These videos of knife locks failing.

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snapshot2017
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These videos of knife locks failing.

Postby snapshot2017 » Sat Sep 08, 2018 9:39 am

I have found BF produced videos of testing of the Spyderco MP2 the Manix and the Delic4 , being tested to their failure.

Are these tests helpful? do they really give us real knife use information? in the BF produced videos using a truck winch this is the results produced.

The MP2 lock failed at a little over 100 Pounds, The Manix2 lock failed at a little over 300 pounds, The Delica the blade just snapped off before lock could fail.

My question is can a human put over 100 pounds of force on a knifes lock in normal really hard use? i am sure anyone can misuse a knife and make it fail, but do these failure test really influence people buying these Spyderco knives?

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Evil D
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Re: These videos of knife locks failing.

Postby Evil D » Sat Sep 08, 2018 9:46 am

You can break a fixed blade if you lean on it enough. I think there's a little value in knowing this stuff but it's more important to have the common sense to know when you need a better tool for the job.
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guywithopinion
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Re: These videos of knife locks failing.

Postby guywithopinion » Sat Sep 08, 2018 10:20 am

Their specific test seemed pretty poor to me. They had no way of controlling the load, and it ramped up very fast. I'm sure there could be a huge variation in the actual load and what their gauge spiked to. Also they had no way of controlling how far up the handle it was pulling. 100 pounds a quarter inch past the pivot on one knife is a lot different than 100 pounds 2 inches past the pivot and resulting in failure.

Also on some backlocks, the cable caught on the backlock, essentially forcing it into the blade, and causing the entire knife to snap in half. I suppose that makes the backlock "strong" for exactly that scenario, but doesn't reflect the behavior of a load that is not being exerted on the lock itself.

Edit: this is the video I'm referring to: https://www.youtube.com/watch?v=ERxHUXAFVs4

snapshot2017
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Re: These videos of knife locks failing.

Postby snapshot2017 » Sat Sep 08, 2018 10:29 am

guywithopinion wrote:
Sat Sep 08, 2018 10:20 am
Their specific test seemed pretty poor to me. They had no way of controlling the load, and it ramped up very fast. I'm sure there could be a huge variation in the actual load and what their gauge spiked to. Also they had no way of controlling how far up the handle it was pulling. 100 pounds a quarter inch past the pivot on one knife is a lot different than 100 pounds 2 inches past the pivot and resulting in failure.

Also on some backlocks, the cable caught on the backlock, essentially forcing it into the blade, and causing the entire knife to snap in half. I suppose that makes the backlock "strong" for exactly that scenario, but doesn't reflect the behavior of a load that is not being exerted on the lock itself.

Edit: this is the video I'm referring to: https://www.youtube.com/watch?v=ERxHUXAFVs4
I agree it was not a very good testing of the Spyderco knives, they had so many problems getting the results they did get.

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Re: These videos of knife locks failing.

Postby fanglekai » Sat Sep 08, 2018 10:35 am

It's only useful if the testing is done properly and if whatever is being tested actually makes sense to test. Several things to consider:
A single sample isn't enough data.
Are all the right variables controlled?
How is the force applied and where? Is it testing slow loading with a linear increase, distributed loading over a larger area, static loading, etc. Different loading will yield different results.
Is the same testing applied to every sample? For example, distance from pivot (calculate applied torque), same rate of loading (linear, exponential, etc).

Designing experiments isn't easy. There are many textbooks and academic articles on the subject. Proper experimental design, testing including data collection (sensors, equipment tolerances, etc.), and data interpretation (statistics, analysis) requires a lot of study and work. If it's not done right all you end up with is junk data and incorrect conclusions.

I haven't seen any rigorous testing yet but maybe someone is doing it right.

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Re: These videos of knife locks failing.

Postby allhatnocattle » Sat Sep 08, 2018 10:39 am

These test are purely marketing, i have broken the handle off a claw hammer by over applying leverage while mending fences, it was the right tool for the job. Anything can break through force, and trying to prove that a pocket knife could support a Volkswagen while you change a tire doesnt really make me want one any more or less.

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Re: These videos of knife locks failing.

Postby MichaelScott » Sat Sep 08, 2018 10:45 am

fanglekai wrote:
Sat Sep 08, 2018 10:35 am
It's only useful if the testing is done properly and if whatever is being tested actually makes sense to test. Several things to consider:
A single sample isn't enough data.
Are all the right variables controlled?
How is the force applied and where? Is it testing slow loading with a linear increase, distributed loading over a larger area, static loading, etc. Different loading will yield different results.
Is the same testing applied to every sample? For example, distance from pivot (calculate applied torque), same rate of loading (linear, exponential, etc).

Designing experiments isn't easy. There are many textbooks and academic articles on the subject. Proper experimental design, testing including data collection (sensors, equipment tolerances, etc.), and data interpretation (statistics, analysis) requires a lot of study and work. If it's not done right all you end up with is junk data and incorrect conclusions.

I haven't seen any rigorous testing yet but maybe someone is doing it right.
I agree. This kind of "testing" is basically worthless except for entertainment or publicity value.
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Re: These videos of knife locks failing.

Postby guywithopinion » Sat Sep 08, 2018 10:46 am

I guess more to your actual question. They seem interesting. I mean, they show a typical quality knife can take a fair bit of force before the lock fails. I don't think their ranking serves any benefit, it will simply encourage some people to parrot how lock type x is better than lock type y. If they didn't rank them at the end, and if they'd explained how crappy their test setup is, people might still do that, but at least they are trying to be as forthcoming as possible. They could still have a click-baity title for the video and have the honesty once you click.

Somewhat surprisingly, Cold Steel publishes lock strength videos where they use spine whacks on a more controlled machine (though the distance the whack is applied can vary, and also how rigidly the knife is retained seems like it would dramatically affect the impulse to the lock). I say surprisingly mainly because the video doesn't involve anyone wildly swinging at a carcass or a rolled up rug. Of course in all of these cases it is debatable if the forces being applied resemble the way in which forces are applied in real use. It seems at least a bit more controlled than someone doing batoning to compare knives.

Mainly I think these sort of crummy tests exist is because there's no easy way to test locks more rigorously. And people want to know how "strong" locks are in the same way they want to know how "good" blade steels are.

It would be interesting to know how Spyderco evaluates lock suitability, or validates that it matched their expectations. I wonder if it involves testing to failure though.

It also seems like a fallacy to think that any particular example of a knife represents the relative ranking of that lock. I imagine two different lockbacks or frame locks, etc, could have dramatically different points at which they yield. As a total guess, I'd think the Manix LW ball bearing lock would perform differently than the G10 lock that is enclosed in steel liners (though I have zero basis for that other than stereotypes and biases in my mind).

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Re: These videos of knife locks failing.

Postby fanglekai » Sat Sep 08, 2018 10:49 am

I just watched the video. The testing wasn't done properly so the data is junk. You can see the whole knife rotating in most of the tests. Damage to the blades means force was being transferred to the wrong location. You can't assume the winch applied force at the same rate since it wasn't controlled. Watch how the holding assembly moves, showing that the knives weren't properly secured. The list goes on.

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Re: These videos of knife locks failing.

Postby michaelm466 » Sat Sep 08, 2018 11:37 am

Also, in statistics class, we learned the larger the sample size the more likely the information was correct and a sample of 30 was in general a minimum to learn anything with any degree of certainty about a given population. for example, say you have 300 people on an airplane you ask the person sitting next to you how much they can bench press, who happens to be a power lifter, he says 505lbs would you then say that the average person on that plan can bench press 505lbs? Take a second sample, his buddy sitting next to him can only bench 405lbs so I guess the average person on the plane you're on can bench 455lbs.

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Re: These videos of knife locks failing.

Postby silvershade255 » Sat Sep 08, 2018 12:08 pm

The only useful thing I saw in those videos is that, assuming proper use, any lock type should be sufficient. Unless they manage to get a hold of each sage variation (and willingly destroy them) or make something it's hard to do any kind of good test.
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Re: These videos of knife locks failing.

Postby M4Life » Sat Sep 08, 2018 1:58 pm

If your putting 300 pounds of force onto a folding knife the lock breaking is the universe's way of telling you to rethink your life.
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Re: These videos of knife locks failing.

Postby Pelagic » Sat Sep 08, 2018 2:45 pm

As long as it's easy to see the specifics of the force applied to the blade it can give you an idea of what it can handle. Realistically any spyderco lock is fine, and there isn't a huge need for locks that can support 500lbs. It's just a data point that is indicative of how the knife is put together and what it can handle. Knives with extremely strong locks give some users peace of mind. If you've ever had a lock fail and cut yourself severely you may want an extremely strong lock even though you know it's overkill.
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Re: These videos of knife locks failing.

Postby sal » Sat Sep 08, 2018 3:05 pm

For our own use, we have a purpose built "Breaking machine" hooked up to a computer and camera.

sal

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Re: These videos of knife locks failing.

Postby attila » Sat Sep 08, 2018 3:37 pm

sal wrote:
Sat Sep 08, 2018 3:05 pm
For our own use, we have a purpose built "Breaking machine" hooked up to a computer and camera.

sal
Are you willing to share more about this? Some of us are fascinated by such machines, testing protocols, and results.

I understand if you aren't willing (not bashing inferior locks/manufacturers or some other reason), but we are always curious and would love to know more.

Thanks
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sal
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Re: These videos of knife locks failing.

Postby sal » Sat Sep 08, 2018 4:14 pm

Can't say too much and no pics. We designed and built the machine over a few year period, and then we updade it as tech / equ becomes available. The machine holds a part and a plunger presses on the part until it breaks. The results are recorded and printed out in a variety of areas for which we are testing. We use a camera so we can see the break and determine what failed and how. If the part is below spec, we strengthen the part (material, RC, size, etc) and break it again.

sal

snapshot2017
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Re: These videos of knife locks failing.

Postby snapshot2017 » Sat Sep 08, 2018 4:37 pm

attila wrote:
Sat Sep 08, 2018 3:37 pm
sal wrote:
Sat Sep 08, 2018 3:05 pm
For our own use, we have a purpose built "Breaking machine" hooked up to a computer and camera.

sal
Are you willing to share more about this? Some of us are fascinated by such machines, testing protocols, and results.

I understand if you aren't willing (not bashing inferior locks/manufacturers or some other reason), but we are always curious and would love to know more.

Thanks
Lets just understand that Spyderco does what testing is needed for their products, and how they feel the testing needs to be setup for the tests.
I have not ever had one of my customers when i was selling Spyderco knives, return one that had a locking system that failed.

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Re: These videos of knife locks failing.

Postby MadmanR1 » Sat Sep 08, 2018 4:43 pm

Interesting, and not surprising Spyderco has developed scientific testing methods for their products. I'm sure since the technology is proprietary we dont get to see but I wonder if the rough ranking order of lock strength has merit. It would not affect my purchasing decisions but it would satisfy a curiosity. The almighty backlock seems to have been touted for years as having supreme strength on knife forums.

I didn't think much of the hanging weight test either, but both were fun to watch.

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Re: These videos of knife locks failing.

Postby Jazz » Sat Sep 08, 2018 6:13 pm

I like them. Nice to get a visual on what they can take. I also appreciate that someone else wrecked a knife and I didn’t. If you don’t like them, just don’t watch. Easy enough.
- best wishes, Jazz.

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Re: These videos of knife locks failing.

Postby fanglekai » Sat Sep 08, 2018 9:12 pm

Jazz wrote:
Sat Sep 08, 2018 6:13 pm
I like them. Nice to get a visual on what they can take. I also appreciate that someone else wrecked a knife and I didn’t. If you don’t like them, just don’t watch. Easy enough.
The problem is they aren't purporting to be solely entertainment. It's not a question of "ignore it if you don't like it." They're deriving conclusions from faulty data and spreading those views.


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