single bevel sharpening

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natto said:
Yes, my point was about geometry. But anyway
[snip]
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Your comments on geometry were most helpful. It prevented me from grinding away at what I thought was a problem, but in fact wasn't. That kept me from creating a new problem.

I was at a point in the process where I was not able to make progress on a second bevel (or convexity) from lamination line to edge using finger placement/pressure alone. I got un-stuck using the suggestion from Fourty Ounce.

Hopefully that clarifies, Thanks again.
 
Next question ...

I think I have the bevel geometry about right. I am having some trouble removing all the roughness (micro-chips) at the edge. I have noticed that I can sharpen on a 1000 grit, feel an even burr, and remove it (ura with 8000 grit), yet the edge isn't clean. It is hard to even see the problem until I go to finer grit, so it's taking a lot of time. A microbevel doesn't remove it (because I wasn't going to make it more than micro). I have been over it 3 times already, and it may be improving. It is cutting cleaner each time. I haven't gone back to a courser stone because I was afraid of making it worse. Suggestions? Otherwise, I'll just keep going on this path until I get it. Latest picture below, but I don't really have a good way for you to see the rough edge, and anyhow, you know what that looks like.

20220321_132343_HDR[1].jpg
 
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noj said:
Next question ...

I think I have the bevel geometry about right. I am having some trouble removing all the roughness (micro-chips) at the edge. I have noticed that I can sharpen on a 1000 grit, feel an even burr, and remove it (ura with 8000 grit), yet the edge isn't clean. It is hard to even see the problem until I go to finer grit, so it's taking a lot of time. A microbevel doesn't remove it (because I wasn't going to make it more than micro). I have been over it 3 times already, and it may be improving. It is cutting cleaner each time. I haven't gone back to a courser stone because I was afraid of making it worse. Suggestions? Otherwise, I'll just keep going on this path until I get it. Latest picture below, but I don't really have a good way for you to see the rough edge, and anyhow, you know what that looks like.

View attachment 171015
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Are you alternating between the back and front when deburring?
 
Forty Ounce said:
Are you alternating between the back and front when deburring?
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Yes.

Almost always on 8000 grit for the ura. I used a 3000 once after the initial rework because the edge was worse.

For better or worse, I cleaned up the edge with microbevel, which I then polished. The microbevel is larger than I prefer (for single bevel). I think the knife can be used as-is for now. As I get more inspiration or ideas, I can see if it sharpens normally.
 
noj said:
I have been over it 3 times already, and it may be improving.
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That's good news.

Heat treat on the hard side not only allows micro chipping. The chips might indicate micro cracks. And cracks can grow further up. It's just one way to look at this compromised materal above the edge.

I checked this on my double bevel. It took some serious sharpening to get rid of this problem. Touch ups or usual sharpening didn't work. The knife is a Mizuno white 2, so nothing crazy hard.

Good news is, after removing compromised material the knife improved. My initial sharpening didn't remove enough material.

And Korin got a vid, mentioning ura sharpening and brittle edges.
Learn How To Sharpen: Episode 11 - Deba Basics
 
noj said:
Yes.

Almost always on 8000 grit for the ura. I used a 3000 once after the initial rework because the edge was worse.

For better or worse, I cleaned up the edge with microbevel, which I then polished. The microbevel is larger than I prefer (for single bevel). I think the knife can be used as-is for now. As I get more inspiration or ideas, I can see if it sharpens normally.
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It kinda sounds like you just have some residual burr left. This is a guess, ofc, since I can't check it out in person, but I'd keep going and see if it improves
 
natto said:
That's good news.

Heat treat on the hard side not only allows micro chipping. The chips might indicate micro cracks. And cracks can grow further up. It's just one way to look at this compromised materal above the edge.

I checked this on my double bevel. It took some serious sharpening to get rid of this problem. Touch ups or usual sharpening didn't work. The knife is a Mizuno white 2, so nothing crazy hard.

Good news is, after removing compromised material the knife improved. My initial sharpening didn't remove enough material.

And Korin got a vid, mentioning ura sharpening and brittle edges.
Learn How To Sharpen: Episode 11 - Deba Basics
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Dunno that I'd recommend that deba video.. Korin vids tend to not be great.
 
Forty Ounce said:
It kinda sounds like you just have some residual burr left. This is a guess, ofc, since I can't check it out in person, but I'd keep going and see if it improves
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I think so too. At least with a clean microbevel, now I can more clearly see what I am doing. Hopefully, the micro chips/cracks have been ground off. If they reappear, I will have to re-evaluate. I have been following Jon's (of JKI) videos.
 
What I seem to be seeing is and edge that is too fragile to hold up. I apply a microbevel (very gently). I see, maybe even feel, "microchips" after deburring on ura (tried 3 different stones on ura 8000 grit or more). Tried refining microbevel with different stones, and more deburring on ura. Tried a tiny bit more convexity near edge. When I say "microchips", what I usually see is a clean microbevel away from the edge, but as I turn the knife towards the edge I can see issues. I know that means the microbevel isn't perfectly flat, but it looks pretty good. The microbevel is about 40 degrees. The steel is supposed to be blue 2 [corrected, said 1].

[begin rant] Repeat .. repeat .. repeat. It's sharp, but can't get it clean. Even if I get it right, I am worried it may be to fragile to actually use. I can't have a knife that goes dull cutting paper, only to spend 20h to sharpen it again. [end rant] ;-)
 
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Lol, I understand. I got mine ground down to the edge, but it still had enough nicks in that edge I'll have to go back to the 220 grit stone for a while. Cuts well considering the edge condition and it's inherent cheapness.

An unstable edge on a new knife isn't uncommon, and if it ever met power tools during manufacture, the very edge can be either de-tempered or de-carbonized. More grinding away of the edge will fix that as you get to good steel pretty quick. This is also true for straight razors. Initial edge may fail pretty fast.

And grinding to the actual edge with a coarse stone or wheel at high pressure in hard high carbon steel will give you fits with microcracks until you grind the damaged steel off.

Straight razor users strongly recommend NOT using paper to test an edge, it's abrasive enough to make a straight uncomfortable just slitting a single sheet, so that may not be a good test for your knife. And then it may be a stressed edge and it's gonna fail repeatedly until you grind off the bad part -- sadly, on single bevel knives, that's a huge amount of work!
 
Well, it's had 2 mm ground off the edge before I even started on it. It came brand new out of box with a 2 mm frown (and other high/low spots near the edge). I sent it off to be professionally repaired. The frown was fixed, but it was so thick behind the edge, it was worse that useless. I have been doing more grinding of the edge now for 2 weeks. Not full time, but several revisions. I am starting at 1000 grit at this point.

I never actually saw it get dull cutting paper;-) As a kitchen tool, it's got to be tougher than that for my taste.
 
I agree, edges that chip really easily are not good for kitchen use. I have to be careful with my Tojiro DP paring knife, I've chipped it by twisting it by accident while slicing up orange skins to candy them. Big pain to grind out.

With that much ground off it may just not be a good example -- or it needs to be re-tempered to drop the hardness at the edge some.
 
noj said:
I can't re-temper it. Maybe just sell it.
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Buyer won't like it either. I've had to take 3 mm off a single bevel to get back to "virgin metal edge temper". What caused it during manufacture or afterwards I can't say, but the edge constantly fractured & flaked off.

It was a pain, but once I redid the final edge it cut fine. No, I'm not talking a literal razor edge, but it was great for cutting on a normal PP or Maple board.
 
noj said:
I have a new-ish single bevel knife, and a question on sharpening.

The knife, as new, was ground so badly, I sent it off for professional help. They did a good job of fixing the major problem: the entire flat section had a significant frown. It may have had other issues, but it was hard to tell with the frown. The knife came back with the frown gone, and nice flat surfaces (no concave spots).
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I have a question about this. Shouldn’t the flat side be concave with traditional knifes? It shouldnt be flat flat. Right?
 


Seems pretty close to your problem on a Suisin blade. I am aware that Sakai Takayuki (Aoki hamono) is different from Suisin (Junro Aoki & Son), but are they somehow related? Was the grind "error" intentional? Could there be something lost in translation somewhere, like their own style of hamaguri or something?

noj said:
I sent it off to be professionally repaired. The frown was fixed, but it was so thick behind the edge, it was worse that useless.
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I don't mean to knock anyone, but personally I would not send a complex job like this to a retail shop. Mate, how about sending your knife to CO? It'd be interesting what Yosuke-san can come up with...
 
Pisau said:


Seems pretty close to your problem on a Suisin blade. I am aware that Sakai Takayuki (Aoki hamono) is different from Suisin (Junro Aoki & Son), but are they somehow related? Was the grind "error" intentional? Could there be something lost in translation somewhere, like their own style of hamaguri or something?



I don't mean to knock anyone, but personally I would not send a complex job like this to a retail shop. Mate, how about sending your knife to CO? It'd be interesting what Yosuke-san can come up with...
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Thanks for the tip. The video was interesting too. I never heard of him before, and there are few references I found on the forum.

The original problem (new out of box) was a 2 mm frown across the whole blade, plus low (convex) spots at the edge, plus a (not very micro) microbevel on both sides. Yes, the ura had a microbevel. I could not evaluate too much of any hamaguri style, or even sharpen it. I did get the impression that it was very thick and convex behind the edge. Neither the retailer or Aoki hamono would help. I had it repaired where I did based on recommendations from the forum. Upon return, the frown was gone, but as I said, the hamaguri was very steep and thick near the edge. I was not able to sharpen it with that geometry, it didn't cut well with that geometry. In order to be useful to me, I need to be able to sharpen it with techniques I understand (ie Jon's videos from JKI). I suspect the geometry was original (vs changed when I had it repaired). I have no way of determining if it's some maker's style or not.
 
More questions .. and not signaling anything different from what I said.

I still don't know where the micro-chips at the edge post-sharpening are coming from.

What should the edge look like before applying a microbevel? It's effectively a razor edge, but I have never gotten it "perfect". Specifically, I can see shiny spots on the edge in bright light (after burr removal from ura work). Before the ura work, it's hard to be sure what I am looking at because of the burr.

What should I expect to feel while doing the ura? I have a couple stones of 8000 grit and above I have tried, all carefully flattened and clean. I try to use just enough pressure to keep the blade flat and not hydroplane. I get a sensation that feels a little rough. I could imagine bits of burr on the surface. Cleaning the stone and repeating doesn't change anything much. What is expected about water/slurry on the stone during the process? The first pass towards the edge acts like a squeegee.

I wonder if applying the microbevel is causing damage to the edge. I use a very light pressure; I can't imagine less, and still have proper angle and pressure control. Whether I use a 5000 or 8000+ grit didn't seem to matter. Is it correct to start at the final angle you want? That's what I have been doing. I can imagine steaking up on it, but I think I would get a wide round "less-micro" bevel.
 
noj said:
More questions .. and not signaling anything different from what I said.

I still don't know where the micro-chips at the edge post-sharpening are coming from.

What should the edge look like before applying a microbevel? It's effectively a razor edge, but I have never gotten it "perfect". Specifically, I can see shiny spots on the edge in bright light (after burr removal from ura work). Before the ura work, it's hard to be sure what I am looking at because of the burr.

What should I expect to feel while doing the ura? I have a couple stones of 8000 grit and above I have tried, all carefully flattened and clean. I try to use just enough pressure to keep the blade flat and not hydroplane. I get a sensation that feels a little rough. I could imagine bits of burr on the surface. Cleaning the stone and repeating doesn't change anything much. What is expected about water/slurry on the stone during the process? The first pass towards the edge acts like a squeegee.

I wonder if applying the microbevel is causing damage to the edge. I use a very light pressure; I can't imagine less, and still have proper angle and pressure control. Whether I use a 5000 or 8000+ grit didn't seem to matter. Is it correct to start at the final angle you want? That's what I have been doing. I can imagine steaking up on it, but I think I would get a wide round "less-micro" bevel.
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Have you checked the blade for straightness? The coarse feeling could be from it being bent.
 
Interesting. I set the ura on the backside of my Atoma, and there's at least 1 mm (could be 2, just eyeballed it) deflection away from the Atoma. I was careful to place the heel at the edge of the Atoma, so this isn't due to something funky near the handle.
 
noj said:
Interesting. I set the ura on the backside of my Atoma, and there's at least 1 mm (could be 2, just eyeballed it) deflection away from the Atoma. I was careful to place the heel at the edge of the Atoma, so this isn't due to something funky near the handle.
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Well.. that sucks. Good news though, I can fix that easily (again, no charge)
 
Forty Ounce said:
Well.. that sucks. Good news though, I can fix that easily (again, no charge)
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I appreciate your offer and this kind forum.

Years ago I got stuck with my first and only single bevel. Thought about this and that or buying another one. But the initial idea was to learn single bevel sharpening. So I'ld have been disappointed with having to send it out to repair.
 
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