How strong is the average frame-lock?

D

darthsoaker

Joined
May 2, 2006
Messages
1,273
OK... so I have this problem with liner/framelocks.... I have a hard time trusting them. After buying a Kershaw Storm ($50 :cool: ) I found that yes, FL can be very reliable. (Duh.)

I still prefer other locks. No big deal, plenty of other fish in the sea. Kinda. FL and LL are verrrry popular on locking knives.

Several Kershaws have caught my eye. Of course, the are all framelocks, or souped up LLs.

I carry a knife/knives with a SD option in mind. Not PURELY for SD, mind you, actually, SD options is one of the lesser things I think about when I get a knife.

I'm wondering how strong NORMAL framelocks (NOT Strider style half inch sheets of steel ;) ) or strong LLs are. How much weight can they hold on the spine? 50 lbs per inch of blade 100 lb?

They type of knives I'm talking about are like the Kershaw JY Dog 1 & 2, Kershaw Lahar, and Kershaw NRG.
 
I just purchased a SOG Trident, excellent knife! Scored it for $50 off ebay. And the ARC lock has been tested to hold 1000lbs! :eek:
 
flatgrinder said:
I just purchased a SOG Trident, excellent knife! Scored it for $50 off ebay. And the ARC lock has been tested to hold 1000lbs! :eek:
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I know the ARC lock is strong, but how far the weight is from the pivot is a key in finding out how strong a lock is. Spyderco rates their locks by lbs. per inch of blade, which gives a reference of how far the weight is from the pivot. For instance, I believe my Manix is rated at over 200 lbs. per inch of blade, meaning it should handle 750+ lbs. an inch out from the pivot, but about 200 lbs.+ at 3.75" from the pivot (the blade length). Someone correct me if I am wrong on that (I am going off of a spotty memory). Those are meaningful numbers, where just saying a knife can hold 1000 lbs. doesn't really define how strong it is, as the weight could be right at the pivot in which most any folder can handle a substantial amount of weight. Put that 1000 pounds 4" out from the pivot and I think you may have some problems with the lock holding the weight. Maybe it holds 1000 lbs. an inch out?

As for Framelocks, I have no idea how much weight any one frame lock can hold, and it will of course vary by a huge margin from knife to knife.

Mike
 
A properly made frame-lock is plenty strong enough for whatever tasks a folding knife might be needed for.

I cannot imagine what one would be doing with a frame-lock (or any locking folder for that matter) to get it to break or fail.
 
I do not have data on specific knives, but i agree that a force measurement has very little meaning in this context, and a torque measurement has much more.
 
The longer the knife is the more weight at the pivot and lock contact when you push down on the tail or middle of the handle or apply tip pressure. Also, the longer the knife the more it will be prone to flexing laterally which has many times caused the longer knives like BenchMade 804s, 710s, Spyderco Military and other longer bodied knives like that with thinner liners to have uncentered blades when closed.

In other words 100 pounds of weight on the lanyard end of the 881 Mini Buck Strider is less weight at the contact than the same 100 pounds of weight on the lanyard end of the Military.

The average frame lock is very reliable by nature of the design. Strength in numbers or weight is not their forte' and I think anyone that has tested them out knows that but they are still quite strong compared to most uses they'll ever see and hold up quite well. However with that said you are not going to find any frame or liner lock that will hold the kind of weight on the tail end of the knife that an Axis lock, Ball Lock, Arc Lock, or Ultra lock will hold easily without fail or problems.

Liner locks can exhibit plenty of strength in use so long as the pressures are straight down but add lateral stress in conjunction with vertical and you have a fault in the design that allows all that strength to be negated real quick because its a recipe for lock defeat that has been proven in more than one test by more than one legitimate knowledgable knife tester. If it were not for the advantage of having your hand behind the lock to prevent lateral movement of the lock on a frame lock it often times can suffer the same fault but fortunately the hand adds a great deal of reliability to this type lock and as a result in the hand the frame lock is actually a superbly made reliable tool that you can trust for the most part.

Even the ones that have some faults like super thin lock relief cuts to spring the lock are still a better design than a liner lock for hard use.

STR
 
Why does everybody worry how much a liner lock can hold on the spine? How many people do you know who cut with the spin of the knife? Or wack people with them? Even if it does fail, your pushing down. Back and forth sawing actions also dont generate much energy. Somebody care to explain why everybody performs a spine wack test or wants to balance a car on the spine of their knife blade?
 
CanonRebelXTi said:
Why does everybody worry how much a liner lock can hold on the spine? How many people do you know who cut with the spin of the knife? Or wack people with them? Even if it does fail, your pushing down. Back and forth sawing actions also dont generate much energy. Somebody care to explain why everybody performs a spine wack test or wants to balance a car on the spine of their knife blade?
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Sure. Its called hype and advertising presenting the knives as if they are invincible and capable of doing things the lock was never capable of actually handling for very long as well as a general feeling or sense of false security generated by this type of presentation.

Many folks use the liner lock just fine with little trouble, and they are fine and handy little knives that I happen to own several of. I have found that Kershaw, BenchMade, and Spyderco make very good reliable liner locks that often times hold up just fine, but there are so many improperly made ones floating around out there that they bring a bad rep to all of them, even the good ones.

The liner lock has an inherant flaw in that its easily defeated and prone to suffering wear sooner than other style locks better suited for the harder use categories. If everyone used the knives as you describe it would not be a problem so much but in the real world that is not the case.

I work on folders all the time and of all styles of locks made the liner lock is by far and away the most frequent one that comes to my bench for work or check up or problems related to how they work. (or don't work as the case may be)

STR
 
I have a CRKT M16-12Z and while it has did great for its intended purpose I can not trust it without the LAWKS safety on. You can take it and tap the spine on something and it folds up. I like the LAWKS feature which give me some comfort.
 
I also like the Lawks on my CRKT M16-03 (aluminum) its an older model. But i rarely use it. I have never had any type of knife lock fail on me.
 
CanonRebelXTi said:
Why does everybody worry how much a liner lock can hold on the spine? How many people do you know who cut with the spin of the knife? Or wack people with them? Even if it does fail, your pushing down. Back and forth sawing actions also dont generate much energy. Somebody care to explain why everybody performs a spine wack test or wants to balance a car on the spine of their knife blade?
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Don't make the mistake of confusing weight bearing tests with the spine-whack-test.
The SWT does NOT test lock strength.

Again, The SWT does NOT test lock strength.

The SWT determines if the lock was created properly.
If the lock is defective or if it has improper lock-up geometry, it will not take 100's of pounds pressure to cause it to fail.
A simple wrist snap of the spine against a padded table is all it takes to cause a defective or improperly designed lock to fold.

How many people do you know who cut with the spin of the knife?
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If you never ever use the spine of your knife, then why have a locking folder at all?
A slip-joint would suit you just fine, right?

The truth is simple....
Humans make mistakes.
And locking folders, that is reliable locking folders, are more forgiving of our mistakes.
 
What would i use the spine of my knife for? Ive owned knives for about 10 years now, only being 19... and i have never come across a use for the top of my knife besides maybe tapping it on the top of my hand when i get bored. I think some people on this forum like to test knives in some really unreal situations you would never encounter and expect knives to be totally fool/bomb proof. This is not the case and i love the reviews that say knives suck because they couldnt tear apart a tree. I'm not getting into a rant i just dont think you should subject a knife to non realistic situations just to see if you can get it to fail, its nothing impressive. I've had one knife fail on me and i got it free in the mail from a tool club. My point being, if you use your knife for what it should be used for then it shouldnt fail on you.
 
What would i use the spine of my knife for?
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Funny that you should ask....

Here's a little tale of how I personally discovered that the spine-whack-test was a valid method of checking lock function:

One day I had been hiking in the woods and had aquired quite a bit of mud in the tread of my boots.
Taking a break, I decided to remove some of the dried mud from my boots.
So I whipped out my trusty CRKT Grey Ghost Hammond Mirage (a liner-lock) and locked the blade open...snap!
Everything seemed fine and the Mirage locked-up rock solid, just like it always had.
But I did not want to dull my blade on some mud so I used the spine to scrape the mud off my boots....clever, huh.
No problems at that point, and I removed alot of the mud.
But there was still dried mud in the tread of the boots.
So I tapped the sole of my boot with the spine of the blade to loosen the mud and, without the slightest warning, the blade closed on my hand.
I still have the scar today.

Much later....
I still could not believe how easy it had folded.
I though that I must not have fully locked the blade or that somehow I must have unlocked it with my grip.
But after reading about the "spine-whack-test" here on the forums, I investigated further.
This time I was prepared and careful.
I locked the blade open and made sure that it was 100% secure.
Then I gave it a light wrist snap on the carpeted floor, and "snap!", it folded as if it had no lock at all.


Well, that's my story.
If a locking folder that fails the spine-whack-test does not bother you, or if you see no need to even test your knife, that's okay with me.
But don't say you weren't warned.


Good luck,
Allen
 
Keep in mind that I was not "tearing trees apart" or "balancing a car on the spine".....I was just tapping mud from the bottom of my boot.

Like I said before, the SWT is not a lock strength test.
 
One could easily place downward pressure along the spine of knife while skinning deer, breasting out ducks and or geese or cleaning any game and probably fish, and when you've done a slip joint test for lack of better term, whereby you try to close a frame or liner lock as you would a slip joint no whack just hand pressure to close and the lock fails with MINIMAL EFFORT, something is wrong, as I wrote on another thread tonight on this post this happened to me recently with a highend production frame lock with titanium handles by highend I mean over 400.00, this was a diret result of the relief cut in the frame lock being extremely thin due to poor workmanship. To say that downward pressure on the end of blade is not a real world scernario is not entirely accurate, it can and does happen and if you can close a frame lock as if it were a slip joint, something is wrong, wrong, wrong, thats why some knife test are not so anti-real world. These harduse knives were buying up at unprecadented rates are not always as advertised or perceived. So its good to know your equipment, you don't want to be out in the middle of no where one night say somewhere inbetween Butler, Al and Camden, Al, skinning a deer by fourwheeler light 40 miles or so from teh nearest hospital and have a locking folder close on your hand while your applying pressure that may inadvertenlty wind up being downfroce on the blade and have your fingers cut to the bone while soaked in deer which may have CWD or some other blood born disease. Just a little real world for you
there Mr. CannonRebelXTI.

Mike C
 
in any manner of real world cutting you may have to twist the blade or apply pressure in something other than a pure downward cutting motion. Used to be limited in what I could do when just carrying a non-locking SAK because of that. Heck, even just cutting up a big cardboard box can have you pressing the wrong way against the blade, depending on the situation.
 
MikeC said:
One could easily place downward pressure along the spine of knife while skinning deer, breasting out ducks and or geese or cleaning any game and probably fish, and when you've done a slip joint test for lack of better term, whereby you try to close a frame or liner lock as you would a slip joint no whack just hand pressure to close and the lock fails with MINIMAL EFFORT, something is wrong, as I wrote on another thread tonight on this post this happened to me recently with a highend production frame lock with titanium handles by highend I mean over 400.00, this was a diret result of the relief cut in the frame lock being extremely thin due to poor workmanship. To say that downward pressure on the end of blade is not a real world scernario is not entirely accurate, it can and does happen and if you can close a frame lock as if it were a slip joint, something is wrong, wrong, wrong, thats why some knife test are not so anti-real world. These harduse knives were buying up at unprecadented rates are not always as advertised or perceived. So its good to know your equipment, you don't want to be out in the middle of no where one night say somewhere inbetween Butler, Al and Camden, Al, skinning a deer by fourwheeler light 40 miles or so from teh nearest hospital and have a locking folder close on your hand while your applying pressure that may inadvertenlty wind up being downfroce on the blade and have your fingers cut to the bone while soaked in deer which may have CWD or some other blood born disease. Just a little real world for you
there Mr. CannonRebelXTI.

Mike C
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wasn't trying to be an a**, just couldnt figure out for the life of me how a spine wack test would test a locks ability, because i mostly cut down. For my hunting i use a fixed blade so i dont much worry about locking mechanisms. If i had to bring a folder i would opt for my buck 110 anyways.
 
For me, frame locks are the strongest lock, and the ones I trust the most. That exception being CUSTOM knives with liner locks.
 
I think a well made frame lock is probably the strongest lock around. I've never had a frame lock fail; even on cheap $20 knives.

I've had a few liner locks fail; one during use. For most cuttting tasks, lock failure wouldn't really matter because I'm cutting in a traditional manner. Even so, a lock should live up to it's name and remain engaged until I make a deliberate effort to close it.
 
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