thoughts on .....

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Jan 27, 2021
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storing assisted openers . how do you keep them? blade out to reduce stress on torsion bar, or closed?thoughts please.
 

sabre cat

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just thinking a spring stored relaxed will last longer?
Like I said, I doubt if it makes much difference. Especially considering that the spring is under tension ether way, open or closed.
 

NorthernSouthpaw

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On a torsion bar type of assisted opener. The bar is not under stress when open or closed. It is the action of opening, or closing the blade that really provides the tension.
 

sabre cat

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On a torsion bar type of assisted opener. The bar is not under stress when open or closed. It is the action of opening, or closing the blade that really provides the tension.
You must know more about this than I do. I figured that there would be some tension on the spring all the time.

I guess it just depends on the knife design and the type of spring that’s used.
 

NorthernSouthpaw

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You must know more about this than I do. I figured that there would be some tension on the spring all the time.

I guess it just depends on the knife design and the type of spring that’s used.

Just take apart a Speedsafe Kershaw. Actually all you usually need to do is remove one scale to expose the mechanism. The reason why there is a bit of grease in there is so the bar doesn't rattle while the blade is closed.
 
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Apr 6, 2017
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Oof, some interesting opinions here. Here's mine:

Torsion bar assists are under slight tension while closed, and are completely free when open (that's why Kershaw/ZT put grease in their handles to hold the springs from rattling while their AO knives are open). The engineering answer here is that, while cycling from high to low stress does cause the majority of fatigue damage to elastic materials like steel, there's also creep to account for with materials loaded for long periods of time, and this can result in additional strain, and therefore damage, to a spring.

Whether this is matters for most users in the context of the lifespan of a knife is questionable. But there is some difference, even if it's largely academic in this case.

To (sort of) answer your actual question, I don't leave assisted knives stored in any way because I always pull the springs out and throw them in a box. If I did store an assisted knife, it would be closed.
 
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Just take apart a Speedsafe Kershaw. Actually all you usually need to do is remove one scale to expose the mechanism. The reason why there is a bit of grease in there is so the bar doesn't rattle while the blade is closed.

You have this backwards. The springs are at rest when the knife is open, not closed. I've taken a bunch of these apart and learned the hard way when removing the grease. Also, the spring is what provides the detent force on most AO Kershaws, and that fact alone indicates that the spring is preloaded.
 
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Joined
Jan 27, 2021
Messages
13
Oof, some interesting opinions here. Here's mine:

Torsion bar assists are under slight tension while closed, and are completely free when open (that's why Kershaw/ZT put grease in their handles to hold the springs from rattling while their AO knives are open). The engineering answer here is that, while cycling from high to low stress does cause the majority of fatigue damage to elastic materials like steel, there's also creep to account for with materials loaded for long periods of time, and this can result in additional strain, and therefore damage, to a spring.

Whether this is matters for most users in the context of the lifespan of a knife is questionable. But there is some difference, even if it's largely academic in this case.

To (sort of) answer your actual question, I don't leave assisted knives stored in any way because I always pull the springs out and throw them in a box. If I did store an assisted knife, it would be closed.
would you happen to have a 0350 spring in that box of yours that you would be willing to post?happy to pay
for spring and post
 

skyhorse

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Jan 30, 2010
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would you happen to have a 0350 spring in that box of yours that you would be willing to post?happy to pay
for spring and post
Give Kershaw a call and they'll send you a spring free of charge . A great company :)
qelz2qe.jpg
 
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I keep them with the spring element stored separately, in a little bag with a label saying what knife it belongs to! :p

Or, I did. The two(?) AO knives that I do have, are in their boxes, waiting for me to take pictures so I can sell them.

When I did use and carry them, I wondered about this, too. I found the same information that others have supplied, which is that cycling, not storage, is what causes wear.
 

DMG

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Dec 30, 2005
Messages
542
Oof, some interesting opinions here. Here's mine:

Torsion bar assists are under slight tension while closed, and are completely free when open (that's why Kershaw/ZT put grease in their handles to hold the springs from rattling while their AO knives are open). The engineering answer here is that, while cycling from high to low stress does cause the majority of fatigue damage to elastic materials like steel, there's also creep to account for with materials loaded for long periods of time, and this can result in additional strain, and therefore damage, to a spring.

Whether this is matters for most users in the context of the lifespan of a knife is questionable. But there is some difference, even if it's largely academic in this case.

To (sort of) answer your actual question, I don't leave assisted knives stored in any way because I always pull the springs out and throw them in a box. If I did store an assisted knife, it would be closed.


No. As long as the spring is not at or near it’s elastic limits, it will be fine pretty much forever. I have seen video of pistol magazines loaded for approaching 100 years that function fine.
 
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Joined
Sep 3, 2012
Messages
533
I used to flip and play with mine constantly and I kept breaking the torsion bars. I stopped doing that and give them some time to rest between firings and it seems like they are lasting longer.. is that in my head or is that possibly a thing?

If Kershaw would start putting a detent hole in the all blades so they could be deassisted and they would stay closed in the event of a spring failure I doubt anyone would complain. It's such a small step that literally everyone else does on every other liner lock, and it would be such a benefit. I've been on this soapbox for years and I have no idea why they won't start doing it. Great knives hamstrung by one glaring flaw.
 

Black Oak Bladeworks

Knifemaker / Craftsman / Service Provider
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Jun 5, 2019
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Two things wear out springs.

1 cycling them

2 forcing them past their limits.

It's the movement / cycling that fatigues a spring NOT storage in tension .

I have pistol magazines from WWII , still work fine , stored loaded .

No. As long as the spring is not at or near it’s elastic limits, I will be fine pretty much forever. I have seen video of pistol magazines loaded for approaching 100 years that function fine.

All the above post nail it in my opinion and research. Springs don't wear out from constant tension, its the compression/un compressing that wears them out or bending them past the limits.
 
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