Knife locks: Strength, Reliability and Spine Whack tests

Ok, my co-worker is at his side job cutting a thick cardboard box with a linerlock knife. He's standing up, kind of bent over holding the cardboard with his left hand and cutting straight down towards the ground with the right hand.

Its very thick cardboard and the knife kind of stops , bound up if you will.
He pushes hard and the blade is just stopped dead but the lock fails and the knife folds onto his fingers.

I don't remember the number of stiches but its a neat scar .
 
Lone Hunter said:
Ok, my co-worker is at his side job cutting a thick cardboard box with a linerlock knife. He's standing up, kind of bent over holding the cardboard with his left hand and cutting straight down towards the ground with the right hand.

Its very thick cardboard and the knife kind of stops , bound up if you will.
He pushes hard and the blade is just stopped dead but the lock fails and the knife folds onto his fingers.

I don't remember the number of stiches but its a neat scar .
Click to expand...


Not being a smarta$$ on this post (I was on the others), but how does a folder close on his fingers if he is holding the folder edge down to cut & pushing down hard? Additionally, what kind of folder was it?

Thanks.
 
I guess it´s just the moves he made. You move up and down in that situation.

I would like to know too, what folder it was.

I never understand why ppl. accept unreliable folders or locks of which they know, they will disengage in use.

A slipjoint is much more secure in that point.

The topicstarter and Vivi said it right and clear.:thumbup:

I consider spinewhacks (a bit harder than taps but not as hard as seen in the cold steel videos) to check the quality and i check how the folder reacts on pressure on the spine.

A kind of quality check. I would give back a folder, that folds on spine whacks and i expect companies to accept that. Destruction, like sal said, is a different point.

I have destroyed a folder, that worked all right over years, with spine whacks, much to hard. I guess i know, what i am talking about.:rolleyes:
 
My dad owns a restaurant and cuts up boxes pretty much every day and has for the last 20 years. Up until last year when I bought him a Benchmite and a Jester for Christmas he used a slip joint to cut them up. To my knowledge he has never cut his fingers doing this.

I agree that if a knife has a lock, I want it to be both secure and reliable, but I think that if someone cuts yourself do to a lock failure, the vast majority of the time they were doing something they shouldn't have been doing with the knife and relying on the lock instead of being careful eith their knife.

Just because a knife has a lock, doesn't mean you don't have to be careful with it and it doesn't mean that you should treat your folder like a fixed blade.
 
Just because a car has a seatbelt and airbags doesn't mean they shouldn't break or not fire reliably when you get in an accident...

The problem with leaf locks is not that they aren't strong, it's that when they fail by slipping, they're neither consistent nor do they fail gracefully.

When they fail by crushing, it's a graceful failure.

When they slip, which is the vast majority of the failures, it slips quickly and without warning either across episodes or across the lifetime of the lock.

A linerlock that's been working fine and holding steady for years can suddenly slip one day under very little pressure.

That's one reason the Omega springs on the AXIS lock is good -- it fails gracefully. It's rare for one spring to break, but when it does, you're given warning before the other one does.

Similarly, the compression lock is good because the more spine-directed force you apply, the more it binds up.

Likewise, the lockback's main failure mode -- debris getting caught in the lock cutout -- gives you some warning (the lockbar isn't smooth on the top) before it fails.

I haven't used the BBL enough to get a good feel for it. It seems to neither suffer from slippage or a discontinuous failure mode.

-j
 
Halfneck said:
Not being a smarta$$ on this post (I was on the others), but how does a folder close on his fingers if he is holding the folder edge down to cut & pushing down hard? Additionally, what kind of folder was it?

Thanks.
Click to expand...
Humans make mistakes....it's a fact of life.
And locking folders....folders with strong reliable locks....are more forgiving of human error.

Ponder this.....
If you always use your knife properly, always "holding the folder edge down to cut & pushing down hard", then why even have a lock on your knife?
 
It was not a "name brand" .I handled the knife but do not know who made it.

Knock off type knife.

I'll try. Open your knife. Now hold it open edge down, thats the how it was used to cut down through the cardboard. Now pinch the top of the blade with your left hand holding tight. Now release the lock the lock with your right hand and press down on the handle, while still holding the blade with your left.

Or try it this way place edge of open knife on top of workbench at the edge of bench with handle over hanging bench . now place hand on top of blade, release lock press down on handle. Remeber the blade was locked in place,jammed if you will in the thick matterial

Your basically closing the knife with your hand wrapped around the handle.

This was very heavy thick cardboard the knife was stopped dead, stuck if you will .

Hope this helps.
 
Lone Hunter said:
It was not a "name brand" .I handled the knife but do not know who made it.

Knock off type knife.

I'll try. Open your knife. Now hold it open edge down, thats the how it was used to cut down through the cardboard. Now pinch the top of the blade with your left hand holding tight. Now release the lock the lock with your right hand and press down on the handle, while still holding the blade with your left.

Or try it this way place edge of open knife on top of workbench at the edge of bench with handle over hanging bench . now place hand on top of blade, release lock press down on handle. Remeber the blade was locked in place,jammed if you will in the thick matterial

Your basically closing the knife with your hand wrapped around the handle.

This was very heavy thick cardboard the knife was stopped dead, stuck if you will .

Hope this helps.
Click to expand...

I think your co-worker just pushed with his palm too much on the end of the handle and that caused the knife to close down. It could have happened to any frustrated person trying to get the knife out in a hurry. The only way to really get a knife out that is stuck like that is to keep constant downwards pressure on the blade and pick the handle up. This should keep the lock from wanting to close, and the handle won't be going towards the blade.
 
Could very well be . My memory of his telling me was that his hand was towards the rear trying to get as much leverage as possible.

I work with him on the fire dept.. He did it on his side job at a stereo shop , I was not there .

Showed me the knife and finger ,told the tale . i thought I'd re tell it here.
 
Halfneck said:
Not being a smarta$$ on this post (I was on the others), but how does a folder close on his fingers if he is holding the folder edge down to cut & pushing down hard? Additionally, what kind of folder was it?

Thanks.
Click to expand...

Not edge down, he was cutting mostly point down, pressing on the buttend of the knife, levering with the spine of the knife, very typical when cutting through material that is too heavy that you would have enough wrist strength to cut edge down. You can put a very large force very easily onto the lock of a knife that way.
 
Dekz said:
Have you ever had a CRKT with AutoLAWKS fail?
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no, but then again they havent had a chance to as i wouldnt own a knife that has autoloawks lol.

the regular lawks is ok, but ya have to aqpply it and ya might not always have a chance to do so.

a decent liner lock doesnt need either one FWIW, crkt is about the only company using it, i wonder why?
 
I just tried a spine whack with an axis lock. Failed miserably. Tried again with four quality linerlocks and all passed with flying colors. Tried one more with SOG's axis copy-failed as well. What does this mean? It means my Crucible II, Browning Ice Storm, Tenacious and Rat 1 will be seeing more pocket time. What can I say? The axis lock is supposed to take 200 lbs of force before the lock fails. It didn't. A moderate whack with six inches of travel shouldn't cause the lock to fail.
 
I see no problem with spine whacking because if the lock is really strong it should be able to handle it. I test all my folders this way, if they fail they go back where they came from. I am not light about it either, I whack them pretty good about 10 times with a thick leather glove on :)

I just look at it like this:

Knives are replaceable, your fingers are not. :D
 
BTW the same test that the axis lock failed, a the much maligned Gerber EZ Out (old version) passed with flying colors. Hmmm...
 
yobbos1 said:
I just tried a spine whack with an axis lock. Failed miserably. Tried again with four quality linerlocks and all passed with flying colors. Tried one more with SOG's axis copy-failed as well. What does this mean? It means my Crucible II, Browning Ice Storm, Tenacious and Rat 1 will be seeing more pocket time. What can I say? The axis lock is supposed to take 200 lbs of force before the lock fails. It didn't. A moderate whack with six inches of travel shouldn't cause the lock to fail.
Click to expand...

And, the issue is?

Send the knife back to Benchmade for repairs.

BTW - Just for giggles, just did a 25 set of pull-ups using a Rukus as a peg to pull-up from.
 
yobbos1 said:
I just tried a spine whack with an axis lock. Failed miserably. Tried again with four quality linerlocks and all passed with flying colors. Tried one more with SOG's axis copy-failed as well. What does this mean? It means my Crucible II, Browning Ice Storm, Tenacious and Rat 1 will be seeing more pocket time. What can I say? The axis lock is supposed to take 200 lbs of force before the lock fails. It didn't. A moderate whack with six inches of travel shouldn't cause the lock to fail.
Click to expand...

You are correct in your last statement - the lock should not have failed. This test was a success in that you now know your lock is not made correctly and the knife should be returned to Benchmade for warranty work. This is not a knock on benchmade or axis locks in general as I have several axis knives that perform superbly. Perhaps your Benchmade would never have been in a position to fail during use, but now that you've tested your knife you no longer have to take that chance.
 
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