What constitutes folding knife abuse?

[Roadrunner]

I've read several threads the last few days in which defferent locking mechanisms for folders were being compared. Specifically this one http://www.bladeforums.com/ubb/Forum3/HTML/002618.html . I noticed a general trend which seemed to me to be that a lock should be strong enough to make folder just as strong as a fixed blade, and anything less is unacceptable. I've noticed this trend here before, only in this case it seemed more pronounced to me.

This quote in particular caught my attention.

<font face="Verdana, Arial" size="2">In regards to strength being irrelevant as its enough for normal use. Well yes certainly if
the numbers usually quoted (torques) represented actual use limit points. However they
are generated in very artifical situations. During use by a human being you are not
exerting a force 100% vertically, not is it a smooth continuous action, nor do you have
the necessary binding pressure on the handle to keep it together etc. .

When you add all these factors together you can reduce the 1000+ in.lbs break torques
to under 100 in.lbs which any one can easily do during use. And I am not talking about
disengages either but actually breaking the locking mechanism. With liner locks you can
break pieces out of the liner face or shear them out of square and do the same thing
with Integral locks.</font>

Also this one.

<font face="Verdana, Arial" size="2">Sure, a folder will be weaker than a fixed blade, but that
doesn't lead mem to conclude that strength is irrelevant. I'm not going to simply accept
that many folders locks fail in response to twisting and bending -- it means folder makers
need to find better ways of doing things. And they have -- my axis lock can take an
astounding amount of twisting and bending, to the point that I think the handle will pop
apart or the blade will break before I break that lock.</font>

While I'm not arguing with the facts of what is being said, namely that locks can be broken or forced to fail by an average person exerting forces on them, what confuses me is why anyone would do this to a folder in use. Let me put it another way; just because a lock or other mechanical part of the knife can be forced to fail, does this mean that it's going to fail while you're using it? The situations in which these locks are presented as failing sound pretty extreme to me. What I'm asking for is examples of a task that you perform with your folding knives that could cause the lock to fail. Not spine whack tests or twisting it in a vise, but something like field dressing a deer or cutting up rope that will result in either a broken lock or a dangerous failure. I just want to see if anyone has any legitimate answers to this question. Fire away if you have something.

 

[Burke]

I think there are several legitimate answers to your question, Roadrunner. The first is that sometimes things are subjected to accidental stresses; if someone were to be cutting a rope on a boat and the pitching motion of the waves slammed their hand into a bulkhead they would probably be more upset by a lost finger than a bruised knuckle. This is just an example of the kind of accidents that can make one wish their knife hadn't closed on their hand. Additionally, with many knives being marketed as "self-defense" or "combat" knives, the fact that the force vectors, amounts, and types cannot really be predicted in such an desperate situation makes me think that more lock strength is better. Just a couple of my thoughts on the subject.

 

[Samurai6]

You are missing the point. The issue is not whether a folder should be as strong as a fixed blade or considered useless. Slip joint folders are still viable cutting tools. The issue is what to expect from "tactical" folders that are marketed as both tools and weapons. In the course of a scuffle, a folding knife can have heavy closing force applied inadvertently to the blade. Most standard folding locks are not up to the strain. There are some that are, however, such as the integral side locks, Axis lock, Arc Lock, Rolling Lock, many button locks, and so on. These reliable locks have raised the bar of folder reliability. If you are going to make a locking folder, why not make it as reliable as possible?

But the issue is really the owner's expectation. If he only expects the knife to be used in a controlled environment, for ordinary cutting tasks, then lock reliability may not be an issue at all.

Oh, and strength really isn't the issue either. I just want a folder to stay locked until something breaks, then I know the lock was abused, rather than that it failed to function.

 

[SALTY]

Much has been said about what is so simple. Let us not despute the obvious.

The strongest action is a full tang fixed blade.

Next question?

Wneh are we getting spelcech?

[This message has been edited by Nimrod (edited 03-02-2001).]

 

[The General]

Abuse is when you put a folder on a bench and hammer the spine with an axe handle.

Abuse is when you try to get a lock to fail by using the knife as something other than a knife and being unreasonable.

A lock does not a fixed blade make. They are your fingers, use a bit of common sense. I don't 100% trust ANY liner lock, frame lock or lockback. I am 99% sure an axis lock is the safest out there. Even that I do not trust 100%. To me a folder is a light/medium use tool. Think about this for a second, what kind of cutting, involves the use of the spine? Well? If the lock fails and cutts your fingers, how can this happen if you are cutting using the edge? I mean duh... Am I missing the critical point that a knife is a knife? And not something else?

W.A.

------------------
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!
Founding president and member number 1! Wana join?

 

[Cougar Allen]

The real issue isn't strength, it's reliability. A great many people have learned the hard way that a knife they thought locked open didn't -- not all the time. It only takes once....

Slipjoints usually have big choils so you can grip it with your forefinger on the choil and your thumb on the spring holding it together while you use the point. If it starts to slip you'll feel it and be warned before you lose any fingers. Locking knives usually don't have choils you can grip, and if they don't lock ... even once.... The old clasp-locks were reliable, but modern backlocks can be unlocked with your grip -- depending on your hand and the knife and the way you grip it that might never happen ... or it might happen once.... That can happen with liner locks, too, and some liner locks don't even have to be squeezed to be unsafe.

General, you won't need to worry about it as long as you only use the edge of your knife; you won't need a lock at all. You'd probably better break the point off, though, just in case you might be tempted to use it someday.

I am not, of course, arguing that all folders are unsafe. But it is not a trivial issue, as any ER surgeon can tell you.


------------------
-Cougar :{)
Use of Weapons

 

[matthew rapaport]

I have to agree with most here that marketing plays a role here. Lock behavior under extreme survival conditions (including a fight with another human being) does not have to be an issue if the knife is to be deployed exclusively in routine and well understood cutting chores. But a lot of the knives under consideration are marketed as being suitable even for those extreme conditions, and those locks ought never to fail until something else breaks anyway because the conditions can sometimes warrent it.

The other situation of course is the freak accident like when the knife has to play the role of a bar that keeps two moving planes (like the hulls of two boats) from coming together and crushing your hand. Certainly one could argue that a simple locking utility folder can't be expected to serve in this capacity, and that such use would certainly constitute abuse. I don't think most of us would argue, but if the knife does serve, and the lock doesn't fail thereby saving your hand from a double tragedy, so much the better!

 

[Walt Welch]

Locks on folders are a lot like safties on firearms; they are there to remind you that the knife may fold at any time (or that the firearm may discharge at any time), not to reassure you that it will NOT fold up at the worst possible moment.

Any device, the old engineers' adage goes, can be made foolproof; no device can be made damnfoolproof.

I was reminded of this while at Steve Harvey's place one day. He took my EDC folder, and subjected it to a spine whack test. It failed miserably. I was apalled, as it was a knife MADE by the person who invented the spine whack test. It turned out that the pivot pin screw had loosened, changing the tang / locking bar geometry. Tightening the pivot pin made the knife pass the spine whack test every time.

Other things which may be encountered without abuse of the knife, such as dirt, or lack of lubrication or wear may also contribute to or cause failure of the lock.

Outright abuse, such as flicking the knife, allowing rust or corrosion to develop and persist or prying with the knife may also contribute to lock failure.

There are some folders, however, which are VERY VERY unlikely to fail. Here is a picture of some of them:

<A HREF="http://albums.photopoint.com/j/View?u=306668&a=2279510&p=34513086&Sequence=0&res=high" TARGET=_blank>

</A>

Most are Mad Dogs, with a Tom Mayo at the top and a Rob Simonich Cetan at right. These knives may be folded by heating the desired fold point until the blade is soft, then folding as desired.

While some of you may think that these knives are accidental foldproof, be advised that a certain poster was able to break a larger Mad Dog blade into six (6) pieces. This should serve to underscore the fact that extreme care should be utilized when using ANY edged object, designed to fold or not.

Hope this helps, Walt

 

[The General]

Cougar! I DO use the point of my knives, however that is for penetrating cuts and ultra fine work. I want a prybar, I get a prybar. Never seen a prybar cut worth a damn, never ask my folders or fixed blades to become a prybar!

W.A.

------------------
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!
Founding president and member number 1! Wana join?

 

[qwertyname]

I think a point that is being missed here is simply time. When extreme tests are run on a NIB knife, it can easily seem to be unreasonable. In some cases it may be. However, consider that alot of people keep their knives for a very long time and use them pretty regularly. During the course of that lifetime, components will wear, pivots will loosen, extremely tight tolerance components will degrade - it is the nature of wear and tear. In most cases, when I read one of these reviews which involved alot of "torture testing" I frame it in the perspective of "is this reasonable accelerated life testing?"

Realistically, at least in my case, my habit with knives is exactly backwards. I am hesitant to trust a new knife, because I am unfamiliar with it. As it "wears in" I tend to trust it more, which is fine, except that it will never be as good as NIB.

I'll give an example I read on the forums here some time ago. Cliff was discussing a method of testing a Mad Dog knife, which involved digging a hole in the ground with it. Now, many in that thread chided Cliff about "why would you dig a hole with a $xxxx knife?". Cliff quite reasonably replied that it represented a reasonable simulation of cutting, which would dull the edge rapidly, so he could see how difficult it would be to sharpen. (I think he wanted to check something else too, but I can't remember) He continued to say that it would take much longer to dull the knife cutting wood or cardboard.

This is a perfect example of the accelerated life testing concept. Find some reasonable alternative method which simulates long cycle use, but provides the aging much faster. The real trick is in understanding how to interpret this information.

 

[Joe Talmadge]

<font face="Verdana, Arial" size="2">
While I'm not arguing with the facts of what is being said, namely that locks can be broken or forced to fail by an average person exerting forces on them, what confuses me is why anyone would do this to a folder in use. </font>

Certainly, it's the reader's right to decide which tests are relevant to him. Sometimes, Cliff's tests are more extreme than I feel I need, so I ignore that part of the review and concentrate on the rest. Likewise, someone who only uses their knife to clean their nails, open envelopes, and cut twine may find my tests -- which I consider perfectly reasonable -- to be inapplicable to them personally. Nothing wrong with that.

But, getting back to your question of "why [would anyone] do this to a folder in use?". For someone who really uses their knives, I think the tests I do are reasonable. When you use your knife, are you ever going to do work that's a bit harder, and grip it tightly? Is it possible the knife might get stuck in the work, so you'll end up torquing it out a bit? Anyway, the tests I do -- white-knuckling, torquing, steady spine pressure, light-to-medium force spine whacks -- all simulate these situations. Many locks hold up fine; many others don't. If you can't possibly see yourself doing any of those things, maybe you're in the nail-cleaning-and-envelope-opening crowd. There's nothing wrong with that at all! But there are lots of real-life lock failures that come down to these things -- white knuckling, torquing, spine pressure -- so these tests are demonstrably relevant to someone who uses their folders for the things the manufacturers advertise that they can do.

I feel the refrain "if you're doing hard work, you should use a fixed-blade" is apologetics for bad quality, when it's used to excuse every folder test or real-life failure. Yes, a fixed blade can be made stronger and more reliable than a folder. But there are many kinds of work a folder can perform, and letting the manufacturers off the hook when their folders can't handle it is not reasonable, especially if they've advertised their knife as a hard use knife. The fact is, there are many folding knives that will go through every test I do and not have problems. Why should I accept a folder that can't?

Joe



[This message has been edited by Joe Talmadge (edited 03-04-2001).]

 

[Cliff Stamp]

One argument that is commonly seen in defence of weak and/or instable locks is that you should be carrying a fixed blade for the kinds of use that would cause problems for the locks on folding knives. Well that isn't a sensible argument at all, because if you can carry a fixed blade then you shouldn't be carrying a folding knife in the first place. They are directly inferior except for the fact that they can be carried in places where fixed blades can't.

The other big argument for high strength and security as as pointed out several times, there are locks that can easily withstand various uses that cause other locks to fail. So the fact is that these locks have raised the bar as to the performance that can be attained and thus have widened the range of uses that folders can be expected to handle without problems. If all locks for example failed the spine whack test, then there would be little argument that it is abusive and you can't expect it to be passed nor use a knife that would submit it to similar forces. But since there are many that are stable under these conditions you can't make the same argument.

That being said, I am looking for a folder with a lock that functions in the sense that I don't have to be concerned about the blade folding except when I intentionally do it. I would prefer the blade itself to break before the lock disengage / break. Is this unreasonable? Well that is something basically every person has to decide for themselves. You are the one using it and thus as long as it meets your expectations then obviously you will be happy with it. Just offer the same ability to other people who may have differing opinions as to what they need in a folding knife.

As for the original question as to what kinds of uses can cause such stresses, well I have seen several, when I was splitting wood with the Buck / Strider the blade got jammed and I disengaged the lock trying to get it out of the wood. The same kind of thing can happen if you are working the knife through a very binding material (composites, plastics, rings/seals etc.). Or, for example, if you are cutting through material that either it or you are subjected to a rapid movement. Press down into a pieces of wood for example and take off a deep slice, now while in the middle have someone jerk on the piece of wood hard and examine what happens to the blade (warning - this could quite easily lead to injury). There are other examples in the reviews forum as this question has been asked before. Not to mention as Steve pointed out, in regards to combat it is easy to imagine all kinds of things exerting forces on blades in various ways.

As a note, even simple cutting chores cause significant amount of force to be exerted on a lock. I spent a lot of time in the last month press cutting up 3/8" hemp rope. The amount of force it took to make the press cuts varied as you would expect across different knives, and some took over 150 lbs of force to make a complete cut. If you were in a hurry and pressed down hard and fast, you could easily cause the knife to twist and thus end up with a torque and pry at the same time, just cutting rope. Cardboard can do the same thing, get really thick cardboard and use a knife with a very obtuse geometry and start taking the cardboard apart. Using forceful cuts it again is very easy to get considerable force to act across the blade, as cardboard doesn't always cut neatly and even simple angled cuts cause sideways forces on the blade / lock.

Note the first quote in this thread was from me.

-Cliff

 

[The General]

Can someone give five times, when a folder is likely to close on your fingers, when you are using a knife as a knife?

Here is my daft list.

1. Prying
2. Hammering
3. Gawd? Its not an easy list...

For me, appart from when using a folder is an offensive/defence nature, I don't think I need a lock. It is reasuring, but really needed? Not for me anyhow. I do like a lock when practicing a defensive stance and thrust into a solid object however. The jarring impact could cause a lock to fail. That is my main concern.

Cheers!

W.A.

W.A.

------------------
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!
Founding president and member number 1! Wana join?

 

[Joe Talmadge]

<font face="Verdana, Arial" size="2">Originally posted by The General:
Can someone give five times, when a folder is likely to close on your fingers,
</font>

For me, it's not the number of items on the list, it's how likely I am to perform any of those items.

One way locks can fail is through holding the knife very firmly ("white-knuckling"). In this case, the fingers or palm contact the lock release button or the liner, and partially or fully unlock it. If, at the same time, any pressure is put on the spine, it can fail. How often do I grip my folder firmly? Anytime I'm doing hard cutting.

Torquing can lead to many lock failures. Why might I torque the blade? Well, how about if I'm cutting something tough, and the knife gets stuck, and I torque it out a bit. Can you honestly claim you've never done that? Right on this forum, we've heard firsthand reports of locks failing because they got stuck in materials ranging from thick cardboard to vegetation.

For defensive purposes, hard thrusting into any material can lead to problems. There you've got all the classic conditions of lock failure. A very firm grip. Sudden impact to the blade, including some component on the spine. And possibly having to torque the blade out. In fact, some defensive schools actually teach giving a little "tail" when pulling out. You should definitely care about these conditions for your defensive knife.

I find myself often doing work where none of the above conditions are present. At those times, I could almost always get away with a slipjoint. Other times, when doing harder work with my folder -- doing work any reasonable person would constitute as use and not abuse, IMO -- I do find that firm grips and torquing occur. There's no reason a folder shouldn't be able to stand up to this; in fact, there are many that do. I do not think I'm being unreasonable in rejecting the ones that don't, and I'm not willing to dismiss poor folder quality by saying "I shoulda used a fixed blade" when it's clear plenty of other folders can do the job just fine.


Joe



[This message has been edited by Joe Talmadge (edited 03-05-2001).]

 

[Samurai6]

One of the primary missions I have always envisioned for a tactical knife is as an emergency escape tool. You should be able to dig your way out of a collapsed building, or a crashed vehicle, or at least chisel an air hole. So one of my first tests of "tactical folders" was to dig a hole through a board, a 2X6 for example. Using the tip to dig and chisel a hole through a hard board, you will quickly find out if the lock is confidence inspiring or not. Like Cougar said, if you want to use the tip hard, you better trust the lock or be very careful. Sometimes you don't have the luxury of being very careful.

But to put my original point maybe a little more succinctly, to my mind, anything that causes a folder to break is abuse. If you break it, not due to any defect, you abused it. If the lock releases without anything breaking, it just was not an optimal design.

[This message has been edited by Steve Harvey (edited 03-05-2001).]

 

[matthew rapaport]

How about using your folder as an ice pick? Could that, for a moment, be a benchmark test? Ice is only frozen water after all, it isn't rock. Ice picking is done like a straight stab, typically without twisting or prying. I imagine most locks would survive this test. I've used my large sebenza this way without problem, but I'm not sure I'd be so confident in some of my lesser knives. Is this abuse?

 

[The General]

Good points Joe!

Food for thought...

W.A.

------------------
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!
Founding president and member number 1! Wana join?