How strong are the UBER-tough framelocks, really?

Walking Man

Walking Man

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The same points are being brought up over and over. Please read the whole thread.
The knifemaker who originally spoke to me wasn't putting anyone down. thank you.
 
It would seem to me that the amount of pressure needed directly on the lock to collapse the actual lockbar would be so great that the pivot would be likely to shear first. That's just my opinion though.
 
I don't have calipers handy but for a sebenza, a strider PT and the airkat tripwire, the "relief" area is thinned to approximatly to the same thickness.

However as I note in the airkat passaround the width of the lockbar, or the cross section varies consierably, also by the time force gets to the relief area it's almost all compression forces rather then shear forces so that complicates matter slightly.

I've not heard of the framelock relief "failing" far more common is the lock face slipping off the blade tang. Which is fairly common.
 
What Cliff and Dave said. The whole system is only as strong (or, rather, failproof) as its weakest point, which isn't that area.

The relief just makes it easier to move the lock--and who knows, maybe it does something to prevent breakage from constant moving of the bar, by focusing the bend in one manageable area instead of somewhere we don't want that force to be.
 
The weakest points on a framelock are usually the pins and pivot. If the lock holds, these are going to be the first to fail by shearing out. But how often do you hear this happening? Lock failure from the lockbar slipping off the tang is far more common.

Some framelocks have a large area scooped out at the base of the lockbar. But that just makes it as thick there as a normal linerlock. Again, how often do you hear of linerlocks failing specifically because the liner buckles and collapses?

It's great that your knifemaker tries to reduce this possible point of lock failure. I hope he's paid far more attention to the pins, pivot, and lockup geometry if he's serious about making stronger folders.
 
SteelDriver said:
It's great that your knifemaker tries to reduce this possible point of lock failure. I hope he's paid far more attention to the pins, pivot, and lockup geometry if he's serious about making stronger folders.
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It's definately a very well built folder.
 
Walking Man,

I'm sorry, did you actually tell us who this maker is?
I'd really like to see the knife in question, as I love seeing maker's interpratations and variations on designs.

Thanks,
B.
 
they are "uber tough"







geeze its right in the name.

oh and tactical. and hard core you forgot about that.
 
SteelDriver said:
The weakest points on a framelock are usually the pins and pivot. If the lock holds, these are going to be the first to fail by shearing out. But how often do you hear this happening? Lock failure from the lockbar slipping off the tang is far more common.
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I'll second that. If it were made well, the pivot assembly might be weaker. But in reality there are droves of liner- and frame-locks that fail through bad lock geometry well before anything breaks.

With liner locks the leaf spring is flexible and curved. If you put a lot of force on the blade, the liner will flex in no controlled manner. With relief scoops on a framelock, the leaf spring is closer to a hinged slab. The angle of contact between the lock and the blade will remain much more consistant.
 
I believe Mick Strider once stated, when asked why the "scoop" (relief) on Strider famelocks was on the opposite side as other manufacturers' framelocks (Striders' "scoops" are on the clip side of the scale as opposed to the inside of the scale), something to the effect that the placement of relief ("scoop") on Striders is in a direct line with the compression forces of the lock, whereas other framelocks have the "scoop" placed so that the force jumps across the "scoop", causing a potential problem if enough force is applied. Since Mick has taken the time to address that issue, by placing the "scoop" on the opposite side on Strider framelocks, there must be at least some merit to the '"scoop"=potential weakpoint' theory.


Best wishes,
3Guardsmen
 
3Guardsmen said:
I believe Mick Strider once stated, when asked why the "scoop" (relief) on Strider famelocks was on the opposite side as other manufacturers' framelocks (Striders' "scoops" are on the clip side of the scale as opposed to the inside of the scale), something to the effect that the placement of relief ("scoop") on Striders is in a direct line with the compression forces of the lock, whereas other framelocks have the "scoop" placed so that the force jumps across the "scoop", causing a potential problem if enough force is applied.
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Doing the scoop on the outside makes sense because the hinge point is closer to being inline with the blade. It's only a degree or two probably, but a good idea in general. One possible problem with a linerlock design is the liner has to push against the handle slab to keep the blade from closing, because the liner comes in from the side. It's not all within a 2-dimensional plane like a lockback. But Striders, having insanely thick framelocks, don't look like that would be a problem because the frame is such a thick piece of titanium.

The flat slab-like shape of the lock leaf (or slabe or whatever you want to call it) is an illusion to a degree (or two, literally). The direction of force to be considered is a straight line from the point of contact between the leaf and tang to the other end where the lock hinges, somewhere around the scoops. Since we have bending material rather than an actual hinge, that point may change a little as it bends. That line is what should be used to decide what angle to grind the contact area on the back of the tang.

No matter which side the scoop is ground, there will be a straight line from the contact area to the hinge. However, Strider's method puts that line slightly closer to the plane the blade moves through on the back end, and if you continue the line past the hinge point, there is more metal "behind" it, while a knife with an inner-scoop has almost no metal behind the hinge point, because the line past that point goes outside the handle.

If anyone knows where Strider's explanation can be found so I can read it myself, I would like to.
 
This is all speculation. Has anyone here ever had a framelock fail (the lock part, not the pivot area) while in normal use? I never have. Yes, I have heard about the lock slipping off the back of the blade in some instances during testing where torque has been applied to a blade firmly stuck into a block of wood or something. I haven't even been able to duplicate that with my large Sebenzas, although I have not applied that much torque because I am afraid the blade will break before the lock disengages.
 
You're probably right. Still, I have seen at least one framelock that I will not buy because of the large relief.
Not that it really matters, I'm not sure I would have bought it anyway.
 
Steelhed said:
This is all speculation. Has anyone here ever had a framelock fail (the lock part, not the pivot area) while in normal use? I never have.
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Strider's explanation in the link above refers to the lock slipping off the blade due to the problem he is describing, not the scoop area actually breaking. He is saying it all in only a couple sentences so I don't know for sure if he is saying the same thing I was, but it's definitely not about anything breaking apart (except maybe fingers :)).

I haven't heard of framelock leafs breaking clean off either. I suppose it's possible, as is anything with either enough force or poor manufacturing or design, but I haven't heard of it happening. Not even from Cliff, who isn't afraid to put things beyond typical use to test manufacturer BS, so it doesn't seem like something any manufacturers of the tank-busting knives have a problem preventing.

However, general not-breaking failures do happen, so Strider's concern over internal scoops is one to keep in mind if it might allow just enough flexing around to let the lock slip out of place.
 
Carl64 - I like testimonials. :) Who has actually experienced a failure with a framelock during normal use (not testing)? I'd be interested to know because I have never seen it happen. I have personnally had lock failures with some liner locks, but not with framelocks or Axis locks.
 
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