Torsion bar

I believe that it is a spring connected to a cam. As the knife opens, the spring is initially compressed, and then as the widest part of the cam passes some axis, the spring decompresses, snapping the knife open. If this doesn't make sense, I'll try to sketch something out tonight.
Aaron

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My sheep has seven gall bladders, that makes me King of the Universe!
aaronm@cs.brandeis.edu

 
I await with interest your sketch. I know how a torsion bar works in a car. I will be delighted if someone will explain how the principle of torque being applied to a rod decreasing the flexibility in a plane 90 degrees to the torque, along the longitudinal axis of the rod, works in a knife. Walt
 
uuuuhhhhhh????????? Walt just threw me for a loop!!
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i am interested in how this system works, and egerly awaiting an explination.
thanks! Chris S
 
Ok, here's my attempt at a illustration. I'm not sure about this one, it comes from me looking at the Kershaw knives, not opening the mech. I am assuming that for the opening mechanism is not a true torsion bar, but more of a spring(bar under torque, torsion bar technically). I am guessing the name was given to get aroung laws about "spring-loaded" knives.

I am not finished with this idea, I still think that there is some rotation of the spring going on, but I don't know exactly what, nor how to describe it. I'll try when my brain works better.
en.jpg

Aaron
ps. The tag line is from a tablet of Akkadian omen texts. They were describing what happened if your sheep had a small gall bladder, a large one, two. Then they just started counting up!

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My sheep has seven gall bladders, that makes me King of the Universe!
aaronm@cs.brandeis.edu


[This message has been edited by amacks (edited 11 February 1999).]

[This message has been edited by amacks (edited 11 February 1999).]
 
Who am I to argue with the King of the Universe (or his unique sheep)?

The classic demonstration of a torsion bar is to take a yard stick, which is easily bent. Twist the yard stick hard from both ends, however, applying torsion, and the yard stick becomes much less flexible.

That is what I meant. Now, let's see that diagram! Tangentially yours,
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Walt
 
Aaron, thx for the diagram. I'm not sure if its a true torsion system as Walt pointed out, but it works. Ok, now lets have a diagram of those sheep gall bladders..

Mick
 
I can't figure out how to make a diagram but I wonder if the torsion bar is in the handle alongside the blade in the closed position. The bar could be anchored at the non-pivot end of the handle and a little tab on the other end of the bar could engage a hole or slot in the tang of the blade. The end of the bar with the tab would be free to rotate (twist) but not move in any other dorection. The placement of the hole/slot, the size/shape of the tab, the diameter and length of the bar would all affect the "timing" of the kick and the force. I guess....

You really got to hand it to Ken Onion. However its done, the prototyping of the knife must have been fun. I wish could afford one of his engineering feats. :-)

[This message has been edited by tom2 (edited 16 February 1999).]
 
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