Real vs. perceived strength of various locks

Well, i have to admit, im one of those guys who really likes a strong lock, the stronger, thicker, the better. I freely admit, some of my desire for a strong lock is based not only on utility, but my love of overbuilt objects, but, that being said, i still feel that a folder isnt a very good one if it doesnt have a very strong, robust lock.

I will quickly point out that along with suitable thickness and strength, the lock must also be well fitted and executed, the thickest framelock in the world isnt any good if the lock isnt done correctly, and some knive makers do seem to have trouble making a consistantly good frame/liner lock. It looks like an easy mechanism, and yet it is apparently relatively hard to get just right.

In a sense, the one thing a folder MUST have is a nearly bulletproof lock, otherwise, its not worth owning and in fact, dangerous.

While its true that all the lock has to do is keep the blade from closing on you, guess what, all it takes is ONE time and you lose a finger or two, and im really ATTACHED to all 10 of mine, and so, when it comes to locks, im a firm believer in overkill and thus, a well designed, strong lock, to me, is a must on a folder and the lock becomes critically important to any folder's design. You know, often people complain about the liners used on Emerson knives as being too thin, i admit, im one of them, and others respond saying theyre not thick, but theyre good enough, well, i dont want good enough, i want THICK, so Emerson, make your liners a little thicker, humor me. :)

Its for this reason l really like extra thick, well executed framelocks like found on the Sebenza or the Strider SnG, or even the liners in the Strider AR series, theyre far stronger than they need to be, but again, when it comes to my fingers, i want overkill, not "just enough to get by".

I know i have heard some people talk about oil on the locking surfaces of some liner locks causing the lock to slip and disengage, i must admit, i have never seen this happen on any of mine and after reading about that, i put some oil in there on a few of mine, and couldnt get it to happen, so i guess it matters what brand knife youre talking about.

Also, i saw in someone's signature line somewhere something to the effect of: "The best folder's lock is only as good as the worst fixed blade's." Wish i could remember it exactly, but thats similar anyway.

I think this is a great topic, perceived strength vs. actual strength, because i have surely seen locks that were thick and seemingly heavy duty, that werent executed properly and thus werent strong despite their thickness, so, appearances can be deceiving sometimes. One thing is for sure though, if you ever examine a Sebenza, a Strider folder, or a Mayo TNT, you can clearly see that these are among the strongest locks made, and maybe thats another advantage of liner/framelocks, you can SEE if theyre strong and you can see how they are holding up under use, where with some other locks, youre relying on some parts you cant see.

All the above is just my opinion and worth what you paid for it...
 
I carry a variety of knives everyday. Today is 7 including a multitool. Lockback(x2), Liner( and spydercard), phantom, and fixed.

I see the locks as a "safety feature" not to be trusted 100%, but to have some faith in. I break down boxes, I cut meat(sometimes frozen), I chop packing straps, and many other things. If i'm doing something that I'll be twisting in, I use the fixed. It's fully legal to carry a 6" in public, I carry a 4" slightly concealed(sheath end tucked in back pocket), and have no problem.

I've had 1 knife fail on me, and it was the pivot. Gerber Gator, less than a week of ownership, and it never came back out of the bush with me. Wasn't worth sending abck in if it failed that easy. I was whittling with it.
 
Originally posted by VampyreWolf
I carry a variety of knives everyday. Today is 7 including a multitool. Lockback(x2), Liner( and spydercard), phantom, and fixed.
Click to expand...

Am I understanding correctly that today you carried 7 knives?????!!!!!!!!!!!!!!!
 
About two weeks ago I had a Uncle Henry Slipjoint close on my while I was Whittling, Even though it was clearly a slip due to my fault, I now whittle with a Spyderco Kiwi. I probably wouldn't go back to the non Locking Slipjoint until this cut heals all the way. :)

As far as locks failing, I have had a Emerson liner lock close on me before while screwing around, no damage was done. I threw that away I was so upset and traded off all of my other Emerson’s. I am sure it's an isolated incident, but I viewed them differently after that incident. I still might get a Commander some day down the road.
 
ichor> yep.

*Millie CE S60V R/F
*Endura SE FRN/ATS-55 L/F
*Meerkat Nav PE/8A L/Back
*Dragonfly PE SS/ATS-55 Neck
*Spydercard PE/8A wallet(right cargo)
*Meula 4" "survival"(skinner blade) right hip/back(bottom tucked into pocket)
*POS Multi-tool ($20 in wallyworld)... soon to upgrade to a Wave

I can go as low as 4 and a multi-tool, to have my work knives and the sheeple knives. The minimum I'll carry is 3 and multi-tool. Right and left 4", sheeple(neck or IWB 2-3"), and multi-tool. I carry an extra fixed blade(4" tanto, hori to left) during the summer so I have a fixed for either hand.
 
Originally posted by VampyreWolf
ichor> yep.

I carry an extra fixed blade(4" tanto, hori to left) during the summer so I have a fixed for either hand.
Click to expand...

Just in case you're attacked in the "middle of nowhere", right? You're infected alrighty. ;-)
 
ichor:
millie and endura are my work knives
'fly and 'kat are my sheeple knives
card is a "empty pocket sydrome" knife
the fixed blade is usually used for the kitchen

the 4" tanto is used as a prybar. Nice thick spine, and the tip is done well enough that I haven't chipped anything in 2yrs of prying. $40 beater...
 
VW, there's a small typo in your signature line, it says: "...first once to..." where it should be: "first ONE to..." :)

Typos in posts are certainly nothing to get upset over, but i just thought since its permanently in your signature and therefore in every post, you might want to fix it. Hey, i NEVER capatilize the letter: "i", so there you go...
 
Megalobyte> you know, I've never really read my whole sig after I put the sections in. Thanks for pointing that one out for me.
 
As Joe said, most good locks these days are strong enough. The lock won't break while you are still able to hold onto it. Lock reliability, though, is a different issue, and a more important one.

So which lock is most reliable?

The one you test yourself and find to be so.
 
I try to pretend that locks don't matter much to me because I don't use my knives for martial arts. At least they aren't carried for that purpose anyway but one never knows what he will ask of his carry blade. I used to really like my EDI Genesis until I read about the spine whack test and it fails miserably. Stopped carrying it for that reason. Kind of ironic when I don't mind carrying slip joints like my Victorinox knives. I guess that it does mean something to me if a knife doesn't function as intended and manufactured.

As Megalobyte said, the Sebenza has a strong lock and I never had it fail. However, the Sebenza has opened in my pocket once when it wasn't securely againt the back of the right pocket and gave me a good cut. Now I am very aware of where it is when I carry it.

There are so many concerns to carrying/using potentially dangerous items that you have to be ever vigilant.
 
quote: " Some people write that they can release a lockback by squeezing with the entire hand, but I have never seen anyone demonstrate this in my presence."

i dont want to bash any lock, but if i grip my endura tightly, it will unlock the blade. mostly in 'paintbrush' or reverse grip. it doesn't have the boye dent though, so probably the new ones dont unlock. however, since i know about this, i pay attention, and it hasn't failed on me so far.
 
Steve Harvey :

The lock won't break while you are still able to hold onto it.
Click to expand...

Many high end locks are now promoting very high break points up to 1000 in.lbs, these are indeed beyond the ability of most people. However this torque can easily be gutted by any number of factors such as twisting of the blade (liner locks and intergrals are very sensitive to such forces) and non-vertical force loads. I have broken high end locks with very small torques (just wrist flex), and under light impacts, easily holding onto the knife in both cases.

-Cliff
 
Cliff,

Can you recomend a practical method to evaluate lock strength and possibly lock reliability of liner locks.
Is this feasable without severely damaging the folding knife.
I am willing to sacrifice using an acceptable protocol.

Thanks,
Momser
 
I'm not Cliff, and my methods will likely be a bit on the pansy side compared to what Cliff does :), but A.T. Barr and I did write a Liner Lock Test FAQ which you might find useful as a starting point: http://www.bladeforums.com/features/faqllock.html

One thing I just noticed is that I didn't include any torquing tests in the FAQ, and I consider torquing tests a must.

Joe
 
When testing a lock (or any aspect of a knife) you need to determine how you are going to be using the knife. As you can see in this thread there are those who would find any lock adequate as all it needs to performs is as good as a slip joint - which is a pretty hard standard to fail. So if you are going to be careful never to load the blade so as to produce any rotation, side loads, or vertical loads, then anything will be fine. But if you want the lock to be able to handle these kinds of forces and others, you will want to look at it in a more critical manner.

If you intend to use the knife for heavy cutting where you will be exerting a lot of force then the "white knuckle" test is critical. Grip the knife and squeeze as hard as you can. Try any position you can think of, and note the ones in which the lock is compromised. Liner locks and lock backs are prone to commonly failing this test, but it also effects Integrals and the Compression lock from Spyderco (for the latter I had to use a very odd grip and really high pressure).

Assuming your hand pressure doesn't cause the lock to release you also want to look at the behaviour of the lock under torques. Most manufacturers will look this with forces applied straight up. All locks are very strong that way, and it makes for really impressive numbers such as 1000+ in.lbs. However no one applies forces in such a rigid manner. Do some cutting in thick materials and twist and pull on the blade and examine how it behaves. You can also drive the blade into a piece of dense wood until it is stuck soundly (or just vice it), and press down on the handle and twist and/or bend the body of the handle to the side. Liner and Integrals are both very sensitive to side bends and rotations and they can then be unlocked and even broken by very low torques while pressing down on the handle. Lockbacks are much more stable under such conditions.

If you intend to use the knife for medium to high dynamic work, where the blade can see high and/or sudden loads such as jerks, twists and impacts, the "spine whack" test is a must. You just take the knife holding by the handle and hit the spine of the blade off of a rigid object. Of course you hold the handle in such a way so as to protect yourself if the lock fails [this is critical in any aspect of lock testing, you should be always be position so that if the lock fails you don't get cut]. Test the blade at both high speeds with low force (a whippy fast snap) and very heavy loads (a lot of force applied during the impact).

[Joe described both of these in his FAQ]

One step beyond this would be achieved by taping or otherwise attaching the blade to a piece of wood and then doing spine whack tests or have someone hit the spine with a wooden or more extreme metal bar. The wood attachment is just to protect your hand, not necessarily to give extra leverage, which is a side effect mainly, unless you want to take it to an extreme. Steve Harvey was the first I know of to do the wood handle extension spine whacks. Note hitting most folders off metal or by metal bars is likely to break the blade as most current ones are made from brittle stainless alloys, so the blade could go before the lock.

With all of these impact tests don't just hit the blade straight down, but tilt it to the side a few degrees each way and examine its behaviour. In actual use it is very unlikely that any impact is going to be 100% straight down on the blade, so your testing should act to mirror such probable cases and not be so artificial so as to be meaningless.

With some of the current locks, they have levers and other do-dads that you have to flip, rotate or otherwise move to engage or release the lock. With such mechanisms you would want to look at how they might be tripped accidently. Take some clothes and do some stabs and slashes through dense multiple layers. Check and see if it is possible for any lever-like object to get caught and thus accidently release the lock. You can also wrap the clothes around foam or whatever to fill it out. Try other objects such as cardboard boxes and such.

Locks can also be harmed by getting filled with debris. This can make them fail to engage fully, or open accidently. Thus can be tested by artificially seeding the lock with dirt of all kinds and seeing how the lock is effected (fruit juice [let it dry], lint, fine gravel etc.) . Some locks like the one Arlee Niemi uses in the Megaladon are very resistant to getting contaminated by debris, others like the Lockback are very easily to completely break with a small amount of dirt. You can repeat all of the above tests with varying amount of debris in the lock and note how they are effected. You should of course periodically test and clean out locks, but some can be come contaminated very quickly so one short pocket carry may be enough to cause problems.

To be clear, none of these are standard in the sense that they are agreed on by all makers and manufactures. You are bound to find makers and manufacturers who would claim some or all of the above are abusive (as their locks fail them). Some have even lower standards. Chris Reeve for example feels just opening the blade quickly (flipping) is abusive, so the Sebenza is unsupported under any and all spine whacks. Mick Strider has also commented that twisting the blade while loading it vertically, and spine whacking are not valid tests (their folders have failed both). Les Robertson has also spoke out against spine whacks and even white knuckle testing, and he sells *many* high end folders.

In the end, it is your knife being used by your hand, in a manner in which you determine is necessary. You decide what a lock must be able to do so test it to that standard.

-Cliff
 
While I don't believe they are made anymore, I heard a ReKat Hobbitt had something called a rolling lock. Now folks, I never saw one taken apart, but the theory is that this lock is like the rotating bolt on an AK-47 or a Browning BAR.

In theory, not a bad idea. The blade is locked by a lateral turn, but the stress on the spine is straight down.

(Josh at PVK sent me one on a memo bill. Ugliest knife I ever saw. I'm surprised that knife didn't turn up as a Klingon knife on Star Trek. Now before I get flamed, I encourage you to have your opinion, and if you bought that knife and like it, more power to you.)
 
Cliff,
I am curious, are you still promoting the Busse Folder as the strongest avaialable, even though it doesn't exist?

In my opinion, to test a lock properly you must first remove all non-mechanical variables. Diassemble the knife if possible, clean and degrease the lock area, and reassemble snugly with loctite on all the screws. The threads of assembly screws are one of the first areas to fail on a knife, and should be adequately secured.

There are very few knives that can hold over 200 inch pounds.
The Madd Maxx is one, the Chinook is also a contender here.
I would guess that the newest Cold Steel "Axis" style locks will come close as they have steel liners and multiple large fasteners.

The Megalodon is surely the strongest folding thing I have handled, but in my opinion the knife has other weaknesses not related to the locking mechinism that keep it out of primary rotation for me.

A properly fitted hardened Steel framelock would be as strong as any folding knife needs to be. A good example of this would be a Camillus EDC, Kershaw vapor, or S&W HRT. They may not have the panache of an Axis or the flash of titanium, but they certainly work better as tools than 99% of most knves out there.

I have recently purchased a "Bad" Axis lock, It was my first such experience out of about 20, and I was very disappointed. I have been singing the praises of the lock for several years and this one was a lemon. With a light spine whack the blade would fold up everytime...poor lock geometry on this particular knife I guess.
 
Spine whacking a properly built framelock will accomplish two things:
1)Up and down blade play
2)Stripping of fastening hardware threads.

A good one will never fail, but just develop some blade play as the lockface moves over the blade tang.

What makes a frame lock?
Usually a knife where the thickness of the locking face of the liner is 80% or more as thick as the tang of the blade. The thicker the liner in relation to the frame (all else being equal) the more reliable the lock.
 
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