Is Lockback Strength Affected by Size?

[James Y]

In the General Discussion Forum in the thread on lockback failures, someone mentioned that several Police models had their lockback mechanisms fail. He said one was a new piece.
If the other failures weren't due to heavy use over a long period, does this imply that a larger lockback might be more prone to failure than a smaller lockback?

I'm thinking if this is the case, it could be due to the heavier blade and more pressure at the pivot area. Is it so, or were these flukes, or are all lockbacks prone to these problems at some point, even Spydies?
BTW, I love my Spydies, but would like to know.
Jim

 

[Sal Glesser]

Jim - Lockback failure in factory knives can be caused by: material selection or hardness, Geometry of the lock / tang interface (critical), Geometry of the lock / pivot pin / lock pin (also critical) and the exectution of same in manufacture (do they meet spec).

Lockback failure in owner use knives are caused by: lint or dirt in the lock interface (most common), hitting blade / handle area with hammer (distorts interface), prying (distorts interface and loosens pins.

Once a lockback fails, it will probably not "fix itself" as the interface is damaged on both tang & lock.

The longer the blade, the more leverage is applied to the lock and the lock should be made stronger accordingly.

Lockback failure in Spyderco pieces are not common because most are checked. Making a reliable lock is dificult (harder than one would guess, because there is always "hand work").

Though many dislike the recommendation, I think a light Spine wack on a new knife will quickly show if there is an obvious problem.

Also keep in mind that lock reliability and lock (ultimate) strength are not the same.

Sal



[This message has been edited by Sal Glesser (edited 03-15-2000).]

 

[James Y]

Sal:
Thanks a lot for the reply and explanation!

Jim