What is the purpose of a spine whack test?

I do it for 2 reasons. First to make sure it doesn't release, and two to make sure if it does start to travel it travels across the lock face to jam the knife open. I think that was the original purpose of the liner lock design so if it did fail it would lock the blade open and not close on the users fingers. keepem sharp
 
It is a test where you whack a spine with a random force to see if the spine will fail. Since the exerted force is completely random, the test is equally useless when performed on knives as it would be if it were performed on humans. In both knives and humans, passing this random test with an unmeasured force provides a false sense of invinceability. Either knives or humans, could fail the next test causing serious injury.
 
pvicenzi said:
It is a test where you whack a spine with a random force to see if the spine will fail. Since the exerted force is completely random, the test is equally useless when performed on knives as it would be if it were performed on humans. In both knives and humans, passing this random test with an unmeasured force provides a false sense of invinceability. Either knives or humans, could fail the next test causing serious injury.
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In one of the spine whack tests that Andrew Demko performed on one of the Tri-Ad locked knives, he did it over and over and over, at what seemed like full force.... and what happened to the knife? Nada... :eek:
 
Folderguy said:
On another forum, there was a question about the strength of various locks, one of them being the liner lock, versus other versions.

Someone asked if the Buck Striders were as strong as the Strider SNGs and so on. And one of the respondants said that some of the Buck Striders had very thin liner locks, and that a simple tap on the back of the spine would be enough for the blade to close. As a consequence, he suggested that before buying one of those knives that a stipulation be made that if the liner lock was insufficient that returning the knife would be alright.

Ahaaaa....

Someone then said that this problem basically didn't occur with actual Striders, just with some of the Buck Striders.

So there you have it....

Testing with a spine whack is not a bad idea after all, is it?

How could it happen in a real life situation? Well, imagine a self defense situation and the knife is swung and the spine hits something like a pipe... you certainly wouldn't want it folding down on your fingers, right?

Folderguy
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Yes, you folding knife could totally close on your fingers if you were stabbing a bear, but missed, and then you accidentally hit a pipe, which then caused your fingers to get cut off, the smell of blood causing the nearby vampires to go into a frenzy...

I'm going to test the strength of my shoe by wearing it inside out.

-Freq
 
What is the purpose of a spine whack test?
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I think it's used to fool people into thinking it's OK to use their folder when they should be using a fixed blade. :eek:





Big Mike
 
Since most of the spine whack tests I've seen on video were performed by Andrew Demko, I wonder if someone knows him and could get him to tell us why he thinks they are important....
 
termiteslayer said:
I feel a decent spine whack is a pretty good test to do and I do realize that the blade wasn't intended to be a hammer.
Nevertheless, when I'm checking out a potential repair job on a boat my knife is poking, prying and tapping (light spine whacks) away in the area of interest. Lightly spine whacking in areas of dry rot will sing you a song about its condition.
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I do the same, have for a few years now, and never had a blade fail on me, other than an old lockback that had already had a hard life before I got it. Might be more accurate to call it spine taps, whack seems to imply a bit more gusto than I use lol

I do occasionally have brain farts and forget I'm carrying a folder and stick it into the wood floor of the cargo containers we have, pretty rare that I do that anyway, but sometimes you need to put the sharp things down in a hurry, poor liner locks never see that coming :o oops
 
At first blush it seems a bit like the old "locomotive test" ~ placing your knife on the railroad tracks then watching to see if A) Your knife is crushed and destroyed or B) The train derails and catches on fire, killing 56. Well maybe not that, but an excessive test is what I mean.
Then you start thinking: "What if I'm caught out in the forest with only a folding knife?" (Obviously you shouldn't go on serious forest treks with only a folding knife, but what if?) You may need to do some hard use with that knife, and it would be reassuring to know it isn't going to fall apart on you if you need to make a fire or a punji pit.
 
I like to be prepared and since I am not clairvoyant and I don't want to lug around all sorts of "right and proper" tools, I just want my folder to be as strong as state of the art can make it at a price point that fits me. I would like my folder which might conceivably be what I use to save my life or others, to be reliable in such a situation and not just reliable for opening packages and letters and slicing bagels and fruit.
 
The purpose is to make sure the lock is in spec and won't fail on you when you use the knife.

Yes it is that simple. :)
 
Ankerson said:
The purpose is to make sure the lock is in spec and won't fail on you when you use the knife.

Yes it is that simple. :)
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I think so too.

And I think a spine whack does not damage a knife in any way (provided you don't slam it down with ferocious force), so why would it be considered abuse?
I do spine whacks on every new knife I get.
 
It seems like one of those tests that tells that you have a very strong lock if the knife passes the test, but doesn't tell you anything if it doesn't pass it.
 
A lock is a lock, and if it doesn't pass, it's not a lock.
You wouldn't want a locked door to open if only you pressed hard enough?

A lock may only fail if some part of it physically breaks.
 
It's main purpose is to provide people with nothing much better to do the opportunity to argue about it endlessly on internet fora.


.
 
Dr Heelhook said:
It seems like one of those tests that tells that you have a very strong lock if the knife passes the test, but doesn't tell you anything if it doesn't pass it.
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If it doesn't pass the test, time to get another knife... or at least, treat it like a slip joint that can fold on you when you least expect it.
 
I've seen a 15 dollar Gerber Paraframe not give no matter how hard it was spine-whacked. The frame lock just moved to the unlocking side and wouldn't move.
I've seen other liner locks and lock-backs give with a moderate rap on a hard surface.
It just depends on which way the vibration from such a sharp abrupt strike causes the lock travel. (in the case of liner-locks and frame, a lock-back it just forces out of it's notch if it fails) The Gerber would break it's cheap handle before it would, but I still don't think that makes it a great knife. I've used hard and stabbed into trees knives that failed the spine whack and they held up just fine. I don't think real life use duplicates the vibration a spine whack does.
 
Has anyone ever seen or heard of one of those Tri-Ad locks fail a spine whack test? What about Benchmade's Axis lock?
 
Spine whacking is pretty useless, in my opinion. It applies force to a blade in a manner, and in a direction, which virtually never occurs in the real world. One might as well shoot the blade with a .22 and call it a spine shot test, in order to test what would happen if the blade were shot.

It is true that force might be applied to the spine in real world usage, like getting a blade stuck in some drywall and wiggling it out. So I understand why some people do it. But even the drywall example does not apply a shock to the spine like a spine whack does.

But mostly I think its just an excuse to play with a knife. Nothing wrong with that.

I don't use folders in a manner which applies force to the spine, so I pretty much ignore spine whack tests. As a general rule, I use the sharp side of the blade. :)

jill jackson said:
I don't think real life use duplicates the vibration a spine whack does.
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That pretty much says it for me.
 
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