How Much Lock Strength Is Needed?

T

Tonie

Joined
Jul 20, 2000
Messages
111
This is a question that's been niggling at the back of my mind for some time.

I've enjoyed all the hype and hoopla from all the manufacturers regarding how strong their new "super locks" are. But what do they really add to a knife, besides cost, when the knife is used IN THE MANNER IT WAS DESIGNED AND INTENDED TO BE USED BY THE MANUFACTURER?

Does a "super lock" really do anything more for a folder than the standard rocker bar or liner lock? If a folder features a "super lock" does the manufacturer now intend for that knife to be used in a manner which puts pressure on the back of the blade rather than the edge?

Several folks have spent a lot of money on testing locks by sticking the blade in a vise and then pounding it with a hammer until the lock fails. It was all very interesting and it was quite a personal sacrifice, but what does it prove in relation to using the knife as it was designed to be used, as is expressed in the manufacturers warranty?

I bought a Sifu because I was hoping that the Rolling Lock would be strong enough to back cut with. It wasn't. Fortunately, while I was too stupid to tape the blade, I was only using a very light stroke and only got a scar rather than losing the finger.

I called REKAT, spoke with Bob Taylor and sent the knife back to them. They specced it out, said it was in perfect condition, performed the spine whack test, and returned it. This time I taped the blade. I did my own spine whack test and it held. I took a few light back cuts with the point and it folded. I opened and closed the knife several times, carefully retaping the blade each time, and three out of four times it folded.

Does this mean that the Rolling Lock is ineffective or that I feel cheated? NO. The Sifu is not advertised as being intended for use in back cutting. But of course I'm left wondering what it's "super lock" really does for the knife beyond that of regular style locks.

Do "super locks" really add anything to a knife as it is designed and intended to be used, other than cost? Or is it simply bragging rights and sales gimmicks?



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All you need is love... a sharp blade and a full clip
 
A couple of years ago there was an infamous Tactical Knife Cult headed up by a rabid knifemaker whose name can not be mentioned for fear of divine retribution and general strife. Anyway, these guys called themselves the 'Cult of Tactical Truth'. Although I thought this stuff was quite amusing and complete BS, some of this nonsense made sense to me. For example, one of the Ten Commandments of Tactical Truth is:

Thou shalt Not fold thy knife

I also point out that fixed blades are fixed because they are no longer Broken. Some locks are better than others. If you are dead set against even the possibility of losing several of your fingers in a knife fight, use a fixed blade.

Paracelsus

[This message has been edited by Paracelsus (edited 03-24-2001).]
 
Reliability is a much more important issue than strength, as many of the folders on the market really don't lock at all, or don't always. But as far as strength is concerned ... in any other application where there is a possibility of injury, safety margins of ten or twenty to one are common. If you were buying a stepladder would you be satisfied with one that's been tested to hold your weight? If you saw one advertised to hold ten times your weight when new would you sneer at that and call it unnecessary? Would you go mountain climbing with 550 cord? Would you buy a house with floors that have been tested to hold twice the weight you think you're going to put on them?

If you search the forums you'll find numerous reports of locks failing and people being injured. If you ask people you know I bet you'll find some of them have been injured. If you ask any emergency room surgeon....

But of course all those people must have been using their knives in ways that the Knife Gods never intended knives to be used, as expressed in the manufacturer's warranty ... so don't worry about it ... and have your next house built of 1/8 inch plywood ... it'll save money ... anything stronger than that is just a lot of hype and hoopla.


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-Cougar :{)
Use of Weapons
 
Hi Tonie. Certainly I cannot speak for other manufcturers, but I can offer opinions.

First, I would have to say that lock reliability is more important than ultimate lock strength. IMO lock reliability is the result of mfg and not design.

IMO, accidentally hitting the back of the tip of a folding knife blade on something should not defeat the knife. Considering arm weight and moving force (eg; turning around with an opened knife and accidentally hitting the blade tip on a door frame).

With 25 lbs of arm weight and 15 lbs of moving force is 40 lbs times 4 inches of blade length is 160 inch lbs of force applied to the back of the blade.

160 inch lbs would would be 40 inch lbs of lock strength required per inch of blade length. For Spyderco, this would be a lock strength rating of "light duty". With this in mind, one would not want to use this knife for a back cut or a reverse grip pass.

In our testing, the Rolling lock's ultimate strength proved quite strong. The defeat problem was one of lock reliability, not ultimate stength. Also, the Sifu has a very long blade (leverage arm) which magnifies the effects.

With regards to "using a knife for it's intended use" vs "bragging rights", I can't go there for other manufacturers as I often am not aware of their intended use.

I can say that having some idea of lock strength is akin to knowing the steel in a knife or the horsepower of a vehicle.

Hope this helps.

sal
 
Agree with the reliability aspect. A piece of grit got caught in the lock-back of one of my knives. The blade closed on me, if I didn't drop it woulda had to get mad stitches to a new finger.IMHO, I think that after reliability, strength is important because the manufacturers know that some people will abuse their knives to some extent, and are just covering their butts, while offering a better product. I'm a fan of the Axis, being a lefty.
 
Can anyone tell me how good the plunger lock is on the MOD CQD?



------------------
Wayne.
"To strive to seek to find and not to yield"
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<font face="Verdana, Arial" size="2">Originally posted by Cougar Allen:
so don't worry about it ... and have your next house built of 1/8 inch plywood ... it'll save money ... anything stronger than that is just a lot of hype and hoopla.
</font>
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Well put! I have had knives with weak locks but then there were many things I would hesitate to do with them because of my confidence in the lock. A "super-strong" lock up gives me confidence in the blade and makes it a MUCH more versatile tool. Not to mention having a much longer usable life due to their strength and adjustability.

 
IMO >no lock< is better than a bad one.
When i use my Laguiole i know it will fold if i do something wrong. No problem, just take care.
But if there is a lock it had to be reliable!
cool.gif



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*so is life : hard but unfair*

~*~*~*~*~*~*~*~*~*~*~

~bigbore`s knives~
 
Tonie:

[super locks]

<font face="Verdana, Arial" size="2">But what do they really add to a knife</font>
Click to expand...

They allow the knife to be used in a wider range of tasks. If all you are doing is simple cutting of rope, wood, cardboard, foods etc., you don't need blades nearly as thick as commonly found. A 1/16" thick blade will easily handle all of the above, and far outcut all the "tactical" folders with their much thicker blade stock.

The only reason to grind a blade out of very thick stock (considering the blade length for folders), is to allow it to handle very larges forces. This would imply that it was intended for heavy stabbing, pounding, prying etc., otherwise as indicated above, you would be much better off with a very thin blade. Now if you want to do those kinds of heavy work you want a strong and stable lock.

<font face="Verdana, Arial" size="2">The Sifu is not advertised as being intended for use in back cutting. </font>
Click to expand...

It is described as being able to take over 1000 in.lbs of torque to break the lock. I would be very surprised if you could generate anywhere near that in a backcut, and if you could, I would strongly bet that your wrist would most likely just fold or you would lose your grip on the knife. In actual fact it is obvious that you are not breaking the lock but simply disengaging it.

The point then is one of security and not limit strength. This is missed by many, a simple test is a press to the breaking point does not indicate functional strength in actual use because people don't exert forces in such a controlled manner. While that does give useful information, using it to promote functional security and/or strength is misleading and is simply spreading hype.

-Cliff
 
Coming back to this thread I reread Tonie's post and this time I read it differently ... instead of arguing lock strength (or reliability) isn't necessary, that post could be read as arguing -- since the Sifu lock is so weak (or unreliable) you can't even do a very light backcut without it failing -- and failing dangerously -- it's a waste of money.

I'm not sure if that's exactly what he meant to say, but if it is he's got a point....

Balisongs and Opinels can do backcuts. Is there any other kind of folder lock that's trustworthy?


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-Cougar :{)
Use of Weapons
 
Tonie,

<font face="Verdana, Arial" size="2">But what do they really add to a knife, besides cost, when the knife is used IN THE MANNER IT WAS DESIGNED AND INTENDED TO BE USED BY THE MANUFACTURER?</font>
Click to expand...

But the question begs, Do you want to be limited by the what the manufacturer decides is fair use? Or do you want to have the confidence to know that apart from an act of God, your knife will stay open?

<font face="Verdana, Arial" size="2">Does a "super lock" really do anything more for a folder than the standard rocker bar or liner lock?</font>
Click to expand...

Well, if all we are speaking of is strength, I do not think it is apropriate to put the rocker lock in the same category as the liner lock, the rocker lock is a better mousetrap, in my opinion. Quite frankly, I wonder why I ever bought a liner lock, or why anyone still buys a production liner lock. And while I want to respect the knife-building skills of all the custom liner lock builders, I still distrust the liner lock in custom knives.

<font face="Verdana, Arial" size="2">If a folder features a "super lock" does the manufacturer now intend for that knife to be used in a manner which puts pressure on the back of the blade rather than the edge?</font>
Click to expand...

Quite frankly, given the stories of failure, I don't care what any company tells me, I would try that sort of maneuver with a fixed blade only.

<font face="Verdana, Arial" size="2">but what does it prove in relation to using the knife as it was designed to be used, as is expressed in the manufacturers warranty?</font>
Click to expand...

I would ask you, are you content to accept the terms of use as set forth by any manufacturer? Sal Glesser's point about incedental contact with a door-jam or such seems realistic to me.

<font face="Verdana, Arial" size="2">But of course I'm left wondering what it's "super lock" really does for the knife beyond that of regular style locks.</font>
Click to expand...

Even the best super lock only can go so far, and if you want to beat that level of performance, a fixed blade is your only option as I see it.

<font face="Verdana, Arial" size="2">Do "super locks" really add anything to a knife as it is designed and intended to be used, other than cost?</font>
Click to expand...

They add value, but how much is up in the air based on your use.

I think the Axis is probably one of the best locks out there, but I dislike every product featuring it, to date, so the great lock does me no good whatsoever.

The handles and latch of a balisong form one of the strongest locks known, if not the strongest lock, but I have yet to meet a balisong that I couldn't live without. I have been looking high and low, but none have jumped into my pocket, yet.

So, for me there are only three options currently.

1) Spyderco Lockbacks. a) I trust Spyderco to do them right. b) I like the hole opener best of all thumb openers. c) Spyderco offers a wide range of lockbacks.

2) Frame/Integral Locks. Camillus is offering the EDC, but I think the 420whatever sucks, which leaves the BladeForums version with 154CM if you want to keep it reasonably inexpensive. Of course, there is the Sebenza, I sold my standard, I will probably acquire a Classic. Or Customs, Kit Carson, Warren Thomas, and Darrel Ralph are known for their frame-locks.

3) Fixed blades. As has been pointed out, no need to worry about lock strength, they are open permanently. Once you have selected a fixed blade of apropriate size, then sheathing will solve the carry issues.

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Thank you,
Marion David Poff aka Eye mdpoff@hotmail.com

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[This message has been edited by Marion David Poff (edited 03-24-2001).]
 
The only lock I really trust is the Axis lock. The force necessary to defeat one of these is astronomical. Same goes for how many weird things would have to happen at jsut the right time, to have it accidentally disengage. It is still a folder, and, therefore, not as strong as a fixed-blade, but of all the folder locks, this is the one I truely feel I can trust.

I still own others. I have a Microtech LCC, which is a liner-lock. I have a Benchmade 42, which is a balisong, and I don't count it the same, since it doesn't lock automatically. I even have a Sifu which, fortunately, doesn't appear as subjectible to release due to back-cutting as Tonie's. I have a few other liner-locks, as well.

I still trust the Axis more, but that doesn't prevent me from carrying the others; I simply make sure that I am aware of the limitations of the knife that is in my hand.

--JB

P.S., whenever I can get away with it, I carry fixed-blades. I turst them more, and I find the blade/handle ratio much more pleasing.

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e_utopia@hotmail.com
 
I hesitate to post here...because Sal has chided me for not using the brass rods on the 204...
smile.gif


I have only been cut 3 times in the last 5 years, and then only because of one hand knives coming open on my belt.

When using a knife I take a page from the gunowners handbook; Treat each knife as if it were loaded. I use each knife within its limits, I consider most folders to be 'unlocked'.

Steve-O
 
Steve-O,

<font face="Verdana, Arial" size="2">When using a knife I take a page from the gunowners handbook; Treat each knife as if it were loaded. I use each knife within its limits, I consider most folders to be 'unlocked'.</font>
Click to expand...

Well put.

MDP
 
Guns have locks just like folders, however the safety on a gun is usually held to a much higher standard. If a gun was made with a safety that would disengage when the trigger was pulled the people who made the gun would quickly be gutted with lawsuits.

In fact the standards that guns are held to are extremely high. I think it was Daisy who was hit with numerous lawsuits from injuries resulting from their bb guns being intentionally fired at people. The defence was that it was possible for a bb to get lodged in the internals and not be visible so the gun would look empty but could actually fire a bb.

Now, the fact is that you should not be using an actual gun as a toy, however is it reasonable to assume that if you cannot see a round in the chamber nor down the barrel that the gun is empty? Well there was considerable amounts of money awarded then people were injured (and even killed) when this didn't hold.

While it is true that you should always treat a gun as if it is loaded, it is reasonable to expect the safety to actually work. It is also reasonable to expect a lock on a knife to actually keep the blade from folding (qualified by "within the promoted abilities").

Simply put, there are locks that are very stable and very strong, instead of treating all locks as instable and weak, keep that perspective to those locks that deserve it. It is very unfair to blanket those makers who have strived for and achieved strong and secure locks under the same qualifier as those who have not.

-Cliff
 
I think a lock should be a little bit stronger than the hand holding the knife. Any additional strength is superfluous.

The main issue, though, with "super locks" isn't strength, but their resistance to accidentally disengaging or getting clogged by dirt. Liner locks have a history of disengaging accidentally, lockbacks as well, though not as often. The new Axis/Rolling/Compression/Arc locks are better because it is less likely that your fingers or torquing pressure will disengage the lock, and they are less susceptible to dirt in the mechanism preventing it from functioning. I carry only folding knives, and I want to be able to use them as though I can expect that they will not close on my fingers. I don't generally pry with the spine of the blade, but a folder with no lock or a bad lock will close on a thrust. That is unacceptable to me, and, fortunately, to knife many knife manufacturers as well.

I've hammered on my wood desk with the back of my Sifu's blade and it didn't close. I think you got a lemon and I think you should send it back in.

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Jason aka medusaoblongata
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"Is not giving a need? Is not receiving mercy?" - Thus Spoke Zarathustra
"Cutting his throat is only a momentary pleasure and is bound to get you talked about." - Lazarus Long
"Knowledge is not made for understanding; it is made for cutting." - Michel Foucault
 
I'm curious about something said here. A couple of comments were made about injuries from a lock failing, and I'm curious as to just exactly what the people injured were doing with the knife when the lock failed? I've been cut a couple of times using a knife with no lock as a "drill". Yeah, it was stupid on my part, but honestly it was no fault of the design off the knife,it was a *defect* in the knife user
wink.gif
. Can someone/anyone share a few details?
 
Lot's of good discussion on lock strength and reliability here, thank you.

Let me rephrase my question/concern:

Does anybody have a "superlock" knife they routinely use for and which will stand up to back cutting without the lock defeating and the knife folding? I've only found one folder so far that I have been able to use for back cutting, the CRKT Crawford KFF, but I'm sure that's because of the secondary lock system they use.

I am not criticising the Sifu for not being able to do so. REKAT is not responsible for my hopes and conjectures. And while they advertise it as taking a huge amount of weight to break the lock, I don't see them advertising it as a back cutter.

Medusa- I've already sent my Sifu back once, they said it was in perfect shape. Other than the CRKT, or if someone else can tell me of a folder they use to back cut with, I would basically agree with Paracelsus and say that no folder lock system is designed to back cut with. You mention pounding on your desk with the back of the blade of your Sifu and it not folding. Back cutting uses the back of the point of the blade, since you don't mention that specifically, I will assume you're striking somewhere in the mid-section of the back of the blade. If you are, her's an interesting experiment you may want to try, tape your blade heavily as a precaution and then start pounding with the back of the point. You might find that it will fold. Mine will.

If all a "superlock" does is give you added strength and security when using the knife, that's fine. But is there any "super lock" out there that allows you to back cut like you would with a fixed blade?

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All you need is love... a sharp blade and a full clip
 
Niggling?.....niggling...nigg....ling NIGGLING...??? I think my grandfather had that one time, I thought they cured that back in the 40's.

biggrin.gif


As far as lock strengh is concerned...Most all my knives are of a good quality. Regardless of what type each one has, I always try to use mine so that if it did fail it wont be on my fingers.



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Keith D.Armacost
"The wireless telegraph is not difficult to understand. The ordinary
telegraph is like a very long cat. You pull the tail in New York, and it
meows in Los Angeles. The wireless is the same, only without the
cat. " AE
 
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