When someone mentions tough knives, my thoughts usually stray to full-tang fixed blades with some heft to them. But the one thing that kept nagging at me was the plethora of newer lock designs and brawny folders. While no one expects a folder to compare to a heavy-duty fixed blade, one has to wonder just how tough they really are.
Folding knives were made for years with no lock at all. While this is technically correct, I like to prepare for a worst-case scenario. For folding knives, this means that they should be able to handle things above and beyond the call of duty without harming me by lock failure.
How much can a modern lock take in an emergency, when some catastrophe has deemed it necessary to abuse a knife in some way? That was my question, and one that two manufacturers helped to answer.
Cold Steel and Benchmade knives both sent samples of several knives. The purpose was not to simply break a knife, but put it through tests that simulate a heavier use than any sane person would put on a knife. This is abuse and goes beyond what we would expect of any knife in normal usage.
Because these tests were to simulate an abusive emergency use of a knife, they were done once on each knife. A benchmark was set, and each knife put through the same test. Because of this, failure would not be deemed due to fatigue or heavy wear. The criteria for passing would be how my fingers would have fared had they been holding the knife.
While it is easy to test a lock by loading the spine of the blade, this does not take into account any shock or spring in the system. That is why a lock that seems good can fail to a spine whack. Realizing that we are testing for worst-case conditions, the knives were tested with the mother of all spine whacks. I developed a test using a lever with just over 50 pounds on the end,, falling 9 inches to drive the spine of the knife into a ½-inch steel rod. This is over 70 ft-lbs of force on the blade at a point about 3 inches from the pivot.
The second test gently loaded the blade with 175 pounds. Each blade was marked at a point 3 inches from the pivot, so the locks would take a similar load, despite differences in blade length represents a large amount of force to put on a handle with your hands. To exceed this would require leverage, or jumping up and down on the handle, provided a person could put the knife in such a compromising situation in the first place. Consider the weight of almost two full 90-pound sacks of cement hanging on the blade, and you get the idea.
All testing was done on the machine illustrated here. The illustration hits the high points. One other point is that the knife is not exactly vertical, but tilted about 5 degrees, which adds some side loading to the lock as well.
There are two things that it are important for all readers to understand. The first is that neither manufacturer knew exactly how their knives were going to be tested. They stuck their neck out in sending these, not knowing how the tests would turn out. The second is that both of these tests are absolutely abuse, and represent much more stress than any user could put on the blade in any conceivable situation, barring stupidity. Onto the knives!
Stay tuned for the knife test results!
By Justin Forrester