Factors contributing to the lock failure of a Spyderco Pacific Salt

[yablanowitz]

I also think too few people consider that these factors apply in the open direction when chopping as well, although they may be less pronounced.

Again measuring the picture on my screen, I get a ratio of 13:1 between the blade length and the height of the stop face. The stop face is also larger than the lock face, say about 8mm x 3 mm, giving a surface area of 24 square mm, or .037 square inch. IF the lockbar face and tang stop face mated exactly so the load was spread evenly over the entire surface, chopping that exerted five pounds of force at the blade tip would transmit a blow of "only" 1,757 pounds per square inch to the stop face.

To put that in perspective, the striking face of my 12 pound sledgehammer has a surface area of about five square inches. To generate the same concentration of force as a five pound chop with the tip transmits to the stop face, I would have to generate over 8,000 pounds of force with my sledgehammer. Even if I could, I doubt the wooden handle would survive.

Then people wonder what I mean when I remind them that a folding knife is not an axe, and whine when their knife develops vertical play after only a little bit of light chopping

 

[spoonrobot]

Still wonder why it was damaged?

You misunderstand. I was not saying "why?" was it damaged by abuse. But more along the lines of "why was using the knife to strike a heavy glass bottle with the spine in a moderate half-overhead swing a major contributing factor to the failure?"

A: Because it caused indentation and rounding of the contacts between the lock and the blade. To see this I had to disassemble the knife and learn.

I guess maybe I'm getting old. I could have told you what you were going to find before you destroyed the already damaged knife, just from what I learned in junior high school.

Yes, but then I wouldn't have seen it for myself now wouldn't I?

Thanks for the input so far guys, this thread has been very educational!

 

[yablanowitz]

I guess I did misunderstand. I was trying to explain why the damage occurred, not what the damage was.