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Spine whacking

May 25, 1999
I hear a lot about liner locks that fail the spine whacking test. What I wonder is if everyone is in agreement about what constitutes a spine whacking test. Does everyone do it the same way? I`d like to hear from folks who regularly spine whack their knives. How do you do it? I`m curious how many different ways there are to whack a spine, and if the data we get is at all useful due to lack of controls in testing.
I confess... I am a wacker!

I test my knives at work on a wooden bench with 4 medium hits. I would say about the same force as the next hit after you get a nail started with 2 light taps. (Like how the third hit is the one before you really pound on it with the fourth.) If they pass all four hits then I cycle lightly a few times and try again. If they pass again I consider them OK.

I find that it is necessary to test carry knives regularly and find that some knives fail after a few weeks use though they passed when new. Also I am proud to report that all knives that failed the test I sent back to the factory, and now they all pass regularly. Just because a knife failed doesn't mean it can't be fixed.



Damn Biginboca!Sounds like you really whack alot.Me ,I usually do it about once a month a couple of good hits on the countertop.Just to make sure everything is working properly.Heh.heh.
Steve B.

Sounds like we are ALL closet WHACKERS....LOL - just kidding
. Every time I pick up a new knife, I do the spine 'TAP' test. I periodically check my own, too. When I am in a shop, I ask the people who work there if they mind me doing it. They usually give me something hard to use, or worse case the I use the soles of my boots/sneakers. If it is going to fail, it doesn't take much force

I use about the same force as biginboca
Ray 'md2020'
Find Joe Talmage's Liner Lock FAQ in the FAQ page. Basicly, I do three things to a liner lock. First, I try to fold the blade with gradual hand pressure. You would be surprised how many liner locks will slip under simple gradual closing pressure. If the knife passes the first test, with the edge up, I pinch the handle at the butt between my thumb and first finger, making sure that no part of my hand covers the handle slot, then I whack the spine moderately on a bench top. If that passes, then I stab the knife into a board at about waiste level, and twist back and forth on the handle with a tight grip to see if I can loosen the lock enough to disengage it with torque.

The ultimate test though, is the stick test. I hold the knife edge down as tight as I can from the sides, again with no part of my fingers covering the slot in the handle. Then I whack the spine as hard as I can with a stick. Holding the knife in your hand absorbs some of the shock, and I think makes for a pretty realistic test. I don't do this test on liner locks because even if they pass, they would most likely never be the same. The Benchmade 710 passes effortlessly, as does the second generation Rolling Lock on my Crawford Carnivore. The first generation Rolling Locks with the release in the front of the handle will release occasionally during this test. The button lock on my new SpeedTech Synergy also passes this test with no failures and no damage. There is no way the integral lock on my Apogee could fail, so I haven't bothered to stick test it.

All my folding knives are whacked!

I usually just tap it in the palm of my hand or on my knee. I have had a number of knives fail this way. They have all went back. I will also grasp the blade and try to force the knife closed. If this happens, it goes back also.
You mean you arent supposed to slam the spine hard as you can against a wood work table??
I m going BLIND...

I do it...I admit it..and I do it alot and I do it hard. And I do it every so often again to make sure things are still up to par.

I don't do a whole lot of whacking to my folders, mostly due to the fact I don't do anything heavy enough to break em, and don't worry about it. I need something heavy done, I grab my Ka-Bar....
I only have two linner locks, a BM Leo. cub and a CS Ultra lock. I test them the same way as Steve, the stick test. Also, use one other test. I put the blade inside a peace of polly pipe and try to close the knife and look to see if the lock moves or the knife closes. As the blade starts cutting into the pipe I will also twist it both ways., left and right.