Questions on spine whack test.

Roadrunner

Roadrunner

Joined
Jun 9, 1999
Messages
4,729
As a semi-newbie, at least to higher priced knives, I have a question about the spine whack test. I've heard everyone talking about performing it, and a few mentioning knives that fail, but no one has mentioned having their hand lacerated. I've thought of testing a few of my knives, but i can't think of a reliable way to hold the knife without my fingers being in the way of the closing blade if the lock fails. One way that I considered is holding the knife with my thumb running parallel to the handle scales with my fingertips along the opposite scale, but this seems a very insecure way to hold the knife. I don't want the lock to hold up and my grip to fail. My other alternative idea was to wear gloves. However, if I'm testing a large knife, I don't think glove will cut it. If I test my Vaquero and the lock fails, gloves or no gloves, I'll probably lose a finger or two. Can anyone tell me how to safely test my locks? Thanks and sorry for the long post.

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Just because I talk to myself doesn't mean I'm crazy. What's wrong with getting a second opinion?
 
If you do any archery, hold the knife at the end of the handle like you hold the nock of an arrow against the string. Then give it a whack. A failed blade won't usualy close with too much force. A slice is always a possibility. It doesn't bug me too much, I've cut myself before. I use my left hand, it's not good for much anyway.

Or you can find a length of pipe that slips over the handle.
 
I hold the knife in a firm "hammer grip," edge up, for a good, strong hold. I then throw a folded towel or two over the top of my hand and wrist. A thick magazine or newspaper would work too, though you'd need something to keep it in place. In a pinch (in a knife store nice enough to let you do this, for example), you might just throw a jacket or large folded chamois over your hand. Don't compromise your grip, just protect yourself - the blade may be moving fast if it releases, but it won't have any additional force behind it.

Maybe I'm a fool, but I don't bother with these precautions on the knives I've owned for a while. I've seen them take it again and again, and I'll take the "risk" to show folks that I trust the knife I carry. If I didn't, I wouldn't carry it.

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-Drew Gleason
Little Bear Knives
 
I'm an advocate for light to medium force only for the spine whack test, and your method of thumb on one side and fingers on the other should be fine.

What I do is this. I hold the knife with only two fingers. At the far butt end of the knife, my thumb is on one side and my index finger curled up against the other. I hit the spine moderately hard at most. When I talk about failing 25%-50% of liner locks I test, keep in mind it's with this hold, so you know I'm not doing it very hard.

Joe
 
Having suffered an avulsion on the tip of my ring finger, left hand. I can attest that one should keep anything they don't want sliced off out of the zone. I hold the knife in my left hand in a saber grip and tap the spine of the blade on a desk edge.
 
Thanks for your sugestions guys. As I said, I am a little bit of a newbie, and I don't know what a saber or hammer grip is. Sorry for my ignorance, but hey, thats part of the reason I came here, to learn.

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Just because I talk to myself doesn't mean I'm crazy. What's wrong with getting a second opinion?
 
A "hammer grip" is simply wrapping your fingers and thumb around the knife, which is held straight up and down, or perpendicular to your arm. Basically how you would hold a baseball bat - it's the most "natural" grip. A "saber grip" tilts the knife forward 30-45 degrees, with your thumb up against the rear guard or on the thumb ramp. In this grip, you hold the knife further out along your bottome three fingers while your index finger typically serves more for control than for grip.

-Drew
 
Another newbie chiming in...

Can this test be done with less risk by placing the knife handle on the edge of a table/desk, blade overhanging the end of the table with the cutting edge down.

Hold the handle securely to the table with one hand and use the other to whack the top of the blade (the spine). If the lock fails there's no flesh in harms way.

Or am I overlooking something? I had the same concern as Roadrunner before trying this.
 
Nah! What good is a test unless you lose some skin!
smile.gif
 
I have always placed a dish-towel over my hand and have never come close to being cut while performing this test. It just doesn't make sense to me to not put something between your hand and a fast moving sharp object.
 
I got a qusetion too...why whack your knives? It seems like a waste of time to me. All knives WILL fold when opposing force is applied...it's just a matter of how much force is required. Most fingers will fail before the lock does. If you need to apply that much pressure...just get a fixed blade. I mean, you can't expect a folder's lock to be as strong as a solid piece of steel can you? What I do is, take the new knife...if there is a question of it's structual integrity, and grip it between my thumb, and my index finger, sharp edge up and away, and whack it on my knee while it's bent. If no fail... me = satisfied.
wink.gif
-AR

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- AKTI Member ID# A000322

- Intelligent men, unfortunately, learn from fools, more often than fools learn from intelligent men.

 
Jackyl,

You're right, all folders will break. And all fixed-blades will snap, though that will take more force in most cases. What I'm interested in seeing is whether a sharp rap on the spine will make the lock fail (i.e. close). If the knife stands up to that, I feel it's secure enough to take whatever I might encounter. I don't doubt that enough force will make the locking liner crumple, the screws blow out and release the scales, or other catastrophic events. But that isn't something the knife could encounter while in my hand. The spine whack is. As Mr. Stamp has said repeatedly, there are too many knives that will pass this test to accept one that won't.

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-Drew Gleason
Little Bear Knives
 
Thanks for clarifying that guys. I think I'll go with my original idea for holding the knife with my fingers out of the way and just hit it lightly.

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Just because I talk to myself doesn't mean I'm crazy. What's wrong with getting a second opinion?
 
Jackyl, you wrote:


> All
> knives WILL fold when opposing force is applied...it's just a matter of how much force
> is required. Most fingers will fail before the lock does. If you need to apply that much
> pressure...just get a fixed blade

... which strongly implies you're under the mistaken notion that the spine-whack test is a test of lock strength. For some people perhaps it is, but it's always been meant as a test of reliability. Plain and simple, this is a test of the lockup geometry, not the lockup strength. In the spine whack test, I use way WAY less force than it would take to make the materials fail. When a knife fails this test, it's because of a badly-executed lock, plain and simple.

Unfortunately, liner locks are easy to make, but also easy to make badly. Knives from guys like A.T. Barr, who actually test their locks and make sure they are done right, should come out just fine in these tests. It's not strength, its lock geometry and reliability!

Joe
 
For all you knife wackers out there: Charkate

The fishing industry uses kevlar and similar gloves with varying results. Any workers from commercial fishing boats out there?

There are more just put 'cut resistant gloves' in your favorite search engine.

[This message has been edited by David Williams (edited 15 July 1999).]
 
Call me paranoid but I wrap that sharp edge with a with a piece of duct tape and wear heavy work gloves and a towel over the wrist is a great idea too. PROTECT those pinkies, unless of course you have no further need of them and don't mind self amputation. Great suggestions one and all. God I love this place!
 
Joe wrote:

<<< but it's always been meant as a test of reliability. Plain and simple, this is a test of the lockup geometry, not the lockup strength. In the spine whack test, I use way WAY less force than it would take to make the materials fail. When a knife fails this test, it's because of a badly-executed lock, plain and simple.>>>

That says it all.

A.T.
 
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