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tk59
11-09-2011, 12:46 AM
I just picked up a knife to sharpen (from a pro) and I noticed a funny thing. The edge is bent to the left very nicely and evenly along the entire length of the knife. I've never seen anything like it. I lent this guy a knife before and it didn't happen to my edge (it wasn't a ton of use though). What could cause that sort of thing to happen? Is it a wire edge or just a very fine edge. I see no deformation behind the edge. It's just that tenth of a mm right at the edge that is folded over.

GlassEye
11-09-2011, 01:32 AM
I have seen what I think you are describing on a knife that was sharpened with a pull-through type device; it was a soft German blade. Maybe it was steeled too hard on one side? Do you know how the knife was sharpened/maintained by the owner?

memorael
11-09-2011, 01:50 AM
I was going to say probably a pull through sharpener. People who use those things tend to develop a strange pattern and end up usually with a gap on the heel since more force is applied there and an edge that points to the left since your arm naturally twists or opens up towards that side. Try to imagine the movement when done naturally and with a ton of force, and you should get a pretty clear picture of how it happened. If he doesn't use a pull through sharpener I have no god damn clue how it happened.

heirkb
11-09-2011, 11:30 AM
How could you tell the edge was folded over? I don't know if this is a wire edge, but seeing that flip is similar to what Dave describes in his wire edge test. I've never been able to see a flap of steel bent in one direction, but I'm not entirely convinced that it's because my edges are wire-edge free. More convinced that I just don't know what to look for.

Benuser
11-09-2011, 01:42 PM
Wouldn't a wire edge been situated exactly on the middle of the edge??

tk59
11-09-2011, 01:53 PM
Maybe I should clarify: The edge was ground on Japanese waterstones, afaik. After using the edge for a while (a few shifts?), it was handed to me. I ran my fingers along the edge. It felt dull. I then ran my fingers up and down the face of the knife. On side felt smooth. The other (left) felt like there is a little ridge at the edge where it is bent over to the left. Close visual inspection verified a surprisingly consistent and even ridge pointing sideways to the left of the blade. It doesn't straighten out with pressure from my finger but it re-aligned without a problem using a glass rod. Is that a wire edge?

Sarge
11-09-2011, 02:35 PM
Perhaps or just a very thin edge gone out of true. If the Rod moved it back it could be either but I'd say probably was more likely a thick wire edge than a really thin and untrue edge

JohnnyChance
11-09-2011, 02:40 PM
Does he use a steel at work? I would say wire edge, got dull, so he steeled it and pushed it all over to one side. See if you can un-align it again and push it back over to one side with a steel or rod.

Benuser
11-09-2011, 04:31 PM
A roll over as seen with soft Germans? That's still no wire edge.

Justin0505
11-09-2011, 04:33 PM
Does he scrape the board with the edge of his knife a lot? If he's right handed and sliding cut product away from himself to the right then it might be enough to roll a very thin edge on a soft steeled blade to the left.

NO ChoP!
11-09-2011, 04:44 PM
Sounds like the burr that can be raised when sharpening one side solely, without properly removing, or through even sharpening of the other side. Is the edge symmetrical?

I guy in my kitchen got a moritaka gyuto and sharpened one side only till it eventually got to the point that it just folded.

TK, aren't you usually the one we all go to with these questions? lol

Cadillac J
11-09-2011, 05:11 PM
What kind of knife is this (steel, etc)?

If it is a harder Japanese knife, I can't imagine the edge rolling without chipping...let alone uniformly. Sounds like a shoddy original sharpening job to me where the edge point is actually aligned on an angle. All I can think of based on the info. :scratchhead:

tk59
11-09-2011, 08:15 PM
Does he scrape the board with the edge of his knife a lot? If he's right handed and sliding cut product away from himself to the right then it might be enough to roll a very thin edge on a soft steeled blade to the left.Yeah, someone else mentioned that to me yesterday. That's seems like the most likely. It's some sort of Masamoto gyuto in carbon steel (maybe KS? it's not 100% obvious to me just based on profile. It's definitely been around a while). I'm still surprised it just folded like that all along the edge. I can't imagine the sharpening job was THAT bad since it wouldn't have been useable. I don't know how the guy maintains his knives aside from stones. It is also sharpened to what looks like about 10 deg on the right and close to 15 deg on the left and 60-40 based on bevel height.

Justin0505
11-09-2011, 09:09 PM
10 / 15 degdoesn't sound like a crazy thin edge, but it's also not very robust if he's scraping it across the board a few hundred times in between maintenance. I've seen some carbon steels that will roll or bend way before they break (like CCK's) and I wonder If he was just constantly rolling and straitening the edge on a high grit stone or rod if it would possibly fatigue even more over time / get weaker and weaker / roll more and more after each board scrapeathon.

memorael
11-09-2011, 10:00 PM
I would consider that a wire edge, a sturdy one but a wire edge nonetheless. Remember that post I did about taking your edge to almost 90 degrees on the finest stone you have and then re form an edge by grinding progressively to the angle you wish using the same fine stone? This is the problem I have since not had, not to mention the fact that my edges last a while longer... like a good while longer.

DevinT
11-10-2011, 12:16 AM
Tell Pesky to stop cutting stuff on top of the steel table. ha ha

Hoss

El Pescador
11-10-2011, 12:48 AM
Tell Pesky to stop cutting stuff on top of the steel table. ha ha

Hoss

Funny! I just bought some new glass cutting boards so this doesn't happen again!

JohnnyChance
11-10-2011, 12:53 AM
Funny! I just bought some new glass cutting boards so this doesn't happen again!

That will only cause you to shatter glass before hammering away on the metal table.

El Pescador
11-10-2011, 12:55 AM
That will only cause you to shatter glass before hammering away on the metal table.

good point. should I put something in between like packing peanuts?

tk59
11-10-2011, 02:59 AM
Looks like we might have a tweener. I would have said it was a thin edge that rolled but I think it might also be fair to say it's a wire edge, depending one where you draw the line. I'm disappointed Eamon and Dave haven't weighed in so we could get the definitive word, lol. Is there a gray area?

Dave Martell
11-10-2011, 01:12 PM
Sounds like a "maybe" to me. :D

Eamon Burke
11-12-2011, 04:14 PM
Somehow haven't seen this thread in a while!

I dunno how such a thing would develop through use and still cut anything...that is really strange. Strictly speaking, if the steel is fatigued, it's a burr, if it's not, it's a rolled edge. I'd certainly watch that guy work if I could and figure out what the heck he's doing

Dieter01
02-04-2012, 06:05 AM
So TK59... Did you ask him a few questions that might help answer this?

bieniek
02-04-2012, 08:55 AM
just grind your new edge on, strop as usual and do everything as usual. When your happy with the edge, drive it on side corner of your wooden board ot the angle of roughly 45 degrees for a few times with some pressure.

Did it changed anything? I do that now for me single bevels if not using microbevel. I also noticed it happened to my yanagi when I was lazy and didnt ground burr big enough for my liking. I dont know why didnt I, but then the edge failed.

tk59
02-04-2012, 12:04 PM
So TK59... Did you ask him a few questions that might help answer this?I did talk with him about it. It's still a mystery, lol. If I had to call it myself, I would say the previous sharpener was fixing some damage or something to the blade in a hurry, used too much pressure, went up in grit to polish it up and left a weak edge on it. How the edge ended up on one side seems like it would have to be a board scraping problem but he says he doesn't so I don't know.