When would a spine whack EVER be necessary?

Danke42 said:
Please do demonstrate whacking the spine while withdrawing the knife from a confined space you were cutting in.

The last time this came up I really hoped to see an example of this but there were no takers.

Now at least in this thread we've got a real user who can show us how it's done. If you're worried about getting nicked tape the blade or use your trainer.

I just can't wrap my head around that movement. I've tried and tried but it won't happen.
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Demonstrate it? Do you want video? It's happened to me and the lock was fine, but I have no desire to replicate it. You'll also create a fair amount of negative pressure on the lock if you stick the knife into something unyielding. Some place far too much importance on lock strength and spine whacks, but if I have a knife that locks, I really do want it to actually lock.

I always hear lots of criticism of the idea of spine whacks, but I never hear any suggestions for a better test of a lock. I don't do it to my knives, just like I don't cut half a mile of manila rope and measure the force required, as I think both will significantly reduce the working life of my tool, but I greatly appreciate those that do the tests when they're done in a repeatable manner.

I'm honestly baffled as to why so many people seem to get so upset about lock tests. I want to know as much as possible about any knife I might buy, no matter how how unimportant it may seem. Not sure why so many want things to remain shrouded in mystery.
 
It really isn't hard to think of situations where you might accidentally whack the spine, causing it to close on your fingers.
 
nails1908@gmail.com said:
I highly doubt any knifemaker worth their salt is producing knives to handle extreme force on that side of the blade. Knifemakers producing knives that can tolerate extreme force on the blade side? Now that is more likely.
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I disagree about the knife maker part. Andrew Demko is a very talented knife maker , he came up with the tri ad lock and all that.

He feeds with family and pays his bills making knives, he came up with something original to the knife world ,and it's his money maker . No matter how much the test matters in the real world it sells products ,thus keeping the bills paid
 
A spine whack may help dislodge that piece of chicken stuck in the throat of an overzealous eater.
Other than that...
 
RX-79G said:
It really isn't hard to think of situations where you might accidentally whack the spine, causing it to close on your fingers.
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Personally I've had one folder fail on me. It was a linerlock and the brand is notorious for very early lockup when new and the knife wasn't broken in.

I was having to change out some spatter shields on a robotic welder snd it required a stab into the thick plastic so you could cut it. When I went to pierce the plastic the lock failed. I assume spine whacks were always meant to test if a knife would fail under a situation like that where the blade would be pushed against the lock.
 
Unnecessary whacking can go wrong. ;)

[video=youtube;1s0dRcdyizU]https://www.youtube.com/watch?v=1s0dRcdyizU[/video]
 
I have had more than one folder lock fail while cutting difficult material in a very tight spot. Cutting hoses on a cubic press, the size of a small room. Not a lot of space for a big guy, and very cramped space.

A weird push cut and the tip bumps the steel press, and it folds up on my fingers. With more than one model.

So I've had it happen more than once.

Another time, I was topping boxes full of frozen beef, and the knife folded on my fingers while trying to poke into the side.

I've also seen my brother go in for surgery when his locking folder folded up while piercing heavy rubber.

I greatly appreciate a solid lock, and I have locking folders that don't get used because the locks are not secure.
 
Piercing strong media with the tip is the work that needs a reliable lock of decent strength. Reliability, by which I mean not being prone to slip and fail, is more necessary than massive ultimate strength.
 
I must lack imagination; that and I watched a movie about how to use tools once.

Well it's too late for me but as for the rest of you kids don't educated. If you do you won't be able to stab oil filters with screwdrivers or pull wild hypothetical scenarios out of your hat.
 
A screwdriver is not a chisel, pry bar or punch. So I guess screwdriver makers could use the cheapest most brittle plastic for the handles and cast the shafts out of pot metal. They would drive a screw just fine and any failure due to abuse would be the users fault.
 
Danke42 said:
I must lack imagination; that and I watched a movie about how to use tools once.

Well it's too late for me but as for the rest of you kids don't educated. If you do you won't be able to stab oil filters with screwdrivers or pull wild hypothetical scenarios out of your hat.
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You mean the wild hypothetical situations a number of us have posted that we've personally experienced?
 
Depending on the blade shape, piercing cuts can put a lot of pressure on the lock. Bumping the spine against something also puts pressure against the lock. A light tap of a few pounds of force should be a sufficient check that the lock geometry is ok. Slamming the spine against something with as much force as you can generate is probably not very useful, unless that's a situation you plan to find yourself in, at which point a fixed blade would be better.

There's absolutely nothing wrong with a spine tap. If the lock disengages and the blade closes from a light tap then the lock is defective and unsafe for use. There's no reason to defend brands or knife models that experience lock failure from a light tap. It's a reason for the company to take a look at the lock and re-engineer it.
 
I know I've been cutting thick cardboard a few times, gotten the blade wedged in, and then had to wiggle the blade up and down quite vigorously to get it back out. That can put a fair amount of downward ("negative") pressure on the blade. This is not exactly the same kind of force exerted during a spine whack, but if a knife can survive a few moderate spine whacks, it seems it would be less likely to fail during this kind of use as well. I'd also imagine there has been someone at some point who has been using their knife for some task under a surface (like a kitchen counter, for example), and accidentally whacked the spine of the blade on said surface upon standing. At least it seems within the realm of possibility. I think most can agree that some of the insane spine whacking we see various people doing goes way beyond anything like the situations described above and enters into the realm of the absurd; however, I do see value in moderate spine whack tests.
 
Insipid Moniker said:
You mean the wild hypothetical situations a number of us have posted that we've personally experienced?
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I have a hard time quantifying a vague personal experience.

I have heard a couple mentions of stabbing into a hard unyielding surface and to that I'd say why? If someone uses the wrong tool for an unspecified reason it's not a given that the tool was defective.
 
Danke42 said:
I have a hard time quantifying a vague personal experience.

I have heard a couple mentions of stabbing into a hard unyielding surface and to that I'd say why? If someone uses the wrong tool for an unspecified reason it's not a given that the tool was defective.
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So you're not supposed to stick knives into things? I'm curious as to why you think they have points. Also, what is there to quantify? These have all been examples of situations that mimic the same forces a spine whack would generate, some with worse results than others.
 
Insipid Moniker said:
So you're not supposed to stick knives into things? I'm curious as to why you think they have points. Also, what is there to quantify? These have all been examples of situations that mimic the same forces a spine whack would generate, some with worse results than others.
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You want to stick the right knife in the right thing.
 
I find it bs, if it folds chances it may. I try to use a locking folder as a slippie. Gary
 
Just apply hand pressure on the back of the blade.
Controlled, and doesn't do stupid wear and tear on the lock for no reason.

Oh, I had a knife that passed spine whacks but failed the hand pressure test; haven't had any that were the other way.

Oh, and don't buy crappy knives; that solves most of the problems right there (the one that failed a hand pressure test was a crappy knife).
 
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