"Spine-Whack Test 101" -- Educate me please.

A

anonymous

Joined
Aug 23, 2003
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so how does it go..

you buy a folding knife, flip it edge upside, find a marble counter or wooden workbench, position yourself like the last samurai, & then "hayyyAAAAH!!!" --- whack the little muddaphucka & see if it withstands the force??

i don't really get it, someone explain to me the finer points of spine-whack testing, since i see a lot of y'all have done it & experienced product failures & successes. i'm not being sarcastic, i really wanna know; i've read how some of you richfolk have been spinewhackin some pretty nice blades.

holler.
 
I spind whack on the meaty part of the palm of my hand.

It's abuse to whack the spine on a hard object with much force to my thinking. It only requires a resistance to determine if the lock fails. I don't need to potentially damage the knife in testing it.

Brownie
 
Before I use the infamous spine whack, I will, as safely as possible, put a good amount of pressure on the spine of an open folder. If I see movement of the lock or I detect that the blade is pulling away from the blade stop, I know there is an issue with the knife. If I don't have a problem there, I go to using my palm for the test anf then to a pine 2x4. None of the whacks are with a lot of force. The pine 2x4 is plenty hard to give a better shock test, while still being soft enough not to cause any issues with marring the knife. Tha's where I leave it.

I have heard tell that Anthony Lombardo has become very good at the spine whack test and can get most folders that have passed other spine whack tests to fail it. And, he doesn't need to use a lot of force, just finese. I would be interested to know his secret. However, since he does test knives and writes reviews for magazines, that is probably a secret he would like to keep.;)
 
Should each individual knife be tested, or is it enough to know a reputable line like BM940 or SR Sebenza are adequately safe?
 
I try mine by putting a pad of paper on a counter and giving it a light/medium tap.

I'd say test every knife.
 
Yep. It's usually a moderate to soft impact on the spine that causes the lock to disengage. You don't need to beat your folder senseless to see if it fails. In fact, many of the folders that I have seen fail the test, do NOT disengage with a hard blow to the spine. Now tap the spine lightly on the heel of your hand, and make sure your fingers are out of the way.

I test every knife - regardless of model. Some will fail, some won't - even within a certain model.
 
Les that's a good question, I can think of two things right away:

1) After cutting something you accidently hit the blade spine on something. It's happened to me. It's accidental but "Normal".

2) After cutting anything that binds against the blade, you continue to cut, try to guide the cut, or try to back out the blade from the material.

While it may not be a perfect test, or exactly duplicate what occurs in the above two examples, it's a heuristic of typical lock performance.

If someone wants to invent a better accidental hit/bind text then thats great, many would be happy to have one.

It's instructive to answer the inverse of this, if you have a lock that fails even a light spine tap, is it really a lock?
I can't imagine a wimpier test.

While not typical of my opinions, I wonder if people that think light spine whacks are abuse are really trying to justify their (possibly expensive) knives that fail.
 
It might not reproduce something that might be sustained in normal use, but there is always the accidental contact that usually produces the type of accidents with a lock failing and closing on fingers. Have I ever had this happen? Nope! And I don't want it to. While I don't think a folder needs to be able to be used like a crowbar, I do like to know that the lock will hold.

I consider this part of a function test of a knife equivelant to function testing a firearm. I know there are many out there that chuckle when they read about the spine whack test and think it is a joke. If it makes me happy and gives me a bit more confidence in my knives, I don't really care what anyone thinks about it.

If knives from a maker or company routinely fail this test, I won't by be buying from them.
 
A spine-wack test will let you know if your folder will hold up to you hitting some hard-headed bozo on top of his head with the spine of your knife without it folding up on you...RIGHT?.:rolleyes:.

I really don't see a reason for this "spine-wack test" for real-life use.
 
A locking folder that can't pass the spine-whack test is more dangerous than a slip-joint folder. At least with the slip-joint folder you know what you're dealing with.

And if you have a liner-locking folder that fails the spine-whack test, it does'nt even have a backspring to hold the blade like a slip-joint does.
 
At first I thought this test was knid of silly, but from reading this I see why it's a good thing to try. Like someone said, what if you're using your knife somewhere and as you pull your knife away you smack it into something? Like under a board, or a step on a ladder, etc. It would suck to wack the blade against something and have it shut on your fingers! :eek: I know I have smashed my hand into things like that accidentally, so I can see it happening to me with a knife in my hand. :)
 
It's a moderately useful test-I prefer to try to push the blade closed, with a little twisting/pulling. BE CAREFUL! Your fingers must be completely clear of the blade path if you try this!--Joe
 
I was fortunate enough to be a cub scout when I got my first folding knife. I was taught you cut away from yourself. As such you would put enough resistance on the blade that it could not close on your hand...no matter how hard you pushed in the correct direction.

Im sure locks came about due directly to manufacturer liability. Selling it as a "safety" feature.

Liner locks became the favored lock due to the one handed feature.

Im sure there have been those who cut their fingers because of a flawed lock. The question is, what were they doing when the cut themselves. More than likely they weren't cutting away from themselves like you learn when your a kid....hopefully.

To many people are trying to use folders for applications that are intended for.

As my Dad always told me as a kid "right tool for the right job".

I was at Home Depot this weekend and saw a guy adjusting a hinge with his knife in the screw head. If my Dad had been there, he would have cringed...I know I did.

Fortunately, it was a factory knife. :D
 
Knives used in ones defense may be called upon to go beyond their design parameters.

Stab a rib, pull up and and out the spine is now under pressure. If the lock fails the spinewhack test, you could withdraw the balde and find yoru own fingers have been severed to some degree as well.

In a dynamic environ like defensive blade work, you want to have the strongest locking mechanism you can get to negate as much as possible the variables which lead one to self injuries.

Anything less relative forethought may be considered irresponsible through lack of knowledge or with purpose.

"AAHhh-------that'll never happen to me" doesn't cut it when your a$$ is on the line.

Brownie
 
I just remembered a real life scenario where a lock failed in a manner similar to a spine whack. For all of you tabacco dippers out there, I'm sure some of you have cut a 20oz plastic bottle top off and used it as a spit can. A buddy of mine was doing this at work one day, he used his CRKT Kapser folder. Stabs the bottle, blade enters a bit and the knife collapes. Due to the design of the knife and the fact the blade was in the bottle a bit, he was in no real danger of being cut. Considering he didn't have any other tools on hand to do this task, his knife was the tool to use.

LES, I will agree with you completely about using the right tool for the job. I also agree you need to know how to use the tool. I will go further and say not only do you need to know both those things, you also need to know the limitations of that tool. Thus, I test the limitations of the lock. As was mentioned, if you know you are using a slip joint, you have no expectations that the blade will stay in place with pressure on the spine. I don't carry or use a slip joint.

A properly done lock gives us the closest thing to a practical folding fixed blade available. Then again, if we use a knife the way it was meant to be used, we don't really need a fixed blade. Do we? ;)
 
Too many production and custom linerlocks have unintentionally folded on my hands while I was cutting through cardboard and the blade binded up on the material.

When you push forward or wiggle it up and out, the lock slips and the blade collapses on your hand.

Real fun stuff.

Honest.

It happens. In a distinctly non-abusive and non-tactical situation.

-j
 
I wonder just how many of these "lock failures" are "operator error", due to squeezing the lock-release without realizing it?
 
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