Spine whack test?

I love the spine whack test, besides testing the lock for shock (that's important to me). It shows just how durable a lock will be.
 
I do not think it it a valid test. Rather than testing the strength of the lock, what is really being tested is the spring characteristics of the liner.
 
It is a silly test, buy performing it all you are doing it possibly peening metal and making the lock looser. I cannot imagine a real world situation that would call for me using a knife in this method. Yes I have tapped with the spine of a knife in the field but never have I whacked it as hard as I could against an immovable object. You want to test your knives lock then put the blade in a vise and then hang 100 pounds of weight off the handle.
 
I don't really know any manufacturer or maker that would consider spine whacking anything less than abusive treatment. Still some are going to do it and if a maker wants to tell his customers hey, I recommend it well, thats their business. Personally I think anyone that does warrant spine whacking is going to end up doing a lot of repairs for no charge with most conventional lock types because people will beat the snot out their knives and expect it to take every bit of what they dish out to it and when it doesn't well, then it's crap right? Doesn't fly with me but whatever.

Spine whacking to me is akin to testing the bumper on your car for safety repeatedly over time by driving it into a wall periodically over time just to feel safer inside as you drive it. :D You guys enjoy your debate. I've said my peace and I'm done here.

STR
 
I think light spine taps are a decent test, but slamming the blade of a knife full force into a table won't do anything good for the lock. I'm sure most if not all of my knives can take a spine whack, but I think a few light spine taps in quick succession will test lock reliability without being overly abusive on the lock. I consider a spine tap the type of force you would use to hit your hand without hurting yourself too bad, basically a light hit. I usually do this once upon recieving my knives and haven't had one fail the test or fail in use.

Mike
 
I always test locking folders by hitting the spine of the blade on the palm of my hand. I don't think a hard whack on a hard surface is a good idea.
 
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The Spine-Whack-Test is most generally performed before the Stabbing-Into-Conrete-Test, executed with full force, if tradition is to be heeded. However, if the knife fails the first test, the subsequent test should NOT be performed. Any reputable knife-maker knows that and that warning should be included in every manual supplied with every reputably manufactured knife (found most often on page 13 of the manual). If the warning is not present in your folders manual, it is recommended you consult the manufacturer's legal liability department.

Yes...the spine whack test. I love that one.

The test is somewhat akin to the Drive-Your-New-Car-Head-On-Into-A-Tree-Test. This is done to see if the airbag will work in the future....in the event you have an "accidental" head-on collision.
 
DemkoKnives said:
most people who don't like the test don't like it because their choice knife will not pass.
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This probably rings true with many folks here.

I think the big factor with this test is defining parameters. One man's spine whack is not the same as the next. STR does note that some aspects of this test are not really yet understood. There is an unpredictability that has not truly been accounted for. I tend to think that some of this may be attributed to tests with poor controls. And of course, once it does happen, the damage done seems to be irreversible.


The test is somewhat akin to the Drive-Your-New-Car-Head-On-Into-A-Tree-Test. This is done to see if the airbag will work in the future....in the event you have an "accidental" head-on collision.
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Good point. This is a valid test, and is done by manufacturers. It is understood that it is a destructive test (as serious spine whack tests should be), but that the results could be interpolated in such a way that the end product can be expected to behave the same way off the assembly line. As a result, if you do crash your car into a tree and the and the airbags don't deploy, you may have a legit beef with the manufacturer.

It's not clear that many knife companies generally perform such tests, let alone make the results available to the general public. As a result, the best we can do as knife consumers is rely on the tests of volunteers.

stormyone said:
I also do not flip the cylinders of my revolvers closed with one hand.
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OT, but the idea that this is abuse always drove me crazy. Why is it that revolver companies can make a cylinder that can withstand 20,000-40,000 psi and more without exploding in your hand, yet cannot be made so that it can be flipped closed without damaging the gun?
 
I don't really do spine whack tests, but I also do not use folding knives like a fixed blade. I have plenty of fixed blades and just a few folders. I use any folder pretty much like I use a slipjoint.
 
imho a lite spine tap on the palm of your hand can tell ya a lot a lot about how your lock is locking up, a lite tap wont hurt anything either, but ya dont have to go nutz on it, if ya whack the thing hard enough anything will fail.
 
A light tap or two on the spine of a knife you've just bought is not a bad idea. I have two Buck 18X series knives bought a few years ago when I was in the USA. I bought them and sent them home with a friend. Back home in South Africa I found that both those knives failed to lock-up. You don't even have to tap the spines - just push on the spine with finger pressure and the blades fold.
Does it matter? Sure it does - those knives are sold as SD / police utility knives. Just try 'hooking' an attacker's punch or straight knife thrust to your centre with one of those Buck knives and you'll be a few fingers short at least.
(Did I send them back to Buck? No. Mailing knives in SA is a bad idea - they'll just be stolen....hmmmm, maybe that's not a bad idea. Let the thief lose a finger or two....)
 
I think I may have spoken to soon, As a designer and maker I do spine whack tests to the point of breaking something. If it does not do what I think it should I try to improve the design somehow. So when I say it's a good test I don't mean for the buyer to do this. It should have been done by the company that makes the knife. I think we all know if we spine whack all of our knives we'll have a bunch of ruined folders even if they do not fail. Cold Steels says 5 "fair" spine wacks. So when I make a knife for them I make sure it can pass that test by far. The problem is factories have very different standards. See the cold steel bushman facts youtube vid around here somewere. I spine whack the heck out of it. Why, decause I designed it and wanted to see what it could do. So in short the maker should do the testing so you will not have to.
 
Spine "whack" slipjoints.
Spine TAP locking knives.

Go break the lock on your knife by abusing it and see if it'll get covered under warranty.

Remember that every lock can be made to fail in one fashion or another.
 
Absintheur said:
It is a silly test, buy performing it all you are doing it possibly peening metal and making the lock looser. I cannot imagine a real world situation that would call for me using a knife in this method. Yes I have tapped with the spine of a knife in the field but never have I whacked it as hard as I could against an immovable object. You want to test your knives lock then put the blade in a vise and then hang 100 pounds of weight off the handle.
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viewFile.html
 
billy blade
Spine whack test?
I bought a new knife from a guy on line cheap! He claims in his listing it has a weak lock spring because it didn't pass his "spine whack test". What is a spine whack test? I'm having a hard time believing the new knife from a quality and beloved manufacture has a weak lock spring. I just want to hear from my fellow blade forum members about this so called test.
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First, let me say that the spine-whack-test is NOT a test of the lock's strength.
The spine-whack-test does NOT determine how strong a lock is or how many pounds of force a lock can withstand.

It is a test to check lock geometry and lock function.

And it does not take much force for a defective lock to fail the spine-whack-test.
You don't have to tape it to a broom handle and beat the daylights out of it.
All you need to do is give the spine of the blade a firm hit on something solid.


I have had only three knives fail the spine-whack:
One was a CRKT Mirage....it was the first one and it occurred before I had even heard about the spine-whack-test....
Years ago, I was hiking through some woods and carrying my CRKT Mirage.
I stopped for a break and decided to clean the mud off my boots.
After using my knife to scrape off most of the dried mud, I then decided to get some of the dried mud out of the tread of my boots by tapping the tread with the back of the knife blade.

On the first tap the blade folded as if it had no lock what-so-ever, and it cut the back of my thumb.
I thought that I had just failed to lock the blade open properly.
But later, I read about the spine-whack-test on this very forum.
So I decided to test the Mirage again (in a safe manner this time)....
And sure enough, the lock failed every time I tapped it on the carpeted floor.
And again, it didn't take much force at all: not even a full arm swing....just a little wrist snap.

My experience with that CRKT Mirage made me a believer in the spine-whack-test, and I have since tested every locking knife that I have ever owned or considered buying.
I typically just grasp the knife (with my fingers safely out of the blades closing path) and give the spine of the blade a firm hit on the sole of my shoe.
Besides the CRKT Mirage, the other knives that failed the spine-whack-test were a Benchmade Crawford Leopard and a Lone Wolf Harsey T2 folder.

I will not carry any folder that fails the spine-whack-test.

Take it from one who has been bitten by a folder that failed....
The test is not destructive at all, and it is 100% valid for checking the reliability of any given lock.


Sal, the owner of Spyderco Knives, also recommends the spine-whack-test.
In fact, Spyderco does this very test on their folders.
From this thread:
http://www.bladeforums.com/forums/showthread.php?t=366883&highlight=whack

#39
10-06-2005, 11:15 AM

Sal Glesser
Moderator

Spyderco began spine whacking its production folders in 1981. We were
heavily criticized by manufacturers in a number of countries but we felt
then, and do now, a manufacturer is obligated to extend their best effort to
make their locks as reliabily safe as is possible. We believe Spyderco has been instrumental in helping to improve lock reliability in production knives.

We advocate that every customer do a light spine whack of maybe 5 pounds of pressure before purchasing a knife. A lot of knives are far too sharp to
take a chance on an unreliable lock.

I don't believe any manufacturer would make a knife that would intentionally be unsafe. We have found that slight changes in angle or length or spring strength affects the geometry and consequently the reliability in the the lock.

I would recommend that before you use any locking folder that you test them and then test them periodically. A light tap is not going to hurt the knife, but a pile of lint somewhere in the lock would be a nice thing to know.

If the lock fails and it is not clogged up with debris, or has not been abused, then send it back to the dealer or manufacturer. I am sure they would want to know if there is a problem and would be pleased that no one was accidentally hurt.

Building a safe knife is the manufacturer's responsibility. But using a
safe knife is the customer's responsibility. Cleaning the knife, sharpening
the knife, periodically checking the lock, regular lubrication, these are
all responsibilities of the knife user. While I have not toured Mick's
factory, I think I can safely say that every Stryder is spine whacked at
least once in the manufacturing process, as is every Spyderco.

Manufacturers love responsible users. It makes everybody's life easier. If
you guys are really into this "I can jump higher than you" game, come up
with a set of requirements, invite each manufacturer to produce a model to
those requirements. Come up with a set of agreed on tests that are as
objective as possible and have a "race". To realistically compare knives
like the Manix and the Stryder is unrealistic. Like a 4-wheeler racing a
sports car, the outcome depends on whether they are racing on a racetrack or through the countryside. Every manufacturer is capable of designing and
building anything they want. The results benefit everyone.

A "standard" method of "spine-tapping" for lock reliability that anyone can use and understand is needed. Cliff? Joe?

sal
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And here's another quote from Sal, from this thread:
http://www.bladeforums.com/forums/showthread.php?t=145078&highlight=whack

Sal Glesser
Moderator

Blil. Don't know what to say on the Lum. All of the Lum's are spine wacked in Golden. Just shows to go you that pobody's nerfect.

Same for the Shabaria.

sal
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Ignore the spine-whack-test at your own peril....but don't say you weren't warned. ;)




Allen
 
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I unknowingly followed Sal Glessers advice one day at lunch and discovered a major knife makers authorized copy couldn't withstand a spinewhack on a leather covered steering wheel.

That's a good indication the knife was a low quality piece of junk, and further use and examination proved it to me, made in Idaho or not. Compared to a original, it really suffered.

You don't have to spinewhack a knife repeatedly, or hard enough to peen the locking surfaces. You don't have to repeatedly flick it open, twist or pry with it, or attempt backcuts while twisting or prying to prove it will stay locked.

But you can do a little of it and get a good idea of what the out-the-door quality is. Those that persist and actually abuse the knife get what they deserve, an example of their ability to be educated on materials strength and engineering compromises. ALL knives are engineering compromises.

If you want an folding piton, pry bar, and an accessory edge for cutting, choose a Extrema Ratio RAO. The compromise is obvious - it's a huge sheath carried hunk. It takes mass and material thickness to accomplish the goal.

Even a titanium framelock with S30V blade is still a cutting knife. At least in that size you get to pocket carry. Sure, you can check build quality with a spine whack, but don't plan on extensive abuse. Abusive knive tests are more a statement of the lack of knowledge by the performer than the strength of the knife. At least I know that if it's a folding knife, it cannot possibly be as strong as a fixed blade, and to treat it like a slip joint.

It's like the rules of gun safety - it's always loaded, point only where you intend to shoot, keep your finger off the trigger. For folding knives: it's designed to fold, it's always sharp enough to cut, and keep your fingers out of the way.

In the days when boys carried pocket knives to school, you learned this in the second week of ownership. Why adults deny the basic rules of operation and then complain is truly a statement of the age. Those that at least check with a spinewhack are finding the boundaries of performance.

And those that beat a knife into pieces and post video are probably compensating for more than their lack of any credible education or training.
 
STR had a photo a long time ago where he holds the knife in both hands and applies pressure with the one hand on the back. I do that rather than a whack!
 
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