Frame vs. Liner Lock

P

phatch

Joined
Oct 3, 1998
Messages
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Why are frame locks glorified and liner-locks vilified? I am talking solely about the failure of a liner/frame to wack and other impact tests.

Yes, I am familiar with linerlocks failing and wearing. I have seen it happen.

Frame locks seem to be the same thing, really. They share the same geometry issues. They share the same criticality of tang/lock interaction. And they seem to be just as tricky to mass produce.

Yes, frames will wear slightly slower on average, are somewhat less likely to flex through the liner/frame member and so on. And they seem to be less influenced by grip induced failures. And those are good things but they are an apple
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range comparison.

In straight impact failure, the bane of the liner lock, why is a frame lock superior, if it really is?

Phil
 
Because the liner locks contact area with the blade tang is smaller, and is more likely to slip off the tang.

-Johnny
 
Frame locks usually only engage on a corner of the frame, of roughly the same size as a comparable liner.

Additionally,if I read your response correctly, there is this rebuttal. Area is not part of the friction equation. Force creates friction. From the liners and frames I have handled, the forces seem similar, but this is not objective testing.

Now, there are strange materials where surface area does matter for friction, and titanium and steel together may be one of them, but steel on steel isn't, at least if I recall my physics correctly.

Please correct me if I misread your post.

Phil



[This message has been edited by phatch (edited 03-01-2000).]
 
I don't currently own either, but frame locks allow you to directly hold the lock in place, whereas a liner can be inadvertantly released.

--JB

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e_utopia@hotmail.com
 
The most important answer to this question is a practical one: we've observed liner locks failing like crazy, but not frame locks. Not just in the garage where people do canned tests, but even from field use, we have loads of liner lock failure stories, but I can't think of a single frame lock failure story, ever. This is a more important fact than any theoretical explanations we have. But, moving on to the theoretical:

With a frame lock, when you close your hand, you are forcing the lock *into* the blade tang. Smack the back of the blade, and even if the frame lock wants to fail, your entire hand is reinforcing the lockup. Torque it, same thing. And to get straight white-knuckle failures with a framelock, your design would have to be outright incompetent.

With a liner lock, the scale prevents any positive reinforcement of the locking leaf by your hand. However, it very much allows and even seems to encourage negative reinforcement of the lockup -- skin from the fingers likes to creep between the locking leaf and the far scale, creating pressures to unlock. Any torquing or spine pressure that happens, the user's hand is definitely not reinforcing the lock, and in fact is most likely helping the lock disengage by sinking into slot between the leaf and far scale.

Note that the theoretical explanation really doesn't even need the hand-reinforcing explanation. Even in canned lab tests, where the user's hand typically isn't even touching the scale in such a way as to reinforce the lock, the few framelocks that are out there very rarely fail, whereas liner locks often do.

Joe
 
The area has a lot to do with whether liner lock or frame lock fails or not. We are talking purely spine whack failures. In these failures the liner slips off the tang. Frame locks have a much harder time slipping off because of the area of contact. I have heard of frame lock failures however. I recall hearing about some Pinnacles failing. I can almost guarantee you that this was because the lock bar was not engaging the blade tang enough, and so it just slipped off when the blade was impacted. There are some liner locks where the liner is a thick .60", half the thickness of a typical frame lock. Since a frame lock usually engages the tang about half way, if a .60" liner lock hit the blade tang half way, they would have the same amount of area contact. Maybe that is the answer.

-Johnny

[This message has been edited by JoHnYKwSt (edited 03-01-2000).]
 
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