single bevel sharpening

[noj]

[snip]

Thanks for sharing your experience and advice. I might not be terribly patient, but I do meter out my efforts. I can understand what you are saying about the thickness at the heel. There was no way I could get the edge in contact with the stone with finger pressure alone; I had to lift the blade. This was true for the whole blade, except near the tip, and worse at the heel. The original "sharpener" made the knife with a big fat frown in it, so my trust in their work is limited;-) I am not quite sure what to do with the idea about convexity near the heel. Maybe not grind that out flat?

 

[SilverSwarfer]

Thanks for sharing your experience and advice. I might not be terribly patient, but I do meter out my efforts. I can understand what you are saying about the thickness at the heel. There was no way I could get the edge in contact with the stone with finger pressure alone; I had to lift the blade. This was true for the whole blade, except near the tip, and worse at the heel. The original "sharpener" made the knife with a big fat frown in it, so my trust in their work is limited;-) I am not quite sure what to do with the idea about convexity near the heel. Maybe not grind that out flat?

I had thought there was some professional intervention, post-frown?

RE: the heel, probably best to ignore the idea altogether! I was trying to offer an alternative possibility/explanation.

 

[noj]

I had thought there was some professional intervention, post-frown?

RE: the heel, probably best to ignore the idea altogether! I was trying to offer an alternative possibility/explanation.

You are quite correct, I had the frown removed by a professional sharpener. I didn't ask them to change the bevel geometry, so I am guessing they just followed what was there.

My impression of the bevel as brand new is that it had this problem. It didn't feel right when cutting. When I tried taking it to a stone, it was such a mess, I couldn't say what I was dealing with:

https://www.kitchenknifeforums.com/attachments/ground-toward-edge-jpg.168845/
Then I put it on a flat surface, and saw the frown.

 

[SilverSwarfer]

You are quite correct, I had the frown removed by a professional sharpener. I didn't ask them to change the bevel geometry, so I am guessing they just followed what was there.

My impression of the bevel as brand new is that it had this problem. It didn't feel right when cutting. When I tried taking it to a stone, it was such a mess, I couldn't say what I was dealing with:

https://www.kitchenknifeforums.com/attachments/ground-toward-edge-jpg.168845/
Then I put it on a flat surface, and saw the frown.

This pic reminds me of a couple Kitaoka K-tip yanis that I worked on a couple years ago... I found those 2 blades had pretty sloppy blade roads straight out of the box. You're most likely right: this knife had QC issues before the 1st owner introduced it to stones.

 

[noj]

This pic reminds me of a couple Kitaoka K-tip yanis that I worked on a couple years ago... I found those 2 blades had pretty sloppy blade roads straight out of the box. You're most likely right: this knife had QC issues before the 1st owner introduced it to stones.

Ha, yes! That first owner was me. The picture is the knife brand new out of box, and all I had done was magic marker and a few swipes on a 1000 grit to see what I was dealing with.

 

[SilverSwarfer]

How's the ura?

 

[Bolek]

All that is just for curiosity as I do not have the level to re profile a single bevel. Why do you blend the two angles in Himaguri sharpening ? Aesthetic, tradition or a function ?

 

[SilverSwarfer]

All that is just for curiosity as I do not have the level to re profile a single bevel. Why do you blend the two angles in Himaguri sharpening ? Aesthetic, tradition or a function ?

For me and my purposes, the primary benefit of hamaguri shape is enhanced food release. I suppose arguments could be made for all 3 reasons mentioned.

 

[noj]

How's the ura?

The ura looks fine. It lost a little after the frown was removed. I haven't had to touch it yet as part of my work so far, with one exception. When brand new out of box, they had a micro-bevel on the ura side, which I promptly ground off.

 

[Pisau]

This knife was awful from the day it arrived. Neither the vendor or knife maker would accept a return, or even "re-sharpen" it.

I once had a seriously damaged yanagiba,

Firstly, thanks for sharing your tales of woe fellas. I'm learning a lot. I'm also horrified by the level of customer service and terrified because thinning is inevitable someday. However, moving on... I immediately checked my relatively new yanagi and this is how a senior sharpener would leave his mark pre-honbadzuke, so this is stock ootb:

One more in opaque...

As you can see the whole blade road is convex but not much, notably on the jigane which is 4-7 mm from the edge (I am guessing where the thinning action should be). It's pretty much flat from the shinogi to the hazakai. The koba is like barely half a mm and there is not even an uraoshi. It's all migaki to the edge, I suppose he's leaving it up to you how to set it up...

Obviously this is just an anecdotal sample, but I can't help but be shocked by the level of the other "Sakai" blade!

 

[noj]

[snip]

Thanks for those pictures and detailed observations. What you described is about what I was expecting. Looking at the light reflection in the first photograph, the convexity appears both small and uniform. On mine, the curvature rapidly accelerates toward the edge. Yours doesn't have a perfectly flat area on the jigane, but close enough to be able to reach the edge and maintain an angle while sharpening with finger pressure alone.

For those interested, here's how the whole saga started ..

https://www.kitchenknifeforums.com/threads/expectations-and-experiences-with-new-blade.56068/

 

[noj]

Pictures and observations after an hour an 120 grit, comments welcome.

First, it's going to take a while to get rid of that thick convexity behind the edge, even with 120 grit. The stone loaded up a couple times.

The forward 1/2 - 2/3 seem to be going well. The width of the overly convex area (ie measured parallel to blade road) is larger near the heel. I might be having some issues with what to do in the first 1/3 of the blade from the heel.. If I place my fingers at even the a little from the edge, I hit the shinogi. If I place my fingers really close to the edge, I am concerned I may start grinding just near the edge before I am ready.

As I reach the forward 1/3, I can place my fingers over the hazakai and not hit the shinogi.

 

[psfred]

Those last two pics look a lot like the condition of my knife at the moment. I finally got out my much too soft "golden tiger" 220 grit stone and sacrificed a couple mm of it. With lots of mud and very little pressure (and lots of flattening) I'm about as close to the edge as you are. Mine is rougher, but so far only slightly convex with a steep bevel to the very rough edge.

Bought a couple stones today -- Naniwa "traditional" 220 in silicon carbide that is hopefully somewhat harder than my mud stone, and a Naiwa Green Brick to replace my blue synthetic aoto that has been glued together twice now.

I should be able to get the grinding done this weekend -- the mud from the 220 works wonderfully on my King Deluxe 300! Very gritty and very fast -- and it stays flat, unlike the 220 grit stone. I think you can rub grit off with your thumb on that stone, it's by far the softest one I've ever used, even worse that a Naniwa Superstone 220.

You will have to decide how much of that convexity you are willing to grind off this moment -- eventually you will get it all gone as you sharpen repeatedly, but I don't want to grind off steel without a good reason. If the knife cuts well with some extra convexity at the heel I'd leave it rather than grind a lot of steel off the rest of the blade and end up needing to restore the ura.

 

[noj]

Still working at it. The stones were a bit of a surprise. The Shapton Pro 120 is very slow to release grit. I could go a rather long time with what felt like 1-3 course rocks and nothing else under the blade. It worked quite well when I forced a slurry first though. As one might expect, the stone is very slow to dish. The Shapton Pro 340 (my next step) was totally different. It releases a sandy grit very fast. A pleasant contrast to the 120, until you look at how fast it dishes. At this point, I may be close to the limit of what I can do with the 340 grit and not eat into the edge. The dark spot near the heel is just a water mark.

 

[noj]

Hours on the 1000 grit, but I can't get to the edge. I cleaned it up a little to see what it looked like, but the edge is still ragged. The ura wasn't on the 1000 grit, obviously.

 

[Forty Ounce]

Hours on the 1000 grit, but I can't get to the edge. I cleaned it up a little to see what it looked like, but the edge is still ragged. The ura wasn't on the 1000 grit, obviously.View attachment 170210

You mentioned that lifting the knife would make the problem worse, but that's not the case. You'll need to carefully lift, just a tiny bit, to get rid of the large bevel just behind the edge and then lay it down a little and grind, then a little more, and grind more, til you have the geometry that you want. It's not easy, but that's how it's done.

 

[Forty Ounce]

This is for grinding a sword, but should give you an idea of how to grind in sections. Blend them together afterwards.

 

[noj]

You mentioned that lifting the knife would make the problem worse, but that's not the case. You'll need to carefully lift, just a tiny bit, to get rid of the large bevel just behind the edge and then lay it down a little and grind, then a little more, and grind more, til you have the geometry that you want. It's not easy, but that's how it's done.

Interesting. Seems to be different advice from what I heard/understood so far. What grit would you start the process based on where I left off? I have about 1 to 1.5 mm of unfinished area at the edge.

 

[noj]

This is for grinding a sword, but should give you an idea of how to grind in sections. Blend them together afterwards.
View attachment 170506

One question on the photo. After being ground in that way, can the knife be sharpened "normally"? My that I mean just using finger pressure near the edge to get a burr as shown in Jon's (of JKI) videos. I ask because the profile in the picture (as envisioned for a single bevel of course) gets increasingly convex near the edge. It was exactly that feature I was trying to remove because it couldn't be sharpened (as I understand it "normally"). There was no preferred angle I could achieve near the edge; I could get "any" angle depending on minor (and not easily repeatable) finger placement and pressure.

 

[Forty Ounce]

Interesting. Seems to be different advice from what I heard/understood so far. What grit would you start the process based on where I left off? I have about 1 to 1.5 mm of unfinished area at the edge.

Depends on how fast you want to do it and how you are on the stones. Coarse would be my preference, but if you do it wrong, you can do more damage than good. Keep in mind that when lifting that you don't lift too much. You should only be removing material down to the edge, forming a burr means you're going too far. This is assuming that you've already got a profile that you're happy with, otherwise you'd want to correct that before thinning.

 

[Forty Ounce]

One question on the photo. After being ground in that way, can the knife be sharpened "normally"? My that I mean just using finger pressure near the edge to get a burr as shown in Jon's (of JKI) videos. I ask because the profile in the picture (as envisioned for a single bevel of course) gets increasingly convex near the edge. It was exactly that feature I was trying to remove because it couldn't be sharpened (as I understand it "normally"). There was no preferred angle I could achieve near the edge; I could get "any" angle depending on minor (and not easily repeatable) finger placement and pressure.

That photo is not meant to be copied. It's just an example of how to grind in facets before blending.

 

[noj]

Depends on how fast you want to do it and how you are on the stones. Coarse would be my preference, but if you do it wrong, you can do more damage than good. Keep in mind that when lifting that you don't lift too much. You should only be removing material down to the edge, forming a burr means you're going too far. This is assuming that you've already got a profile that you're happy with, otherwise you'd want to correct that before thinning.

Thanks for all the interesting information and advice. I'll have to ponder what stone to start the next phase on.

Ian suggested using a course stone because you avoid having to hold a precise angle through many strokes. psfred said to be careful using a course stone in contact with the edge. With only 1-1½ mm of rough area left, it will be a delicate balance. I may start with a 1000 grit just to get the feel of the process, and correct mistakes before I remove much metal. If it needs more work, I can switch to a courser stone.

One last question before I start this phase. There is a small wobble in the edge where it should be dead flat. In this case, I mean holding the knife perpendicular to a flat surface (back side of Atoma plate) and looking for light from behind. I can't really measure it, but I would guess it's off by only a 1-2 mil (0.001 inch). The rough area at the edge isn't 100% uniform either, though much improved; it's wider in the middle part of the blade. Would it make sense to start with a very flat stone, and create a uniform and known high (angle = TBD) bevel, and correct some of the irregularity first?

 

[Forty Ounce]

Thanks for all the interesting information and advice. I'll have to ponder what stone to start the next phase on.

Ian suggested using a course stone because you avoid having to hold a precise angle through many strokes. psfred said to be careful using a course stone in contact with the edge. With only 1-1½ mm of rough area left, it will be a delicate balance. I may start with a 1000 grit just to get the feel of the process, and correct mistakes before I remove much metal. If it needs more work, I can switch to a courser stone.

One last question before I start this phase. There is a small wobble in the edge where it should be dead flat. In this case, I mean holding the knife perpendicular to a flat surface (back side of Atoma plate) and looking for light from behind. I can't really measure it, but I would guess it's off by only a 1-2 mil (0.001 inch). The rough area at the edge isn't 100% uniform either, though much improved; it's wider in the middle part of the blade. Would it make sense to start with a very flat stone, and create a uniform and known high (angle = TBD) bevel, and correct some of the irregularity first?

If this is your first single bevel project, I'd say just leave it and correct it later on. Since yanagi aren't used on the board in the same way that gyuto are, it's not crucial that the profile is perfect.. a little recurve is no big deal. It's fun chasing perfection, but it can be maddening.

 

[noj]

If this is your first single bevel project, I'd say just leave it and correct it later on. Since yanagi aren't used on the board in the same way that gyuto are, it's not crucial that the profile is perfect.. a little recurve is no big deal. It's fun chasing perfection, but it can be maddening.

Thanks. Not my first single bevel sharpening, but never had to re-grind the whole thing before.

I've thinned double bevels, but that's another topic.

 

[natto]

It may have been answered before, but I want to be sure I understand your ideas. Assume I flatten the entire bevel (shinogi line to edge). Should I set a second bevel from the lamination line to edge? If yes, how?

This only works if there is no taper. Please check the spine. My usuba only has about .5mm taper, hard to see with naked eyes. Edge and shinogi beeing parallel means the angle inreases a little from tip to heel. Flattening the whole bevel will move up the shinogi at the heel or shorten the bevel at the tip.

Please don't ask how I know.

 

[noj]

This only works if there is no taper. Please check the spine. My usuba only has about .5mm taper, hard to see with naked eyes. Edge and shinogi beeing parallel means the angle inreases a little from tip to heel. Flattening the whole bevel will move up the shinogi at the heel or shorten the bevel at the tip.

Please don't ask how I know.

Thanks, and I hope your usuba feels better now;-)

Yes, there is a small taper (I measured with micrometer just before the shinogi). I think that explains why the bevel at the heel was getting ground, as if something was amiss, and in fact it was. Thankfully, I now have a method (from member natto) to get the secondary bevel started, and I can hopefully steer clear of any further issues there. My shinogi is only 1 mm taller at the heel vs tip, so hopefully isn't noticeable.

 

[noj]

[snip]

I gave it (ie suggestion from member natto) a try, and it looks promising. I spent 90 min on a 400 grit. Sounds like a lot of time, but it wasn't all grinding. I went slow, used magic marker several times, examined, thought about the process and what I observed, etc. The rough junk is gone, looks like a gentle convexity from lamination line to edge. For the first time, I can apply just finger pressure and grind at the edge, and not scrape the shinogi at the heel, and it sounds "good" on the stone. I need a bit more work on the last 5 mm of the tip, and I'll see if I can finish the job. But I have had enough for today.

 

[natto]

You are pretty fast. thumbs up

Thanks, and I hope your usuba feels better now;-)

Thank you, I am fine with that trainig knife. My initial idea was to sharpen the bevel flat on the stone, you see? But my memory saves the moment I got it sorted out, not hours of grinding bad to worse. The topic is explained on a vid in the awesome thread.

 

[noj]

I gave it (ie suggestion from member natto) a try, and it looks promising. [snip]

Oops .. the suggestion from Fourty Ounce was the main one that was tried here. Specifically:

" You'll need to carefully lift, just a tiny bit, to get rid of the large bevel just behind the edge and then lay it down a little and grind, then a little more, and grind more, til you have the geometry that you want. "

Tips from natto used also.

 

[M1k3]

You are pretty fast. thumbs up

Thank you, I am fine with that trainig knife. My initial idea was to sharpen the bevel flat on the stone, you see? But my memory saves the moment I got it sorted out, not hours of grinding bad to worse. The topic is explained on a vid in the awesome thread.

Togitogi?