Does grip strength actually reinforce a frame lock? All frame locks?

hardheart

hardheart

Joined
Sep 19, 2001
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This is often brought up as a feature of frame locks, that without a scale covering the lock, your grip will reinforce the lock and prevent it from slipping. Is this actually the case? For a frame lock to fail by slippage, I would estimate that the lock bar needs to move approximately a sixteenth of an inch in most cases, sometimes less. The lock bar and the rest of the frame are the same thickness, plus the pocket clip is on the same side for most righties. When held in a hammer or saber grip, the fingers seem to wrap around where the proximal phalange of the fingers contact the lock bar. How hard must the handle be gripped to prevent 1/16" movement of a bar in contact with the flesh of the hand? Is it possible to actually use the knife in a cutting action with the necessary grip? Is it possible with all handle profiles, scale overlays, clip placements, lockbar dimensions? Does the benefit transfer to similar locks, like the Elishewitz bolster lock, the Kershaw subframe lock, The hybrid PPT lock?
 
Interesting, which frame locks have you had that failed spine pressue or spine tap tests that did not fail when gripped firmly in hand? Did they have a pocket clip, if so, what was the orientation? Thanks.
 
I have not had a failure but I would say yes, it does prevent the lock bar from slipping back to the open position. I know when I grip my ZT hard the lock moves further into engagement from my hand pressure making it practically impossible to slip out. I would think the cut-out would buckle as designed long before a slip would occur while being gripped.
 
My Leek has a frame lock, and pressure has no effect on it. I would assume it is dependent on the knife itself, not just the style of lock.
 
It has more to do with the angle of the lockbar face and blade tang ramp engagement, as well as depth of lockup. At the risk of sounding like a total CRK fanboy, which I am :), Chris got it right a long time ago.

A lot of non-CRK framelocks have drastic engagement angles in the interest of retarding long-term wear that actually make it more succeptible to accidental disengagement, and it doesn't matter how tight you're gripping it.

All framelocks are far from having been created equal.

Just my .02.

Prof.
 
I think it's a personal way of assuring yourself that you can be dumb with (read: abuse) a folding knife. Unless your hands are literally vice grips, I highly doubt you will be able to prevent a lock failure. But that's my $.02.
 
When applying a lot of pressure to a blade it is going to act like a lever and magnify forces at the lock interface. I don't use frame locks or liner locks any more so I haven't had a failure while using a really tight grip but I have had a frame lock disengage and close unexpectedly 2 times. I think depending on the knife, the grip, and the hand holding the knife, that a frame lock could come unlocked while in a heavy grip if it is prone to do so.

Many people say they like choils because if the lock did fail it would hit there finger and stop. The only other knife failure I have had did this and the choil pushed my finger out of the way like it wasn't there. I don't think people realize how easily there hands and fingers can be pushed out of the way a small distance, especially when the meaty part of your hand is involved and there are simple tools like a lever, multiplying forces.
 
ibute21 said:
I think it's a personal way of assuring yourself that you can be dumb with (read: abuse) a folding knife. Unless your hands are literally vice grips, I highly doubt you will be able to prevent a lock failure. But that's my $.02.
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yes, this
 
ibute21 said:
I think it's a personal way of assuring yourself that you can be dumb with (read: abuse) a folding knife. Unless your hands are literally vice grips, I highly doubt you will be able to prevent a lock failure. But that's my $.02.
Click to expand...
I agree. If the lock fails, it will fail with a hand gripping the handle. As Hardheart pointed out - a movement of the blade point will be translated in 1/16" movement of lock bar. That is not only very small movement by itself, making it difficult to prevent. It is also an indication of lots of leverage involved.
When you unlock the flamelock you do it with no forces applied against the blade. So the only resistance you have to overcome is the lockbar spring. So there is an illusion that the lock may fail under very light pressure and your hand holding it may affect it in some way. But if there is a significant pressure applied to the blade point - forces acting in the lock are multiplied many-fold... Just look at the leverage! Where is the blade point in relation to pivot, and where is the locking area! That is just ... unbelievable!
 
P.S. If you still believe it - get some on-hand experience. ;)
Put lots of tape on the edge, some graphite on the lock (by pencil), probably add a drop of oil and check it out...
That would be on your own risk though. And I myself probably would not do it. Even if I believed.
By the way, I do believe that titan makes lock stronger. As I have already mentioned in some other topic - friction coefficient for titan-steel pair is much better than the one for the pair steel-steel. The steel-steel one sucks.
So titan makes the lock stronger. But it reduces locks longevity - because titan is softer and less wear resistant... So the liner/frame locks are still the subject to the "rule of two" - out of strength-size/simplicity-longevity you can pick only two, you can not have all three... ;)
And this type of lock is always associated for me with the first two...
 
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Poez said:
By the way, I do believe that titan makes lock stronger. As I have already mentioned in some other topic - friction coefficient for titan-steel pair is much better than the one for the pair steel-steel. The steel-steel one sucks.
So titan makes the lock stronger. But it reduces locks longevity - because titan is softer and less wear resistant...
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Most people don't realize this, and complain about a "sticky" lock bar, which is actually favorable.
All the frame-locks with steel lock bar faces will fail with less force applied, as opposed to those with bare titanium lock bar faces.
 
Professor said:
It has more to do with the angle of the lockbar face and blade tang ramp engagement, as well as depth of lockup. At the risk of sounding like a total CRK fanboy, which I am :), Chris got it right a long time ago.
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I couldn't agree more. Also, unlike frame-locks which have the stop pin pressed into the blade, the frame-mounted pin can be replaced to adjust lock bar face/blade tang engagement.
 
ibute21 said:
I think it's a personal way of assuring yourself that you can be dumb with (read: abuse) a folding knife. Unless your hands are literally vice grips, I highly doubt you will be able to prevent a lock failure. But that's my $.02.
Click to expand...

I'm a professional olde time strongman, my hands are as close to a set of vice grips as most people will ever encounter. My HEST folder had a faulty framelock and I could SLOW it's closing. But I had to exert so much pressure on it that there's no way I could have the dexterity left to actually cut anything. The failing lock is a lever, it doesn't matter how strong your hand is, the lock has a mechanical advantage.
 
hardheart said:
which frame locks have you had that failed spine pressue or spine tap tests that did not fail when gripped firmly in hand?
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It's not mine, but my brother has an $8 frame-lock which slips right off the tang from 100% engagement with slight spine pressure. That's way more than moving 1/16", more like 1/8".
When held in a regular forward type grip (saber or hammer), it moves not at all. You can stab it through thick cardboard or into trees at odd angles which put lots of spine pressure on the knife with no worries.
You aren't fighting massive forces here, just the tendency of the lock-bar to slip. That's why a single finger can do the trick.:)

Sorry for those who don't believe it; you're just wrong.
 
I would imagine we could probably uncover examples of failed locks that are improved with grip strength, and examples of failed locks that do not seem to be appreciably improved with grip strength.

The real question here is WHY would anyone want to?
 
I've had a couple of framelocks that failed the spine whack test. Unless I made a special point of squeezing the lock bar, the lock still failed when I was holding the knife. There are good framelocks and there are those that don't work as well.
 
I am in agreement with stabman. The hand just prevents the lock/blade junction from slipping, simply, but effectively. You are no longer relying purely on the spring tention of the lock itself. Of course, if the lock-up is too early, there's the chance it'll slip anyways. But, they generally seem to lock up tighter (more lock/tang contact) once you grip them hard.
 
I also wanted to mention that if the knife is set up for tip down carry, sometimes, depending on design and clip placement, you're not able to actually take advantage of the frame-lock. What you might end up with is the clip acting like a scale, and therefore a liner-lock type of lock.
 
hardheart said:
Interesting, which frame locks have you had that failed spine pressue or spine tap tests that did not fail when gripped firmly in hand? Did they have a pocket clip, if so, what was the orientation? Thanks.
Click to expand...

Kershaw Vapor.
 
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