Spyderco Forums

Does spine whack testing hurt the lock of the knife being tested also will it impact the reliability of the lock?

My Dear Friend,

mm1 wrote:Does spine whack testing hurt the lock of the knife being tested also will it impact the reliability of the lock?

Yes, you can irrepairably damage the lock doing this. It also immediately voids your warranty. :p

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Hannibal

Once or twice when you first buy a knife is all that is necessary...if that.

I think spine whacking a knife is like hitting a telephone post with a baseball bat just to see if it will break.

There was a thread on that Topic regarding a video test one of our beloved spelling-deficient member did including comments by our beloved "member" responsible for us being here...

http://spyderco.com/forums/showthread.p ... ne+wacking

Simon

If you use the spine of your knife like a hammer on a desktop it will hurt it sooner or later as has been shown in the past.One or 2 light wacks is all it takes to test it.

I imagine that repetitive spine whacks could hurt a back-lock with time but the liner-lock and even more the compression lock are pretty much safe with this test. the force to bend a liner would have to be very important and constant.

Senate wrote:I imagine that repetitive spine whacks could hurt a back-lock with time but the liner-lock and even more the compression lock are pretty much safe with this test. the force to bend a liner would have to be very important and constant.

Remember that it is not just the lock that is recieveing the force of the impact,the pivot and stop pin also take the beating.
Constant spine wacking is kind of like water dripping on a rock.One drop does nothing but if the drip keeps it up long enough there will be no rock.

I think its a 100% valid test, anybody who doesnt do it is putting themselves in danger.

will it hurt your lock, some say yes and other no. I am going with no because I feel it is a valid use of the knife. if it did hurt your lock then the knife is subpar.

J Smith wrote:Remember that it is not just the lock that is recieveing the force of the impact,the pivot and stop pin also take the beating.

true I didn't think of that... in fact I imagine they would probably break before the liner.

:spyder: Friends don't let friends spine whack :spyder:

I only do spine whacks if I have a liner lock (which is never these days). I have spine whacked Benchmade's and Spyderco's before with no problem. However, I am talking like holding the knife with one hand and tapping the spine on a desk somewhat lightly. Maybe one or two times. Most of the time I simply put pressure on the blade as if I'm trying to close it. If it holds I move on. I've not done spine whacks in a long time and I don't plan to because I don't intend to own any more liner locks. :)

Will it harm the knife, the lock, the pivot etc? I think so. I think a couple light whacks may not but a few more forceful ones may.

Unless it is a Manix or Chinook, I wouldnt reccomend it if you like your fingers. As far as spine whacking those two, it does absolutely nothing to the lock but like spine whacking any knife, it accomplishes nothing.

Michael Cook wrote: :spyder: Friends don't let friends spine whack :spyder:

michael is correct... well what if i own a chinook? :p :cool:

Spine whacking to me makes about as much sense as crashing your car into a wall to see if the airbag works. If you are that worried about lock strength, buy a good FIXED BLADE and use it. I promise it won't fold up on your fingers when you misuse it.

I think you can tell if the liner won't pass by looking at it (for the most part.) If you have to second guess, then it's probably not right. No need to ruin the knife, and then say "well, it didn't pass" after hard spine whaking. Ask yourself if you are ever going to need to test it that hard, in the field.

IMO, Zen is on the right track!

In any lock testing, I would hope you use thick leather gloves, just in case.

::Zenheretic sits, down, overcome by a sickening sense of fecund deja vu'::

...wack a spine,
go to prizun...

Not sure where people get the impression that spine whacking hurts the knife or lock. I've spine-whacked some of my knives for years with no ill-effects. If a few spine whacks now and then hurts your knife, that's a pretty strong indication that you should get a better knife ... in which case, the test has proven useful for you! Only junk or a knife with a manufacturing flaw would fall apart so easily.

You should perform this test from time to time, not just a few times when you get the knife. In particular with liner locks, which are notorious for being rock solid for months or years and then suddenly becoming unreliable. As the lock wears the lockup geometry changes, and you can always slip into a bad geometry. It's an easy test, no reason to test your lock a couple times per year, as the lock wears.

I perform this test by doing a few light-to-medium whippy snaps, with my fingers pinch-gripping the handle so that if the lock releases, I won't get cut. I don't hit the spine on a desk hard like a hammer. Ironically, light whippy snaps reveal more problems than slow hard hits, so there's no reason to use your knife like a hammer to do this test. Remember, you are trying to test the lock geometry to see if will release under impact loads.

Lastly, and most importantly, since we've heard anecdotes of people doing real-live work and hitting the spine of their knife on something (for example, if the blade gets stuck and tugged out), that is proof that this test simulates a possible real condition. So there's no need to argue about whether it's realistic, since it proveably is; the only argument can be over how likely this condition will be. Note also that if you stab the knife something and don't punch it in perfectly, the impact can send an impulse down the spine, again simulating the spine whack.

Joe

I don't care care what the lock is, I always give a new knife a couple of light to moderate spine wacks.

Nothing more anoying (and sometimes darn right painful) than having a knife fold when doing some cutting.

Thrust, stabbing, and twisting during cutting tasks can unlock unsound knives. Been there, done that, and hear about it regularly.

If the design and materials are good, there should be no damage to the lock unless you go to extreme force in the testing. Extreme force would be destructive testing.

Don't want to test, fine. Don't cry when your knife folds on you.