Zero Tolerance Liner Lock Closures?

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DRLyman said:
I don't know what else to say but WTH. I'm glad I didn't order that knife. I had it in the cart, but something told me to remove it. Glad I did.
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It wouldn't be so bad if ZT would take responsibility and fix or replace these defective knives, but they won't. As is shown by the 7 in the video the guy sent back and they marred up the locking surfaces and they still won't hold. Oh well, ZT won't get a dime of my money again, until they address the problem. Just this morning I took a Chinese frame lock, 40 dollars shipped, hit it as hard as I could on a 2x4, nothing didn't even faze it.
 
jill jackson said:
So, you're saying the ZT's that won't take tiny spine taps against a person's hand are too sharply angled and that would cause them to push outward into unlock? (just trying to figure what's wrong)

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It sure appears that way. Liner/frame locks rely on proper contact geometry. It needs to be an acute enough engagement angle for the coefficient of friction/contact forces to keep the lock in place, but enough of an angle to allow for wear over time. That's a delicate balance and it's something that a number of knife makers have ignored over the years, to their detriment.

Spyderco makes their knives with a concave blade tang and it locks properly. A number of ZTs apparently use a lockbar/tang engagement geometry that lets the lock slip, which seems to me to be a result of a steep angle.
 
jill jackson said:
So, you're saying the ZT's that won't take tiny spine taps against a person's hand are too sharply angled and that would cause them to push outward into unlock? (just trying to figure what's wrong)

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LMAO.:eek: My SAKs would hold better than that ZT.
 
I’m also curious. The video that jill jackson jill jackson just posted is crazy. Slamming the spine against a roll of tape to make the lock fail is one thing, but lightly tapping it against your leg and causing failure? That’s absolutely ridiculous. I’m not crazy about ZTs regardless, but this would certainly keep me from buying one.
 
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This phenomenon only occurs with linerlocks? I’ve tested both of my ZT edc framelocks, the 0804cf and the 0562cf and couldn’t get them to slip no matter how hard I whacked the spine. Also tried some Millie’s, and couldn’t get slippage. Maybe I’m doing the test wrong?
 
Yonose said:
This phenomenon only occurs with linerlocks? I’ve tested both of my ZT edc framelocks, the 0804cf and the 0562cf and couldn’t get them to slip no matter how hard I whacked the spine. Also tried some Millie’s, and couldn’t get slippage. Maybe I’m doing the test wrong?
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Watch the video on the 1st page and the one I posted of the 0450.
 
Yonose said:
This phenomenon only occurs with linerlocks? I’ve tested both of my ZT edc framelocks, the 0804cf and the 0562cf and couldn’t get them to slip no matter how hard I whacked the spine. Also tried some Millie’s, and couldn’t get slippage. Maybe I’m doing the test wrong?
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It won't occur on every knife. It's a qc issue and will happen to some of them. It seems fairly common and dating back a few years also. Mostly framelocks.
If yours isn't doing it consider yourself lucky. That is good.
 
I know I haven’t adjusted either of those ZT’s; but I do tend to check the locks on knives I buy before using them, and after each “reassembly.” Otb I don’t trust any folder for hard use, though this isn’t hard use everyone is talking about. ZT has been known to ignore qc issues before.
 
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jill jackson said:
It wouldn't be so bad if ZT would take responsibility and fix or replace these defective knives, but they won't. As is shown by the 7 in the video the guy sent back and they marred up the locking surfaces and they still won't hold. Oh well, ZT won't get a dime of my money again, until they address the problem. Just this morning I took a Chinese frame lock, 40 dollars shipped, hit it as hard as I could on a 2x4, nothing didn't even faze it.
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I still love my 0392s which I tried this with and neither one failed. Those I’ll never let go and continue to use. After seeing these posts I won’t be buying any more ZT knives, though. There is no excuse for these knives failing like they are, especially like the one in that video.
 
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Maybe ZT should let China produce their knives. This 15 dollar Kershaw Injection would not fail on hard surfaces.
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I still haven’t done the test on my 0909; I may have already bent the linerlock inward, though I can’t remember now if that’s the case. I have to dig it out of my knife drawers before I can tell. Although I’m glad Kai still manufactures the line in the US, I feel like ZT knives should come with a warning label of some kind.
 
Yonose said:
I still haven’t done the test on my 0909; I may have already bent the linerlock inward, though I can’t remember now if that’s the case. I have to dig it out of my knife drawers before I can tell. Although I’m glad Kai still manufactures the line in the US, I feel like ZT knives should come with a warning label of some kind.
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I can attest that bending the lockbar does help to certain extent, although I am not 100% sure that it will completely eliminate the possibility of the blade folding accidentally.
 
The only ZTs I own are an 0350 and an 0400, and I just checked them. I lightly spine whacked them against the heel of palm of my hand, and luckily they didn't fail. I've had both of them for years, but admittedly I haven't used them much at all. I did the same with my Spyderco Military. Even though the ZTs didn't fail, my Military felt more solid when doing that than my ZTs did, even though at first glance, the Zts "look" stronger.

I really don't habitually spine whack, but tend to use hand pressure to the back of the blade as a test.

Jim
 
sharp_edge said:
I can attest that bending the lockbar does help to certain extent, although I am not 100% sure that it will completely eliminate the possibility of the blade folding accidentally.
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I wonder if using a small diamond file to concave the lockbar top is the only solution in this case? If Kai isn’t taking responsibility I’m sure they will blow off individual attempts to fix the knife. I paid the sale price, so I’m not as upset as others, but if it’s between either fix it myself or trash can, I’ll try fixing it myself.
 
Yonose said:
I wonder if using a small diamond file to concave the lockbar top is the only solution in this case? If Kai isn’t taking responsibility I’m sure they will blow off individual attempts to fix the knife. I paid the sale price, so I’m not as upset as others, but if it’s between either fix it myself or trash can, I’ll try fixing it myself.
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The problem of your proposed fix is that if not done precisely, it will result in lock rock and also potentially void the warranty.
 
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