liner lock failure

Q

Quy4n8

Joined
Nov 27, 2002
Messages
659
Just out of curiosity for those of you that have had liner/frame locks fail, under what circumstances has this happened and on what knives? I have had only one liner lock knife that has failed the “spine whack test”, but so far I haven’t had any fail during use. I would just like to see that if there is some pattern, I try to either check my own knives in such an instance or if possible avoid the situation altogether. Thanks for any input.
 
The spine whack test is not valid in determining if the knife is made properly or not.

When was the last time you were holding your knife where the spine could be whacked hard enough to effect it's locking mechanism. In my hand mine are either protected by the thumb in sabre grip or the palm of the hand in recverse grip.

I had one fail after years of use. See the threads here today on what happened to my Elishewitz titanium linerlock after 8 years of use.

Brownie
 
I have one frame-lock that fails the "torque" test, the knife will unlock if you twist the handle clockwise with the blade held in place. I attribute this to the fact that the lock bar is quite long, over 3-1/2 inches, allowing too much flex.
 
I really don't trust the spine whack test as a valid testing procedure, and will NEVER perform it on one of my knives.

I have never had a linerlock fail on me, and I trust them to do the job, even in a 'stressful' situation. The 'torque test' passes with flying colors on all my linerlocks, and so has the 'squeeze' test.

The only hint of a problem I have had with a linerlock was on a Commander, and EKI remedied that right away. (Lock would stick, and not release without forcing it)

The best locking mechanism out there IMHO is the Axis Lock, followed by a properly built framelock, then the linerlock.
 
Hmmmm....if a knife lock has this many issues about
saftey how can it be called a lock?:rolleyes:
 
The same way you can put different padlocks on a hasp.

Some will fail to anyone with a sledge, others will need special skills to thwart.

Safety issues are raised about linerlocks all the time with this person or that person stating this particular lock or that particular locking setup fails their unrealistic testing [ which spine whacking is, BTW ].

If the test is not valid and the knife never subjected to the type of stress the tester is using, what valididty does the test have.

I can destroy about any knife in 5 minutes whether it's a 800.00 custom or a 20.00 POS.

I test knives at www.folders-r-us.org and have never had a liner lock fail in stab tests. That test is valid of course because you may stab someone with it and catch a rib or skull.

If I can destroy a custom knife that quickly with unrealistic testing criteria are we to assume no folder in any config is safe to use?

Of course not. People cause others with less knowledge to worry about something that may ocurr, if at all, once in a million times.

I like those odds myself.

Brownie
 
Of course the spine-whack is relevant. Do a search on Bladeforums and see what has already been said on the subject.
 
Originally posted by brownie0486
... unrealistic testing [ which spine whacking is, BTW ]...
Click to expand...

The people that have had their fingers cut by collapsing liner locks have done some unfortunately all too realistic testing. They probably would have preferred something less realistic.
 
I will admit I don't have experience with many many liner lock knives. What expereince I have with liner locks leads me to believe that they are perfectly safe.

That said I have had only three locks fail on me in the three or so years I have been buying quality knives. One was a CRKT that I took apart, and reworked a bit, after which it would fail easily. I blame this on my alterations, as it was strong before I dismantled it. The second was a Camillus EDC that I much abused, and actually would only fail a torque test. Again I fell this is my fault, not the design or manufacturer. The last was an Emerson Commander, which I believe might have had a faulty lock. After I bought one the lock was redisgned and some of the issues that I felt made it weak were changed. I tweaked the lock a bit myself it hasn't yet failed.

All of these cases of failure weren't doing spine whacks or anything else real abusive. It was either encountered in normal use, or by applying some light closing pressure to the locked blade.
 
I once owned a Spyderco Military. I really liked that knife, but as a "lefty", when I'd hold the knife tightly, the liner-lock would slightly dis-engage, causing the blade to slightly move towards my fingers. I figure that it was better (for me) to lose the knife than it was to (maybe) lose my fingers (or at least some blood) to a collapsing (razor-sharp) blade.

I now stick to lock-backs.
 
Originally posted by marty123
Of course the spine-whack is relevant. Do a search on Bladeforums and see what has already been said on the subject.
Click to expand...

I have read all the "Spine Whack" material on here..., and although I can see minimal relevancy to using a knife, I do think the prime relevancy is to determine which knife will win the "Annual Spine-Whacking Competition".

I simple don't see the reasoning (maybe just me), but if a user is looking for that sort of stability without any doubt, then it's absolutely silly to not get a fixed blade and take out the variable all together.
 
I've had some had experiences with linerlockers, although all of them were what you might consider "lower end".

1. Outdoor Edge Magna, Al scales. I posted about this one, I inadvertantly rapped the back of the knife against a desk, and gave me a bloody gash across the knuckle, the scar's still there. Easily something that could be replicated under normal working conditions.

2. CRKT Mirage, Zytel. First, the lock slipped under a white knuckle grip. I filed the exposed part of the liner off, and thought nothing more of the locking mechanism, as it *seemed* sound. Then, I was working on some cardboard and while pulling it out, the blade dragged against the ground beneath and closed partway (I was holding the knife in a reverse grip), luckily no blood this time.

3. Kershaw Vapor, the smaller version. I've worn the lock down pretty well, and the spring was around 3/4 of the way down the blade tang. I was working with some water and WD40, blade tang slipped, knife closed partway.

Overall, not exactly a good track record for linerlockers in my experience. I think I'll stick with other locks for EDCs, but maybe I'll find a well made, higher-end linerlocker that meets my needs. But I doubt it. Although it may be reliable and strong enough in many cases, it doesn't compare to something like the AXIS lock, IMO, which is much more reliable and less susceptible to failure through a variety of reasons. When using a folding knife (essentially a broken fixed blade), I'd rather not get a knife with a lock that's "good enough"; buying the best available is only natural.

Maybe I'm just unlucky, but...I should mention that I inspected the linerlock on the Mirage at the hardware store where I bought it, and it *looked* solid (locked up half-way across blade tang, etc,) in outward appearance.

For me, the spine-whack test in now standard for any knives that come under my possession. Somehow, the idea of four plus inches of razor sharp steel landing forcefully against my fingers distresses me greatly.


Edited for spelling, content.
 
I think the spine whack test is definitely relevant. It is WAY better than the alternative (losing your fingers when you least expect it). That being said, I don't whack the sh!t out of my knives either! Just a quick thump of the back of the blade against my opposite hand is sufficient. I would never take a folder and try to deliberately make it fail.

I have had a couple of knives fail the spine whack test. My Rekat Sifu (not a liner lock!) almost took all my fingers off with that 5.5" blade - I sent it back to be fixed and it was fine after that. I also had a boker Brend linerlock fail on me. I was not surprized since the liner was almost as thin as a sheet of paper!

I have had VERY good liner locks that passed my whack test that I think I could really count on: Al Mar Sere2K, Spyderco Wegner and Military, CRKT Crawford/Kasper, Emerson Commander, Emerson P-Sark, Buck Strider, just to name a few. There are good ones out there - if you get a bad one send it back!
 
Everyone has their opinions on liner locks,and spine whack tests.

Personally, I only buy quality knives, and I do a simple test to see if the blade has any lateral play, and if the lock is tight. If the lock won't fail when I attempt to close it without disengaging it, it passes.

As I have stated previouly, I have never had a linerlock fail on me, even during hard use, so the high quality ones have earned my trust.

ExamonLyf summed it up very well:
I simple don't see the reasoning (maybe just me), but if a user is looking for that sort of stability without any doubt, then it's absolutely silly to not get a fixed blade and take out the variable all together.
Click to expand...

Folding knives are a compromise at best. Use them for their intended purposes, and if you really need a knife who's lock won't fail, take ExamonLyf's advice!
 
Folding knives are a compromise at best.
Click to expand...

I couldn't agree more! IF IT AIN'T FIXED, IT'S BROKEN! I like fixed blades a LOT more than folders! I have more of them and I use them a lot more. If I'm going to really use a knife hard and anticipate lots of heavy duty cutting, chopping, etc. I'll take a fixed blade. Heck, I carry one around most of the time in addition to a folder.

I just use a folder for everyday cutting tasks like cutting open envelopes, slicing food, opening packages, cutting rope, etc. because they are convenient to carry every day... But if a folder can't withstand a couple of light whacks against my palm without folding up on me, it will not be riding in MY pocket. Fingers are a lot harder to come by than knives.
 
Most critics of the spine whack test assume that hard blows to the back of the blade are required to make the liner lock fail. Hence the complaining about how this constitutes "abuse". This assumption, however, is incorrect. I've found that a light to moderate tap on the spine will be just as likely, if not more likely, to cause the lock to fail. I would never use great force on the "wrong" end of a knife, but I certainly do not consider a light to moderate tap on the spine as "abuse." It's not unlikely that the user might inadvertantly bump the back of his knife, for example when cutting in a confined space. For that reason, I believe that moderate spine whacking is a perfectly valid test of a liner lock.

When I discovered how easy it was to make a very solid looking liner lock fail, I decided not to buy any more liner locks. I prefer the frame lock, lockback and Axis lock, in that order.
 
Steve Harvey:

You know people who have lost fingers on linerlocks through inadvertently whacking the spine of the knife? If you can, ask them to explain how the spine was whacked under use and get back to us.

Just exactly how does the spine get whacked when you are holding the knife in your hand in a using grip? Isn't the hand covering the spine of the blade, sorta prttecting the spine?

Linerlocks failing under use when made poorly seems valid and correct to me. I know of several Emersons liners that release with no effort at all. The question remains how you rap the spine of the knife while you are holding it.

I've carried linerlocks [ and others ] for 15 years and never whacked the spine of any knife on anything in normal use as well as some hard use.

Someone here who feels the whack test is valid could explain how the whack ocurred under normal or any use while in the hand please?

It's relevant if it is something [ whacking the spine ]that could ocurr under normal use. Lets hear from some people who can explain how they whacked the knife on the spine under any use if they were holding the knife which protects the back of the folder. Not hypotheticals but actual cases of people who have had the liner fail under whacking the spine during normal use.

Whacking the back of a knife on the desk is not something I consider "normal". Was this a test or were you using the knife somehow and this ocurred.

Brownie
 
I'd finished sharpening the knife, and sat down in a chair. The back of the blade rapped the desk, and it closed. That doesn't constitute "abuse". The same could have happened if I had been doing some fine work inside of a piece of piping, and bumped the blade against the inside of the pipe (has happened). If I want a lock with the strength of a slipjoint, I'll buy a slipjoint. I'd rather have a lock I don't have to constantly worry about.

From my experience, low to mid-end production linerlockers are generally hit and miss, and learning that a lock was faulty after it cuts my hand isn't exactly acceptable to me, for the obvious reasons, which is why I believe spine-whacking is valid.

Edited to add: There's a thread in the archives somewhere, about someone cutting themself badly with a Mini-SOCOM when the lock failed when withdrawing the blade from *cardboard* where it had bound. I don't believe the poster said that torque had caused the lock to fail. This is a knife from *MicroTech*, *the* high end production knife company, IMO. And why would you cover the spine of a blade when using it? :confused:
 
sph3ric pyramid:
I agree that the mini socom liner should not have
failed in cardboard but that failure wasn't due to spine whack and most likely due to the user inadvertantly releasing the liner.

I have had one of those knives before and it is too small for most purposes I use a knife for. Releasing the lock when grasped is somewhat common on the smaller models from my experience. For that reason I sold it and prefer bigger gripping area and blade length.

A more valid test would be to put heavy pressure on the blade when opened to determine if the lock releases as was the case on my Elishewitz after many years of use and a valid test as the knife is used in such a manner but whacking the spine [ though it may have the same results ] isn't something that happens under normal use of a folder. Thats probably what happened in the instance you cite.

The worst linerlocks I see now are the Emersons. Have had two that the locks were not made right and could be closed manually [ unlocked ]without touching the liner mechanism in the last year.

Brownie
 
Gentlemen,

Thank you for all of your responses. They are sincerely appreciated. As I said, I have never had a locking knife fail under using conditions, only one when doing this test. I agree that doing the spine whack test is not a normal circumstance, but I believe it has some validity as evidenced by sph3ric pyramid’s post. If one thinks about what is happening during this test, significant stresses are placed on the hinge pin as well as the liner and if done hard enough, I suspect most liner lock knives would fail. This is similar to flipping the knife open, where large stresses are placed on the stop pin and hinge pin. Since the hinge pins on most folding knives is somewhere between .156” and .218” in diameter and these are usually two piece designs their shear strength is relatively low. I do believe some negative pressure on a folding knife is a valid test as I often find this happening in some applications when getting a the knife into position to make a cut, for example cutting wire ties off of a bundle of wire. Pressure in this and other situations is MUCH lower than in hitting the spine on some surface as there is no impact. I also agree that if I need a knife that isn’t going to fold, a straight knife is the only way to go. In most of our positions, however, it is impractical or against company policy to walk around the office with a fixed blade knife on my belt, so a sturdy folders is all that may be available when I need to cut something. Thanks again for all of your posts.
 
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