Warning and advice for liner lock owners!

The General

The General

Joined
Jun 6, 2000
Messages
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After writing about the differences between the old and new Military knife in the Spyderco Forum, I tried the spine whack test on my old model and as usual it passed just fine. I was about to try the new model and turned to my Starmate in the pocket. I slammed it into a book and the knife folded right away! This is the first knife I have ever had fail this test! I tried it with less force and the same result each time:( . It got to the point where very very little force made the lock fail every time. I was so annoyed by this I started hammering the knife in the spine whach test and after about 40 failures it began to resist the test and not fail every time! The lock bar now goes over a bit more and it now after 50 more whacks will not fail the spine whack test!:D . If you value your fingers I suggest ALL of you liner lock owners try this!
 
Did you try the new-model Military? I have one coming soon.

Do you, like me, think the Axis lock makes a whole hell of a lot of sense?
 
General;
I suppose I can whack the heck out of my knives but I'd rather ask you what your theory is on the problem and what whacking the spine >40X helps.

Is it a matter of repositioning the liner lock for more engagement??

TIA,

191AHC
 
I've read comments from several people that suggest that the spine whack test can actually "fix" a liner lock. I don't know why it works, but supposedly it does. However, I'm with Shmackey on this one. Why trust a liner lock that might or might not be fixed and may decide to fail again at any time when you can have an axis lock?
--Josh
 
Liner locks? Oh, now you tell me. I've been whacking the spine on my Griptilian for days and it just won't fold. I wonder if should I get a liner lock to spine whack? Nah, Axis locks rule! :D
 
I actually have no idea why, I guess it must be peer pressure (or stupidity :)), but I did the spine whack test on a few of my knives.

As I look back, I guess I was just filling time. I am not into martial arts, don't use my knives in an inappropriate manner and use common sense with any tool that could be dangerous.

For my type of use, this test seems like loading a rifle, pointing the barrel at my head and slamming the butt of the stock into a hard surface.

If I were ever in a survival situation, I'm sure I would have far greater worries than the lock on my knife...I would just be glad to have one. :)


Steve-O
 
Steve, normally I would agree 110% with you, my next folder will probably be a custom slipjoint folder in CPM 420V! Or a Woody Sebi;) !

However I got thinking about this as I tend to use my folders when camping fairly hard, that includes prodding and stabbing, gouging and cutting. Can you think of a more scary thing than stabbing your knife tip first into a bit of wood to keep it out of the way and looseing your fingers as the liner bar collapses?:mad: . I know, simply fold the knife and put in pocket, but would you trust a gun with no saftey and a hair trigger?:confused: . Me either.


Shmackey I have not tried the new model Military yet, it is the inlay Formite model with the laser design and grey NOT polished liner bar. I must admit seeing how the Starmate failed with top honours, I am more than a little upset about the Formite Military doing the same
:eek: . Still I will try this tommorow when I am not tired, not a SAFE test with a knife THAT sharp when tired:rolleyes: !


191ahc, if I was to guess, I would argue that not enough steel is in contact with the tang and as a result the contact area is neither enough or so close to opening that a little vibration 'snaps' it back open. Considering the sounds the lock made when I was spine whacking it with quite considerable force (I was VERY upset) I think the liner bar was actually wearing away and thus allowing it to engage more closely and further into the tang area. Thus I would argue it is a more tight fit (less chance of movement) and if it does move slightly it is still engaged with the tang and not 'air'.

I might add that the blade now still has NO blade play in any direction and the lock snaps shut with more authority than before. The lock bar now engages rather more than before but still has PLENTY of wear left in it. The liner bar now covers the tang to about 35% (I don't mean it covers 35% of the tang in total, but rather that in now moves over about 35% of the tang rather than about 20% before which ment a tiny bit of the liner bar was not engaged to the tang at all) of the tang, while before it covered about 20%.

All I can say is I will test the Military and all my liner locks (The LCC D/A was impossible to make it fail without a hammer and a vice
:p ).

As to the axis lock argument, the day Spyderco start using this a frame lock or a rolling lock I will be in HEAVEN! I love my 710 M2, but something about Spyderco products is so much better than any Benchmade I have seen so far. I just guess Spyderco products appeal to me a lot more than Benchmade ever did. I don't think this is neccacerily the fault of Spyderco, but an inherent weakness in the liner lock, no matter how big or beefy the lock looks. AS Joe once said to me, 'liner locks can be good, but it is very hard to get them right, until that point I will avoid them where possible' (Paraphrasing, hope that is right, sorry).
 
IMHO, the "spine-whack" test doesn't prove anything about the integrity of a liner lock.

A far more telling test is to engage the blade in a slow, twisting movement which will be a far more accurate test of lock reliabilty under more realistic working conditions.

Simply beating the back of the blade spine repeatedly will do nothing more than void your knife warranty.
 
knifenerd, that was always my opinion as well, but would you trust a knife that would fail with a 'tap' on its spine? The knife at first failed with the force needed to press a key on a keyboard fairly hard, the pressure ONE finger can generate. That is not the kind of thing to encourage finger retention and if you see how sharp this thing is...:eek:

It failed the torque test as well at first...:mad:

Now it passes both 99% of the time and very rarely fails the torque test and only when I really twist it in my grip with lots of pressure on the scales near the lock. I feel the lock is now about as safe as any liner lock can realisticly be. Yes the Axis, integral even the lockback is better, but at least it won't fail with a simple tap now.

Imagine you are using it in the woods to cut fuzz sticks (I do this a lot with a folder) you swing round to grab another and the back of the spine hits a branch or tree or something. Result? Lock fail and amputated fingers. Any knife aught to resist some pressure on the spine from time to time. If you can't bring a knife spine down on a book 2 cm thick with the force of a wrist snap and not have the knife fail, something is wrong in my humble opinion. The problem seems to have fixed itself with what I have done, I just want others to give it a go if their knife fails as well.
 
I realize the spine whack test is controversial. I think it's perfectly valid for a number of reasons, that I won't go into here. One ironic thing about the spine whack test is that while it can show bad lock geometry, it can also fix a dangerous lock by setting it. There are many many cases of a knife failing the liner lock test once or twice, then never failing again.

I personally don't "beat" my knife when I do a spine whack test. I do a light-to-moderate whippy snap, just once or twice. The objective is to test the lock geometry. In my opinion, a lock that fails this test will also fail a torque test at some point. In other words, the test does highlight bad lock geometry. It's more difficult to get a torque failure during testing, because it's difficult to duplicate every position and exact torque you might be using. So, while I think torque tests are a must, a spine whack test is a must as well. Besides, there are a number of reasonable situations that can result in impact forces to the spine, so the test is not totally unreal in any case.

Joe
 
So if a liner lock passes a light-moderate whack or two then its a-ok? My Starmate still fails when I do the spine whack, but at what I would call slightly more than moderate force, enough to dent a 2by 4 or a book cover. Even at that force not every time. All I can say is it is a LOT better than before. The beating on the lock was me being annoyed and frustrated, I had at that point prety much decided the knife was worthless and had written it off, which was a pity as it is my current EDC. I think I can trust this knife up to a point, but then I look at my older model Military which is 100% solid under a much more severe impact.:confused: . Perhaps I am looseing faith with the liner lock as a tough using knife? If you don't trust your knife 100% will you carry it?
 
General,
I too do the "spine whack" test occaisionally on my liner locking folders. Sure, as several others have said other types of tests may be a better representation of "real-world stress" but I cannot do them safely!! It is easy to hold a knife without your fingers in the path of the blade and rap it on a table. (I usually do it on my knee)
The torque tests and other pressure test are more dangerous due to finger position neccessary to create the stress.
Lets face it, a liner lock is designed to wear and at times "seats" better than others. I think you found that you can "force" some of them to "seat" if they are slipping. IMHO, it would be very foolhardy not to check the "reliability" of ANY tool with moving parts from time to time.
Yeah, fixed blades are best and not all locks are created equal but for the few liner-locking knives that I love; I sharpen them and I make sure that the lock is seating well every once-in-a-while . . . whether they need it or not.
 
I don't think it's news that linerlocks can fail the Dreaded Spine-Whack Test. I can't say I'm very surprised, but neither am I terribly concerned that the linerlocks I own are sitting in their drawer plotting to reduce my typing speed.
 
Bob Terzuola once told me at the NY Custom Show that he "sets" his liner locks by giving them a good whack on a work bench.
 
Update, the newer model Military passed the test with flying colours! No failure even with a LOT of force:D !:cool:

The Starmate however, while not as bad as before will still fail the test with moderate force:( . Pity.
 
Well, I've whacked my Starmate a whole bunch since reading this latest thread, and no failure. My Starmate, as you may know, has a bit of vertical play. Until I recently adjusted the eccentric pivot it had more vertical play. But, I've whacked it before, with the play, and no failure. I've whacked it, usually into a book, sometimes my arm or leg, with a light-to-moderate whippy snap, dozens of times. I've also pressed down on the spine slowly. No failure.
That's too bad, General. And if you have to send it in to Spyderco from England it must cost. Not to mention the trouble with customs. That's why I wanted to adjust my eccentric pivot myself and not send it in.
Still, it seems that all knife brands have their share of problems. Spyderco seems to have fewer than some others, thgough.
 
Agreed! They are a better company than most. I have decided to e-mail Spyderco and see what they will/can do. I don't blame Spyderco in any way for this, some have to slip the net aven for the best.
 
Even the spine whack test doesn't prove a whole lot. I had a Sifu that you could spine whack on all day and it stayed locked solid. But I had bought it in hopes of the lock being strong enough to use for backcutting. In one of those stupid moments, while I was slicing and thrusting my cutting dummy, I threw in a light backcut just to see what it would feel like. I didn't have the blade taped or my gloves on and I paid for it with a slight cut across one finger.

I taped the blade and tried it again. You couldn't keep that knife open with a clamp, it folded up every time. I sent it back to REKAT explaining exactly what happened. Bob Taylor took it apart measured it up and pronounced it good. In his phone call to me you could hear him whacking the spine quite vigorously.

I got it back, taped it up and whacked the spine, it held. I threw a light backcut, it folded. I took it to class and showed the Sifu to my classmates. The least knife oriented guy in class took it and tapped the back of the point against his bare palm! The knife folded. I related the story to a friend of mine expressing my disappointment and desire to get rid of the knife. He wanted it and bought it knowing full well the story behind it.

On the other hand, while I have never tried backcutting with my Spyderco Military, I did do some thrusting tests. I taped a phone book to my 75 pound punching bag and while palming the butt of the knife threw in 10 thrusts hard enough to make my hand hurt. I felt the handle torque and twist, but the liner lock stayed solid.

I won't buy any more rolling lock folders, although their fixed blades look interesting, but Spyderco has a loyal customer.
 
The spine wack tested is over-rated as a reliable indicator of liner lock safety. The impacts may very well set an ill fitting liner lock and very well make manifest poor geometry BUT ...

I had a liner lock from a well known manufacturer who spine tests each knife before shipment. I also mildly tested it once or twice before putting it into service. Well, one day I was using the spine of the knife to lightly tap and knock off marine growth from a propeller (sort of like repeated low intensity spine wacking) and the blade closed on my fingers. As the English would say, it was a bloody mess.

Interestingly enough. Subsequent spine wacks either passed or failed depending on the severity of the impact, with lighted wacks causing most of the failures!

Once again, I take the opportunity to state that the best lock is a full tang, fixed blade. After that, the axis, framelock and others, to the exclusion of the liner lock, are fine.
 
nimrod -- No doubt, the spine whack test isn't a catch-all for all liner lock ills, but I don't know that anyone is presenting it as such (read, for example, the Liner Lock Test FAQ, which has lots of other tests in it). It will indicate some forms of bad lock geometry, but certainly won't catch all torquing problems (like those caused by compressing washers or really twisting handles), won't catch white-knuckling problems, etc. I think the spine whack test gets the most discussion because it does catch the most problems, and because it's the most controversial, as there will always be disagreement as to whether or not impulse forces to the spine constitute a reasonable concern.

To answer another question, I tend to use light-to-medium impact whippy snaps in my spine whack tests. The General noted his lock only fails with higher-power tests. I've tested a whole lot of liner locks, and I can often fail a knife with a light snap that it takes most people a hard snap to fail (if they can fail it at all), so I'm comfortable with that kind of testing. I like to bring this up because of the classic look on Steve's face, but a year or two ago Steve Harvey handed me a knife he had absolutely put through the ringer, including tying it to a stick and smashing it on the spine (!!!!) with no hint of a failure; I failed it with one or two light snaps. Anyway, do whatever test you think is relevant. They're your fingers, in the end it's you who needs to feel comfortable, and if doing a harder-power test is what makes you comfortable, it's all good with me.

Joe
 
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