backspring breaking question

comoha

comoha

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Joined
Jan 12, 2006
Messages
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I would like some edumuckation on how backsprings can break while opening multiblade/multibackspring knives.
I here little bits here and there but would like to hear the whole story. Is it just splitspring whittlers that have this potential problem?
 
this is a problem i experienced on earlier cheap folders. certainly most suppliers suggest not opening several blades at the same time , modern quality knives have little fracture rates. a contributing factor is lack of good lubrication. rust buildup is a prime detriment to smooth operation creating torque & friction leading to spring failure.dennis
 
This is making me nervous of opening all the blades at once, horror!

The link blames early and poorly treated stainless for this. But what about now? Anybody had a knife break up on them lately?
 
willgoy said:
This is making me nervous of opening all the blades at once, horror!

The link blames early and poorly treated stainless for this. But what about now? Anybody had a knife break up on them lately?
Click to expand...

My first break was an Ulster SS Scout in about 1977 as a result of opening the blades for cleaning.

In the last year I've had two Chinese knives one Steel Warrior that went lame and a Buck that snapped. Both out of the blue.
 
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I can't really see how opening all the blades at once would necessarily put any unusual strain on a knife.

Once a blade is fully opened the spring returns to its original position and the strain would be minimal. If a blade is opened to its half-stop position, again, the spring is returned to its original position and the strain would be minimal. The only position in which the spring is stressed is at the points between closed, half-stop, and open, and therefore, I could see that you would not want to open two blades (on the same spring) to any position stressing the spring at the same time.

If you open a knife like a pen knife to a position such as half open (on a knife not having half-stops) you would stress the backspring to its maximum stress and, if the spring were to break, I would think that that would be the point at which it would do so.

JMO

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