It's here!!!! FK Destruction Video!!!

on_the_edge said:
I think Nathan is probably best qualified to answer this question. :)
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Agree - that's implicitly who I imagined I was directing that inquiry at :). That said, I'm interested in any opinions or speculations more educated than my own halfassed guesses!
 
While Nathan gets on with doing what he does best, I will make a couple of observations, if I may.

The ABS test is widely acknowledged by the Smiths themselves not to be an example of their finest performing work but rather a demonstration that you have mastered enough specific skills to qualify. To pass the 90° bend test blades are frequently (often? always? I’m not close enough to put an exact percentage on it) differentially hardened or tempered so that only the very edge is hard enough to actually hold an edge. The bulk of the blade is quite soft so that it can take the bend without fracture but that also means that it takes the bend without putting up much of a fight leaving you with an intact but very expensive hoof scraper. Many will clearly say that when making blades for sale and/or use they will fully through-harden their knives so that they are much (much) more resistant to taking a set and/or impacts to the spine.

So, given a widespread (but not universal it must be said) preference for a fully hardened blade that will take all the loads that can reasonably be applied to it in rationally conceivable use without folding like a new scouts tent in a stiff breeze, you could reasonably ask why did the Field Knife not come around like Nathan’s video of the Light Chopper? Primarily, because there was a lot less length of blade available to flex. I’ve had to jump around the video and try to pick the edited highlights because my connection means it would take me about a week to just watch the whole thing through from beginning to end but if memory serves there was something like 2” of actual blade sticking out from the vice when it was bent to failure. I can’t recall if Nathan fixed his lever/pipe on the same way, taking a lot of the handle out of the game, but assuming he did and that left 8” of LC blade to adopt the same curvature for the same load; 8” to 90° = 2” to 90/4= 22.5° while under the same torque. If Nathan’s bending amplifier actually attached further back on the handle then 8” becomes 10” or 12” or … you get the idea. So even if 2” is a bit of an underestimate, I expected a radical difference in the apparent results, pretty similar to what I saw. I know I am simplifying but I didn’t see anything that lead me to a radically different conclusion.

While I was hugely impressed by the effort that on_the_edge put in to do the work and to edit and upload it all for our benefit, and let me add my thanks to those previously expressed, I really wanted to know how long that pipe was and how much load it took to get the bend that he did. Maybe it was apparent somewhere in the video that I didn’t jump to. The fact that it broke where and when it did, that didn’t surprise me at all, but I would like to know how far that point was from any conceivable condition I could put it through. This is a much stiffer set up than the LC and since work = force x distance or torque x angle you have to put in a lot more energy to put the same load onto the more flexible set up. Something that is strong but stiff can seem to fail easier than an equivalently strong but more flexible alternative since you have to put more energy (not force, but energy) into getting to the failure load.

Hope that helps a bit.
 
The ABS bend test is done with a much longer blade. Typically 9 to 10 inch blade. In a virgin, unstressed bend test.
 
sandgrouper,
In answer to one of your questions, although I don't have the exact measurement at the moment, the pipe was @ 3.5' long. I can't tell you how much force I applied at the end of the pipe (where my hands were) to get the knife to break during the bend test, but I will say that while probably not impossible, it would take an exceptionally strong person intentionally trying to bend the knife in two to accomplish what I was able to with that lever. For 99.9% of the population, it is IMO a non-issue.

Sometime in the next day, I am going to post here some observations of mine as well as some of the reasoning for the tests I did and what I was hoping to learn from the tests. If anyone has any questions, they are certainly welcome to ask.
 
There's a good chance it might tolerate more flex than that had it not been wailed on with a ten pound sledge first, but this pattern will never flex to 90 degrees. Blades that flex that far are generally a soft spine, thin, or longer (flexed over a larger area).

The Light Chopper actually will do a 90, but it's longer and an HRC point softer.

The heat treat on the Field Knife balances ultimate gross toughness for edge retention. I bumped the aust temp to force some plate martensite (3V is usually mostly lath) in order to get that crisp edge that stays sharp in rough use without needing to be overly obtuse.

A person would be very hard pressed to break that knife without tools or a cheater bar, and it was made for cutting performance and edge retention more than just an indestructible rough use knife.


If I remember correctly, the genesis of this test was a thread a while back where someone was asking how much abuse this pattern would tolerate. I think the op did a great job documenting it.



edit to add:

In the video the knife took two big chips in the edge while being hammered into a thin steel plate. The op speculated the plate must be hardened. I will speculate the plate wasn't hardened, and in fact there may have been less damage had the plate been hard because the knife wouldn't have sunk as deep into it before the plate twisted in the vise.

The edge angle and thickness behind the edge is pretty thin to be used in that manner, but it will do it if you control lateral stress by keeping the cut straight. That vise is not strong enough to hold that plate steady. The plate needs to be backed up with something so it can't rotate like that, otherwise it's grabbing a bite of the edge then twisting it off.
 
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The last few posts have probably been the most informative that I've run across on any topic, on any forum, especially given the deceptively simple nature of the inquiry. Awesome stuff, fellas, and much appreciated.

Regarding the washer chip-out, I had the same suspicion: driving the edge into the washer caused the washer to rotate and effectively act as a shear working perpendicular to the edge. Cool to see that intuition validated.


Sent from my iPhone using Tapatalk
 
Thanks very much on_the_edge, that is exactly the context that I was interested in. As before, your efforts are greatly appreciated.

timichango - I have to say that Nathan's posts are, in my opinion anyway, the most consistently information dense and credible that I know of. This one on his testing methods back in 2011 stands out for me as a terrific example of how to not kid yourself, but he has other old threads that set the standard that others should aspire to. http://www.bladeforums.com/forums/s...eat-treat-edge-retention-testing?highlight=d2
 
I love Nathan's response to this (and that he offered up a knife for this abuse to start with). Let's face it - this knife suffered a complete series of flat out negligent misuse and abuse that no one would ever purposely inflict on a knife. And Nathan has a rational response about how it may have tolerated a little more, or fared differently if it weren't "wailed on with a ten pound sledge first." I love it! Like it needed an explanation at all!

It is staggering what these knives will tolerate. I can't conceive of any ordinary use, even extremely hard use that will touch this thing.
 
I'm kind of sad you had to break that knife... I was looking for a field knife for months without success and then this
 
Revolverrodger said:
I'm kind of sad you had to break that knife... I was looking for a field knife for months without success and then this
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Considering the test knife was a blem so not available for sale and was sent to Chris for the sole purpose of destruction testing, I think most of us would have been sad had he not gone to the extent he did.

Earlier several of us that had done some more realistic testing said there was no realistic knife related use that would break the knife, or even really damage it severely so someone was bound to take it to the extreme at some point.

Never fear, you will get an FK before too long. Just a few more days to the next sale, though this one is sure to be a fast one.
 
Revolverrodger said:
I'm kind of sad you had to break that knife... I was looking for a field knife for months without success and then this
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Not sure if this will make you feel any better, but I have tried many times and failed. I only have one Carothers, and that one is a Field Knife. My 15 yo biological son was so impressed with the abuse this knife took that I may end up giving him mine because I know that he will be able to rely on it for the rest of his life and that it will never fail him. His confidence in this knife may make a significant difference one day, though I hope he never finds himself in that position. That said, that would leave me with a grand total of ZERO Carothers knives. Unfortunate, but c'est la vie.

Keep trying. You never know--you might get one yet.
 
Some final thoughts...

Testing

Re the edge--

Outside of what obviously happened with the square washer, far and away, the frozen elk antler beam was the most difficult media to get through. Remember that the knife was frozen solid too when that test was done. I thought for sure that test would break something, sort of the irresistible force (knife) vs the immovable object (elk antler). Progress through the antler was very slow. Thank goodness for the sledge because had I tried that with a hammer, I'd still be there today. In the end, the frozen knife beat the frozen elk antler, and it faired very well in doing so I might add.

Re the tip--

A lot of folks end up sticking the tip of a knife through some piece of car. While “cool” looking, I thought the steel flat that I pounded the knife through was much more difficult for the tip. IIRC, I think I have seen video where someone could actually penetrate a door of a car with the tip of a knife using just the force of their swing. I would be shocked if anyone was strong enough to be able to do that with the steel flat I used. I really don't think someone could.

I also thought about throwing the knife tip first into wood. The reason I opted to not do that was that it just seemed too random. On some throws, the tip might not be the first thing to strike the wood or it might strike it at an angle. My giant dead Eucalyptus stump also had a lot of rocks and rocky soil around its base. I did not want the knife to bounce off the tree only to fall, hit a rock and get damaged that way. So instead, I opted to drop the knife onto its tip from 7' instead. Easier to do, repeatable and consistent, and much more controlled, and probably much harder on the tip since it was hitting concrete type media. It may have been hard to see on the video, but in person, I can tell you that the tip hit first and solidly on every drop.

Lessons Learned

Nathan's explanation about what happened to the edge as I attempted to pound the knife through that square washer makes perfect sense. It helps me (heck, all of us) to better understand what really happened that was too fast for the camera to capture. Thanks for that explanation, Nathan. :thumbup:

The handle was very comfortable. I intentionally wore no gloves because I wanted to get some feedback from holding the knife while pounding on it. IMO, the handle is perfect for my hands, which are medium/large in size. I had no hotspots or blisters whatsoever. (The wood baton was not so kind, however.) The micarta is very tough, strong, and abrasion resistant. I could not dent it or chip it, only break it in half.

Honestly, I was not expecting the knife to last nearly as long as it did. I have seen many tip and edge destruction videos/images with many different knives, both production and custom. The tip and edge both lasted much longer than I thought they would have. Hype and extreme performance are commonplace in the knife industry, but this knife truly delivered. It does not look indestructible or bad@ss, but its ability to remain sharp, useful, and intact in the face of overwhelming destructive forces is nothing short of remarkable. The "Honey Badger" or "Wolverine" would have been a very apt name for this knife. It just didn't seem to flinch at most of what I threw at it and it was capable of handling things that many knives would not stand a chance of handling.

The knife is an excellent "all-arounder". It stayed very sharp for a long time, was easy to sharpen once dull, was obviously very strong, and was just a real pleasure to use. I think the design of the knife was very well thought out as was the ultimate choice of materials to use, heat treat of the steel, and the size and profile of the knife. I'd probably square the spine up a tad to make work with a firesteel a bit easier, but that is an easy fix.

Finally, a very big "Thank You"...

I want to recognize and thank rodriguez7 for providing the elk antler used in the test. He sent it on his own dime as well. Without his generosity and effort, there would have likely been no such test as I don't really have access to elk sheds. Thank you and best of luck in your remaining hunts this year. :thumbup:

Thanks to Nathan for his willingness to send me a knife for destruction. It was a hell of a lot of work, but I found it rewarding as well. I think we all can learn at least something from the video, but having gone through the process personally, I think I have an even greater appreciation of what this knife can do. To that end, I would encourage anybody to jump into the fray if they ever have the opportunity to do what I did with this knife. It was a great learning experience and I don't think you would regret it.

If anyone has any further questions or concerns, feel free to hit me up by PM or ask them here. I am happy to answer whatever I can. :thumbup:
 
Chris,

Thanks for well thought out and documented test. Great to read responses from Nathan and fellow forum members. Just a wealth of edged tool knowledge around here. :thumbup:
Thanks again.
 
I haven't had time to watch the whole test, but from what I've seen I'm rather impressed. Seems much tougher than sr101. I'll weigh in more when I've watched the whole thing. Thanks for the effort, looked tiring.
 
Great job on the test. I too would like to see the bend test done on a new blank.
 
I too am curious why the tip broke off ....guess it was bent backwards and forwards, always thought it would survive wood. great video! :thumbup:
 
sfrigon1 said:
Why did the tip break so easily ? Would that happen with any knife in 3v ?
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No, this is not indicative of a weakness of 3V. It shows the weakness of the point of that knife design. Lo and behold, a thin knife can be broken if you set your mind to it.

People need to understand what a particular knife is intended to do, and how the geometry of a knife reflects that use. A 3V knife is going to be more durable than almost any other knife of identical geometry. But that doesn't mean that any knife made in 3V will automatically be unbreakable.

The tip is relatively thin. The information in the sales threads specifically states the tip isn't reinforced. This isn't a rough use tactical knife, it is relatively thin, the geometry is intended for cutting performance rather than gross durability.

Once he re-pointed it, it was thicker at the tip and more nearly unbreakable. But at that point it is too thick for good cutting performance.

This illustrates the problem with many of the knife destruction videos you see out there. Some viewers don't understand the significance of the role that geometry plays. Without an understanding of the geometry of the knife and how it relates to other knives it is difficult to form a meaningful judgment. This is why I usually describe the real actual geometry of a knife with dimensions, so that experienced knife users can better understand them.

I have a Busse knife here that could go tip first into that log and be torqued out without breaking. You could probably do it all day, or at least until you got tired. But do you know how thick a Busse knife is behind the edge and how obtuse the factory edge comes? <--- it matters, both in durability and cutting performance. (and also how deep the point penetrates)
 
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