Pivot: Weakest Point on a folder?

singularity35

singularity35

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Mar 1, 2010
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I have heard here and in other forums that the pivot is the weakest point in a folder. So has anybody seen a knife break at the pivot?
 
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Never broke a lock but did break a few tips..

I think I have seen more advertising about oversized pivots but I highly doubt it is the weakest part of the knife. If anything the material holding the pivot in place is the weakest. It depends on the knife, the liner on a liner lock is probably the weakest point. For linerless CS triad locks, the G10 around the stoppin is the weakest
 
Depending on the blade grind, stock thickness, etc. the tip very often will be the weakest point on a knife, whether folder or fixed.

The point about the pivot being the weakest point on a folder is typically made in the context of comparing folders to fixed blades, and particularly in what sort of use/abuse each could stand up to before experiencing a failure that would render the knife unusable (which breaking the tip wouldn't). More specifically, at least IMHO, the main place where the point about the pivot being the weakest point is applicable is in discussions of blade thickness/strength and prying. On nearly all folding knives, making the stock very thick (say, above 3/16") without substantially increasing the pivot strength will simply decrease cutting performance without any added benefit to the overall strength of the knife, since the pivot will fail before a thick blade will.

The other candidate for weakest point on a folder will be the lock, although that will of course depend on all sorts of factors, ranging from the type of lock to the quality of fit/manufacture to (in the case of frame and liner locks) how thick they are at the cutout.
 
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Tips breaking (not just the tip's edge chipping off) and liner-locks (then frame-locks) going to crap are the main things I've seen. I don't remember seeing or hearing about a folder actually breaking at the pivot but have seen bad build quality and loose pivots affect lock-up and cause problems down the road but not something immediate like a broken blade or the special liner-lock design.
 
neuron said:
Depending on the blade grind, stock thickness, etc. the tip very often will be the weakest point on a knife, whether folder or fixed.

The point about the pivot being the weakest point on a folder is typically made in the context of comparing folders to fixed blades, and particularly in what sort of use/abuse each could stand up to before experiencing a failure that would render the knife unusable (which breaking the tip wouldn't). More specifically, at least IMHO, the main place where the point about the pivot being the weakest point is applicable is in discussions of blade thickness/strength and prying. On nearly all folding knives, making the stock very thick (say, above 3/16") without substantially increasing the pivot strength will simply decrease cutting performance without any added benefit to the overall strength of the knife, since the pivot will fail long before the blade (a solid piece of steel) will.

The other candidate for weakest point on a folder will be the lock, although that will of course depend on all sorts of factors, ranging from the type of lock to the quality of fit/manufacture to (in the case of frame and liner locks) how thick they are at the cutout.
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My one and only experience with this is the opposite of what you described. How "informative" it was, you can be the judge.

I had a SRM 710 as a loaner/beater and I'm glad I did because my buddy wanted to borrow I knife and I let him have it. He tried to pry his stuck locker open, so it snapped about .5" of the tip off. Deciding the knife was worthless I decided to abuse it just to see how much it would take, Noss4 style. I put it in a clamp and applied horizontal stress on it just to see what would fail first. The blade snapped right where it was clamped. Now missing about 1.5" of the business end of the blade, I clamped it again very close to the handle and reapplied the stress. The blade snapped again, and only about 0.5" of the blade was remaining, so I made it a boxcutter.

I think for most folders, the pivot is thicker and stronger than the steel stock on the blade.
 
Never broke a pivot , but hard use on a folder tends to invite a lot more blade play as things get torqued and stressed.

All my knife tips are intact over many years of use as I use prybars or screwdrivers, not knife tips.
 
the torque required to break a 1/4 pivot for example exceeds the normal use parameters of a folder by about 10 miles. i wouldnt worry about breaking a pivot unless i was planning on destroying the warranty on a knife anyway.
 
res1cue said:
My one and only experience with this is the opposite of what you described. How "informative" it was, you can be the judge.

I had a SRM 710 as a loaner/beater and I'm glad I did because my buddy wanted to borrow I knife and I let him have it. He tried to pry his stuck locker open, so it snapped about .5" of the tip off. Deciding the knife was worthless I decided to abuse it just to see how much it would take, Noss4 style. I put it in a clamp and applied horizontal stress on it just to see what would fail first. The blade snapped right where it was clamped. Now missing about 1.5" of the business end of the blade, I clamped it again very close to the handle and reapplied the stress. The blade snapped again, and only about 0.5" of the blade was remaining, so I made it a boxcutter.

I think for most folders, the pivot is thicker and stronger than the steel stock on the blade.
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Check this out.
http://www.knives.mutantdiscovery.com/destruction.html

It's only a 3/32" pin in G10. No washers, bushings, titanium, steel. Just a pin and G10. Freaking crazy.

I doubt I will ever break a pivot, regardless of use.
 
singularity35 said:
What about those tanto points?
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I'll assume you mean "Americanized" tanto, all angular and straight edges. But that really doesn't factor into it. Thickness of grind does. Tantos are just usually thickly ground. In fact, the more angular a facet of a knife is, the weaker it should be, because of stress risers. If there's an abrupt corner somewhere in the grind, that's where there's a weakness. Curves spread out stress, while sharp corners accentuate it. Think of bridges, and how they use arcs to distribute weight.
 
Planterz said:
I'll assume you mean "Americanized" tanto, all angular and straight edges. But that really doesn't factor into it. Thickness of grind does. Tantos are just usually thickly ground. In fact, the more angular a facet of a knife is, the weaker it should be, because of stress risers. If there's an abrupt corner somewhere in the grind, that's where there's a weakness. Curves spread out stress, while sharp corners accentuate it. Think of bridges, and how they use arcs to distribute weight.
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Yeh, that sounds right.
 
IMHO, the weakest point on any knife (fixed or folding) is the hand that wields it. Let's face it, the user is what usually results in a knife's success or failure at a given task.

Barring that, I'd say it depends on the knife/materials used/design/etc. Its not fair to make a blanket statement about it being the pivot.
 
My experience with breaking folders has been two tips and one blade. I've broke about 1/16 of an inch off the tip of both a Spyderco Endura and a Delica. The Endura went back to Spyderco and they fixed it with a regrind for no charge. The Delica remains to be fixed and sadly it was an original and rare blue handle. The broken blade was a buck 110. It broke right in the middle from an impact on the knife and was repaired by Buck knives for no charge whatsoever even though I told them it was not a fault of the knife.

Both of the Spyderco tip breaks occurred when the knives were accidentally dropped on a hard surface. One was a ceramic tile floor and the other was dropped on pavement. Lastly both Spyderco knives were the early all FRN (no metal clip) models from at least 12 years ago or more.
 
Beats me. I was wondering once whether putting a larger and larger pivot hole in the blade eventually would lead to a weaker condition.
 
It's not so much that that pivot is the weakest part of the knife, it's that the pivot is typically not as strong as the lock. Folks focus on the lock as if it were the weakest link. They keep focusing on having the strongest lock.

Now in actuality, to me, what you want is a "the most reliable" lock, which is one which does not unlock until you unlock it on purpose. I don't hear of a lot of locks which actually break. I do hear of some locks that do not stay locked. Not quite the same thing.

BTW, if you want to change the title, go to the opening post and click <edit>, then click <go advanced>. That will give you the option of changing the title.
 
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