To Spine Whack, or Not to Spine Whack. That is the question

It is completely within the rights of the maker/manufacturer to consider the spine whack test as abuse. It should though be pointed out clearly in their warranty information. At that point the person thinking of purchasing the knife can can make an educated decision based on this info.

This has become such a popular test that I think makers/manufacturers are going to have to include a specific mention of it in their warranty, so that there can be no misunderstanding on the part of the person purchasing the knife.

If a person buys a knife that's warranty clearly states that this is abuse and does it anyhow, then that person should not whine when they are told that they have to pay for repairs.
 
I think we already see some confusion in here. What is the standard of a, "Spine Whack Test?" You see people cite the Spyderco Video, that is not a "whack," that's a tap folks. Now, let's be honest, does the Spyderco Video demonstrate what is done in Cold Steel's Video Demo, "Proof?" I have them both and I don't think so.

Let's be honest, some people on these forums, you can tell by the way they approach this topic, they are going to smack the hell out of the knife.

I'm not saying it was you, Sir, but let's look at this quote from AntDog;

Here's a question to all the "non-whackers". Say you were assaulted by a thug with a knife. Say you pulled out your trusty "non-whack-tested" folder. Say you stabbed into some ribs, tendons, bone, etc... and say the lock failed and the blade folded and cut your first 2 or 3 fingers off. Would you test your folders "before the fact" after that?
Click to expand...

I don't think what I am going to say applies to what you wrote because by your own definition, I think you're just basically "tapping" that spine and not abusing the knife. I think it would be more logical to use the palm of your other hand, but that is another story...

But to answer your question for you, let me ask you this...in theory.

We have someone who thinks a knife should sustain a fairly good smack on the corner of a table.

He does so.

The knife's lock holds fast.

Everthing is good to go!

What happens if he damaged that knife and he won't know that until he either;

a. Suffers a catastrophic failure of the lock.
b. Spine Whacks it again.

Just because it survived once, does not mean it will do so again because the knife may have out of round holes in the liners, etc., whatever. You know what I mean?

So, are you supposed to smack or tap the thing every day before you put it in your pocket like someone with Obsessive Compulsive Disorder or what? At what point is it enough? Because you are never going to know anything because it is a train of abuse, it only indicates it did not fail when you did it.
 
Don. you have hit the nail on the head. This is something I brought up earlier in another thread and it is something that is of utmost importance. If a spine whack test is allowed how does the knife's maker then tell someone how hard they can hit the knife, and once the knife is returned to the maker/factory what kind of test is there to determine if the spine whack was done within the limits described in the warranty? I suppose it is easy to tell if someone used a sledgehammer, but it is more likely that it will not be that obvious.

You either have to allow the test, and that means allow for the possibility of the knife being abused, or not allow the test at all. For most manufacturers/makers the last choice makes the most sense.

This has of course been my opinion, but I can not see how this test can be allowed to be done by the knife's maker and then how that maker will determine if the test was done properly.
 
Don, you brought up a very valid point I didn't think of. If I did spine whack a folder and damage it, I would not know the damage was done until it manifested itself in a later failure. I really wouldn't know the knife had been damaged until then. Depending on the situation, that realization could prove to be VERY costly!

I really don't "whack" mine that hard though. I just test the stability of the lock with a white knuckle test (sometimes) and by whacking the spine on my left palm, just like you described. I just do it one time to see if I think it's safe or not. I would never pound a knife against the corner of a table or something - if I had done that, I would definitely consider it abuse, and would not be surprized if the lock failed on me later.

I only conduct my own test for my own peace of mind. I'm not advocating it for everyone, or suggesting everyone else should do it. I just do it to my personal knives to make me feel more confident about their locks. I didn't by any means pose the question as an insult. I was just curious to hear different viewpoints.

You did bring up something that didn't cross my mind. That's why I'm thankful for fixed blades!
 
KWM, you had a good point also. How could a "spine whack test" be standardized?

I'm sure no two people do it the same, so who is to say when it is just a test to see if the lock will hold under *reasonable* pressure, or an abusive and destructive test which should never be done? Is there any "standard spine whack test"?
 
Well, just because a test isn't standardized, that doesn't necessarily mean that it can't provide usefull information. For instance: People always talk about how sharp a particular knife might be, but when was the last time you saw someone employ a standardized sharpness test?

Also, I really don't know where the idea is coming from that spine-whacking is abuse that can cause damage. It's not using the knife like a hammer and I've never heard anyone advocate something like that. You're just giving the spine a moderate tap on a solid object... it's no big deal. That shouldn't damage even the cheapest of ultra-cheap folders. If there's a maker or company that considers the spine-whack test abuse, then where are they and why haven't we heard from them?
 
I practise the “spine whack” test because it’s a safe method to test the lock mechanism regarding unusual strains.
I think it’s a question of the personal usage. If you think that the lock mechanism of your folder maybe could go stressed in this way then IMO the “spine whack” test is meaningful.
 
I learned about the spine whack test from AT Barr. I use the test the same way he does, as a test of basic lock geometry.

Regarding the legitimacy of the test, the first reasonable question is, does it test anything you might actually run into? Obviously, I feel it does. Aside from the kinds of examples as illustrated above, where someone pulls a stuck knife and hits the spine on the backswing, we also know that any time you stab the knife into something, if the knife isn't exactly perfectly aligned, there will be some kind of component downward impulse force. Also, since many weapons-based martial arts teach defanging-the-snake techniques, it is reasonable to speculate that for a self-defense knife, it is possible that the opponent could hit the blade spine.

In any case, for any knife advertised to be a work or defense knife, there's just no way to justify not including spine impacts as one of the many features worth testing in the lock (along with torquing, white knuckling, etc.). In fact, if it weren't for the fact that the most popular lock format has trouble passing this test, I don't believe it would be controversial at all, since it's rare for other formats to have problems with it.

Does the lack of a spine-whack standard make the test irrelevant? There are really no knife testing standards, yet we all seem to agree that we can read reviews posted here, and provided they include enough detail, we can draw conclusions from those reviews. The main point is, as long as I know what's being tested, and how, I can draw my own conclusions as to whether or not the knife was tested in a way that is relevant to me. But using "lack of standard" as a way to dismiss it, basically rules out drawing conclusions from almost any review posted here.

Likewise, the "it could do damage" angle. Testing my knife but cutting really hard with it could in theory damage some of the same things mentioned above. But, since we have no evidence whatsoever that at least a moderate whack doesn't break the knife, there doesn't seem to be a reason to rule out the test. If occasionally someone does a spine whack and the knife doesn't work right after that, but in this case the test probably outed a knife that was destined for quick failure anyway. In summary: any time I use the knife, I could put impact or twisting or heavy forces just about anywhere, and any of them could hurt my knife -- I test specifically to see if it will. If spine whacking inevitably led to some kind of breakdown, the loads of us who do it regularly would see it, but we don't. And frankly, this is another argument that could be broadened ad absurdum and make all testing moot: since any force-based testing, like torquing, etc., could cause some theoretical undetectable damage, should we give up lock testing altogether? It's your fingers, you do what you like, but me, I'll stick to testing.

I do think that the manufacturer of course has the right to say that the spine whack is considered abuse for warrantee purposes, just like I have the right to ridicule that manufacturer for doing so. Furthermore, I think anytime someone discusses the test, it's probably worth mentioning how exactly they do it. I won't claim my way is better than anyone else's, but I use a light-to-moderate-power whippy snap, and specifically do not use a hard hammer blow. Someone who only trusts hard hammer blows shouldn't trust my tests when I say the knife passed. Someone who only believes in delicate taps shouldn't trust my tests when I say the knife failed.



Joe
 
I think that by knowing exactly how the locking mechanism works, one can inspect a knife to ensure that the knife will lock up and can form an opinion on how hard a theoretical spine wack has to be before the lock fails. The knowledge should include where the critical stress points are, where the locking / mating surfaces are, where the opposing or bearing points are and how forces can be multiplied in the given configuration.

One should check that the mechanism engages properly, then apply moderate pressure (not wack) to check that the lock up doesn't slip or that the bearing points are not loose or cracking. Then one should inspect the various bearing points for material used and size (and therefore typical strength), and check for cracks or other defects.

That should allow one to figure out how well the knife would stand up to abuse, without actually wacking it and possibly causing some damage that may lead to future failure.
 
Beat'em up Friends! Hey, it's your knife...further...just as a thought.

Alot of people worry about losing their digits. Just as an afterthought...

I wonder how many people that spine whacked their knife several times and the knife passed every time...I wonder if they had a catastrophic failure and did in fact lose a finger or maybe just cut one to the bone...

I wonder how many people would admit they did that to that particular knife and instead of flaming the Manufacturer/Maker, would consider the possibility that they did in fact damage their own knife doing this...and would simply pay for their own medical bills instead of going after a Manufacturer/Maker for their own non-scientific "testing."

I think the basis for this whole thing is what Jerry Hossom reminds me of every time we discuss folding knives...he always reminds me;

"Don, that thing bends in the middle..."

Guess what? You're never going to get a folder as strong as a well-made fixed blade, you can make them better than something like a Gerber Mk I and II, which are rather weak, overrated fixed blades, but never as good as a well-made fixed blade.

It's called..."compromise."

Balisong Knife? Check.
Sebenza or other Frame/Integral Lock? Check.
Well-made Liner Lock? Check.
Spyderco Compression Lock? Check.

I wonder...should I trust my Airbag? Shall I bump a telephone pole at 30MPH, just because I have Obsessive Compulsive Disorder and I don't really trust it, it has not been through a "Whack Test!"

By all means, beat your knives up! Ha! Get mixed results and then swear by them because for almost every knife that some people claim have "passed" their personal test, another has failed. The CRK&T KFF is a prime example. Some fail, others don't. Spotty QC or a variance in a non-scientific test?

Maybe we should just send them to Cliff and Joe... ;)
 
Here's my thoughts on spine wacking:

1) The test is a good way of detirmining the reliability of a knife.
2) There is no standard force being applied, so a knife that passes a factory test may not pass the owner's.
3) Although not necessary to the functionality of a knife, manufacturers commonly include data on blade hardness with a new knife.
4) The hardness test is a good way of detirmining the reliability of a knife.
5) The Rockwell Hardness test is standardized.
6) A standardized test of lock reliability, with each manufacturer supplying pass or failure data (ie: how much force was necessary to make the lock fail, or if it never failed) would help the knife buying public understand the limitations of the knife/knives and alleviate the cost of warranty claims from spine wacking abuse.

Just my $0.02, but I think the first major manufacturer to to this is going to come out looking real nice.

-Al-
 
The spine-whack test is quite valid. A light-to-moderate whippy snap into the palm, leg, a phone book, etc., reasonably simulates real-world possibilities. Most of the arguments against it make no sense.
 
Esteemed fellow forumites:

The problem is not spine whacking, the problem is that a whole lot of expensive "tactical" folding knives don't lock-up worth sh!+. Not all of them, but a lot of them, and I want to know which ones do and which ones don't, simple as that.

You cannot discern which ones will lock up reliably by visully inspecting them, as some one suggested earlier, though I have developed my own rule of thumb for doing so. I look carefully at the blade channel, and if there is a liner lock in there, I assume it will fail. :p

So, if you want to know if the lock of a folder will stand up to a reasonable amount of impact, you have to test it. If you don't want to know, if the mere presence of a lock, functional or otherwise is enough for you, don't test.

The test that you do depends on the reliability you expect from the knife. I would not expect any folder to survive being clamped in a vice and struck hard with a heavy object. I have never destroyed a knife doing the tests that I do. I have never seen a liner lock even slightly damaged doing the sort of tests that Joe Talmage does. I do not use any solid objects when I test a folder lock. If the knife is a large folding "tactical" knife like the Sifu or Chinook, I prefer to tape the open knife to a stick and hold the stick in my hand while I hit it with a sharp, but moderate whack with another stick. My arm provides some realistic dampening of the shock. If the knife is a small pocket folder like my Mini AFCK, then just hold the knife between your fingers and give it a gentle tap against something.

I always quit short of what I think the strength of the materials and construction will bear. Even my knives that have failed have continued to lock up tight and resist slow closing pressure. As long as you employ an ordinary amount of common sense, the "spine whack" test is non-destructive, unless the knife is a piece of junk. If a knife lock could not withstand at least some impact without suffering damage, there wouldn't be any reason to bother with the lock at all. It would probably be safer just to assume that the knife would close if the blade were bumped, and join the ranks of those who simply say there is no such thing as a "tactical" folder.

Lifetime spine whacking cult member #003.
 
Jezzzz. . . Is there a "monthly or quarterly" requirement to post a "spine whack test" thread ?

Approx. 50% will agree that a spinal whack test is required and 50% will agree that it's a useless test. . .

Is Spark charging to use the "search" function ? If not. . .use it ~ there is a S@#t load of spine whack tests out there ! :rolleyes:
 
I spine whack once in awhile, I'm really concerned about blade play is all. I'm quite leary to try and take apart my knife as well.

I've seen Joe spine whack and make some popular folders fail and he doesn't slam dunk the blade. His drink doesn't even move when he does the test. Spyderco often spine whacks folders, doing a light tap once just before placing them into the box.

I've spine whacked a Chinook once, the filework managed to crack the plastic of a mousepad. I've heard about various anecdotes of failures and honestly, it's taught me not to perform backcuts or certain sword moves with a folder.
 
I just dont see how hitting the back of a combat folder could destroy the lock or the knife.I have been whacking my cqc-7 on the cutting board and since last night I have probably given the lock over 1000 hard whacks.The entire edge if the cutting board is chewed up and the knife locks up just like it always has.I just dont see where the damage can occur.The lock geometry is right on this knife .The tang engages the liner fully with no gaps.The liner is a titanium leaf spring-the energy from the whacks on a properly fitted liner should be absorbed by the spring.I think waving a Commander open against the fixed stop pin is much more abusive to a knife than any kind of spinewhacking short of what Steve Harvey does;).It just has not been my experience that this damages or loosenes a knife.
On a side note:I was fixing my car the other day and rounded off a nut.I could not get a bite on it so I did what I always do when this happens.I grabbed my trusty $7.99 small visegrip pliers,locked them on to the nut with so muck pressure I was sure the pliers would self -destruct.I then grabbed my 20 oz. Estwing hammer and beat on the back of the handle of the ViseGrip until the nut loosened.The pliers never came unlocked and when I pressed on the release lever the pliers released just as designed.I have done this many times with this pair of vise grips.I got the pliers from my dad who also had done this many times with the same pair.(thats where I learned this trick.Other than cosmetics the pliers function fine.I realize that it is comparing apples to oranges,but should I expect less performance from a folder designed for combat.Should a hard rap on a table with the spine of a knife really destroy a hard use ,properly designed and executed folder lock?
Like I said before:it's your fingers- not my problem.

for the record: a year ago I was in the anti-whacking camp...
dedicated whacker #034,
troy
 
Actually cerulean, the reason that all these threads have started recently is that it has been pointed out that R.E.K.A.T. consider the spine whack test to be abuse of a knife. Many manufacturers do not post here so they will not be replying to this thread. Maybe companies like Spyderco and SOG that do take part here could let us know how they feel about this test. That would be quite interesting.

GigOne, it is correct that there have been many threads related to this subject. I find however that everyone that I read has different ideas being expressed by different members. With new members joining in large numbers, maybe some of them would like to express their opinion about this topic. Doing a search for what has come before is a good way to get info. So is asking the question again and trying to get more opinions from different people.

I do think that the spine whack test when done by hitting the spine into your hand is a good way to check the reliability of a lock. It is also unlikely ever to damage a knife.

I also agree with what Steve Harvey has posted. He has stated that if he did damage a lock doing the tests that he does that he would not expect the manufacturer to pay for the repair. As long as that is your view and you are willing to live with the consequences then you have every right to do whatever you want to your knives. They are yours after all. Just don't come on here and bitch about being told you have to pay for repairs. You will get no sympathy from me.
 
Hmm... REKAT really considers the spine-whack test to be abuse? Geez, I'll make sure I never purchase one of their knives. Didn't someone here say that they sent their Sifu in to be fixed after it failed the test? Did REKAT actually charge for that?

I don't know about other companies, but Spyderco's public policy has been that if your knife fails the test even once, you should send it in to be fixed free of charge. Maybe their private policy is different, but that's at least what they say in the forums.

If someone does damage a knife from spine-whacking and the company charges you for repairs, by all means feel free to bitch about it in these forums. :) Let the people here decide for themselves whether or not that information reflects poorly on the company in question.

A couple of years ago, I bought one those increadibly cheap Eagle Brand lockbacks. You know... the ones made in China that rip-off Spyderco designs. I just wanted to perform some destructive tests on it to see what it could stand up to.

The tolerances on these knives are unbelievable awful. :barf: I thought that if any knife is going to fail the spine-whack test, it's got to be this knife. There were a couple of serious problems with the lock, but strangely enough, it passed the spine-whack test with flying colors. It didn't appear that the test damaged the lock in any way and it passed the test consistently.

If an Eagle Brand knife can pass the spine-whack test without incuring any damage (these knives cost about $5), you wouldn't think that a high-end tactical folder would be hurt by it. Of course you shouldn't slam the spine against a metal bar (and no one is arguing that you should), but the companies who produce tactical folders make all sorts of claims as to how tough their knives are. Sure, the term "hard use folder" is an oxymoron, but I just can't see how a moderate rap on the spine is going to hurt anything.
 
Cerulean, it was me that had to have my Sifu sent in for repairs after it failed the whack test. They did not charge me anything to fix it. I just told them the lock didn't work properly, sent it to Bob Brothers and he fixed it and sent it back.

When I got it back, it worked perfectly, and passed the whack test - go figure...

I have also played around with those knock off eagle brand cheapos. I spine whacked the HELL out of one very hard against my steel squat rack just to see if I could get it to fail - it didn't... BUT the lock did fold the other way later when I was just cutting some cardboard. (the blade folded backward!!) I flipped it over and a bunch of lock pieces fell out from between the liners. I guess that goes to show that you can damage a knife by spine whacking it VERY HARD and actually trying to break it.

That was a cheapo knife though, and I would never do a destructive test like that on anything that cost more than $10!
 
Ahh... that's very cool that your Sifu got fixed free of charge, AntDog. I think that's the right thing for them to do.

About the blade on your Eagle Brand knife folding back the wrong way: that exact same thing happened to my Eagle Brand folder. LOL! When I would cut with it and put a lot of pressure on the edge, the blade would get forced back and its spine would actually get jammed in underneath the rocker bar, levering the lock apart. What a piece of crap! So yeah, I'm sure you're right that a really hard spine whack could damage a knife that.
 
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