Expected edge retention/how to tell you're sharpening correctly

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Benuser said:
In general, yes. Simply because a thicker edge requires more force, resulting in a harder contact with the board. In the case I had in mind, this isn't the case. The backbevel is sharpened to zero. The edge itself is what a lot of people would call a micro-bevel — technically it is not, due to the absence of a secondary bevel.
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Harder contact with the board is most likely part of it, but we see this phenomena of more acute angles staying sharper longer even when a machine cuts with the same force. I am sure there are special cases and maybe your case is that. In general we want as acute of an angle as the steel/heat treat can support without chipping or deforming for best edge holding. There is a discussion of this here Maximizing Edge Retention - What CATRA Reveals about the Optimum Edge - Knife Steel Nerds as well as in the later articles linked from this.
 
Barmoley said:
Right. That’s why harder contact with the board can’t be the whole explanation. I still think that even in your case your dulling mechanism is most likely not wear.
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With Sabs, it was. As with Herder C75 @60Rc. With stainless: rolling with 4116 and 19C27, microchipping with SG2.
 
captaincaed said:
Like I said I only have one so 🤷‍♂

I have heard a bunch of people say they're easy and I've been tempted to try another to found out if I'm nuts or not (probably yes)
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It was yu kurosaki. I ended up messaging the person that I sharpened the knife for, and asked him.

He did a great job on that knife.
 
That's why ya gotta love magnacut. Tough, able to get fairly hard, corrosion resistant, and on top of that, decently wear resistant.

If larrin gets around to making a stainless 10v (or maybe vanadis 8, since that seems to be a bit more balanced). I think I'll just make that my go to for everything.
 
The edge width of the dulled knives ist interesting also. High angles become dull with less edge width... - from the CATRA test. From my limited experience @Barmoley and Larrin are right. So I had to revise my "sharpening model".

Barmoley said:
This sounds like, assuming no wire edge and such, that your edge dulls due to chipping or deformation/rolling when you lower the angle. In such a case conservative angle would improve edge retantuon. As long as your edge doesn't chip or deform, lower angle would increase edge retantion.
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There have always been some people claiming lower angles to make edges last longer. It looks like they have been right in some cases, depending on the wear.

Benuser said:
Doesn't correspond to my experience. The best edge retention I can get is with a very thin blade combined with a very conservative edge that adds a lot to the edge's stability, especially with AS.
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I don't get it. Are these quotes controversial, or different views at the same topic? If you are close to your optimum, lower angles might lead to chipping or deformation. But what about incresing the angles further? Will that improve edge retention?
 
natto said:
The edge width of the dulled knives ist interesting also. High angles become dull with less edge width... - from the CATRA test. From my limited experience @Barmoley and Larrin are right. So I had to revise my "sharpening model".



There have always been some people claiming lower angles to make edges last longer. It looks like they have been right in some cases, depending on the wear.


I don't get it. Are these quotes controversial, or different views at the same topic? If you are close to your optimum, lower angles might lead to chipping or deformation. But what about incresing the angles further? Will that improve edge retention?
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Perhaps the context of my remark may clarify.
Screenshot_20220914-133848_Opera.jpg
 
Barmoley said:
Right. That’s why harder contact with the board can’t be the whole explanation. I still think that even in your case your dulling mechanism is most likely not wear.
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I would agree here. even with the Sabs and Herder I think it is possible that you might have rolling just at a much smaller scale. Rolling and abrasion are very hard to differentiate. I usually just depend on what I expect to happen and if the edge isn't chipping assume that that is happening. Given that you are getting rolling and chipping on steels in a similar hardness range. I think considering the issue as if these two rolled might shed a little more light on the problem.
 
Troopah_Knives said:
I would agree here. even with the Sabs and Herder I think it is possible that you might have rolling just at a much smaller scale. Rolling and abrasion are very hard to differentiate. I usually just depend on what I expect to happen and if the edge isn't chipping assume that that is happening. Given that you are getting rolling and chipping on steels in a similar hardness range. I think considering the issue as if these two rolled might shed a little more light on the problem.
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I have no problem in recognising rolling, thank you for your concern. Not sure the hardness was the determining factor.
No rolling, only wear Sabs 54, Herder 1922 60. Rolling Wüsthof 58, 19C27 60. Chipping SG2 62, and, forgot to mention Cromova 58. Non of those troubles AS 64.
P.S. Cromova managed to show both edge rolling, and chipping. The usual carbide clusters breaking out.
 
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Benuser said:
I have no problem in recognising rolling, thank you for your concern. Not sure the hardness was the determining factor.
No rolling, only wear Sabs 54, Herder 1922 60. Rolling Wüsthof 58, 19C27 60. Chipping SG2 62, and, forgot to mention Cromova 58. Non of those troubles AS 64.
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My point wasn't that you couldn't recognize it my point is that rolling on a very small scale is hard if not impossible to differentiate from wear without the use of some serious magnification equipment. Especially with a higher sharpening angle, the rolls could be tiny (on the scale of the low 10s of um) and thus could easily feel and look like a worn-down edge.
 
Benuser said:
Perhaps the context of my remark may clarify.
View attachment 198575
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I think this can actually line up with your experience(not that it necessarily does). Effectively by having a very thin blade you have reduced the maximum extent to which the edge can dull and the conservative edge keeps microchipping down. This sort of technique is something I have used in the past on steels with very low toughness to good effect. If you think of the scale a bit differently the grind of the blade could easily by <10˚ per side. So in a sense, you have the ultimate low edge angle and then micro it to add strength!
 
Brakedeezbohnz said:
I have pretty good cutting habits, I rock for mincing herbs but that's pretty much it. I use a bench scraper so I never scrape with the blade, no twisting, etc. The one time I've ever had microchipping was with a factory burnished edge through bacon that had a frozen spot in it.
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If that is all the micro chipping that you see that would be a clear indication to me that the knife can go thinner. 😆

I'm kidding but not really. It's all a balancing act. And if I don't see damage after a few shifts of hard work then I will know that the knife can handle a thinner edge.

Whittling hairs doesn't have much to do with whether a knife feels staying sharp going through produce. For basil chiffonade and slicing sashimi that kind of edge can be great. But for general western cuisine veggie production, geometry is king. Like they are saying above, thin geometry behind the edge is key to feeling sharp and staying feeling sharp. More important than whatever is happening right at the apex or how cleanly you can cut circles in tissue paper.
 
I actually bought another set of calipers because I lost my old ones to measure, think I'm at 1.16 mm at 10mm behind the edge but I'm going to measure more points.
 
Brakedeezbohnz said:
I actually bought another set of calipers because I lost my old ones to measure, think I'm at 1.16 mm at 10mm behind the edge but I'm going to measure more points.
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Where are you directly behind the edge?

In my mind 1mm 10mm above the edge, seems thickish, but not too terrible.
 
jwthaparc said:
Where are you directly behind the edge?

In my mind 1mm 10mm above the edge, seems thickish, but not too terrible.
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I just got off my 7th shift in 4 days, so I will measure after a nice long shower and some fried flounder.
 
jwthaparc said:
Where are you directly behind the edge?

In my mind 1mm 10mm above the edge, seems thickish, but not too terrible.
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What value do you generally shoot for on a thinner knife? I’ve been curious about this measurement lately since I was thinking about thinning a knife and took a few measurements to figure out what to shoot for.

At midblade, 10mm above the edge:
Shibata bunka: .87
Yoshikane 210: .96
Shiro Kamo 210: .96
Myojin 180: 1.14
Kamon 220: 1.2

The Shiro Kamo surprised me as it feels about as thick through food as the Kamon, nowhere near the Yoshi (or Myojin) which has the same measurement. And the Yoshikane and Shibata feel just about the same through food to me.
 
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