Is My OTF Knife Configuration Safe for Everyday Carry?

  • Thread starter Thread starter goldliger
  • Start date Start date
  • Tags Tags
    Knife Safety
AI Thread Summary
The discussion centers on the safety of carrying an OTF knife, which has a blade that ejects straight out and is held closed by a magnetic force of 1 lb, 12 oz. The user conducted various tests to assess the knife's stability while carried in a pocket. However, the conversation shifted to the legality of such knives, as many jurisdictions, particularly in the U.S., have laws against switchblade and butterfly knives. Due to these legal concerns, further discussion on the knife's safety configuration was deemed inappropriate. The thread was ultimately closed due to these legal restrictions.
goldliger
Messages
3
Reaction score
1
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!
 
Last edited:
Engineering news on Phys.org
goldliger said:
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).
 
Last edited:
Yes you're correct about that - and thank you, good to be here. :)
 
  • Like
Likes berkeman
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.
 
Thread 'What type of toilet do I have?'
I was enrolled in an online plumbing course at Stratford University. My plumbing textbook lists four types of residential toilets: 1# upflush toilets 2# pressure assisted toilets 3# gravity-fed, rim jet toilets and 4# gravity-fed, siphon-jet toilets. I know my toilet is not an upflush toilet because my toilet is not below the sewage line, and my toilet does not have a grinder and a pump next to it to propel waste upwards. I am about 99% sure that my toilet is not a pressure assisted...
After over 25 years of engineering, designing and analyzing bolted joints, I just learned this little fact. According to ASME B1.2, Gages and Gaging for Unified Inch Screw Threads: "The no-go gage should not pass over more than three complete turns when inserted into the internal thread of the product. " 3 turns seems like way to much. I have some really critical nuts that are of standard geometry (5/8"-11 UNC 3B) and have about 4.5 threads when you account for the chamfers on either...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...

Similar threads

Back
Top