The last of the photos for now. Just thought I'd get a picture up before the patina.
This is the "before" thinning pic
After ..
![20230201_081632[1].jpg](https://cdn.imagearchive.com/kitchenknifeforums/data/attach/212/212701-20230201-081632-1-.jpg "20230201_081632[1].jpg")
![20230201_081707[1].jpg](https://cdn.imagearchive.com/kitchenknifeforums/data/attach/212/212702-20230201-081707-1-.jpg "20230201_081707[1].jpg")
This is the "before" thinning pic
After ..
thinning questions (yet another thread)
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I did a round of work on my H. Togashi Nakiri 180 in W1, and it made a big difference. Ever since new, and several sharpening's, the edge wouldn't hold up in use. Not even after adding an edge leading microbevel. It sat in my penalty box untouched for about a year. After 2 rounds on a course stone, I made that problem go away - finally. I did a bit of thinning. Looking at the edge bevel size, and blade convexity, it could go further if I decide to. Still, it is much improved in cutting resistance. The grind still strikes me the wrong way. The very end of the blade (from spine to edge) has a 3 mm area that is thicker than the bevel right behind it, and I still haven't gotten rid of all of it. The other oddity is the spine had a distal taper (or maybe a simple straight taper in the upper 1/3). However the taper is in the spine, but the thickness at the shinogi line doesn't change (so it's thicker there than at the spine). Also, caused by that or not, it was distinctly thicker BTE towards the tip, which I mostly fixed now. Keeping the shinogi straight with the lumpity-bummpity in the cladding was mission impossible.
Very interesting. I recently thinned an old Gengetsu and it has the same concave area on the blade face (between spine and shoulders). Also the thickest area is right in the middle (lengthwise and heightwise), which I believe is the "bulge" you mentioned.
Of course it came with great F&F so these features only became apparent when I started thinning. I remember Jon saying somewhere that this bulge is common with J handmade knives.
OK, guess I won't sweat it and ruthlessly murder vegetables instead. The thinning improved that a lot!
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I tried a relief bevel on my nakiri, and like the result in the kitchen, but had a question (which may be more applicable to say gyuto, but still relevant).
The questions are:
1. Is the edge angle typically the same from heel to tip? I am sure there will be personal preferences.
2. Assuming the edge angle is the same from heel to tip, is the relief bevel also the same from heel to tip? **
3. If you use a variable edge angle, I imagine it's a variable relief bevel as well, correct me if I am wrong.
4. How do I judge my results, besides vegetable murdering ability? For example, I used a pretty constant edge angle of 14 degrees, and relief bevel of 7 degrees. That said, the sudden taper at the tip suggested (intuition and/or ** I guess) a lower angle for a relief bevel. How clear should the distinction line be between the flat, relief, and edge bevels be? My result looks like a very fast, but smooth convexity from wide bevel to relief bevel, and a crisp edge bevel.
Thanks in advance.
** If the knife has a distal taper, the wide bevel angle changes from heel to tip, and that has to be accommodated, if I was polishing (a different topic). Yet it seems an interesting question because it affects the width of the relief bevel, if I understand the geometry correctly.
The questions are:
1. Is the edge angle typically the same from heel to tip? I am sure there will be personal preferences.
2. Assuming the edge angle is the same from heel to tip, is the relief bevel also the same from heel to tip? **
3. If you use a variable edge angle, I imagine it's a variable relief bevel as well, correct me if I am wrong.
4. How do I judge my results, besides vegetable murdering ability? For example, I used a pretty constant edge angle of 14 degrees, and relief bevel of 7 degrees. That said, the sudden taper at the tip suggested (intuition and/or ** I guess) a lower angle for a relief bevel. How clear should the distinction line be between the flat, relief, and edge bevels be? My result looks like a very fast, but smooth convexity from wide bevel to relief bevel, and a crisp edge bevel.
Thanks in advance.
** If the knife has a distal taper, the wide bevel angle changes from heel to tip, and that has to be accommodated, if I was polishing (a different topic). Yet it seems an interesting question because it affects the width of the relief bevel, if I understand the geometry correctly.
I wasn't sure if those comments were for overall thinning, vs relief bevel, or if the authors make a distinction. My question was specific to a relief bevel.
If that was unclear, I was making a distinction between relief bevel and overall thinning based on replies here:
https://www.kitchenknifeforums.com/...aper-sharp-to-paper-towel-sharp.63779/page-10
The example: edge sharpened at 15° per side, ... setting a bevel of 10° behind it
makes me think the relief bevel is different than thinning the entire wide/convex bevel.
Relief bevel is thinning directly behind the edge, roughly 5-10mm from the edge.
Thinning is removing material from pretty much the whole blade face, laying the knife flat on the stone, or almost all of it, depending on the knife and goal.
Thinning is removing material from pretty much the whole blade face, laying the knife flat on the stone, or almost all of it, depending on the knife and goal.
And regardless of what bevel you’re talking about (kireha, relief bevel, primary bevel, microbevel), as soon as there is a change in the width - i.e. unless the top reference edge of the bevel is of constant width - then either the height of the bevel or it’s angle has to change to create a constant apex.
That was my general understanding.
Still feeling utterly lost.
Maybe my 4 questions above would help?
In other words, got knife in front of me that's too thick behind the edge. I want to start with a relief bevel. What do I do? After I start doing it, how do I judge it's correctness I can adjust to make it better?
Maybe my 4 questions above would help?
In other words, got knife in front of me that's too thick behind the edge. I want to start with a relief bevel. What do I do? After I start doing it, how do I judge it's correctness I can adjust to make it better?
Sorry, I am not sure I can parse exactly what you are saying.
The heel of my nakiri is so flat and thin it's hard to create much width to a relief bevel, whereas there's more thickness and convexity as I approach the tip. This would make it hard to create a constant width relief bevel, and I would have to pretty much grind away all the original maker's design to change that fact. But I don't know if that (relief bevel width) is even a concern. Totally lost.
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I think a lot of knives you can buy are not made to be thinned, or more precisely, lot of knives design don't care about maintenance and future thinning and resharpening.
Still, even if most blade design could be : distal taper at the spine from handle to tip, even distal taper at shinogi from like 2.5 to 1mm, same height of wide bevels parallel to edge. It doesn't mean all knives should be absolutely made this way.
In the case of your nakiri, it looks like it is inverted and you got a thinner heel part and a thicker more convex tip part. It could be absolutly not made on purpose but it could be made on purpose to give more weight at the tip
So if you want to thin that knife and keep the spirit of the maker design, just follow his design and get you heel part a little bit thinner but still flat, and your tip part a little bit thinner but still thicker than the heel and more convex.
Don't like it ? Well change it and start where you think there is too much material and grind the tip for a flatter, thinner geometry. You would like the heel convex?, well make it convex but as it is where there is less material on the knife, be ready to grind a lot the all knife and to get a smaller knife at the end.
Hope it helps.
@milangravier ’s answer above is more articulate than I could manage, and great advice.
I was just trying to make the general axiomatic point that changes in blade width are an important factor, and you may not want to be fixated on a constant angle depending on the context. Sorry if it added confusion.
Thank you for the detailed reply.
Would be interested in knowing what to do (see my 4 questions) with a more typical gyuto. By "what to do", I am just asking about a relief bevel on a new-ish knife that has never been thinned. Probably, doing it because the edge bevel is getting too thick. So, not polishing, making major repairs or changes.
With regards to the nakiri, it has no distal taper at all: 2.5 mm at the shinogi. The thickening is happening because as the edge sweeps upwards (from middle of blade to tip), the shinogi does not. I feel inclined to leave the heel alone, and make the shinogi follow the shape of the edge. Good, bad, neither, I don't know. It's a lot of work. Should I even bother with a relief bevel on the nakiri now? Good, bad, neither, I don't know.
Which ever knife I use, I am not sure about relief bevels. Should I be grinding at a constant angle (like 10 degrees)? Should I be grinding to achieve a particular bevel (scratch pattern) width, and or geometry? Maybe it depends, but on what I don't know. If it does depend, I don't know how to adjust for whatever it is, or what to look for.
No apology needed. Just trying to understand. Thanks for the reply.
Can you share a photo of the knife, perhaps reflecting a regular series of stripes e.g. Venetian blinds so we can gauge the contour? It sounds like the grind is backwards so of course this is going to be frustrating.
Btw, others will correct me if I’m wrong, but I have the impression that while the notions of relief/back vs edge/micro bevel are well defined under a guided system, freehand sharpening tends to be looser, like jazz, and at the extreme a hamaguri approach just convexes the whole thing anyway.
Nonetheless, as Picasso said, you must first be able to draw a horse the normal way, and I am still working on getting enough angle control to snap to the flat spot, the flat bevel, while freehand.
So far I am comfortable taking a knife whose face goes pretty much all the way to the edge, and putting a 1–2mm wide bevel on it. Some call this “thinning the shoulders” and it helps with carrots. But there’s a definite convexing there, which I tell myself doesn’t matter as long as the edge microbevel is more keenly structured. With some knives I have finished on a Sharpmaker to get that 15° assurance. Just one or two strokes.
What sharpening setup are you working with?
Nonetheless, as Picasso said, you must first be able to draw a horse the normal way, and I am still working on getting enough angle control to snap to the flat spot, the flat bevel, while freehand.
So far I am comfortable taking a knife whose face goes pretty much all the way to the edge, and putting a 1–2mm wide bevel on it. Some call this “thinning the shoulders” and it helps with carrots. But there’s a definite convexing there, which I tell myself doesn’t matter as long as the edge microbevel is more keenly structured. With some knives I have finished on a Sharpmaker to get that 15° assurance. Just one or two strokes.
What sharpening setup are you working with?
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1. Mostly yes. Everybody can do what they want of course ! but in my mind when I grind and polish an edge, I want to make it strong enough and consistent so the steel can hold its shape. Looks like about 15 degrees is working well with most hard steels, this angle (so 30 degrees total) will keep its shape for some time and that's the idea. We make tools so they can be efficient but also so they can be efficient for a certain amount of time. If you sharpen, to 15 degrees at the heel and go thinner at the tip, like 10 degrees : you will have a sharper edge there (a more acute angle) but the steel won't be able to keep than acute shape for as long as the angle you put at the heel. So in the end you're wearing your knife not evenly.
2. Sorry I am not really good on the concept of relief bevel : so if you have one, your knife is made with primary bevels (the general geometry of the knife), the relief bevel (about 10/15 degrees), then a final bevel (or micro bevel I guess, about 20 degrees). In that case, I would make both of them consistent. Relief bevel is your main edge so you want it consistent because 1. and your micro bevel is consistent too because 1. too, it will be just a bit stronger to help even more the steel to keep its shape.
I generally sharpen (meaning the all geometry) my knives with a primary edge (wide bevels) which is flatter surface and acute angle toward shinogi, and a convexity starting before the edge (which could be some kind of relief bevel I guess, but it is blended). At the heel my general angle is about 6 degrees, at the tip it is about 3 degrees. What angle is the convexity before arriving to the edge I don't know but average maybe 8 degrees. This convexity is starting higher at the heel (about 1/3 or 1/4) and will be lower the more it goes to the tip, finishing at the tip at about 1/15 of the wide bevel (it is all blended so this is shematic). This convexity is going to zero. Then I will make an edge (or microbevel) to reinforce the knife : about 15 degrees both sides.
3. you can do what you want. The main primary bevel (wide bevel) is made of variable angles (that's a fact on 99% of the kitchen knives). You could put a variable relief bevel, and why not a final edge with variable angles too (so all angles are following global geometry) but as said for n°1, I would keep my last edge consistent and same angle because it is there not for the global geometry of the knife but for the steel to get a sharp shape that it can hold at the edge. For relief bevel (if you get my description at n°2), it is also consistent with no variable angles (yet because it is convex it is more subtle) with my way of doing it. The fact that my convexity (relief bevel) is starting higher at the heel and lower at the tip, means that it is mostly consistent and just follow the thickness and geometry of the wide bevel.
4. There is more than one question here ! For me two most important things to judge : vegetable murdering ability (that what most knives are made for normally) + the capacity to maintain that geometry and wear the knife evenly through its lifetime (that is mostly rare among knives). If you have great time cutting things in the kitchen + your knife wears evenly + can be sharpen and thin with ease and consistence = well what do you want more ?
4bis : how clear should be the distinction etc ? In my case I do a blended surface from flat to relief (using convex surface) then I make a distinct even crisp edge so the knife can hold its shape mostly but also thanks to that edge I can play with different edge textures from very toothy to very smooth.
This should be a sticky somewhere… great post
Thanks so much for the detailed and thoughtful reply!
My primary use case at the moment is for a newish knife who's geometry is good, but just has been sharpened enough to make the edge bevel a bit wide. Perhaps a starting point might be less about rigid angles. Maybe start by reducing the edge bevel width using a few TBD degrees more than putting the blade flat on the stone, but checking so the scratch pattern isn't across the whole blade. Whether that's 3 mm or 10 mm or whatever, I guess depends on what needs reduction. Maybe then blend that change smoothly into the existing blade geometry. I don't know if I am keen about adding a fixed/constant new angle into a nice convex shape. If that's crazy, let me know, else I need to ponder a bit, and try some things before asking more of you.
If you are asking about the nakiri, the flat bevel is scratched (from thinning) stainless, and not reflective. I can get some measurements (I have a caliper now), and end/choil shots, if that would help?
I think I may be more comfortable with your thinning the shoulders, along with convexity, than grinding a fixed/constant relief bevel angle.
I sharpen freehand, and sometimes listen to jazz.
