Zero Tolerance Liner Lock Closures?

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I had a linerlock ZT that close under pressure, not from a spine whack but simply from pushing it with my thumb. None of my ZT framelocks seemed to have that issue, but I never really tested them.
 
I'd be more concerned about said dropped item landing on my head than closing my knife on my fingers. But I get the point, even if there are no realistic sutuations that might close the knife, that blade closing from spine pressure is still an unwanted flaw and a sign that something wasn't done right.
I'm just suprised that it seems nobody who has experienced this problem and takes issue with it has seen what ZT themselves have to say or will do about it.
 
It is time for KAI to describe explicitly what it means by "built like a tank," "hard use," and "tactical" so that we know exactly what tasks ZT folders should and should not be used for. Of course I am talking about usual and unusual tasks that may require the use of a knife. I will continue to buy ZTs even if KAI states that ZT folders should only be used for tasks where pressure on the spine is NOT a possibility.
 
sharp_edge said:
It is time for KAI to describe explicitly what it means by "built like a tank," "hard use," and "tactical" so that we know exactly what tasks ZT folders should and should not be used for. Of course I am talking about usual and unusual tasks that may require the use of a knife. I will continue to buy ZTs even if KAI states that ZT folders should only be used for tasks where pressure on the spine is NOT a possibility.
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I gotta agree. To everyone saying “that is not how you use a knife.” “I’ve never put pressure on the spine.”

Ok granted. Does that mean it is ok for these knives to have locks that fail so easily? Is that not still a flaw in their design? Even if you never have any pressure on the spine and use every folder like a slipjoint I would still be mad about paying $200+ for a knife with a defective lock.

I’m going to bring it back to the car analogy. If I buy a vehicle that lets me select between 2x4 and 4x4 which I never ever drive off road and it never snows (etc.) so I never need to use 4x4; I am still going to be pretty pissed off if the 4x4 doesn’t work.

I don’t understand the “i never put pressure on the spine so it is a non issue.” Just because it doesn’t cause an issue for you in your use doesn’t mean there isn’t an issue with a lock that fails from extremely light spine taps or even just finger pressure.
 
Man. I was absolutely cringing watching him spine slam those blades (that he knows will fail no less!) that hard and fast. Looks like an easy way to get a nasty cut. What’s the old saying? Play stupid games, win stupid prizes.
 
I guess stabbing your knife into a wood table or tree stump is abuse and dumb to do ?? Lollololol

A knife shouldn't fail doing light spine whacks.

Its a qc issue. Doesn't happen To every one but happens often enough to be a problem some people will see. Most people who buy zt's don't use them for much so they won't see the issue a problem.
 
I think the video does bring up a good point, and that is that steel inserts increase the risk of lock failure. Since Ti galls against steel, the lock is more secure. It seems ZT has just given in to market pressure and I would bet their framelocks aren't the only ones that do this. Not an excuse for ZT, but there always seems to be a trade off, and this is one for steel inserts. I have moved completely away from framelocks (only own one) for numerous reasons, but my worst experience was with a brand new ADV Butcher with a steel insert. The thing might as well have been a slipjoint. Barely pushing on the spine closed the knife. Was it due to the insert? I don't know for sure and didn't care to find out. I sent the knife back in exchange for a few Spydercos and have never looked back.
 
Mo2 said:
I guess stabbing your knife into a wood table or tree stump is abuse and dumb to do ?? Lollololol

A knife shouldn't fail doing light spine whacks.

Its a qc issue. Doesn't happen To every one but happens often enough to be a problem some people will see. Most people who buy zt's don't use them for much so they won't see the issue a problem.
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Right. I stab my knife into wood quite a bit when I'm working with it without really thinking, and that is one of my main concerns with a framelock. Should I do it? I don't know, but I don't consider it abuse, and I AM going to do it, so I'd prefer my folder not close on me.
 
jstn said:
I think the video does bring up a good point, and that is that steel inserts increase the risk of lock failure. Since Ti galls against steel, the lock is more secure. It seems ZT has just given in to market pressure and I would bet their framelocks aren't the only ones that do this. Not an excuse for ZT, but there always seems to be a trade off, and this is one for steel inserts. I have moved completely away from framelocks (only own one) for numerous reasons, but my worst experience was with a brand new ADV Butcher with a steel insert. The thing might as well have been a slipjoint. Barely pushing on the spine closed the knife. Was it due to the insert? I don't know for sure and didn't care to find out. I sent the knife back in exchange for a few Spydercos and have never looked back.
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The galling (or lock stick) is not enough to make a lock anything more than marginally secure. A well made with a lockbar insert will work just fine.
 
ZT makes knives with slippery lock faces and weakly sprung lock bars. A little more pressure can negate the slippery face sometimes; the reason why many can "fix" their ZTs by bending the lock bar a bit more.
 
Kizer Dukes lock is flush and tightly fitted. It would not fail spine taps.
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Not to cloud/derail this entire discussion, but I've decided to keep the 0450CFZDP knife that I have herein detailed the issues with.

Over more than 50 very hard flips over 3 days, the knife remains locked open, and light pressure on the spine does not close the knife. Why is this OK for me to do? Well, I will remember which knife it is in my collection that bit me, and remember to flip it hard to lock it until it breaks in. I cannot say that 50 or so more flips like this will be good for the knife, and so it goes.
 
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In regards to Jill's knife, I wonder if slightly grinding down the the inside half of the top edge of the insert lock would cause it to lock in deeper and negate the problem. Looking at these ZTs it seems that the locking stud (not sure what exact terminology to use here) on the bottom of the blade has an angle that is not macted by the top of the insert, resulting in the corner of the insert locking against the face of the stud rather than two faces meeting together and thereby reducing friction between them.
Don't know if that will make sense to anyone.
 
Regarding steel inserts:

I’m inclined to think that this is an appealing “60mph” explanation, which fails to hold up under a cursory exploration.

Beyond that is the matter of context. I’m enjoying imagining a person using a knife under drop-risks, in a way which doesn’t apply force against the lockbar, holding the knife at such an angle that a drop from above would result in force applied to the spine of the knife, keeping hands out of space which would catch the flipper tab against a finger in the event of failure, while also having hands positioned to be injured by the closing blade.

And I think to myseeeelllllfffff, what a wonderfuuuullll woooooooorrrrrllllllddddd.
 
Although I agree with those who have said spine whacking a knife is not within the scope of normal use nor is putting negative pressure on the blade I will admit that the number of incidents I've heard about with ZT fail this test is a little troubling and seems to be more than just a one off problem. I suspect they are not putting in the time and energy to get the lock geometry and lock bar tension exactly right which is disappointing at the price point.
 
G. Scott H. said:
I still have mixed feelings on the whole spine whack phenomenon. On the one hand, I agree with Jill that it's pretty depressing seeing an expensive folder have its lock slip after a minor shock to the spine (especially when I too have $20 folders that pass just fine). On the other hand, I've used the 0920 off and on since last year and have never had the lock slip during actual use, so does the spine whack test really mean anything in terms of real world performance and safety? I'm not sure. I mean, it seems reasonable to assume that a knife that handles spine whack tests better should be more secure and safe to use; however, since a knife can fail a moderate spine whack test yet still perform perfectly safely in actual daily use, it seems the perceived advantage of the knife that doesn't fail the test does not really translate into reality (at least in any meaningful way). :confused::D
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This is exactly how I feel about all this fuss. Does a spine wack prove anything? Maybe not, but in theory it shouldn't be this easy to unseat a lock, and ZT basically only makes one kind of lock that is "built like a tank"...

Regardless of whether this test actually relates to real world use, it is hurting their reputation in the eyes of many. Hopefully ZT is taking note and evaluating their lock face geometry.
 
I only have one ZT and even though it has a really early lock up, it is rock solid secure, with no failure regardless of said spine whacking. However, it is a flipper (aren't most ZT's flippers? I don't know) I would think that the flipper tab would bang up against the index finger negating any injury?
 
I've had one ZT with a lock issue. It was a 350st that I used hard ( no abuse, no prying. Just lots of dirty cutting) as a work knife for about a year before I discovered that if I put just a bit more than firm pressure against the spine, it would slip the lock.
I figured a trip to ZT would fix the issue. I also decided to pay the 30 bucks to have them put a plain edge blade on it over the serrated one.

I got it back with a more firm lock up and no issues with it folding again. No issues with my 850, 920, 909, 456, 462, or 630.
 
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