Kershaw Spine Whack Fail

Status
Not open for further replies.
One thing I have noticed is once you get a knife to fail a spine whack they will fail more easily from then on and after many times being whacked will fail with no effort at all. I comes from glazing of the locking surfaces. I have a Needs Work that you could spine whack with a cheater bar and it would pass with flying colors and it is a blem.
 
I have literally never used a knife in a way that puts pressure on the spine this way. I can't even think of a conceivable reason to do something like beat the spine of your knife on anything. As such, this test tells absolutely nothing about the value of a knife. If I can't push the knife closed with my hands the lock is PLENTY strong for literally every cutting task I can imagine.
 
oharal said:
I have literally never used a knife in a way that puts pressure on the spine this way. I can't even think of a conceivable reason to do something like beat the spine of your knife on anything. As such, this test tells absolutely nothing about the value of a knife. If I can't push the knife closed with my hands the lock is PLENTY strong for literally every cutting task I can imagine.
Click to expand...

Personally, I can think of situations in which something may impact the spine of my blade. It wouldn't be I tentional, but accidents happen. There's also the minor point that, with the Needs Work, the OP could get the lock to fail with hand pressure.
 
oharal said:
I have literally never used a knife in a way that puts pressure on the spine this way. I can't even think of a conceivable reason to do something like beat the spine of your knife on anything. As such, this test tells absolutely nothing about the value of a knife. If I can't push the knife closed with my hands the lock is PLENTY strong for literally every cutting task I can imagine.
Click to expand...

I agree. If I can't push it to a closed position, no problem.
 
oharal said:
I have literally never used a knife in a way that puts pressure on the spine this way. I can't even think of a conceivable reason to do something like beat the spine of your knife on anything. As such, this test tells absolutely nothing about the value of a knife. If I can't push the knife closed with my hands the lock is PLENTY strong for literally every cutting task I can imagine.
Click to expand...
Exactly.
And Kershaw makes some of the best locks on the market.
Spine whacking mars lock mating surfaces and contributes to possible easier future failures. I will not purchase knives in the market sold by known spine whackers as I then consider them damaged. It is abuse, plain and simple.

There was a member here once, who complained a knife was poorly designed because it had closed on his hand while dressing a hog.
When questioned he admitted to twisting the knife while cutting. He likely disengaged the lock on the knife while he was twisting.
Not the fault of the knife, but of the user.
 
Uhm a spine whack shown in the video is a very valid test for the most part (the latter spine whacks were a bit too hard) to ensure the locking mechanism is where it needs to be, it will easily weed out bad lockbar geometry.
Also I know exactly what the op means by hitting the spine by accident at work.
 
Is there a way to increase traction of the mating surfaces? Possibly honing a crosshatch pattern lightly? I have noticed my ZT 301 only engages the tang with about 60% of the frame lock flat. I would think 100% mating would provide a more secure lock up.
 
It's an old, well used knife. In the time you've been using it the locking surfaces have probably polished each other. I would take it apart and hit the surfaces with some course sandpaper and maybe tweek the lockbar a hair to put more pressure on the lock and see if that keeps the knife from unlocking so easily.
 
Show of hands: who thinks this knife performance is acceptable?

No whining about abuse. That was some of the lamest abuse I've ever seen.
 
Video has been removed...

I think the spine whack is a legitimate test of any liner lock. How hard is a matter of what the knife is designed for. A gentleman's knife should pass a lite whack, a Starmate or any self defense knife should, and will, take a good crack on a 4x4 support post in the basement.

The basic geometry of a properly made liner lock, should not fail with pressure to close, wether it be steady pressure or by impact.

In my experience, knives fail for a variety of reasons, the most common being loose screws, the second being poor design.
 
I can understand the frustration. Liner and framelocks are difficult locks to make, despite what people tend to believe. Here is post I did.

"Please. Have a look at these posts I did to see what goes into making a proper liner/framelock.

Those that think it is easy to make a liner/framelock well are ill informed IMO.

Please read the following link:

http://www.bladeforums.com/forums/s...in-Frame-Liner-locks/page4?highlight=terzuola

Now, there is also been some good testing and evaluation done by Kyle Harris (cKc Knives) from new Zealand discussing blade play vs lock security. In short, though we think blade play is bad, making a truly dependable lock in the framelock/linerlock conversion requires some blade play.
Have a look at these videos:

http://www.youtube.com/watch?v=7I3fJVL3DT4

http://www.youtube.com/watch?v=M2cZQv5cIqQ

You can see from the videos that even with blade play a lock can still be very secure, very reliable and would require the entire lock to self-destruct in order to disengage.

[video=youtube;A2f5h9zFQvE]http://www.youtube.com/watch?v=A2f5h9zFQvE[/video]

Real interesting comments from Gavko on the folder of Kyle and what makers such as Bob Terzuola said about bladeplay being a threat for the specific market, yet there is nothing wrong with the design.

People presume that blade play is bad, but not for a reliable lock. I would venture and say that the Victorinox soldier will only fail if there is a catastrophic failure of nature, same as the Tri-Ad. Under static load, the soldier might even surprise the best of us.

Interesting thing on how durable a liner can be:

[video=youtube;-MxCDbAW638]http://www.youtube.com/watch?v=-MxCDbAW638[/video]

I tried to repost all my lengthy posts but the server keeps interrupting."

I hope this might be of some interest. I am now just going to sit.

original
 
I stated in a previous post that I wanted to know how my Kershaw/ZT knives would do. Oak 4x4 on a cement floor, not a table. I held the end of the grip just like the vid. I didn't mess around with taps, but gave each knife 5 good whacks that left a pretty good impression in the wood. Maybe not quite as hard as the Cold Steel, but harder than the 0350. Results......Kershaw Tanto Groove - pass, ZT 0350 - pass, ZT 0200 -pass, ZT 0400 - pass, ZT 0550 - pass, and last a lowly Kershaw Scallion frame lock blem - pass. None of the knives exhibited the least amount of lock rock afterwards. I do need to mention that when I receive a frame or linerlock that has less than 60% lockup, I remove the blade and use a jewelers file and/or 220 grit sandpaper on the tang.
 
Spine whacking is abuse. Prying with a knife is abuse. Cutting metal with a knife is abuse.
 
I use slip joint knives a lot. They always fail when I smack the spine. I can't understand why I keep using them....stubborn I guess.
 
Morrow said:
I use slip joint knives a lot. They always fail when I smack the spine. I can't understand why I keep using them....stubborn I guess.
Click to expand...

I love my slip joints, but I do like it if there's actually a significant difference between them and my knives that supposedly lock.
 
Insipid Moniker said:
I love my slip joints, but I do like it if there's actually a significant difference between them and my knives that supposedly lock.
Click to expand...

Sometimes locks fail. Some fail often when getting whacked on the spine. My slip joints fail 100% of the time with this "test." Somehow I've managed to keep all my fingers using knives with a failure rate this high. If your cutting with the edge down, when would this test be valid? I don't cut with the spine down so I feel confident. Banging on the spine of folding knife has almost zero value to ME as a test but YMMV. Like I said before.....I'm probably stubborn.
 
All these people talking about not cutting with the spine of a knife. You're all such wimps! Listen, I ONLY cut (and chop) with the spines of knives...never with the edges. Sure, it takes longer and sometimes doesn't work at all but, hey, it definitely makes me feel better knowing the knife's lock won't fail when I'm doing it! BTW, I also pound nails only with hammer handles and install screws by hitting them as though they're nails ;) . Sorry, couldn't resist. It's just that spine whacks are such inordinately stupid measures of knife quality and strength that I can't resist posting something sarcastic. My fingers type uncontrollably at such times so please forgive me. I can't help it.
 
Lycosa said:
Spine whacking is abuse.
Click to expand...

I consider it destructive testing. I generally won't do it with my knives, because I don't have money to throw around. But like other destructive tests, I don't disregard the results, when others do them. Because a lock is a safety feature and unintended things happen.

Why do manufacturers market thick liners, "rock solid lockup", and ever new "strong" locking mechanisms when a thin liner or a good old slipjoint would suffice?

Lycosa said:
Prying with a knife is abuse.
Click to expand...

Why do manufacturers of modern folders then market ever thicker blades even though added thickness is clearly a big disadvantage in cutting performance?
 
Status
Not open for further replies.
Back
Top