Liner locks fail???

[chrisbrogden]

My Kershaw Boa's liner lock failed under any spine whack or modertely heavy pressure applied to the blade. Since then I've used two Spyderco lockbacks, a Delica and a Native, and I can't make them fail with any amount of pressure.

The only other liner lock I've used was on a Matt Cucchiara custom, and it felt like a fixed blade when locked. Unbelieveably strong.

Chris

 

[Cliff Stamp]

My Kershaw Boa's liner lock failed under any spine whack or modertely heavy pressure applied to the blade.

Often times liners/integrals are not seated properly initially and can fail really light spine whacks and even fail to lock up when opened. A few inertial openings and/or a few spine whacks often seat the lock and it can then become stable. So if the lock does fail, try to break it in a little and test it again, sometimes this fixes the problem.

-Cliff

 

[Tyrkon Lawson]

Gee guys. Now I am looking at my Emerson CQC 7b mini w/ slight distrust.

I have a CRKT M16-13Z as well. Neither have failed yet but I do only light cutting. But I was wondering if the LAWKS system on the CRKT knives make them safer than the more expensive Emersons.

Very interesting input. I'll keep watching.

 

[longbeachguy]

I always test out a new liner lock with hard spine whacks, and even those that do fail, I've been able to fix by making the bend in the liner more aggressive. Someone else who responded to this post said they use a flathead screwdriver for this. I use the needle nose pliers in my Leatherman Wave but any NNP would work. I just grab the liner as far down as I can and give it a hard twist. If you bend it too far up toward the blade, you'll have a hard time disengaging it.

Some that I've had to tweak are Kershaw Talon, Kershaw Scallion, and Boker Copperliner. Once fixed, they are as strong or more so than the ones I didn't have to mess with.

 

[Laceration]

Folding knives compromise security and safety for convenience. ALL locks can fail or be defeated. It doesn't matter whether you're talking a lock on a knife or a bank vault. A good quality folder can withstand alot of abuse, even a liner lock, but if you're going to be using a knife that demands to be able to withstand extreme forces, buy a fixed blade. Common sense dictates that one piece is sturdier than two.

 

[The Falcon]

I've had several Emersons that started to fail - the liners moved part of the way toward the disengaged position.
Kind of scary but EKI is super on customer service. I had one knife returned to me in 6 days with a rock-solid lock-up, all new screws and sharpened.

 

[Cliff Stamp]

Folding knives compromise security and safety for convenience.

They pretty much compromise all aspects of knife performance for ease of carry.

ALL locks can fail or be defeated.

There is a difference between breaking a lock and accidental release. If you were buying a lock system for your bike and you discovered that if the lock was given a sharp blow with a hammer it would release would this be a concern or would you just accept it because after all, any lock can be defeated?

Various locks on folders have varying degrees of security and raw strength. The more secure and stronger the lock the wider scope of work of the knife. On some folders the lock isn't the weak point any more and the blade will go before the lock in a lot of heavy work so it would not be any more durable if it was a fixed blade.

-Cliff

 

[Wunderbar]

I'm at the point where I'm considering no longer carrying folders, but fixed blades instead. It seems like the simplest and most effective solution to the problem. Plus, good fixed blades are generally cheaper.

Good point! There are many small fixed blades out in the market today also
that can be easily carried.

 

[Troll Bait From Hell]

The only linerlock that I have ever had a problem with is an Emerson PSARK that I bought new when they first came out. I can close it one handed with just slight force on the back of the blade with my index finger, and WITHOUT disengaging the lock!

I've had it in the drawer for quite some time, and keep telling myself that I'll send it back to have it fixed, but I haven't bothered to do so yet. I understand that they have outstanding customer service.

Otherwise, it seems like an excellent knife. Very good handle ergonomics.

 

[STR]

That is not acceptable on that Emerson. Send that baby back to them to replace or fix.

I find it interesting that so many negative posts are listed around the forums for liner locks and yet so many "knife of the year awards" go to....you guessed it, liner lock folders at the blade show. I don't know what knife won this year but seems to me going from memory that it has been a liner locking folder of some kind for a few years in a row now. So, apparently there is a vast market for them and people still make them to please that market.

Cliff's statement;

"If you were buying a lock system for your bike and you discovered that if the lock was given a sharp blow with a hammer it would release would this be a concern or would you just accept it because after all, any lock can be defeated?"

makes sense on the surface but he misses the point that any lock can be defeated so sharp blow or not, you have to accept that fact for the possibility on any lock system, not just one. I've used the Jeep analogy several times. Jeeps can roll. Do you just not drive one or do you drive one and make sure to be a little more careful in the way you drive it working within the limits of the vehicle you have at hand?

It all boils down to common sense. If you push your folding knives to the limits of their ability a lot you probably should just carry a good high quality fixed blade and be done with it or if you can't do that from a legal standpoint carry a fistful of bandaids in your wallet for the inevitable accident coming when you defeat the lock on your folder. It is a fact that a folder has always been a compromise giving up many of the security and work benefits of the fixed blade for the convenience of compact carry hidden away in your pocket.

 

[Megalobyte]

AM, here is what I don't get about you.

You tested a knife or 2 and based on this very limited sample, you drew a broad conclusion that liner locks in general are reliable.

Then, when people come forward who have tested hundreds if not thousands of knives over a long period of time, and their experiences are different from your own, leading them to draw a different conclusion about the inherent reliabilty of liner locks, you feel persecuted, and it almost seems you expect these people to ignore their own experience in favor of yours, you expect them to give your very limited testing more weight than their own? And when they don't replace their conclusions with yours, you say they are part of some silly anti-liner lock, or anti-Artfully Martial conspiracy, I think you are giving yourself a little too much credit here.

You found a few reliable liner locks, which isn't surprising since the majority of them are reliable, but the truth is, liner locks are a lock type that is hard for makers to get consistently right, and thus, many people feel they are not as reliable as other lock designs. I like liner and frame locks and most of my knives are of that type, but, I also know that you really need to test them before you buy, or rely on one, I have seen way too many, in all price ranges, production and custom, that would fail a light spine whack on the palm of my hand, and I don't care what anybody says, if a lock fails when you exert slight closing pressure on the blade, as hitting the spine against my hand does, it is not a safe knife and can be legitimately called defective.

I'm glad your liner locks so far have been good, but I guarantee you if you buy enough of them, you will start to run across a few that fail very light spine whacks as I and many others have, and I'm sorry, but I'm not about to ignore my experience and testing just because you tested a knife or 2, I'd be pretty foolish to do so.

 

[Cliff Stamp]

The only linerlock that I have ever had a problem with is an Emerson PSARK that I bought new when they first came out. I can close it one handed with just slight force on the back of the blade with my index finger, and WITHOUT disengaging the lock!

How does the knife close with the lock engaged? Many liners/integrals have seat/engagements initially. They can often be fixed with inertial openings of spine whacks.

Makes sense on the surface but he misses the point that any lock can be defeated so sharp blow or not, you have to accept that fact for the possibility on any lock system not just one.

I didn't miss the point, I addressed it specifically. It isn't the fact that it can fail which is of importance it is the mode and how it fails specifically how much force/impact/torque. If you bought a knife and it had to be sharpened after every foot or so of carboard would you accept it because after all, all knives blunt.

Similarily, it doesn't matter what steel a knife is made from, you might as well just use 1020 because any knife will break if you apply enough force to it, thus the strength of the steel doesn't matter. Of course no one would agree with that, but it is the same logic constantly used to justify insecure locks.

An no you don't need to carry fixed blades, I carry lots of folders for which the scope of work is usually limited by the blade geometry and not the lock which is how it should be assuming the knife is properly designed. If it isn't then the design is inconsistent because the strength of the blade is useless as the lock can't handle the loads.

Concerning the bike lock, a very popular brand was actually recalled because it had a weakness similar to the above. No one defended it because you can defeat all locks. Just like I severely doubt you would defend the locks on your house if you found they would release easily under similar conditions.

-Cliff

 

[Artfully Martial]

I give up.....

 

[STR]

Meglobyte: I love that video clip of the guy breaking the sword in your signiture line. Hilarious!

Cliff I agree fundementally that there are better locks. That much is obvious. We have had some really great inventions and improvements in the locking folder in our life time for sure. I have them. If you check my profile my favorite most all the time is my 420 BM Resistor that is an axis lock. Even still it doesn't mean I don't own liner locks. I own more of them than probably any other and I carry and make them as well.

I just don't see liner lock failures as the big problem you seem to see them as. Obviously the manufacturers and the buying public don't either. All locks can end up in a situation where they defeat from any number of causes to broken springs, pocket lint, dirt, or just stupid people using them. I see a defeated lock as a defeated lock regardless of what system or type it is. How it fails is not as important to me as the fact that it did when it happens but I agree that testing is important so you know the limits and weak points, as well as strong suits of each lock system you happen to use a lot.

 

[Cliff Stamp]

I really wish folks tested their lockbacks ...

They do, they people who are vocal about lock security like Joe and Steve apply the same criterial to all knives they use, Steve was one of the first if not the first to really load an axis including the really heavy assisted spine whacks he does. I have taken lockbacks to failure on more than one occasion, and do stability checks on all the ones I use.

But lockbacks are still considered by most to be number 1.

In some respects, they have their problems, accidently release due to indirect pressure which for example ER has addressed with the safety latch which is similar in intent to the LAWKS.

I read about people talking about how liner locks should fail all the time.

No one has said this, as I noted in the above, which Joe noted in your origonal post, which he noted in the FAQ, he who is one of the biggest detractors of liner locks states clearly in the FAQ that he has evaluated many which were perfectly stable.

They get so much undeserved bad press.

Their reputation is based on them failing and the incidence being higher than other lock types, it took quite some time for this to actually develop. It isn't like Joe used one liner lock then wrote the FAQ and then declared that the lock type was insecure.

Which however is pretty much exactly what you are doing, and you complain people are ignoring you when they have done the same thing on a much greater sample of knives and seen a high incidence of failures.

It is also based on makers calling these tests abusive to the lock. When they won't support such evaluations of their knives it obviously doesn't lend itself to a belief in the lock.

I tell the new guys not to believe any of us and go test it himself. You'd look like liars if you told these folks just to trust you, liner locks are less safe, and go with a lockback, instead of agreeing with me on testing it.

Again, read the FAQ. Joe clearly promotes testing the knives. He does not promote simply taking what he says on faith, he goes out of his way to describe exactly what he does so you can try it for yourself. Joe even encouraged you to keep using and evaluating locks and to post about the results.

-Cliff

 

[Lone Hunter]

Had a Buck Crosslock that would fold its blade with a VERY light spinewack on the palm of my hand. Seeing as it was made for fire/emt (which is why I got it) I had very little trust in it and got rid of it asap.

My first gen. LCC had a liner that went from locking up all the way on the left to all the way on the right in short order. In fact it went so far over it kind of got stuck their. Microtech fixed it, and I use the knife today.So far it stayed kind of in the center. But today I do try to avoid them.

 

[Carl64]

Hmm, always so much to say.

I think not everyone agrees on how hard a blade should be whacked. If you only see yourself ever putting so much force on a knife, it makes sense to not worry about failure at extremely high force. But if you think you might ever use the knife for defense, that means you might be stabbing at something with all your might. Keep that in mind before tapping the blade on your palm and saying "seems to work."

I think Cliff and I both have tried a lot more knives than others. Cliff has a lot of his on his website. I of course am aware of the many scores of knives in my posession. If someone says "I never had a problem," they should specify how many knives they are talking about. I have used well over 100 liner locks and about the same for lockbacks (a lot are no longer in my posession). If you have tested only one or two knives, I wouldn't be surprised of they were both good or both bad. It's a small sample and almost any knife could be made correctly by accident. A small variation in shape can make a lock good or bad, and the size of that variation is less than the quality control margins for a lot of knives. I don't doubt your Kershaw or Buck may have actually had a lock that passed your test, but please be open to the possibility that there are a dozen others out there that aren't so good.

Lack of lawsuits, nationwide complaints, and manufacturer awareness don't mean much because there is no general public knowledge/interest or authority on the matter. A relatively small number of people (manufacturers and users) put effort into the finer points of engineering folding knives. Most buyers and sellers are just trading knives to be used for very light duty and don't expect much. They don't care about what happens if a folding knife is stabbed into something with 100 pounds (easier than you might think). As a hobby and matter of personal study, a few of us are interested in what makes one knife better than another. Folding knife design is not bound to get the same attention from corporate giants as steel and handle material formulas (which become useful for many things, not just people wanting $100 pocket knives), so it is left to a handful of manufacturers and users who are personally interested to study in detail.

 

[Cliff Stamp]

Lack of lawsuits, nationwide complaints, and manufacturer awareness don't mean much because there is no general public knowledge/interest or authority on the matter.

There are a lot of nuts out there though, and it does surprise me that someone hasn't flipped out and sued already given what has hit the courts already. Awhile ago on TV there was a case were a woman lost a finger because she walked her dog with one of those leashes on a coil spring and wrapped the leash around here finger and when it either retracted or the dog pulled it out fast it cut her finger off. They now have warnings not to wrap the small piece of cord around your finger. Given how aggressively some of these knives are promoted, "WAR KNIVES!" and similar, I can't imagine defending a lock closing under a light tap as being acceptable, especially when you are able to duplicate the failure readily in other samples and that it is a know defect not publically stated or warned about. You get that happen to someone who depends on their hand for their work and it could get costly.

-Cliff

 

[Dijos]

my 2 cents. I am less concerned about spine whacks and other testing methods, but I consistently accidentally release the lock with my finger. I obviously have the wrong hands for linerlocks.

 

[STR]

Disengaging when white knuckling is an issue at times depending on how big a surface area the manufacturer/maker puts on the handle for accessing the lock to depress it. Many make them very subtle now with as little opening as possible to prevent this. It could be argued that the Spyderco compression lock can be moved with heavy gripping also.

Again though some of you guys amaze me the way you zero in on one thing (spine taps) and make it look like the liner lock is the only one suceptible to failure should it occur. Personally, I think a properly made liner or frame lock actually holds up better to spine taps than other locks. They certainly have in my own tests which by no means are as strenuous as the ones I've watched but still enough to show that they hold up to it.

We have seen here on this forum and others quite recently MBC rated locks from 'heavy duty' folders fail spine taps, not whacks, and also a video of a BenchMade axis lock not just failing a spine tap but failing very light spine taps miserably. Funny how those are forgotten. I call that 'selective memory loss' because I know some of you guys read and watched those clips.