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

N

Naftoor

Joined
Oct 29, 2015
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Hey friends!

Hopefully this is the right place for this question, but here we go. So I managed to snag my first CPK (yay!), a UF2 specifically. Outside of some cheapie moras, this is my first real fixed blade. I tend to be a kitchen and folder guy so not much fixed blade experience. The thing is a gorgeous monster, fit and finish is beyond reproach.

I figured a feather stick was a pretty good way to break it in. 20 or so cuts into a pine 2x4 (nothing near knots) I noticed there was some edge deflection. No chips, but noticeable under the pad of the thumb and caught the light pretty good. I spent 30-40 minutes stropping on a stone that veers towards fine/extra fine and got most of the damage out, but I was wondering if anyone happens to have any advice or tips and tricks for using fixed blades to avoid it in the future.

Thanks!
 
Naftoor said:
Hey friends!

Hopefully this is the right place for this question, but here we go. So I managed to snag my first CPK (yay!), a UF2 specifically. Outside of some cheapie moras, this is my first real fixed blade. I tend to be a kitchen and folder guy so not much fixed blade experience. The thing is a gorgeous monster, fit and finish is beyond reproach.

I figured a feather stick was a pretty good way to break it in. 20 or so cuts into a pine 2x4 (nothing near knots) I noticed there was some edge deflection. No chips, but noticeable under the pad of the thumb and caught the light pretty good. I spent 30-40 minutes stropping on a stone that veers towards fine/extra fine and got most of the damage out, but I was wondering if anyone happens to have any advice or tips and tricks for using fixed blades to avoid it in the future.

Thanks!
Click to expand...

That shouldn't happen. Is your knife made with D3V steel? My DEK1 is D3V steel. When I was building one of my benches with the 2X4 Basics workbench legs, there was a hump on the polymer, or whatever it's made of, that needed to be removed so that the 2X4 piece would sit flush in one of the legs.
I used my DEK1 to cut it off. The hump was about 1/4" wide and about an inch long. I had to put a lot of force into it to cut that stuff, and my knife slipped 4 or 5 times and slammed into the side before I finally got it cut flush with the bottom. That stuff is a lot tougher than a pine 2x4. There was no damage to the edge at all and it would still push-cut printer paper after I finished.
And I cut that polymer after I had already re-profiled the edge to a flat-V grind. So, the factory convex grind should be even tougher to deform - at least I would think so.
So, my guess would be that there's something that went wrong with the heat-treat on your knife.
Here's a photo of one of the benches that I built. This one is my Firearms/Knife Bench.

2x4 Basics-workbench-1a.jpg
 
Edge damage on 3v in pine is hard to imagine - especially D3V. Without pics it’s it unimaginable. People have put these knives though hardwood , plastic , nails , concrete without edge deflection.

Most wood - all you need is a strop to get back to hair popping sharp.
 
with great respect, a rounding and a rolling of the edge isn’t really edge damage if it did not chip. That’s just use. And, if it did not chip (you describe it as deflected - I’m assuming there’s a rolled edge and a little burr) then you should be able to knock off the burr or wire edge in 30 seconds or less with any grit stone or strop. Stropping on a stone that long could also round an edge. You might try marking the edge with a sharpie permanent marker and making sure you are applying the work where you need to mold the steel. Marker will then come off with isopropyl alcohol if needed. This is my experience and not a comment on yours. I’m sure you and CPK will sort it out. Good people and good product. can we get some feather stick photos?
 
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in my experience, knives almost always lose their factory edge fairly fast during use like you describe.

Trying to make a feather stick from a 2x4 is a little bizarre, compared to what someone would usually use, but I'm not slamming it or anything. It's just a lot of leverage needed to get into kiln dried lumber of that dimension- pine or otherwise-, to make controlled diagonal cuts and requires a fair amount of energy to just hold on to the wood itself which can affect your ability to maintain efficient angles and whatnot. Also, construction materials can have all sorts of abrasive shit stuck in it. So, a fair amount of lateral strain is probably the big issue from what you describe, but fortunately the fix is easy.

Don't strop the knife- run the edge along a ceramic rod in a cutting motion, edge forward. All the little machining/abrasive ridges along the edge will gradually polish out over use and with regular light maintenance. Your edge will actually get more durable over time. A lot of people talk about a toothy edge, and it's great for slicing things, but it breaks down quicker under load like with wood working.
 
That isn't normal at all. Our focus has been on edge retention through enhanced edge stability and your knife can feather stick an entire 2X4 to shreds with very minor wear and ZERO observable (with eye or touch) edge damage.

I'm not doubting your story. I'm just very surprised by it.

I'm very confident in both the heat treat and the edge geometry. We have reliable processes in place to assure those things are correct.

In my mind, the most likely thing to have happened is one of two things. It not impossible that you have made an error somehow and unknowingly have run the edge across a hard object such as an embedded stone in the wood. And it's not impossible that we may have made an error when sharpening your knife and I failed to remove all of the wire edge.

We sharpen at low speed under flood coolant to preserve the edge from heat damage. This is done on a belt grinder. At first it is edge leading, which minimizes wire edge but the belt bunches up slightly ahead of the edge which leads to a somewhat blunt edge. Then we reverse the belt and go edge trailing which makes for a sharp edge but it also creates a wire edge. I then stone a micro bevel. It is possible your knife may have received more edge trailing sharpening than normal and I may have failed to remove all of the wire edge. This would be exceptionally uncommon but it is the only way that I can think of that whittling pine would cause ANY edge deformation at all. Your knife is capable of whittling a lot harder material than pine with zero edge damage.

If you could return your knife for a replacement, I will run it through some tests here and publish what I find.
 
I had this happen on my FK2 while digging out a broadhead from a partially frozen, rotted log. There were a few spots where the edge had flattened slightly but as Lorien said, a quick 2 minutes on the Sharpmaker and the edge was back. Since that day I’ve field dressed deer, hacked through some 1” branches and it’s seen other use at camp and in the field with no issue.

I’ve seen this happen on other knives as well so it doesn’t bother me much on the first few uses, I know it’ll hone out easy.
 
Jsega51 said:
I had this happen on my FK2 while digging out a broadhead from a partially frozen, rotted log. There were a few spots where the edge had flattened slightly but as Lorien said, a quick 2 minutes on the Sharpmaker and the edge was back. Since that day I’ve field dressed deer, hacked through some 1” branches and it’s seen other use at camp and in the field with no issue.

I’ve seen this happen on other knives as well so it doesn’t bother me much on the first few uses, I know it’ll hone out easy.
Click to expand...

Again, a frozen rotten log should be no problem at all. A dirty muddy log or a log with an embedded stone would be different. We should have high expectations here, but we need to have reasonable expectation also. If you hit a stone or even just a bit of grit (knowingly or otherwise) you're going to pick up some damage.

I had a customer once who complained his skinning knife wasn't sharp when he went to process his kill. I came to find he'd been using a steel tailgate as a cutting board and had blunted the edge. Sometimes people can cause damage to the edge without realizing it. I'm very sensitive about the quality and performance of our product and this sort of situation keeps me up at night.



Edit:

I'm not saying that "it's your fault". I'm saying that you should consider the possibility that something happened to your edge that you didn't realize. Because this steel and this heat treat and this manufacturing process have been exhaustively tested, refined and proven (in competitions and otherwise).

Since the advent of the Delta protocol there has never been a CPK shipped with a problem with the heat treat. We have a handle on that and I'm confident saying that it has never happened. The same is true for the edge geometry. However I'm sure it is possible that some wire edge has slipped through. I appreciate the feedback and I will investigate this further.
 
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Naftoor said:
Hey friends!

Hopefully this is the right place for this question, but here we go. So I managed to snag my first CPK (yay!), a UF2 specifically. Outside of some cheapie moras, this is my first real fixed blade. I tend to be a kitchen and folder guy so not much fixed blade experience. The thing is a gorgeous monster, fit and finish is beyond reproach.

I figured a feather stick was a pretty good way to break it in. 20 or so cuts into a pine 2x4 (nothing near knots) I noticed there was some edge deflection. No chips, but noticeable under the pad of the thumb and caught the light pretty good. I spent 30-40 minutes stropping on a stone that veers towards fine/extra fine and got most of the damage out, but I was wondering if anyone happens to have any advice or tips and tricks for using fixed blades to avoid it in the future.

Thanks!
Click to expand...
Did you buy it directly from CPK or get it second hand?
 
Hey all! Sorry, didn’t expect this to blow up this way.

I should clarify I’m not saying anything about the knife or the steel, I believe both are exceptional and was assuming it was me being an idiot with poor technique! I have no reason to suspect the heat treat, I know these guys get batch processed so I figure if something had happened to a furnace during the heat treat it would be seen on other knives, obviously this seems to be highly unusual thus why I suspect it’s just me messing something up.

I definitely agree that a 2x4 isn’t exactly prime featherstick material, I was frankly excited to test the knife and had been watching a few too many bush crafters so so I grabbed what was on hand. Took one cut and when it occurred so easily I got carried away and continued for a dozen or two more.

Regarding the edge rolling, good to know it’s normal, thank you Tim! My background is mostly in kitchen knives where edge rolling is normally followed by chipping since they use much more brittle steels and heat treats in many chefs knives that can’t handle the plastic deformation long term. I used a hunk of jade ( a pretty slow stone to begin with) finished to sharpen at probably about 1-2k grit equivalent. I said stropping but I should probably clarify it was maybe 30% edge leading and 70% edge trailing strokes to try and realign the edge.

I was able to remove about 75% of the area that’s reflecting light, and it no longer can be felt under the thumb pad. I’ll try to attach a picture of the remaining area and the offending wood. In the side profile of the knife, my index finger is located at the rolled section. The lumber is pretty clean stuff, it’s been sitting in the basement for 5-6 years at least, worst it’s been exposed to is me (failing) to use it as a test for a reseated drill press chuck.

Not sure if I can upload pics without gold so here’s an imgur upload in the interim.(
https://imgur.com/a/cq9Q6rA
)

It was purchased new unwisefool, I’ve realized I am far, far, far too slow to grab CPKs on the secondary 😅
 
Naftoor said:
I should clarify I’m not saying anything about the knife or the steel, I believe both are exceptional and was assuming it was me being an idiot with poor technique!
Click to expand...


No! You're missing my point! You're not an idiot and poor technique is not a problem. We'll see bent bevels on thin choppers from poor chopping technique where a novice user slaps instead of cuts or gets a turn in a wonky hit but that's not what is going on here. There is no amount of poor technique that would cause a rolled edge in this knife from cutting pine. I'll post a video of what I'm talking about. I'll beat the shit out of one of these in pine and you'll see what I'm talking about.

Naftoor said:
I have no reason to suspect the heat treat,
Click to expand...

Sure you do! What you're seeing is not normal and one of us made a mistake. While it's possible that at some point you hit something hard with your knife and didn't notice it (with thousands of users out there, that's going to happen) it's also entirely possible that I left a wire edge on there. I try to always be through, and my process gets tested frequently and this isn't a common problem, but it's possible.
 
I just shot a video of some knife abuse. Exact same knife pattern, it came out of the same heat lot of steel and heat treat and probably even sharpened in the same batch. So this is as close to a twin as we're going to get. I just beat the shit out of it in some pinewood just to demonstrate that there is pretty much no amount of abuse that the knife won't tolerate if the medium is pine.

So I figure there is either a wire edge (which is unlikely but possible) or there was something in the wood that damaged the edge.

The video is uploading but it's going to take an hour
 
Nathan the Machinist said:
I just shot a video of some knife abuse. Exact same knife pattern, it came out of the same heat lot of steel and heat treat and probably even sharpened in the same batch. So this is as close to a twin as we're going to get. I just beat the shit out of it in some pinewood just to demonstrate that there is pretty much no amount of abuse that the knife won't tolerate if the medium is pine.

So I figure there is either a wire edge (which is unlikely but possible) or there was something in the wood that damaged the edge.

The video is uploading but it's going to take an hour
Click to expand...
What music did you set it to?
 
Thank you for all of your responses Nathan! It’s definitely a relief to know the knife can handle more then what I threw at it. I’ll sharpen it out and am looking forward to years of good work with it =D The only thing that surpasses the amount of knowledge you share with other knifemakers on the forums and the build quality of this knife is your customer support, can’t wait to own many more CPKs!
 
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