Why are spinewhack-tests not indicitive of lock strength?

Ive never understood why someone would use a folder for this, but if you check the HQ they have field test videos for the Spyderco Paramilitary 2 and the Benchmade 551 Griptillian. For some reason they see the need to chop/baton with their folding knives. I won't spoil it for you, but one of the locks fail while they are smashing the spine of the blade. This particular failure doesn't really bother me and I'll still buy this knife. Mostly because I know thats not how these knives were designed to be used. I have a Becker BK-2 that can do all my batoning for me. If I carry a folder, its for smaller and more detailed jobs.

Give the knife a once over. See if the blade wiggles. Learn how the lock works. Use it as intended and be careful. Hopefully you will get to keep all your fingers and you won't break your knife trying to test it.
 
gooeytek said:
Spine-whack tests are invalid for folding knives, because when you are exerting impact pressure to the spine of the knife, you are obviously using the knife incorrectly. By the nature and premise of a spine-whack test, you are automatically discounting two whole (and popular) categories of folding knives: slipjoints, and friction folders. How about a handle-whack test to determine integrity of handle construction and materials used? How about an edge-whack test? I think that'll be a truer test of how a knife blade should hold up in the real world. Maybe a dirt and mud test to check how well or badly the folding knife still functions after being subjected to debris and grit internally? At no time during real-world use of any of my folding knives would a spine-whack matter.
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Slip joints have both a stop notch and spring tension and friction folders are what they are so neither is really a valid comparison to locking folders.

Apples to oranges....
 
gooeytek said:
Spine-whack tests are invalid for folding knives, because when you are exerting impact pressure to the spine of the knife, you are obviously using the knife incorrectly. By the nature and premise of a spine-whack test, you are automatically discounting two whole (and popular) categories of folding knives: slipjoints, and friction folders. How about a handle-whack test to determine integrity of handle construction and materials used? How about an edge-whack test? I think that'll be a truer test of how a knife blade should hold up in the real world. Maybe a dirt and mud test to check how well or badly the folding knife still functions after being subjected to debris and grit internally? At no time during real-world use of any of my folding knives would a spine-whack matter.
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So what is the lock on a knife for? To look pretty? I mean I figure its there to keep you from accidentally closing it on yourself right? Even when using the knife correctly and only exerting pressure on the edge of the blade, accidents happen... So you can't say "I am using the knife correctly only exerting pressure on the edge, therefore the knife will never be subject to pressure exerted on the spine".
 
shecky said:
There's no reason why the spine whack test is not a valid way to test lock strength. Except in places like bladeforums, where people don't like to see their favorite knives actually put to the test. It makes us look like chumps when our favorite brands by our favorite knifemakers that we spend so much money and adoration over fail.
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+1 on this
 
I use the back edge of my folder to strike fire steels, scale fish, hold down a live minnow to hook it without cutting it in half, you can score a wire with your blade then use the spine to slide the insulation off the end, it's a paint scraper in a pinch, it's a letter opener, hide scarper, egg cracker, marker, bee stinger remover, bug smasher, this list goes on and on. My knives are tools and are treated as such, a locking blade makes the tool that much more versatile and I would like for it to not fold up on me when used as such. Sounds to me like some of you guys honestly think that a knifes only purpose is to be sharp and that any other use is improper and wrong. I just don't understand :confused:
 
kniferbro said:
Also, there was a post from a forum member here a few months back about him slipping from a roof and as he slid towards the edge of the roof he stabbed (in reverse grip with edge facing away) his Griptilian into the roof and it held his weight and possibly saved his life.
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I'm not an engineer or anything, but in that situation when the knife stabs into the roof (edge facing away) and the guy is holding onto the scales and pulling downwards, isn't the pressure being exerted on the edge of the blade? Which means the direction of the force is pushed to OPEN the knife instead of closing it.

The only thing that would even remotely concern me about the lock strength in a knife is when you're stabbing something. I don't typically stab hard/solid objects and I don't foresee myself ever needing to. I don't think most people will need to do something like that either.

IMO the whole spinewhack test and worrying about lock strength is retarded. For those like NK (the youtube idiot) who worries so much about it they should just use fixed blades and never touch a folder again.
 
longbow said:
Every single liner lock and frame lock I own has passed the spine whack test. My knives and my test. My peace of mind. For instance more years ago than I care to remember I had a high end liner lock(MOD) Tempest, first iteration. My wife was using it to cut something off the inside of the refrigerator door, a piece of gasket or something. Anyways she raises up and the knife hit one of the shelves spine first and closed on her fingers. Talk about surprised, me, and pissed her. So that is why I specifically do it. Also I always hit out towards the end of the tip where if it is going to fail it will. keepem sharp
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All you're doing is describing a scenario where someone is misusing a knife. Sorry, you're wife used the back of a blade to hit a solid object? She didn't get cut because the knife "failed" she was cut because she used the knife to perform a task that its CLEARLY not meant to do. Go get a hammer.


longbow said:
Every single liner lock and frame lock I own has passed the spine whack test. My knives and my test.
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Also, this whole "my knife, my rules" thing is silly. You're making yourself sound a little childish. OF COURSE they're your knives! you can do whatever you want. This is not a valid argument for the effectiveness of a spine-whack test.
 
The whole purpose of a lock is to keep the knife from closing on your hand when using it.

How does a knife close on your fingers when you are using it? When the blade has force applied to it in a direction that causes it to close, most typically from pressure on the spine.

How does one conclude that the lock keeps the knife from closing one ones fingers? By applying pressure in te direction which causes causes said knife to close, such a pressure to the spine.

If you tap the spine of your knife on your knee and it closes, you can conclude that if you were to apply pressure to the spine in a non controlled environment in a similar fashion, the lock would fail.

Therefore the test is valid.
 
KalEl said:
If you tap the spine of your knife on your knee and it closes, you can conclude that if you were to apply pressure to the spine in a non controlled environment in a similar fashion, the lock would fail.

Therefore the test is valid.
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This is not a spine-whack test.
 
frenchmade said:
All you're doing is describing a scenario where someone is misusing a knife. Sorry, you're wife used the back of a blade to hit a solid object? She didn't get cut because the knife "failed" she was cut because she used the knife to perform a task that its CLEARLY not meant to do. Go get a hammer.
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You misunderstood the situation. She did not use the spine as a hammer. The spine accidentally hit something when she stood up, causing the blade to close and cut her. This is exactly the situation a lock is supposed to prevent. The knife lock failed.
 
If you are putting that much force against the spine to make it fail you are either A: holding the knife the wrong way, the Blade goes down for cutting, thats why it has an edge B:mistaking a knife for a hammer
 
frenchmade said:
All you're doing is describing a scenario where someone is misusing a knife. Sorry, you're wife used the back of a blade to hit a solid object? She didn't get cut because the knife "failed" she was cut because she used the knife to perform a task that its CLEARLY not meant to do. Go get a hammer.
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You realize longbow was describing an incident that was not intentional right?

The logic you and several other people are putting up is akin to saying drop tests for firearms have no use because firearms are meant to be held and fired, not dropped.

Manufacturers put up the extra cost of design and manufacture associated with locking folders because a lot of people who really use knives on a regular basis realize its a good idea.
 
I believe the tests that Cold Steel performs on their knives are indicative of their strength.

Like it or not, many tactical knives are designed for combat or self defense uses. Spine whacks ensure that if any stress is placed on the back of a blade that it won't fail and fold back on you. If engaged against a foe with a heavy, blunt instrument, he may use it to try to make your blade fail on you, or to knock your knife out of your hands. Years ago, using a folding knife in situations where you'd normally use fixed blade knives was ill advised; however, today many companies produce high quality tactical knives that are nearly as strong as fixed blade knives. Cold Steel led the way by offering large blades and strong locks. Other knife companies like Benchmade developed locks like the axis for extreme lock up. And CRKT and other companies offered liner lock knives with the Lake and Walker Knife Safeties (LAWKS). Finally, Cold Steel offered Andrew Demko's outstanding Tri-Ad locking system on many of its folders, and I've yet to see a Tri-Ad lock fail any test of strength. It's as close to having a fixed blade as a folder can get!

Spine whacks don't test a lock's test as much as they detect a defective lock's strength. I've seen cheap liner locks pass spine whacks with no problem and expensive knives fail because of bad quality control. I got a nice S&W pocket knife with a very sharp, flat grind blade and a lockback design. It was fine, but the locking mechanism didn't work. It might have snapped back on me had I not checked it first, so it's always good to check.
 
I had a cheap liner lock that would pass a spine-whack test easily.
However, when steady pressure was placed on the spine of the blade by hand, it slipped right off the tang.
Crappy knife. Unsafe. And it passed the useless spine-whack "test" every time.

I threw it in the river.
 
The main problem with spine whack tests (like pretty much all destruction tests) is that the they offer no real empirical evidence. How hard did you hit the blade in foot pounds? What was the distance traveled from start of the strike to when you connected? How far up on the blades spine did you hit the medium you are striking? Did you hit it the same way every time? Are you running a sample of multiple knives, because one knife does not a valid test make? Until I see a spine whacking robotic machine testing multiple knives and strike with every knife the exact same way, then I find spine whacking to be anecdotal at best and more than likely a foolish way to treat your own property.

As most people know, knife manufacturers have expensive and scientific quality control measures in order to make sure safety and quality assurance are met. Whacking a knife blade over and over again against a hard object does nothing but transfer stress to an area that will wear out over time. In short, you're probably shortening the life span of your life in order to prove that probability is most likely on your side and your knife won't fail.

By all means, wail away on your folders if it makes you feel more secure. However, most quality folders are going to be able to more than handle the "test", and you are putting more wear and tear on a part that isn't generally designed to be subjected that amount of shock.
 
Steely_Gunz said:
The main problem with spine whack tests (like pretty much all destruction tests) is that the they offer no real empirical evidence. How hard did you hit the blade in foot pounds? What was the distance traveled from start of the strike to when you connected? How far up on the blades spine did you hit the medium you are striking? Did you hit it the same way every time? Are you running a sample of multiple knives, because one knife does not a valid test make? Until I see a spine whacking robotic machine testing multiple knives and strike with every knife the exact same way, then I find spine whacking to be anecdotal at best and more than likely a foolish way to treat your own property.
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My thoughts exactly. It's the same reason I think "destruction tests" are usually worthless: no consistency, unequal forces applied, varying angles at which the forces are applied, etc. If a machine that tested let's say even a dozen examples of a particular knife applying the same force at the same angle to the same point on the knife and all the knives behaved similarly we'd have a clear picture of what we might reasonably expect if we hit the knife in that spot with the same force after looking at how all the knives performed as a set and of course adjusting the data for any margin of error and looking at the average value obtained.

In order to determine the maximum force a knife can sustain it might require testing tons of knives because each successive hit potentially weakens the lock mechanism by a certain amount. Over time the lock might not be able to withstand as much as it could when it was new.

Repeatedly applying force to the spine is a different test than applying the largest force possible one time.

Overall there are too many variables to be conclusive, but with some testing some average values could be determined at least.
 
This is complicating a simple thing, just give it a few light whacks on a sturdy piece of wood or plastic. I would hate to have wasted money on a folder that the design and materials are so poor where this would be destructive.

Which knives do people think are too delicate? Sal Glesser said Spyderco started doing spinewhack tests in the 80's and my old 90's clip-it Endura and CS Voyager did the tests and a lot more for over a decade with no problems. What locking folders are we talking about that can't hang with these 1990's zytel pinned construction lightweights? Common sense should be enough to tell you how hard to do it. We're not talking about a kid with his first hammer.
 
OrdnanceBubbaUSMC said:
This is complicating a simple thing, just give it a few light whacks on a sturdy piece of wood or plastic. I would hate to have wasted money on a folder that the design and materials are so poor where this would be destructive.

Which knives do people think are too delicate? Sal Glesser said Spyderco started doing spinewhack tests in the 80's and my old 90's clip-it Endura and CS Voyager did the tests and a lot more for over a decade with no problems. What locking folders are we talking about that can't hang with these 1990's zytel pinned construction lightweights? Common sense should be enough to tell you how hard to do it. We're not talking about a kid with his first hammer.
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Yeah exactly. :D
 
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