Until a few months ago, I was unaware of the spine whack test. I have come to believe it is a valid test to ensure the knife will not accidentally close under "normal" operating circumstances. However, the definition of "normal" operating circumstances has many times been assumed by the user and not often defined by the manufacturer.
From the many knives I've examined recently, I've noted several reasons for a knife failing the spine whack test. One is the presence of excessive lubrication on the edge of the lock and/or locking face of the blade. Another is improper geomentry at the lock/blade interface. This applies to lockbacks as well as liner locks.
The excessive lubrication is usually easily corrected by the user or manufacturer. Improper geometry must be left for the manufacturer to correct.
If the knife has an edge (or other function, such as a bottle opener, fish scaler, etc.) on the side opposite the main sharpened edge, the spine whack test is most important to the user. If no such function exists, the test should be used to check for "accidental" closing.
Now, as far as the terms "normal" and "accidental" are concerned:
I've seen a photo of some fellow securing a liner-lock knife to a stick and preparing to beat the top edge of the open blade with a broomstick. This will not only test for excessive lubrication and improper geometry, it will also check to see if the lock will fold up like an accordian! Destructive tests always find the weakest point, and most folks don't know how much abuse something can take until they actually break it.
If you think you're going to use a folding knife that hard: buy one with a really thick lock, don't complain if the action seems a bit stiff, and ask the manufacturer or maker if the knife was designed to endure such extreme use. Don't buy a VW Beetle and expect it to perform like a M1A tank!
I believe the blade should be tapped against a hard surface using moderate force. If the lock is going to fail due to excessive lubrication or poor geometry, it will fail immediately. (Maybe I should call this the "spine tap" test!)
If you want a knife that won't fail if you slap it full force against a telephone pole, buy a fixed blade. (Some, not all, will pass this test.) Why not a folder? Maybe that folder might hold up to the telephone pole test 99 times and fail on the 100th try - you still lose your fingers!
I agree that the SERE looks like a heavy duty/use knife. Several people have them, use them, and like them. Give the folks at Al Mar a chance to fix the problem with your knife. If they don't, I'll be glad to hear your gripes.
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Tom Anderson
Hand Crafted Knives
[This message has been edited by Tom Anderson (edited 01-17-2001).]
