Wtf Spine Whack!!!

Macchina

Macchina

Joined
Apr 7, 2006
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The "W" in WTF is for Why. Why would you want to spine whack a knife as a test of a locks strength? I have carried knives of all lock types for years, and under no circumstances have I ever hit the spine of my knife on something hard enough that I was worried the lock would fail. It is a test that causes many good locks to fail because other things are more important than a knife being resistant to a spine whack (such as an edge whack, but nobody ever does those). It's like testing a gun to see if it will shoot underwater (don't get me started on that test), if it passes or fails, it doesn't tell you hardly anything about lock strength. Personally, I want a lock is designed to take force placed on the edge, I don't discount knives at all if others say they fail a spine whack. Just my opinion, that's all.
 
Some people whack the spines to see how dependable they are before using them. Other people just do it to see if they can just get a particular knife to fail. The people in the first group don't want to find out their knives won't lock solidly when they're working those knives under stress. (You might be surprised how many failures there are, and failures can cause not only nasty cuts, but nerve damage.) Whacking the spine will reveal a weakness if it's there. Of course, it might also cause a weakness to develop if overdone.

I had a small folder with a lockback that was a beauty. The first time I tried to cut something, the blade doubled back on me and nearly took my finger off. I've never trusted a knife out of a box since.
 
I had one knife that would close against the lock falling 2 inches by gravity onto the heel of my hand. I expect that any lock should withstand a moderate whack. If it doesn't might as well be a slip joint.
 
My personal opinion is the ony real purpose for a lock on a folding knife is to lull you into a false sense of security. A folding knife with a lock is still a folding knife. They call them that because they fold. A lock doesn't make one into a fixed blade.

Maybe if all folders were slip joints, people would figure that out. They might even figure out how to use a folding knife safely. There is even a tiny possibility that a few might discover that some things shouldn't be attempted with a folding knife, as it is just not the right tool for the job.

Wishful thinking, I know.
 
This issue has been hashed to death a million times already.

In a nutshell:

Just because YOU don't use a folding knife in a certain way, or if you live in a state where you can carry a fixed blade concealed, doesn't mean that someone else doesn't NEED to use the tool in such a manner.

I've had an expensive custom folder (a framelock-class one, natch), whose blade would collapse onto your hand if you wiggled it in the tape around a cardboard box when it bound up on the adhesive.

It provided less closing resistance than a SAK's slipjoint.

To me, that makes the knife worse than useless -- it becomes dangerous, and I need to know that before I make the mistake of using it.

-j
 
biogon said:
This issue has been hashed to death a million times already.

In a nutshell:

Just because YOU don't use a folding knife in a certain way, or if you live in a state where you can carry a fixed blade concealed, doesn't mean that someone else doesn't NEED to use the tool in such a manner.

I've had an expensive custom folder (a framelock-class one, natch), whose blade would collapse onto your hand if you wiggled it in the tape around a cardboard box when it bound up on the adhesive.

It provided less closing resistance than a SAK's slipjoint.

To me, that makes the knife worse than useless -- it becomes dangerous, and I need to know that before I make the mistake of using it.

-j
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You are quite right, it has been. I apologize for making my view public.

Just FYI, every job I have held for the last twenty-five years has seen me using knives on a daily basis. I haven't carried a fixed blade in ten or twelve years. I use slip joints for about half of the work I do, and I haven't had one fold up in use in thirty-some years. What I learned as a Cub Scout in the sixties has stood me in good stead. YMMV. Peace.
 
Heh, I'm sorry if I came across brusque.

This is a topic that I'm a little sensitive about.

Not everyone has the benefit of being taught how to use a knife 'properly' before they have to use it. Sometimes, they have to use it in a most expedient and precarious fashion, with no training in advance.

The more foolproof it is, the less likely someone is going to get hurt.

Many years ago, I found myself in the unenviable position of having to cut away a bundle of insulation inside a crawl space, from the door. I was reaching completely around in a small area, unable to put my hand on the flooring.

This is before when I had a fixed blade (which I would use today), and, not having been in the Scouts, never taught the proper use of a slipjoint.

In the process of finding where the top of the bundle started, I pushed the spine of the blade against a stud. Not a whack, not a slam, just a little upward pressure, to confirm I was at the beginning. (I couldn't see where I was cutting easily and was doing it largely by feel.)

Imagine my surprise when the blade was no longer in front of my hand, but on the knuckles of my gloves.

Fortunately, I didn't get cut, but this is one (of many) incidents that has made me very wary of folder locks and certain to test them before I use them.

I do spine whack tests when I get a new folder, and rarely ever after that.

If it's bound up in some material like cardboard, I'll test the lock with some light wiggling first, before wiggling it vigorously,

If it's a fast cut and then I put the knife away, I'm not going to bother checking.

-j
 
I do agree that part of the problem is the illusion that the lock is solid.

When an object has the appearance of being another object, people will tend to treat it as if it is the same as the other object.

People have a lot of experience using kitchen knives or Stanley utility knives.

A folder locked open appears to be a knife of the sort that people have a lot of experience with -- kitchen knives -- and treat them accordingly.

Therefore, the nature of the beast is such that unless taught otherwise, people think of an open folder as having the properties of a fixed blade.

The worst offenders are liner- and framelocks.

Watch someone use an AXIS-lock folder. After opening and using it, most of them (at least the ones I've seen) will see the AXIS button and slide it to close the knife. Similarly with a back- or mid-lock.

Someone using a liner or framelock will look around for something to manipulate, and failing that, try to force the blade closed while it is locked open.

-j
 
yablanowitz said:
I use slip joints for about half of the work I do, and I haven't had one fold up in use in thirty-some years. What I learned as a Cub Scout in the sixties has stood me in good stead. YMMV. Peace.
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Yes, but what are the blade sizes of your slip joints and what sort of jobs do you do with your knives?For years people have given me slipjoint knives: Barlows, Case, Victorinox, promotionals, all types. And they all went into the giant suck hole in my top drawer. It was only when I bought an el cheapo linerlock knife in a dollar store because I needed it for a quick job that I started liking knives. I wore that el cheapo more and more and finally I came to the conclusion that I needed something better. Now I've owned CRKT, Spyderco, Cold Steel, Kershaw and other knives and find that I really love them.

It's kind of like bicycles. As long as they had those 10-speed, skinny-tired, hunched over, high a$$ monstrosities, it was no thanks. I couldn't ride one-speeds very well, but mountain bikes represented the ultimate quantum leap in technology I was looking for.

Now I carry a Cold Steel 4-inch or 5-inch Voyager most of the time and none of them has ever failed. I've never done spine whacks and I use them with care, even though I had a small lockback that failed. (I cut into a taped box and upon extracting the blade found that it was coming back on me. But I wasn't cut. Ticked, maybe, but not cut.)

Like any piece of equipment, you have to know your knife and its limitations. Over time you learn what it will do and not do; and if you're not wreckless, you'll be well served.

Bigon: ...otherwise, people think of an open folder as having the properties of a fixed blade.
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It doesn't help that CRKT equates its linerlocks with the LAWKS as being roughly the same as a fixed knife. Even though the safety is welcome, it certainly doesn't transform a folder into a fixed.


///
 
yablanowitz said:
My personal opinion is the ony real purpose for a lock on a folding knife is to lull you into a false sense of security.
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Yes, of course that's what they're for. They can't possibly be, you know, safeguards, or mechanical improvements. No, they've gotta be for fooling all of you tools.

And those seatbelts and air bags. They're useless. Their only purpose is to lull you into into a false sense of security. Learn to drive better instead.

Do you even listen to yourself talk?

yablanowitz said:
A folding knife with a lock is still a folding knife. They call them that because they fold. A lock doesn't make one into a fixed blade.
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No, it doesn't. But it makes the knife hell of a lot more safe - when unknown factors are thrown at you. Sure, nothing will prevent idiots from hurting themselves; and to an idiot, safeguards do offer a false sense of security. But that doesn't make safeguards worthless for the rest of us.

Yes, one definitely SHOULD learn to use a folding knife correctly. This will make the knife safer than by any other means. But, saying that that somehow makes a folder lock useless is like saying that all safety features in a car is useless because everyone should just learn to drive safely, and is a ridiculous, elitist view. There are plenty of unknown factors while using a knife that you can't possibly plan for, and redundant safeguards are absolute necessities in tools.
 
Having used only slip joints or lock backs for 20 years before I used liner, frame, axis and other locks I came to one conclusion. A lock on a knife is just like a safety on a gun. If possible neither knives or guns should be used in such a manner that will cause injury should the safeties fail. This is not always possible, but has worked very well for me.
 
A gentle spin wack on occasion makes sense to test the lock reliability. Most of the issue arises at the word "gentle" whose amount of force varies with any two people.

An interesting defect of spine wack testing is with liner locks. Many reliable liner locks actually vibrate enough due to the specific force to unlock...yielding a false negative reliability result. To further muddy the issue, a gentle spine wack is the most expedient method to see if a liner lock is faulty.
 
michaelmcgo said:
The "W" in WTF is for Why. Why would you want to spine whack a knife as a test of a locks strength? I have carried knives of all lock types for years, and under no circumstances have I ever hit the spine of my knife on something hard enough that I was worried the lock would fail. It is a test that causes many good locks to fail because other things are more important than a knife being resistant to a spine whack (such as an edge whack, but nobody ever does those). It's like testing a gun to see if it will shoot underwater (don't get me started on that test), if it passes or fails, it doesn't tell you hardly anything about lock strength. Personally, I want a lock is designed to take force placed on the edge, I don't discount knives at all if others say they fail a spine whack. Just my opinion, that's all.
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i have to disagree with you here. Good knives will survive a good spine whack. Whack hard enough and any lock will fail but most people who perform the test arent putting it in a vice and hitting it with a sledge hammer.
It is also about quality. If a knife has a lock that locks up dolid and crips and holds just as well then you know the rest of the knife will be well made too.
The lock is a very inegral part of the knife. Yes most people dont do cutting that involves pushing on the back of the knife but good products are made to out perform what you would need it for.
Whats the max speed limit in your state? Lets say its 60mph. Would you buy a car that wouldnt exceed 60? Afterall 60 is all you need? My guess is you wouldnt. Instead you want a product that can handle more than you need so that way incase the crap hits the fan, youre still covered.
First example off the top of my head, what if something fell on your hand while you were cutting with a cheapo knife and caused the blade to close? Likely or not id rather have my fingers.
 
michaelmcgo said:
The "W" in WTF is for Why. Why would you want to spine whack a knife as a test of a locks strength?
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If you think that the SWT is a test to determine the strength of a lock, then you don't understand the test at all.
It does not test strength, it tests reliability and lock security.
The object of the test is not to hit the spine with so much force that cause a reliable and secure lock to break...you don't need but a firm whack on a soft carpeted floor to make an unreliable lock fail.

I have carried knives of all lock types for years, and under no circumstances have I ever hit the spine of my knife on something hard enough that I was worried the lock would fail.
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If you use a lot of liner-locks then I would say that you've been extremely lucky.

It is a test that causes many good locks to fail because other things are more important than a knife being resistant to a spine whack (such as an edge whack, but nobody ever does those).
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No, a "good lock" will not fail the SWT.
Only those that are improperly made.

It's like testing a gun to see if it will shoot underwater (don't get me started on that test), if it passes or fails, it doesn't tell you hardly anything about lock strength.
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Judging from this remark, it's apparent that you don't understand the SWT.
It's nothing like shooting a gun underwater.
It's like cocking an unloaded weapon, putting the safety on, and then pulling the trigger...it the hammer falls even with the safety on, then the safety itself is unreliable.
That is the same as the blade folding when a SWT was done on a locking folder....if it folds then the lock itself is unreliable.

Personally, I want a lock is designed to take force placed on the edge, I don't discount knives at all if others say they fail a spine whack. Just my opinion, that's all
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If this is true, then you don't need a locking folder at all....any slip-joint or box-cutter will do.
 
This sounds like it should be a FAQ, Joe you might want to think about writing that.

I think you might start off with who came up with the idea, the purpose, what it actually tests, how to do it, and the variants that some people have. End with a correlation with use noting some common problems people have with failures of a similar loading.

michaelmcgo said:
Why would you want to spine whack a knife ...
Click to expand...

When you buy a new knife you have to show it who is the Alpha male, this is similar to when you get a male pup, especially of the aggressive breeds. Each time you do a spine you are supposed to shout "Klatu verata niktu"*, be especially sure not to mutter the last word.

-Cliff

* This translates basically as "Who's your daddy!" in old english.
 
I am serious man, you do not want to mess with Deadites. You lose your boom stick and man are you in a world of hurt.

-Cliff
 
Cliff Stamp said:
This sounds like it should be a FAQ, Joe you might want to think about writing that.
Click to expand...

True. This is an area where you get pretty far-ranging opinions, even from otherwise reasonable folks.

Here is what I think is my standard answer -- not in FAQ form, just my stream-of-consciousness response:

I'm a strong believer of the spine whack as a necessary, but not sufficient, test of the lock. The lock being an obviously-vulnerable mechanism, I test the locks on all my folders, using what I feel are reasonable and non-absusive methods, and in total I check for integrity under torque, white knuckling, and impact.

When I spinewhack, I use a light whippy snap. A reasonable question to ask is: does this test reproduce any force I might see in the real world? The answer, to me, is obviously "yes". I have seen numerous reports of someone having their knife binding in a material, then as they pull or yank it out, it suddenly releases and the spine strikes something else, which by itself is proof that it happens. Under combative use, it's easily possible to hit the spine under the heat of battle. In addition, any hard thrust could result in sudden impact against a bone with an impulse force that runs spine-to-edge. And I've seen people talk about doing back-cuts with a Chinook before ... that's pretty much exactly a spinewhack.

Next question is, is it abusive, and does it damage my knife? I personally see no reason to do this test by pounding like a hammer. A light whippy snap is all that's needed to be able to see whether the lock-tang geometry is sound. I have knives I've tested for years that are no worse for wear. Frankly, if I had a folder whose lock got damaged by a light spine whack, I'd go get a better knife, because the vast majority of knives will take a whole lot of light whacks no sweat. Many people on this thread have big robust folders with meticulous heat treat and oversize pivots for maximum toughness and strength. The idea that a light spine impact will somehow damage these things seems incongruous.

What the spinewhack shows is, if there is an impulse force spine-to-edge, will the lock fail? This is a good thing to know. No lock type is immune. However, there's one lock type that is particularly vulnerable, and I wonder if the liner lock's popularity coupled with its susceptibility to spine whacks is what makes the idea of a light spine whack test so controversial. Certainly, since a light whack will not damage the lock and will definitely show a problem with the lock geometry, I have a really hard time understanding why there's animosity towards the test itself. Yes, liner locks are susceptible to it, even liner locks from the big name custom makers ... all the more reason to double-check, so if you're going to count on this knife under conditions where any kind of impulse force might be directed on the spine, you know it will hold up.
 
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