doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com A V-spring does not break through more use

The statement below was put to me, to which I could offer no qualified opinion.

"A V-spring has exactly the same chance of breaking on its ten thousandth compression as it does on its first compression. A V-spring does not break because of more use."

Thoughts?

The variables for fatigues stress are strain (deflection) and cycles. So the number of firings matter. A new V spring is more likely to last through 10,000 cycles than it is to last through 10,000,000. The Vspring would be more likely to fail on its 10,000,000 firing than on its 10,000th firing.

The statement is a contradiction. There is a difference between the spring weakening, as in losing expansion/compression strength, and breaking, due to the stresses AmarilloMike pointed out. The spring may or may not have its power right up to the end.

Chief

"Weakening" would be a misquote on my part. The conversation was about breaking.

Horse hockey. They CAN weaken with extended use. I have owned original hammer guns that had a much weaker right hammer spring than left. This is because the right barrel is used so much more often when hunting. This was obvious to me many years ago. Dig and I debated this briefly awhile back on another thread. There is just no other explanation for why the right hammer spring will be weaker than the left nearly every time. The left is never weaker than the right.

I won't address the chance of breakage, having no opinion on that. Weakening is another matter entirely.

SRH

While this distinction between weakening and breaking is interesting in itself (isn't a break the result of a weakness?), I've edited my original post to refer only to breaking. I think I'm getting the picture from what Amarillo wrote.

It is a binary event. It either breaks or it does not. Two events, only one which can occur at any point of time. Each event is 1:1 chance of being the result. It either breaks or it does not.

You get caught up in trying to predict when it will fail using logic or perceived possible events based on assumptions. Everything fails in time but will it be now or later? If later how much later? Common sense tells us that the later it is the greater the chance of failure should be. But it is false. Each event has the same chance because it has two outcomes. Like a coin flip, head it does not break, tails it does. Just because it comes up heads does not mean that the odds are greater it will come up tails in the next event.

Start out with 100 ostensibly identical Vsprings. Cycle half of the V springs 10,000 times and the other half 10,000,000. Then pick one spring at random from each group. The 10,000,000 cycle spring is more likely to break than the 10,000 cycle spring on the next cycle. The odds that either will break on the next cycle are very low, but the higher cycled spring has a higher probability of breaking than the lower cycled spring.

kyjon, I think your logic fails because unlike the flip of a coin, which has a binary outcome but is of no consequence to the coin, the flexing and sudden stop has some fatigue consequence to the spring. Therein the binary theory fails. No metal can sustain continued flexing without eventual damage if not out right fracture. If the spring is not highly polished and unscratched it may serve a long time. But one scratch in the critical area and it goes down hill fast. I am sure at some point you have deliberately flexed metal to the point of failure. The spring is the same issue. The springs in your car gradually decline over their life -why would you argue a gun spring is any different?

So I can win or lose the lottery. That makes my chances of wining 50/50?