Edge damage from feather sticking with a UF2, tips for improving technique?

Nathan the Machinist said:
I grew up here and even I find this current humidity just staggering. There's enough moisture in the air you could almost swim. The local airlines are launching submarines now. I can't take a rifle with optics outside without the external glass fogging up. There is a real problem with condensation everywhere, I'm running big dehumidifiers in the house and the shop to prevent water damage. It's early in the morning and the dew point is already 70. It is staggering. Yeah, the grass is very green.
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Use that new sword or k18 to cut through the humidity and you will be fine.
 
I’m going with option C. Crucible makes tons of steel every year. There’s a possibility of a minute flaw in the making. There would be no way to tell until it was made, sharpened and used. Every CPK I own has been perfect in all aspects. Crucible can’t possibly make 100% of the steel right 100% of the time.
 
Gatorsbfd said:
I’m going with option C. Crucible makes tons of steel every year. There’s a possibility of a minute flaw in the making. There would be no way to tell until it was made, sharpened and used. Every CPK I own has been perfect in all aspects. Crucible can’t possibly make 100% of the steel right 100% of the time.
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.... I also don't think that's how that works


If it were a bad batch of steel I'd have caught it. And you're not likely to just have a bad knife if there was a problem.

Remember, I'm having the steel made for me and I'm buying the ingot. It's not like there is a mix of heats in there and I do test.

Fun fact: there was a batch of 3V made, years ago, that did not respond to HT the way it normally did and Dan, Guy and I independently noticed and this is where the development of the Delta protocol originated.

Also fun fact: I actually have returned a run of steel before because I didn't like it.

We're all always looking for problems. Dan, Guy and I talk regularly. Problems can occur so we do look for them.

There could always be a small hidden inclusion in the steel that slips through but it wouldn't manifest like that. I'm pretty confident the steel and the heat treat are good in that knife.
 
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Nathan the Machinist said:
.... I also don't think that's how that works


If it were a bad batch of steel I'd have caught it. And you're not likely to just have a bad knife if there was a problem.

Remember, I'm having the steel made for me and I'm buying the ingot. It's not like there is a mix of heats in there and I do test.

Fun fact: there was a batch of 3V made, years ago, that did not respond to HT the way it normally did and Dan, Guy and I independently noticed and this is where the development of the Delta protocol originated.

Also fun fact: I actually have returned a run of steel before because I didn't like it.

We're all always looking for problems. Dan, Guy and I talk regularly. Problems can occur so we do look for them.

There could always be a small hidden inclusion in the steel that slips through but it wouldn't manifest like that. I'm pretty confident the steel and the heat treat are good in that knife.
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How big is an ingot of steel?
 
pease said:
How big is an ingot of steel?
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I'm honestly not sure. The amount for a compaction is different than the amount for a roll. And there are losses. If I want a tweak to the alloy or a special particle size it would be a larger run but it isn't finished out from that size, they have to cut it. I typically take about 2,000 lb at a time.
 
murat1983 said:
I think at the beginning you said you are more into kitchen cutlery. But as you already know, outdoor fixed blades, especially the hard use ones have whole different sets of design criterias. You would get edge damage with what you were doing if you were using one of your superhard super thin kitchen knives. But with outdoor knives that is not the case unless you are using a knife with a very delicate grind such as zero grind scandi with acute bevel angles.
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Oh for sure! Most kitchen knife makers seem to be pursuing either a specific type of steel for the type, or chasing a single criteria like edge retention. If they do chase a secondary characteristic it’s normally something like “make the steel just soft enough it doesn’t detonate when it hits a pepper seed”. It’s refreshing when you do find one that’s trying to intentionally chase the performance that comes from picking two from the triangle of knife steel properties, although many of them get there pretty much accidentally by experience.

If I tried what I did with this knife with my kitchen cutlery; I think they would be removed from my home and placed in foster care with a local sharpener or knife shop. 🤣

Some updates here for the fine folks, I did another series of chops with the lower half of the blade. Interestingly it seemed to clear up the damaged edge from the second set of tests, and that section of the knife ended up sharper then it was on arrival, which definitely lines up with the idea of a wire burr being present. I didn’t mess with the larger rolled section so that should be unchanged. This little bird should be landing at home in the next few days, figured after opening this can of worms the least I could do is send it back so Nathan could confirm the issue and/or have stern words with the edge
 
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I hate dragging this old thread up because it's a wart on my reputation, but it isn't finished yet so here we are.

The owner of the knife in question was kind enough to return it and we took a look at it. I apologize for the two weeks it has taken me to go through the process. It arrived here in the shop right before we left for a weeks vacation (first time in years) and I was only able to start evaluating the issue before we left.

I finished today. I took pictures and video. Both suck but it's not for prime time.

The videos are uploading slowly so I'll put all of that stuff together for you later and give you the corn without the shucks now.



I could not duplicate an edge roll or flattening anywhere along the edge in pine, showing no edge deterioration beyond what was present on the knife at any point.

It looked completely normal in Osage Orange hardwood making some brutal peal out cuts. No roll, no flattening, perhaps some slight wear, but nothing visible without magnification. In contrast the damaged areas look like parking lots.

We carved aluminum (which many makers do) and couldn't find any problems.

We cut a 1/4" bolt and it looked normal.

After all of this (and including a bent primary from the bolt) the actual edge still looks pretty good with the most noticeable shine (the rolled flat spot) still the two areas that were present on the knife when I got it.


The very first thing I noticed when I first saw the knife was the nature of the damage reminded me of a knife from years ago that had grit in the sheath and the grit damaged the edge. The edge didn't look rolled, chipped or worn, it looks scraped. It's quite shiny as if the damage describes a facet or a plane which is not what rolls usually look like.

I drilled out the rivets and opened the sheath and did indeed find a pretty big piece of grit in an area that potentially could be a culprit. If it was the case, it would have started high in the sheath and then worked down after some contact creating the damage in at least two (and probably more) sheathing and unsheathing cycles.

This isn't remotely definitive and I'm not saying that's what caused it. But after a Rockwell hardness test and cut tests and finding no anomalies and being unable to worsen or reproduce the problem I don't have another theory.

The grit, which I photographed, was a tan beige color. We don't use that color in our shop (we don't use any abrasives on the sheaths at all) and the sheath maker uses a maroon colored abrasive. If that grit was the problem I don't know how it got there. It's likely a red herring.

I recognize that this outcome looks very much like the best possible outcome for me (there was nothing wrong with the knife) and I am not an impartial observer nor was any aspect of this a blind study so this is not a scientifically valid outcome, but it's the best I can do. I tried to duplicate the problem and I looked for wire edge and edge stability problems and couldn't find one and so I have to say I don't know what happened here, I can only speculate.





Once, when I was a little kid, I got a nice bicycle from a Schwinn shop. I was so happy and proud of that bike. Soon after getting it I noticed that the chain stay behind the chainring was all chewed up. I showed my mom and told her "look they gave us a defective bike and I'm scared it's going to break" so she brought it back. The owner (who would one day become a good friend of mine and I would become a mechanic at that bike shop) told her I was full of shit and a little liar and that I had done it. This is the man where I first heard the term "Jesus Fucking Christ!" which was pretty edgy for the late 80's. He was a real charmer. Over the years we bought more bikes from a different shop but it would be years before I ever returned to that shop.

As I became a more experienced cyclist, I learned what chain suck is. Now, here's the thing. I never noticed doing that to that bike and to this day I don't know if it was me (in my inexperience) or if it was a floor model that someone else damaged and I only noticed it after a day. I did learn that it was fine, it didn't matter.


I think this might be a similar situation where the end user may have created an issue and not recognized it. But I'm telling you, there was nothing wrong with that knife, but I do appreciate the problem being brought to my attention and being given the opportunity to view the issue for myself. A lot of people would have just said "meh, the edge stability they talk about is bullshit, that company is overhyped". Sincerely, thank you for giving me the opportunity to clear this up. My reputation is the most valuable thing I own. I'll post pictures and video later once it is loaded.

The owner will receive my gratitude for being good to work with and a shiny new knife and I encourage him to look at the edge when he gets it and cut some feathers with it {in some nice fresh clean wood} and then look again and confirm for himself that our edge stability is what it is supposed to be. No special cutting technique needed, go nuts, you can't harm it in clean pine.
 
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