I am unable to remover a burr from a knife. At first everything was great and I got a 11.5 degree bevel with Norton Crystolon and then did 12 degree angle with a ceramic rod following with few strokes on a paper loaded with Flexcut Gold on a glass surface as I always did. Then I checked that the knife cuts paper and was ready to call for the day but because of a new and extra bright lamp I noted tiny reflection of light at the very tip of the edge, which made me to do research to confirm my guess that this is a small burr. I got a ceramic rod and tried to remove it at a higher angle as Dr. Vadim Kraichuk advices but it was there no matter how hard I tried. To make the long story short I tried paper strop, leather strop Arkansas stone, ceramic rod, was raising the angle up to 35 degree - nothing helped! After about an hour of experiments I gave up!. I found that I can bend the burr with my finger from side to side and if I do it for a while it falls off as a tiny rope of half a hair diameter. But that is where the mystery starts: as soon as I do several passes on a leather strop the new burr develops on the same spot! I did not know that a strop can develop burr! This brings two questions: A) what I do wrong and what is the proper technique to remove the persistent burr and B) I clearly saw small metal shavings and metal hairs falling of the edge. If the burr is not removed completely I assume we eat it with the food which we cut. I routinely used a ceramic rod between meal preparations and it definitely made knives sharper. But it should also produce metal shavings which should end up in the food.I guess it is not the healthiest thing to do?
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Persistent Burr
- Thread starter Barmaley
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I had a Buck 119 do that to me. I would sharpen the knife and then the edge would crumble off in little slivers. Sharpen again... same thing. Increased the angle...same thing.
I think maybe sometimes a knife doesn't get heat treated correctly and/or gets way to hot when grinding.
I am no metallurgist or knife maker, so take my words with a pinch of "I have no idea on what I'm talking about".
I think maybe sometimes a knife doesn't get heat treated correctly and/or gets way to hot when grinding.
I am no metallurgist or knife maker, so take my words with a pinch of "I have no idea on what I'm talking about".
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Yes, you do know what you're talking about. I have had that experience before, and it only happens 'to me' when sharpening very cheap steel.
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I have a $9 Mossy Oak folder with 3Cr steel. If I try to get it sharper than about BESS 300, the apex crumbles.
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Don't undersell yourself my friend. That sounds exactly like what the problem could be. Sometimes after a being sharpened a few times, you get down to fresh steel and the issue can rectify itself. But steel not heat treated properly can cause this problem. And i definitely have no idea what i'm talking about.
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I'd also assume the steel near the edge is probably weakened by heat damage. Some knives will need a few resharpenings over time, to fully remove that weakened steel and get back into something more stable at the edge. I've also had some edges like this, which either flip-flopped back & forth under light pressure (thumbnail), and one that actually seemed to crumble into dust when it became thin enough to form a burr. In all cases, these problems were eventually fixed by sharpening away that damaged steel near the edge, over considerable time. I sometimes spent weeks or months doing this, putting the knife away for awhile after each resharpening. Have to resist the urge to give up or throw it out, and just be patient with it.
These days, if I found an edge like that, I'd probably draw the edge vertically (90° to the surface) across a coarse stone with some pressure, as if cutting the stone in half. If there's weak steel at the edge, most or all of it should get stripped away doing that. Then set a new edge from the beginning. It takes time in the near term to do this, but should save a lot of frustration over the longer run.
Similar behaviors can happen with knives in simple stainless that get 'steeled' regularly to maintain the edge. Steeling aligns a thin edge (sometimes abrades a bit too) by bending it into alignment. All that bending back & forth, over time, will work-harden the steel a bit. In the short term, that can be a good thing and the edge will seem to get a bit stronger than you'd expect. But eventually, the edge gets weak and brittle by too much work-hardening. And it'll become unstable in similarly weird ways, when that happens. That's the cue to scrub off the edge on the stone as described above and set a new edge.
These days, if I found an edge like that, I'd probably draw the edge vertically (90° to the surface) across a coarse stone with some pressure, as if cutting the stone in half. If there's weak steel at the edge, most or all of it should get stripped away doing that. Then set a new edge from the beginning. It takes time in the near term to do this, but should save a lot of frustration over the longer run.
Similar behaviors can happen with knives in simple stainless that get 'steeled' regularly to maintain the edge. Steeling aligns a thin edge (sometimes abrades a bit too) by bending it into alignment. All that bending back & forth, over time, will work-harden the steel a bit. In the short term, that can be a good thing and the edge will seem to get a bit stronger than you'd expect. But eventually, the edge gets weak and brittle by too much work-hardening. And it'll become unstable in similarly weird ways, when that happens. That's the cue to scrub off the edge on the stone as described above and set a new edge.
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If I find that problem I usually just reprofile the edge down a few dps to get to some good steel. I don't buy cheap knives anymore, so I don't see the problem much now. I just feel like if a knife isn't worth around $100, it isn't worth buying.
Thank you all. After additional research I concluded that it was the original knife's still what caused the problem. That was an old klever which I bought many years ago before I learned that knives need sharpening. I found it on the web: https://www.webstaurantstore.com/8-..._vAbA1mI33Obk9r4dUtEVo3vjp1Lv2hoaAmW7EALw_wcB
I tried other knives and that problem seems absent.
To wrap up persistent burr issue should I just give up on the burr removal from this cheap Chinese knife or I still can do something to completely remove the burr? The cleaver was very useful (ones or twice a year) to chop chicken bones and similar tasks.
However, it seems that nobody paid attention to the health problem, which I consider times more important than a dull knife. The wire shape burr looks ugly and dangerous. I am not a biologist by any means and I wonder if tiny sharp metal chips can make cuts and holes in our body tissue or our bodies have a protective mechanism against it? Should I worry?
I tried other knives and that problem seems absent.
Great point!
To wrap up persistent burr issue should I just give up on the burr removal from this cheap Chinese knife or I still can do something to completely remove the burr? The cleaver was very useful (ones or twice a year) to chop chicken bones and similar tasks.
However, it seems that nobody paid attention to the health problem, which I consider times more important than a dull knife. The wire shape burr looks ugly and dangerous. I am not a biologist by any means and I wonder if tiny sharp metal chips can make cuts and holes in our body tissue or our bodies have a protective mechanism against it? Should I worry?
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If the persistently hanging burr is the main concern, just set aside the blade for the time being. Use it for sharpening experimentation and/or practice. Some of the issues like this that I noticed with knives of mine were on inexpensive knives or old, well-used cheaply bought 'beater' knives (or hand-me-downs) that I was using for sharpening practice at the time. I just kept resharpening them periodically, sometimes to test a new stone I'd bought. After some time and all that extra sharpening, I noticed the edges became more stable and started behaving like I expect a 'normal', freshly-sharpened edge to behave. And that's after I'd also spent time thinning them out near the edge to improve cutting geometry. I got a result that made the edge cut better and last longer at the same time. That's when the 'lightbulb' came on in my mind and I realized it was all about removing bad steel. A very good lesson learned - and one that will never be forgotten.
I think it's extremely unlikely the blade will ALWAYS have this issue regardless of how many resharpenings it gets. Even cheap knives, or other knives that've been abused by overgrinding on powered equipment, can usually be resurrected at some point to behave like a decent knife should - at least in terms of being able to take a sharp edge. More often than not, it comes down to two things to get them cutting decently: (1) either thinning them out behind the edge, or (2) removing damaged steel near the edge. Sometimes it's both. I've been tempted to toss out knives over the years for issues like this getting in the way of making them decent slicers. But eventually I've been able to turn them around and make them usable.
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Yes, use it to learn from and gain more experience, every little bit helps. Things like this that are sent to test us and frustrate us are also good learning tools/curves.