# Knife safety question....

goldliger
Hey guys, brand new here but looks like I'm in the right place :D

I've got an OTF knife (a.k.a. "out the front," where the blade ejects straight out from the handle) that is held in the closed position with 1 lb, 12 ounces of magnetic force. I.e, upon measuring it takes 1 lb, 12 oz. of finger pressure against the knife switch to eject the blade (automatically). The blade itself weighs 1 oz.

Basically, I'm wondering how one would go about determining whether this is a reasonably safe configuration, considering the knife will be carried in the pocket and generally tip pointed down (within the handle, of course). I've done rudimentary testing such as jumping up and down, stomping, shaking my pockets, etc, with the knife in my pocket - pretty much everything short of jumping off a 100 foot cliff with rock slab at the bottom, since I figure knife safety would be the least of my concerns on the way down. :)

Any ideas, mathematical formulas, etc, are most welcome, and thanks for your time!

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Mentor
I've got an OTF knife (a.k.a. "out the front," where the blade ejects straight out from the handle)
Welcome to PhysicsForums.

You need to check your local laws about that knife. Knife laws vary by country, state and local jurisdiction, but in many parts of the US at least, switchblade knives and butterfly knives are illegal (they are illegal in the part of the US where I live).

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goldliger
Yes you're correct about that - and thank you, good to be here. :)

berkeman
Mentor
Since the knife is most likely illegal, we can't really discuss it here (that's in the PF rules). I once bought a butterfly knife online many years ago before I found out they are illegal here in California. I thought it was a nice design and a handy way to be able to open a useful knife with one hand (I wanted to use it for hunting and fishing, etc.). Then I found out it was illegal (I still to this day do not understand why -- something about the tiny springiness that is used to help start opening it), and destroyed it and threw the pieces away. The risk was not worth the utility.

Anyway, sorry but this thread is now closed.