Wtf Spine Whack!!!

Um. Cliff's post was funny.

Joe, rock on.

You seem to approach the issue with less heat than I can, although I did have a nice treatise on lock failure modes, with emphasis on leaf-style locks on "another" forum that went largely ignored. Reference it at your peril. ;)

I would love to see a FAQ on this... spine whacks as a subset of general knife functionality tests are something I find pretty useful.

Thanks for taking the time to write this!

-jon
 
Locks can, and will fail. If you keep in mind the limitations of a folder, there should be few problems. Big hassles arrive in spades when folders are subjected to twisting motions. A nervous trip to the ER should propel you into using a fixed blade.
 
Any folder I plan on using hard, I have to test hard before it earns a place in my pocket as EDC.
Spine whacks are always a part of that testing.
 
Stubai said:
Locks can, and will fail. If you keep in mind the limitations of a folder, there should be few problems. Big hassles arrive in spades when folders are subjected to twisting motions. A nervous trip to the ER should propel you into using a fixed blade.
Click to expand...
But if you have 50 knives that easily and consistantly pass the SWT, and you have 1 knife that consistantly fails the SWT, why would you continue to use the one that fails?

Most of the knives I have ever owned passed/pass the SWT everytime....but I have had about 4 that failed everytime.
Those are the ones I cannot trust.

And of you never do the SWT, you'll never really know which one of yours is trustworthy.
 
I do spinewhacks a lot to knock debris off my knife, so if a folder of mine can't pass one I wouldn't use it for very long. Even my SAKs can take them (Well, at least the Alox ones and my Nylon Solo, smaller ones provide a weaker backspring).

I always test my liner and framelocks with a few good spinewhacks, mainly to see how much, if any, the liner moves across the tang. If it jumps really far, or moves every time I spinewhack, I consider the knife defective. A good liner lock imo either won't move, or will move slightly the first time a good amount of force is placed on the spine, then settle in that area and not budge during future spinewhacks.
 
IMO spine whack testing like Cougar Allen describes, combined with further lock testing done by clamping the blade of the open knife in a vise and applying various possible vertical, lateral and torsion forces -- preferably at least as hard as you would every reasonably expect to use the particular knife -- makes a pretty good overall safety test protocol.
 
Dog of War said:
IMO spine whack testing like Cougar Allen describes, combined with further lock testing done by clamping the blade of the open knife in a vise and applying various possible vertical, lateral and torsion forces -- preferably at least as hard as you would every reasonably expect to use the particular knife -- makes a pretty good overall safety test protocol.
Click to expand...

I agree with this test completely. My point is that you should never whack the spine of your knife (just like you should never pry with it) during normal or rough use. A light spine whack is good, it's the spine whack that bends liner locks that I think people are stupid for doing. I believe the blade in vice test is much better at testing the reliability of a lock, and a LIGHT spine whack is not all that bad.
 
2 cents time. I have had several knife locks fail and cut me. Not just when abusing the lock. One Buck liner lock folded on me on a daily basis cutting open cardboard boxes. If you sneezed around it the lock folded. Lots of cuts from that piece of crap. Decided it was time to junk drawer it when my older brother nearly paralyzed his right hand thumb when using it to puncture some rubber.

Switched to CRKTs. Both folders seemed to have very solid locks. after a while they started to fail too. After a while both locks could be forced to fail with light finger pressure (keeping fingers out of the way).

None of these knives would pass a spine wack test, let alone making my fingers feel all fuzzy and warm and protected. I could still use them, but in the same way I would use a slip joint knife.

Bought a CS Recon 1 Tanto (the older zytel handled). It has what they call "ultra lock" which I think is an axis lock type (so not really an apples to apples but oh well). Same cost as the other knives (all three of those finger biters). I have been using that one for 6 years now every day. It will pass the spine wack test. In fact you can hit the spine very hard on a hard surface if you want (I don't really care to). But importantly the lock up is great even after all these years. I literally carry it every day. Hard cutting, slashing, stabbing (which really makes my fingers itch with other knives....tingle with anticipated pain). I know lots of people are down on the CS Video's but watching them put 200 pounds on the lock while it is in a vice, or having some one do pull ups on it, or swing on the locks like monkey bars makes my fingers happy. I know for a fact that those other same priced knives would not hold 20 pounds when new. It is good to know that in awkward cutting situations that it won't eat my fingers like a shark.

I am sure I can get that same feeling with lots of other quality manufacturers knifes (not exclusively CS, or expensive customs either).

So spine wack test has it's place.
sorry that was so long
 
I had a microtech amphibian that I really liked. I was really impressed with the thickness of the liner (type) lock, and it had no detectible blade play. I went ahead and bought a new socom elite with the same lock. I never spine wacked the amphibian because it looked and felt very solid. Then one day I threw the amphibian at some folded cardboard boxes and it folded on impact. That worried me, so I spine wacked it. It folded with very little impact on a carpeted 4x4. Instantly I thought about the socom. I tested the socom and it behaved equally to the amphibian. -Very disapointing. Both of these knives locked up with no blade play. I couldn't even feel a little. I probably could of lived with them the way they were, but with so many better knives out there, why should I. Since then, I've tested every knife I carry teh same way and the only knives I've had close were all liner type locks. So I think it's important to test liner locks especailly, and not so much other designs. I've tested several emerson liner locks and all locked solid and all passed the test. I've tested 2 spyderco militarys, one with play (g-10) and one without (s30v, cf), and both passed. A buck sng copy (the cheapest one) had play and folded "very" easily. I've had multiple spyderco lockbacks pass (chinook2, endura3, 4, ect.), as well as spyderco compression locks (ti atr), and a few benchmade axis locks. All without an issue. -My basic thougth on spine wack testinig is that if I spend good money on a knife that's supposed to be tough, I'd like to at least be able to stick my knife 1/4 inch into a soft piece of wood without even the thougth of it closing. If I can't expect that, I might as well have a swiss army knife for 30 bucks.
 
That folder sure as heck better be able to pass a simple spine whack!

I stand firmly with Biogon and Joe Talmadge on this issue! A light and snappy spine whack should be no problem for a well made folding knife.

For those who have criticized people who choose to test their knives with a reasonably performed spine whack, saying it is "abusive" and doesn't mimic "normal, everyday use of a folding knife," don't say we didn't try to warn you if you ever find yourself forced to use less than perfect technique, possibly due to emergency/time constraints, and your blade folds after bumping something by accident (I've seen it happen several times). But, heck, they're your fingers, not mine.;)

Regards,
3G
 
biogon said:
Joe, rock on.

You seem to approach the issue with less heat than I can, although I did have a nice treatise on lock failure modes, with emphasis on leaf-style locks on "another" forum that went largely ignored. Reference it at your peril. ;)

-jon
Click to expand...

I read it and very much appreciated it "over there", Jon!

Regards,
3G
 
Hi Michael,

My thoughts on this question are in line with Joe's, but I wouls like to share thouhts.

We began spine wacking (more like a whippy tap) 100% of our knives in QC in 1981. I had been cut with an early prototype and this was an important issue. Do not bite (or cut) the hand that feeds you! We added this test to the knife mfg in Seki.

Any and all locks can fail. Making them "right" is more important that the type of lock. Some types of locks are more difficult to "make right" than others.

Locks are many small bits of metal that all have to function properly for a locking mechanism to work. That includes not only the tang / lock interface, but also the pins, scales, holes, liners, etc.

I have seen knives that had been spine wacked so hard and so often that the lock / tang interface parts were actually coined out of shape,
(Rc 59) pins were bent, holes were elongated. The cause of of lock falure was, in fact, spine whacking.

Reliability is what you are testing for. Strength is another issue and cannot be tested without breaking the knife. Reliability comes into question as a result of useage. debris a major cause. Wear is another, material fatigue is another.

1. Inspect and clean the knife. if there is debri in the lock, which causes the lock to fail, often times the FIRST failure deforms the interface and it will NEVER lock again. Check the lock out, clean it, and then a light spine tap to make sure the lock is funtioning is, in my opinion a good idea. If the lock fails because of debris and is now not useable, this is not a factory defect, it is an owner defect. Maintain your knife. An edge is a potentially a dangerous adversary if not in control. A dirty lock may be out of control.

2. If you do have a problem, send it back to the manufacturer. All manufacturers will want to know if there is a problem and there is nothing like "real world" use to learn, improve and refine.

sal
 
Siggy, if you still have those microtechs, try spinewhacking them about half a dozen or so times. My Mini-socom had a similar problem until the 5th spinewhack after which it began locking solidly and without fail. IIRC almost all the microtech nested leaf-locks had a reputation for this when alot of MT owners tried it on their knives.
 
I wack mine good. Just once or twice. I think it helps settle the lock. If it fails, it's gone. Maybe more of a mental thing, but if it fails, I am afraid of it.
 
i dont' think i've ever had the problem of a balisong cutting my fingers under normal use or if it collapsing when i didn't want it to.
 
From what I can ascertain, linerlocks seem to be the least dependable, or least stable, locking knife technology available today. If one wants a solid locking folder, I would think that a well made lockback or framelock knife would be the way to go. The operative term here is "well made."

Many users on this board warn that every locking folder should be treated like a slip joint for safety reasons. Although they mean well, if what they say is true, then all knives should be slip joint, because there would be no need for locking knives. But people need, and want, good, dependable, locking knives that they don't have to treat like slip joints.

No one, for example, would want to go into a self defense situation with a slip joint. True, not all locking knives survive spine whacks, but virtually all of the slip joint knives will fail a spine whack test because they all are...well, slip joints! The same is true for torquing or stabbing (penetration).

I don't know of a better linerlock system than CRKT's LAWKS. But though most of us gag at Lynn Thompson's "mash 'em, slash 'em" videos, there is something to be said for testing a knife before depending on it. I have a Benchmade Ascent that I absolutely love. It's one of my favorite knives, period; yet it's so lightweight that I wonder how much abuse it could take in a self defense situation, even though it's a lockback. It seems to be a deceptively strong knife, but how strong I don't know. (And who's going to torture test a Benchmade? Not moi!)

Fortunately, most of us don't need self defense knives. Just a locking knife will do for ordinary cutting chores and, if done safely, won't bite the hands that need them.

linerlock_s.jpg


grip_s.jpg


Defensive situations call for many different grips.
 
I'll just post some of my thoughts from another earlier thread.

I think that people forget that the knife should speak for itself in the end based on the condition its in each time its cleaned and maintained and that all knives are as unique as we are as individuals. Just like people they age, they wear, their skin cracks, they get blemishes, and from this natural aging as well as use and abuse it more often than not has nothing to do with how well it was made or by whom when you develop a problem with one. With that said, circumstances are sometimes responsible for lock failures/defeats and accidents and not the knives or the makers of said knives. Many makers and manufacturers get the blame in the end but its not usually the case at all and I think most guys using their knives hard, or spine whacking them needlessly know this all too well. Neglect on the end line users part is many times the real fault/reason as to the condition of a knife when it has problems. I mean lets face it if you have a car and don't take care of it very well, don't expect it to function flawlessly all the time. It won't and neither will your knives. Many end line users forget that there is more to maintaining a folder or fixed blade than just the cutting edge.

Also, we are all only human. It doesn't really matter how many books the maker of a knife has written, how famous the maker is or how much metallurgical skill, knowledge, or experience they have, or if they have mechanical engineering degrees or anything else regarding how well made the knife was when it was shipped out to an end line user. When it comes to the individual knives and circumstances behind why and when a lock fails you have to look at the knife and many times as Sal just said in his post these things are not evident outside where they can be seen. I see them all from all levels of the craft and in price ranges from very very high end expensive knives to the lowest priced China made knives on the market and yes even some of my own and for some normal as well as bizarre reasons.

Locks can defeat and they certainly do. They need to be looked over and even tested over time to make sure you are still getting that same level of function and that they still deserve that trust you have handed over to them regarding your fingers. I am not a big fan of spine whacking, but an occasional spine tap is a necessary part of testing IMO. In the event that one defeats its most always when you least expect it and when your guard is down which is why I always stress that for hard use knives folders do one thing fixed blades don't do and thats fold. Doesn't matter if its a top line axis lock or the gents liner lock. You should always be wary of them regardless of any hype you might read or actually believe. This goes for all locking type folders. I'm sure people can relate to this that have carried a knife for years.

All manner of things can happen to change the lock up of a folder. If its a trusted daily knife it deserves some daily or at least some routine weekly care and going over and your fingers are worth that believe me. Pocket lint can take the most trustworthy well built lockback and turn it all around for you in the time it takes to flick it open and use it to cut down a cardboard box to fit in the trash can. And we read reports of that nature several times or more a year. In the time I have been a member here we have seen every lock type on video at one time or another fail spine whacks from the axis, down to the liner lock and all in between.

I think you can learn all you need to know about your lock without the need for whacking the spine but if you want to whack it hey, its your knife.

STR
 
Very well said!

But despite each knife having its own strengths and weaknesses, wouldn't you say that knife design also is a major factor? Taking everything you said into consideration, what knife locking design is better and which is more liable to be problematic?

Cold Steel boasts the strength of its Recon folders. I've only seen them a few times, but I have no idea if they're as good as, or better than, lockbacks...in design.

I had a lockback design fail me on one knife, a small one. But it manifested itself with just minor preliminary testing that most would instinctively try before using a knife. The blade locked with a decisive "clickkkk" and then folded just like a slip joint! I've also had an inexpensive linerlock lock so powerfully that I needed a screwdriver to unlock it. The bloody thing's almost as strong as a fixed blade!

Knowing your knife on a personal level is advisable because accidents can be messy. Knives, as weapons, are feared for a reason. For the same reason you want to avoid knife confrontations, you don't want to be bit by your own knife. There are some on this board that have permanent nerve damage and stubby digits because steel always wins over flesh.

big_wound.jpg


In Wisconsin, the number one
reason for emergency room visits
is bagel knife injuries.
 
Oh we could really go on all night for opinions on best design. Personally I think the best design has to do with more than just the best lock type, whatever that may be. For example, I like mid back lock folders with a built in choil on the blades which is my 1st choice and how I usually make one for myself when I sit down to do a folder for myself. Well, like the one in my signiture line which is with me a lot of the time even if I have another folder on me at the time.

I also like frame locks and when built as I like, with a choil I put them at the #2 spot but only when they too have a choil feature. Personally I incorporate this choil whenever I can and not only as a way to choke up on the handle better for detail work with the point or tip third of the blade when I use it because I feel it adds greater control but also as a built in safe guard for a defeat of the lock for any reason during normal use and perhaps even during some uses outside of normal as well.

If there is no choil advantage I will almost always drift to an axis lock of some kind.

In my mind this choil feature makes it very hard for the blade to close on my fingers if my index finger is wrapped around the blade good in front of the pivot and my other fingers securely behind the pivot.

STR
 
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