New ZT0350. Spine whack failure?

[OrangeBlueOrangeBlue]

I did a cursory look, I didn't find any videos regarding failed ZT liner-locks more recent than 2018, so it may have been an issue that's resolved by having the knives lock-up later than 20-30%.

But as many have pointed out, it's a test that has very little relevance to how you actually use a folding knife. The frame-lock ones are even worse, since they have to purposefully hold the handle without contacting the lockbar, since having it there (like it would be if you were actually using the knife) keeps the lock from slipping.

 

[MarkN86]

Instructions unclear; spine whacked my Chevy and nothing happened.

I've never bought a ZT, but my USA made Kershaws are made in the same factory and have never had the problems that so many people complain that the ZTs have had. Maybe I've been lucky, or maybe it's that when there's a problem people are extremely vocal about it. Then again, expecting .05% lockup out of the box, bashing the spine against a cinder block, and then complaining when it fails is kind of silly.

Hitting the knife so hard that it shocks the whole pivot assembly can make ANY lock shift and possibly disengage. A light tap or simple pressure making the blade unlock sounds like some kind of lock geometry problem that needs to be addressed by the warranty department. If I have to full arm swing it or hit it with a hammer to get it to unlock then obviously it's fine.

The more I learn about knives the more I prefer a lockback even though it's slower to operate. Lock slip is an unfortunate reality when it comes to the ease of operation of a liner or frame lock.

 

[metsfan]

Spine whack tests are stoopid V Vis07 , don’t be drawn into that nonsense. Enjoy your ZT’s or whatever knife you fancy and keep on cuttin’

 

[Steely_Gunz]

I honestly think the lock slip on the ZTs is due to the fact that they are trying to balance silky actions with Ti frame locks coming off a production line with blades made out of premium steel for under the $300 mark. Like the old business triangle says: You can have it good, you can have it fast, you can have it cheap...pick two. That over simplifies it, I know. I'm just saying that the ZT line is a remarkable value for an American made knife that uses titanium and premium steels. There has to be "give" somewhere, and I think that maybe relying on the super fast ball baring action locking up perfectly with a lock face that isn't hand fit to the tightest tolerances may have something to do with why some slip.

I wouldn't have known mine would "fail" if it hadn't been for a thread about it. I never spine whack my knives to test them. I figure that if they lock up and lock doesnt stick too bad, then they are good to go as long as they are centered and don't wiggle. What surprised me, after watching a decade of Cold Steel "Proof" videos from back in the day when they would send you a DVD/CD ROM in the mail, was how little shock it took to get the ZT to slip its lock. 3 out of 8 of mine would slip with a very light tap toward the tip on a soft cloth triple folded on my kitchen counter with about a 1/10th strength tap if I made a special effort to not engage the lock with my hand. When I gripped the knife naturally, no failure. My hand pressure kept the blade tang fully engaged on the the lock face. So I would truly need to hold "hold my mouth just right" to get them to fail, but it is important to point out that I tried several other lower end knives that would NOT fail the test no matter how I held them. It goes back to my hypothesis of the ZT line doing the best they can with the parameters they are setting. I'm not bashing ZT. Just giving my very non-empirical and anecdotal findings to try an make a scientific wild ass guess as to why some slip their locks.

2 of the 8 would slip off their locks with moderate pressure put on the spine of the blade toward the tip. Not a whack, but just constant downward pressure. Maybe 1/5th strength. There is currently a bit of a hullabaloo on the CRK forum because the Sebenza 31 (as well as other models) demonstrate lock flex. They never slip off, but the lock bar will deflect with pressure. My ZT 0630 wouldnt flex much when I did this, but it would just kind slip off the shoulder and shut. This bothered me a bit more than others as there is no AO mechanism, so it falls free compared to my 350. The other thing is that was bought as a SD knife. Not that I was planning on locking blades with someone, but i wanted to make sure it was rock solid and held up to abuse. My beloved 909 would also slip its liner lock if I did this test. Not a big issue. I never imagine needing to use this knife in such a way as to cause it to slip the lock. Its a bit concerning due to the fact that I can't simply grip it tighter to shore up the lock strength like I can on the frame lock versions. Still, when I carry a folder in the woods, its the 909. Love that beastie.

In short, I have had 5 out of 8 ZTs that I could get to "fail" that did not require whacking the hell out of them. Not scientific. Not a dig against them or their function. Just that they simply slipped off their locks with less effort than other knives I have had. I think they are fine and robust knives that are well worth what they go for. I think they will pull your tail out of the fire and come back for more if you require them to. I just think I should be honest in what I have found. If they ever release a knife more like the 909 or another fixed blade like my edc 0180, I'll be all over it. I've got all the flashy ones I like, so I haven't bought any ZTs in about 2 years except for the limited 303 and Spark digging me up a 0180 he had in his shop. That has nothing to do with lock issues and everything to do with aesthetics.

YMMV

 

[JeremiahWeaver09]

i bought a zt 0550 when they were in production, and right out the box the lock would immediately fail with even a little bit of pressure to the back of the blade. the zt's ive bought since then have not had this problem. ive also had a couple new emerson knives that i could make the liner lock easily fail with light pressure to the back of the blade. i just dont trust liner and framelocks and try to avoid them if i can nowadays. ill buy one if i just really like the design, but i prefer backlock or axis locks. i just have no confidence in liner locks and dont want to obsess over the lock loosening or slipping or whatever.

 

[Bastler]

Once I dropped a liner lock knife on the ground and that caused the lock to release. Since then, I've preferred back locks. I use slip joints commonly, so I understand the reasoning that a lock can only be trusted to a limited extent, but the sudden release of a failed lock concerns me more than closing a slip joint on my fingers. To that end, I've never spine whacked anything. I visually examine locks and sometimes check for deflection under constant closing force applied with my hand.

 

[Twindog]

This. Spine whacking is absurd, I have yet to have anyone give me any realistic reason why this is a legitimate concern for any folder. I would love to hear a real world scenario where this could happen.

I live in the rainforest in Washington. Vegetation quickly grows over trails -- and much of that is thorny stuff like devil's club and salmonberry. And I often go off trail to reach the river, where undergrowth can be thick.

My Rukus 610 is a big knife with an overall length of 10.2 inches. It has a lot of chopping power, but I depend on the Axis lock to hold, otherwise that big 4+ inch blade will be coming for my fingers. It has happened with lesser knives with poor locks, but never with the Rukus.

Of course, a machete would be better, but a machete is too much to carry, especially when part of my hike goes through a beach where surfers hang out.

Having a pocket knife that can do heavy-duty tasks without failing -- and that is always with me -- is important to me.

 

[unwisefool]

Nonsense. My calculations dictate a speed of at least 50 mph while going down a road inclined at 45 degrees. Then you stick your knife out and smack that sucker on a signpost.

Really depends on what s

Nonsense. My calculations dictate a speed of at least 50 mph while going down a road inclined at 45 degrees.

That really depends if you are West of the equator or not. I won't get into the science behind it, but suffice to say it involves imaginary numbers and fractals. It's basically a quantum computation.

 

[OrangeBlueOrangeBlue]

I live in the rainforest in Washington. Vegetation quickly grows over trails -- and much of that is thorny stuff like devil's club and salmonberry. And I often go off trail to reach the river, where undergrowth can be thick.

My Rukus 610 is a big knife with an overall length of 10.2 inches. It has a lot of chopping power, but I depend on the Axis lock to hold, otherwise that big 4+ inch blade will be coming for my fingers. It has happened with lesser knives with poor locks, but never with the Rukus.

Of course, a machete would be better, but a machete is too much to carry, especially when part of my hike goes through a beach where surfers hang out.

Having a pocket knife that can do heavy-duty tasks without failing -- and that is always with me -- is important to me.

So how is the spine whack failure relevant to cutting plants? Do you chop them with the spine? Baton through them?

 

[Twindog]

So how is the spine whack failure relevant to cutting plants? Do you chop them with the spine? Baton through them?

No. The best way is to give a short, hard chop at a 45 degree angle to the woody stem. You do a snapping action with your wrist, which ends with a very fast stop to the blade. If the lock is weak or faulty, it won't hold the blade. This technique puts the same force on the blade as a spine whack.

Also, I found out the hard way that you can't use this technique with a lockback knife, like the Cold Steel XL Voyager that I first tried it with. The action forces the lock against your hand, releasing the lock.

 

[whp]

I kind of want an 0350 after all this talk. Ive been on a budget quest lately.

It s a great work knife. I deassisted mine and it flips fine.

 

[Triton]

I live in the rainforest in Washington. Vegetation quickly grows over trails -- and much of that is thorny stuff like devil's club and salmonberry. And I often go off trail to reach the river, where undergrowth can be thick.

My Rukus 610 is a big knife with an overall length of 10.2 inches. It has a lot of chopping power, but I depend on the Axis lock to hold, otherwise that big 4+ inch blade will be coming for my fingers. It has happened with lesser knives with poor locks, but never with the Rukus.

Of course, a machete would be better, but a machete is too much to carry, especially when part of my hike goes through a beach where surfers hang out.

Having a pocket knife that can do heavy-duty tasks without failing -- and that is always with me -- is important to me.

Honestly it sounds like you are attempting to use a folder for something better suited for a machete or at least a large fixed blade. However, I guess that is a real world example.