Comment on Liner Lock Failures

Oct 10, 1998
I wonder how many of these failures happen
after the pivot pin has been adjusted by the consumer for more opening speed?

Just a thought.
Great question AT. Operator monkey fingers is usually the factor in most of the blade and gun accidents I have seen.

"Yeah, I filed down the Sear to get that Hair trigger." Famous last words of nine toed Joe.


Have a GREAT weekend.


"Cet animal est tres mechant;quand on l'attaque il se defend."("This animal is very mischievous: when it is attacked it defends itself")
To AT:

Loosening pivot tension should not be a factor as long as side-side play does not exist. A good liner lock should be silky smooth and have no side play. If the pivot is loosened so there is sloppy side movement, yes, this changes everything and most definately could cause a liner lock to fail. A very loose pivot will vary all the angles of lock engagement as the blade moves side-side. A precise lock engagement angle (combined with a few other details) is probably the single most important factor in making a good liner lock.

Outdoor Edge Cutlery Corp.

David Bloch,

A lot, I bet.

The rule of thumb I tell people is this. If you mess with the tensioning, do this test. Open the knife completely. Now thumb aside the liner lock. Now, lightly wiggle the handles back and forth. There should be no play at all -- just the force of the washers should hold the blade steady.

I wonder now if this is really enough test. I think many torquing failures are due to the the blade tang moving a little, and the lock subsequently slipping down the angled tang. I think the test I outlined above might not test for that enough. Maybe after that test, the user should tape up the edge and then torque the blade a little, make sure the handle pressure is holding the blade firmly.

What do you think?

I feel that the majority of "Quality" Liner lock makers do their absolute best to give their customers a safe and smooth action.

I could back the screw out a little and get a faster "flipping" action, but that would not make the knife smoother.

That's one reason I put my pivot bolt beneath the bolsters. I also use permanent lock-tite on the pivot screw. The pivot screw can back out without the lock-tite.

AT, I don't know a general response, but I can tell you that several people, including "KnifeNut," have warned me that while nice-looking and inexpensive, the Smith and Wesson S.W.A.T. knife has a poor locking liner, someone even called it "paper-thin." Stay away from this knife because of these problems.

I know the Gerber Gator uses ATS-34, a great steel, and has a nearly indestructible locking liner. Check KnifeCenter's review of the Gator for a great example!

The Carson M-16 from CRKT has a regular screw pivot head for the locking liner, at least that's what the picture shows. Should I stay away from this knife because of it?


[This message has been edited by Gator (edited 25 June 1999).]
As far as a manufactured (not custom)Liner Lock, you can't go wrong with a Benchmade or Spyderco.

You do get what you pay for.
While everyone is comparing the reliability of a Liner Lock to a Lock Back. I have another question. How many Lock Backs, allow you to take them apart and adjust the pivot?
I agree with what was said about blade play relating to failure. So long as the pivot is not loose enough to allow substantial play and thus alter the locking angle, loosening the pivot should not play a part in lock failures. Pivots screws may loosen by themselves, so I've sometimes fitted modified Benchamdes with a slotted pivot instead of hex or Torx - that way any turning is plainly evident and the knife may be adjusted with a Leatherman.

Being able to take the knife apart is a major advance, in my opinion. It allows cleaning, adjusting, and even customizing. Instead of attempting to prohibit folks fro taking their knives apart, we should put effort into showing them how to do so safely. Benchmade voids your warranty if you disassemble the knife - thumbs down. Kershaw gives you instructions, parts, and proper tools - thumbs up! I trust my customers not to be morons and I encourage others to do likewise.

On the S.W.A.T., I purchased one of these as a "beater." Yep, the liner is very thin and doesn't inspire confidence, but you know what? I can slam it spine first into a table hard enough to take chips out and the lock doesn't budge or even get tight. These knives are real sleepers, and you should not judge a lock by appearances alone.


(Why else would a bear want a pocket?)
Corduroy - I would guess that Benchmades (& Spyderco's) reluctance to promote ELU taking apart their knives are based on several factors.

Most ELUs are not knifemakers as you are and more often than not, the knife is not properly put back together.

Sometimes it is sent back to the factory in a baggie with a "Please put back together" note.

Sometimes the ELU taking apart the knife modifies it and alters performance. Displeased, the parts then sent back to the factory for a necessary rebuild (usually more expensive than the original mfg cost).

Occassionally the ELU takes apart the knife, puts it together improperly, cuts himself, sues the manufactgurer and now the factory would be liable (unless making a statement that protects them).

Car makers can't stop ELU from repairing their own brakes, but warrantees protect them from ELU error that may cause an accident.

Americans are often "sue happy". Manufacfturers must protect themselves from potential abuse.

Kershaw has undergone a majore transformation as they shifted from Seki to USA manufacture. Let's hide and watch to see how long it takes Kershaw to realize this fact. Just some thoughts to share.
I'm glad A.T. brought up this point. The one thing I don't like about the axis and rolling locks, is that it seems like it would be difficult or complicated to take them apart. I have taken all of my liner locks apart at one time or another. Is it even possible for the ELU to take the axis or rolling lock apart?

This is exactly why I tend to prefer the integral lock, like the Sebenza. It is every bit as strong as the axis/rolling locks, but much easier to take apart for a good cleaning and lubing. I think the integral lock is as ideal as it's going to get. It combines the strength of the axis/rolling locks, with the conveniences of the liner lock. Now, if only Spyderco would make one, so I could have that hole!

Marco - I have been "bugging" Chris for years to design a Spyderco Sebenza Clipit. He's tough. but I'm persistent. You might bug him also?
Mr. Glesser,

I'm much happier to see it as a liability issue than one of customer ineptitude. Really, I shouldn't even suggest that it is "inept" or "moronic" if someone can't put their knife back together - different folks have different skills. Now, suing over a problem they caused themsleves... that's moronic.

The way I see it, Spyderco already has a number of people devoted to free-of-charge tasks like sharpening and repair, and re-assembly would only be another such task. Why would Spyderco offer this? For the same reason they offer other free work - it gets them buyer loyalty and the best reputation in the industry, and the money comes back in increased sales. I do think that re-assembly would be a very small workload if knives had proper illustrated manuals printed on a little slip of paper and packaged with each one. I remember how scary it was to pop open a Benchmade for the first time and not know what I would find! Maybe I was lucky, but this should be simple task for most folks with proper instructions.

The other question is how to keep Spyderco from being liable for those folks who don't do it right... that's a bit trickier, but as you mentioned, there is precedent in other industries.

I've been watching the Kershaw "experiment" avidly, from the very beginning when they called up their dealers and asked if they should make disassembly of the "Starkey Ridge" off-limits. The response I heard was that disassembly was a major selling point! Has it paid off for them or caused endless headaches? Unfortunately I no longer ahve the connections to find out, but maybe someone else knows. It certainly doesn't seem to be emphasized in their newer knives.

For the record, I still haven't popped open my Military yet. It would take tricky milling to give it fancy scales, and there is nothing with the function that I feel I might improve. I've never said that about a Benchmade


(Why else would a bear want a pocket?)
Why on earth would Chris Reeve make a collaboration knife with another mass manufacturer when he's tapped into a goldmine of consumers who wish to pay in excess of $300 for a his own? He's hit the motherlode.


[This message has been edited by Jedi Knife (edited 26 June 1999).]
I wonder how many of these failures happen
after the pivot pin has been adjusted by the consumer for more opening speed?

As a knife seller it sure would be a lot easier to assume that it is the consumer's fault when knifes malfunction, but I've seen name brand knives straight out of the box with liner locking mechanisms that fail. Fortunately the dealer I bought it from never tried to shift the blame on something I did, and rightfully so.

Corduroy - We're considering a kit. Once the dust settles and SKUs controlled we'll look into this more carefully. We'ved even considered James M's idea of a modular model.

Thanx for the encouragement. As a kit, the ELU would be putting it together fromthe beginning, so taking it apart would be easiedr.

regarding the taking apart of the Military; There is a special purpose built tool required to re-adjust the pivot. Millwork is tri level and is at .001 tolerance. You would have to exactly match current config. verfy difficult, if not impossible. Easier to make a knife with separate liners by far.
First off I am not a fan of liner locks, I have made a few and at first thought what a neat deal. The dang things are finicky, especially in the pivot tension area! Now let me say that there are some makers out there that make absoulutly fine linerlocks. I played with a couple of Kit Carsons, Chris Reeves, and Darrell Ralphs at the Blade show and they were the finest linerlocks that I had ever seen. I would be proud to own any of them. I am sure there was more but these are the ones that stick out, and the show was huge! A few days ago I was looking at a very well known makers knife, very smooth action, well made and nice workmanship. It seemed to lock up very well,and had 1/16th Titanium liners, but when I tried I was able to close the blade easily like a slipjoint! The lock just popped out of the way with what I would call medium pressure on the back of the blade. I adjusted the hidden pivot for the customer a bit tighter but still the same problem.

The rolling lock is a much stronger lock than the liner lock, even the Sebenza frame lock. Spyderco tested a lot of locks and the rolling lock smoked them all. I have a Carnivour and it is a very impressive knife. It wears in, not out.

My fix is to carry a small fixed blade instead of a folder, I have as much blade and ultimate strength. I dont feel confident with making a good linerlock, so I am going to stick with the Rolling Lock, a lockback, or a fixed blade. Just my 2 cent worth!

Mr. Glesser,

Tri-level milling, you say? OK, I had noticed that the liner was sunk to one depth and the area behind the lock to a second to allow overtravel when the ball is riding on the blade. What's the third level? You can tell me, I promise I won't "try this at home."
I'm leaving this one alone, except for taking the clip off to bend it to a slightly less aggressive grip and tightening one of the screws in the stop pin that I caught working its way loose (naughty thing!)

Benchmades circumvent all the milling work by using those immensely over-thick washers. Very nice for the consumer wishing to make modifications, but it means they always have slight lateral play from the compressibility of the washer material. I know that with no mill, getting a nice relieved area for the lock to travel back into has been a really tough area on the few linerlocks I've made myself.

I love the idea of a Spydie kit! Hey, if you really want to get folks into the creation process, sell folks the blade untreated so they can filework it easily, then wait eagerly as it's sent back to Spyderco for treatment (for a hefty portion of the initial price, of course). Better than Sea Monkeys! Yeah, slim chance of that happening, but it's an idea... Well, I'll buy one however you do them.


(Why else would a bear want a pocket?)
Guess what? No matter what is said, I've seen knives out of the box that didn't lock up, so although it is much easier to blame it on the "end user" sometimes it is just the knife.


[This message has been edited by Jedi Knife (edited 27 June 1999).]
Corduroy - Regarding the tri-level milling. My error, "Having a senior moment". Military is bi-level. (I'll send you a milled backside scale to "check out".

Sorry for the slow response...went to AKTI mtg...then lost the thread.