovel

you can blend it to make the convexing less aggressive.

 

[mikaelsan]

you can blend it to make the convexing less aggressive.

Thanks what I meant was the side ended up too flat, still convex throughout but too flat, wanted a little more aggressive convex think I may have had better results with your suggestion creating a wide bevel and blending/tuning it in from there. I'm still quite happy with how this one turned out though maybe not potato slayer but not the worst either

 

[refcast]

Partly, I think the lack of responses is also cause the question asked has caveats

If the knife is lefty ground and more convex in the left side (happens somewhat often on japanese forged double bevels), the there are three options I've done: (1) thin the left side, (2) grind the left side flat, (3) hammer to bend the knife to make it more right, which I don't necessarily recommend due to difficulty, (4) grind down the edge and resharpen only from the right side, then thin, which loses height and takes more labor and also not what I would necessarily recommend.

How you want to distribute the convexing is up to you. . . Different cutting feel vs food release. Just avoid flat blade faces that tend to stick, and edges that are too thick they wedge.

 

[panda]

while thinning it's really just a Rollercoaster ride. knife cuts a little differently after every session, lol.

 

[HumbleHomeCook]

while thinning it's really just a Rollercoaster ride. knife cuts a little differently after every session, lol.

I've found this to be especially true when you have the knife pretty thin and right around where you like it. I've done just a few bad strokes and felt like I totally messed everything up.

Still working on my proper convexing game for sure. It's pretty easy if it is already established and you're just following but creating and doing it right can be tricky.

 

[ethompson]

I intentionally created facets when doing coarse grit work so I can control convexity. Blend it all in on the second stone making a smooth clamshell surface. I find intentionally faceting rather than trying to blend as you go to give me more control over the final outcome.

Here for instance you can see the scratch pattern up top, the scratch pattern down low showing the terminal angle into the edge, and the intermediate angle. Lets me keep track of where everything is on coarse stones until it’s time to blend together at 400-800 grit at which point it becomes a smooth surface.

 

[ethompson]

I intentionally created facets when doing coarse grit work so I can control convexity. Blend it all in on the second stone making a smooth clamshell surface. I find intentionally faceting rather than trying to blend as you go to give me more control over the final outcome.
View attachment 339628
Here for instance you can see the scratch pattern up top, the scratch pattern down low showing the terminal angle into the edge, and the intermediate angle. Lets me keep track of where everything is on coarse stones until it’s time to blend together at 400-800 grit at which point it becomes a smooth surface.

This has the added benefit of letting you use different grits in different areas to control abrasion speed too. In the above image I’m using 800 grit at the edge because the edge was extremely thin already then 200 higher up where I’m trying to remove a bit more material.

 

[KasumiJLA]

You know that you are a wizard @ethompson

 

[Seemore]

For convexing I use a medium-fine Chosera 2k, looking for friction and correct facetting. From the lowest possible angle, moving the blade edge leading until I feel some resistance. That position gets one pass. Go back to the initial position, and repeat. After a few passes I have a smooth convex bevel, forming a continuous arc with the face.

Could you possibly expand on that, or restate it, or better yet show a short video or even a small series of still photos? Especially “From the lowest possible angle, moving the blade edge leading until I feel some resistance. That position gets one pass.”
This sounds sensible and straightforward, but I cannot quite picture it. Thank you.

 

[Seemore]

I intentionally created facets when doing coarse grit work so I can control convexity. Blend it all in on the second stone making a smooth clamshell surface. I find intentionally faceting rather than trying to blend as you go to give me more control over the final outcome.
View attachment 339628
Here for instance you can see the scratch pattern up top, the scratch pattern down low showing the terminal angle into the edge, and the intermediate angle. Lets me keep track of where everything is on coarse stones until it’s time to blend together at 400-800 grit at which point it becomes a smooth surface.

If you still have that blade in that condition (stage of maintenance), could you photograph it from a little further away for context? The scratch pattern gives the optical illusion of a raised plateau in the area I marked, which of course it is not. Thx.

 

[Benuser]

Could you possibly expand on that, or restate it, or better yet show a short video or even a small series of still photos? Especially “From the lowest possible angle, moving the blade edge leading until I feel some resistance. That position gets one pass.”
This sounds sensible and straightforward, but I cannot quite picture it. Thank you.

Perhaps you're familiar with the trick to find the sharpening angle with an unknown knife: moving the edge edge-leading on cardboard, leather, whatever, while raising the spine, until it bites. The sharpening angle should be a tad lower.
Here the same idea, but starting with an almost flat blade, on a stone, applying no pressure at all, even retrieving weight. Move it edge-leading while raising the spine little by little, until you feel some resistance. It's a mini-shoulder you want to abrade. A single stroke should do. Go back to the initial position with a flat blade and repeat. It's a way of blending the facets. With a simple carbon steel, only a few strokes will do to have a smooth, convex bevel.

 

[Seemore]

Perhaps you're familiar with the trick to find the sharpening angle with an unknown knife: moving the edge edge-leading on cardboard, leather, whatever, while raising the spine, until it bites. The sharpening angle should be a tad lower.
Here the same idea, but starting with an almost flat blade, on a stone, applying no pressure at all, even retrieving weight. Move it edge-leading while raising the spine little by little, until you feel some resistance. It's a mini-shoulder you want to abrade. A single stroke should do. Go back to the initial position with a flat blade and repeat. It's a way of blending the facets. With a simple carbon steel, only a few strokes will do to have a smooth, convex bevel.

I can see it - thanks very much.

 

[ethompson]

If you still have that blade in that condition (stage of maintenance), could you photograph it from a little further away for context? The scratch pattern gives the optical illusion of a raised plateau in the area I marked, which of course it is not. Thx.
View attachment 339692

Not an illusion actually - thats another, softer facet I put in

 

[Benuser]

One more suggestion:
With strongly asymmetric knives, it's good practice to have the right bevel convexed and flushing with the face. The left one a straight one at a much higher angle. All to balance the friction on both sides and somewhat reduce steering. Especially important if the user comes from strictly symmetric blades.
When someone has got used to asymmetric blades, and easily compensates by the position of his wrist, you may consider convexing the left bevel as well. First, by removing the shoulder and thinning a bit.