Why are spinewhack-tests not indicitive of lock strength?

kniferbro

kniferbro

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Jan 22, 2011
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Let me preface this post with the statement that I am fully aware that spinewhack tests are NOT a measure of lock strength. I read somewhere (still can't find it) about why spinewhack tests aren't a real test of lock strength, but I forgot the reasons why! Could anyone reeducate me on the subject?

Also, there was a post from a forum member here a few months back about him slipping from a roof and as he slid towards the edge of the roof he stabbed (in reverse grip with edge facing away) his Griptilian into the roof and it held his weight and possibly saved his life.

If knife "X" fails a spinewhack test does that mean it would fail in a situation like the one described above? The difference being an abrupt, jarring strike (spinewhack) versus a (relatively) slower loading of the lock.

Again, I am FULLY aware about the invalidity of spinewhack tests! I just would like to know why!
 
I don't trust liner locks or even frame locks. I have never had an axis lock fail a spine whack test. Many liner and several frame locks I've owned have. I consider it a test of how the lock will hold up in certain circumstances like you mentioned. Others say it doesn't matter, folding knives are made to fold, or get a fixed blade. I just use Fixed blades and Axis locks. I feel pretty safe with those.

I do go against the grain on this topic though. If I can tap a liner lock in the palm of my hand, and it fails, how can it be a good lock? Yes even Benchmades I used to own did that along with Microtechs and brands I won't mention.
 
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I saw that, then I read the last sentence. For me, lock rock is more of a concern than spinewhacks.
 
RevDevil said:
I saw that, then I read the last sentence. For me, lock rock is more of a concern than spinewhacks.
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Right on the spot! I am not spinewhacking my knives daily, I use them for cutting tasks. And I want my knives to perform without bladeplay in either direction and last a long time sustaining many opening and closing without wear and tear issues. That is what I would call lock strength and spinewhack does not tell me anything about it. So no use to me.
 
Spinewhack and blade play wiggling to me is just a quick test to see if the folder has an actual lock mechanism or if its just pretending. Can't just hope they got everything right because of brand name, origin, or price.
 
Because when you cut something with a knife, the force of the cut is pushing against the blade, towards the stop-pin. Its never on the lock itself. You simply don't use knives in such a way that would make a spine whack test useful.

The locking mechanism is meant to prevent the blade from closing on your fingers in a thrust cut, or in fine tip work. But you would never exert enough force to even come close to breaking the lock. Which is what a spine whack is trying to accomplish.
 
There's no reason why the spine whack test is not a valid way to test lock strength. Except in places like bladeforums, where people don't like to see their favorite knives actually put to the test. It makes us look like chumps when our favorite brands by our favorite knifemakers that we spend so much money and adoration over fail.
 
Every single liner lock and frame lock I own has passed the spine whack test. My knives and my test. My peace of mind. For instance more years ago than I care to remember I had a high end liner lock(MOD) Tempest, first iteration. My wife was using it to cut something off the inside of the refrigerator door, a piece of gasket or something. Anyways she raises up and the knife hit one of the shelves spine first and closed on her fingers. Talk about surprised, me, and pissed her. So that is why I specifically do it. Also I always hit out towards the end of the tip where if it is going to fail it will. keepem sharp
 
shecky said:
There's no reason why the spine whack test is not a valid way to test lock strength. Except in places like bladeforums, where people don't like to see their favorite knives actually put to the test. It makes us look like chumps when our favorite brands by our favorite knifemakers that we spend so much money and adoration over fail.
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Haha, this!
 
shecky said:
There's no reason why the spine whack test is not a valid way to test lock strength. Except in places like bladeforums, where people don't like to see their favorite knives actually put to the test. It makes us look like chumps when our favorite brands by our favorite knifemakers that we spend so much money and adoration over fail.
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Please, describe how it's valid. How much force is used, how close to the pivot is the impact, how is failure measured: by the blade closing, or the vertical blade play that will occur?

It may test some sort of impact resistance, against and contrary to a knife's design. It doesn't test lock strength, at all.

With some liner locks, whacking it will, probably, damage the lock enough to make the knife unsafe. I'm surprised people still do it.
 
longbow said:
Every single liner lock and frame lock I own has passed the spine whack test. My knives and my test. My peace of mind. For instance more years ago than I care to remember I had a high end liner lock(MOD) Tempest, first iteration. My wife was using it to cut something off the inside of the refrigerator door, a piece of gasket or something. Anyways she raises up and the knife hit one of the shelves spine first and closed on her fingers. Talk about surprised, me, and pissed her. So that is why I specifically do it. Also I always hit out towards the end of the tip where if it is going to fail it will. keepem sharp
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Yep, I had two Socoms that would fail a spine whack in the palm of my hand. I found this out too late as I was just hearing about the spine whack back in 1999 from here. Well, I ended up pulling a Socom blade out of my knuckle, Because when I squatted down with the knife open, blade facing up, the tip hit the granite counter top and got me. (I was repairing a drain or something under my sisters sink).
 
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strength and reliability are not the same. people ask for a strong lock but what they really want is a reliable one
 
shecky said:
There's no reason why the spine whack test is not a valid way to test lock strength. Except in places like bladeforums, where people don't like to see their favorite knives actually put to the test. It makes us look like chumps when our favorite brands by our favorite knifemakers that we spend so much money and adoration over fail.
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It's a flawless way to test whether the knife is safe and reliable when used to do things like drive nails by hitting them with the spine of the knife. Oddly, though, I've never used a knife for this. :rolleyes:
 
I CAN eat a steak with a spoon if I want. That don't make it real world use..... ... .. . Or something
 
If the decent $60-80 folders from 20 years ago could do it and a $1 Wal-Mart Ozark Trail can do it....any locking folder today should really be able to. If anything other than positive pressure that is placed against the edge does not matter then there is no point to the extra expense the manufacturers and consumers put up - a backspring on a slipjoint is plenty.

Some people want a folder to really lock open instead of just having an extra step for closing the knife.

Its only in theory that you will only put pressure on the edge, in real life people who are primarily coordinated and saavy do dumb things and drop tools all the time. If you only collect or are a school kid just getting into knives you don't see it the same way. Nothing wrong with that bit you have to of had some sweat in your eyes and dirty hands while using a tool to see why people want something a little bubba proof.
 
I always thought a better test would be a hanging weight test much like , dare I say, Cold Steel does. Perhaps someone on here would like to set it up and post results with various common knives we all may have.
 
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