ZT 0452 lock up

Just thought I'd follow up:

I just got an email back from KAI yesterday. They're happy to service my knife if I send it in but they will not ship out any lock-bar inserts.

So I'm just gonna try & make some myself instead.
 
Jill, I'm glad that someone has brought this problem to attention besides myself. I remember when I first described my issue, fanboys jumped all over me and wouldn't acknowled the problem I described.

I do a lot of cutting that require force put on the blade, such as cutting wood lath, push cutting rope, cutting thick plastics, etc. I've noticed that when doing such tasks, my ZT's lockup to the point where it requires 2 hands to close the knife; not good for a fast-paced work environment or when wearing gloves.
The only thing "production" I really carry now is CRK's, which have proven reliable in any situation I've thrown them into.



I have learned that when Blues talks, I listen. Good man! He uses knives in such a way that it tests whether they really work or not. I've had a bunch of ZT's, although they're all gone now. Have an 0808 coming in; I hope it's okay.
My CRK's have always been rock solid and never a complaint. I suspect that Chris will keep them that way.
 
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I have learned that when Blues talk, I listen. Good man! He uses knives in such a way that it tests whether they really work or not. I've had a bunch of ZT's, although they're all gone now. Have an 0808 coming in; I hope it's okay.
My CRK's have always been rock solid and never a complaint. I suspect that Chris will keep them that way.

My 0450CF lands at perfect 50% lockup when flipped open, but if I cut cardboard with it the lockbar travels to 100% and the pocket clip, no matter how tightly screwed down, will slip downward toward the lockbar. I have decided after using this knife that it will not be my EDC as a result. It's a great self defense knife (if you think a knife is even really a good self defense tool), and has no problem cutting tape open on boxes. It also looks very attractive and is fun to flip, but it's barely a light use EDC knife. For comparison sake, my regular EDC, sebenza 21, has never moved past 60% in the hardest use I've put it through. It appears to be the curl of my index finger that pushes the lock bar all the way to 100%, and the palm of my hand below my ring and pinky finger on my right hand that slide the pocket clip downward. This is somewhat disconcerting because I really wanted to EDC this knife frequently and I spent $180 to own it. I'm actually thinking about selling it because the only time I feel it will come in handy is for fancy events or if I want to have a knife when I go out to dinner. Kind of bummed TBH!

Also, Blue's has given me the best advice of anybody on this forum! I trust his comments and judgements.
 
Just another person chiming in to say that I've had the same problem. lock moves to 80 or 90 percent whenever I push hard on the blade while cutting. Also slips off too easily when negative force is applied to the blade (not spinewacks, just hand pressure).
I've been falling out of favor with ZT lately, too many quality issues compared the knives I have from Spyderco and Reate.
 
Not sure why this thread reemerges, but I wonder if the use of a lockbar insert somehow contributes to this issue of lockbar overtravel under pressure. I have a frame lock big folder of another brand without lockbar insert that I have owned for two years, which no matter how hard I push, the lockbar stays where it is and does not travel a bit.
 
Not sure why this thread reemerges, but I wonder if the use of a lockbar insert somehow contributes to this issue of lockbar overtravel under pressure. I have a frame lock big folder of another brand without lockbar insert that I have owned for two years, which no matter how hard I push, the lockbar stays where it is and does not travel a bit.

There was a long thread discussing this exact issue of ZT folders (I recall the knive being discussed initially was 0452). It was suggested by some folks that tightening the pivot screw would help.

Because you referenced it in another thread :D
 
I think Jill solved this by tightening the pivot. Don't remember though it's been almost a year.
 
Sonny, DK, thanks guys! I'm glad my posts have been helpful to some:)

I think Jill solved this by tightening the pivot. Don't remember though it's been almost a year.

Indeed. I did the same, and my locks still aren't right. Also, my 0454 is starting to get cracks in the CF by the bladestop. Sooner or later, it's gonna give and the blades gonna swing free. Oh well...
 
I think Jill solved this by tightening the pivot. Don't remember though it's been almost a year.

OK - I can confirm that tightening the pivot screw will lessen the problem of lockbar over-travel under pressure but won't completely eliminate the over-travel. I tried it with a ZT0452cf just now by first tightening the pivot to a point that I feel more tightening would mean stupidity and then pressing hard on the lockbar toward the cf side (well not hammering it). It still traveled a tiny bit (maybe ~5-10%) but definitely not to 100% mating with the tang. BTW, the action of the blade is still very smooth after the super tightening. Therefore, I do agree this method can help a lot.

Edit: tried the technique on a ZT0801 user and the result is different. First, over tightening the pivot would lead to less smooth action (the 0452cf is basically a new knife whereas the 0801 is a user). Even with that, hard pushing the lockbar would cause it over-travel to nearly 80-90%.

More edit: on a second thought, it does not make much sense to purposely hard-push the lockbar to see if it over travel. I think the knife should be deemed quite acceptable if after an extended period of one hand firm grip (i.e., to mimic a normal use of the knife) the lockbar neither travels to ~90-100% nor requires two hands to disengage. My 0452, 0801, and 0561 all passed this test when the pivot was tightened firmly bot not excessively.
 
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Crack is happening at the stop pin.

This is for reference, you can't see the crack here.

B1D64517-60AA-4B9F-B651-502E834AF83E_zpscgqmaljz.jpg


It's hard to see, but there is a crack that starts at the bottom of the hole, and goes up towards the top of the scale. On the top right side of the hole, there are some stress cracks from where a small layer of CF is peeling up.

AA6A8189-98DB-499C-863D-324BBA71AF4F_zpsotm8wqhs.jpg


Highlighted for clarity

16963E96-D695-42C8-8C29-6F71F664F5D9_zpslu8vckc4.jpg


Same crack from another angle, showing where it goes up the scale

6751C4DC-4B02-46D9-B8E4-81378BB164DC_zps80scnhsu.jpg


Highlighted for clarity

0071A52F-B693-4561-98B0-9C6F42042FFA_zps96ftqz2r.jpg


Bought directly from ZT on 9/30/14, and was not this way out of the box. Knife was used and carried, but never dropped on any hard surface.
 
More edit: on a second thought, it does not make much sense to purposely hard-push the lockbar to see if it over travel....

I read your whole post, I agree it does not make sense to purposely push the lock bar in to see when it stops, but on my 0450 it travels to 100% when I'm cutting cardboard. I think it's a combination of pressure from the index finger pushing on the lock bar (95%) and also leeway of the pivot while the blade pushes against the stop pin relieving pressure of the tang on lock bar (5%). Neither problem was resolved by tightening the pivot to a reasonable degree while still maintaining the signature flip-happiness of the knife. I think it's a design flaw, but I'm resolved not to "use" this knife...sadly. It'll do pocket time out to dinner, at weddings and events, etc, but will certainly not be an EDC in the conventional sense.
 
Crack is happening at the stop pin.

This is for reference, you can't see the crack here.

B1D64517-60AA-4B9F-B651-502E834AF83E_zpscgqmaljz.jpg


It's hard to see, but there is a crack that starts at the bottom of the hole, and goes up towards the top of the scale. On the top right side of the hole, there are some stress cracks from where a small layer of CF is peeling up.

AA6A8189-98DB-499C-863D-324BBA71AF4F_zpsotm8wqhs.jpg


Highlighted for clarity

16963E96-D695-42C8-8C29-6F71F664F5D9_zpslu8vckc4.jpg


Same crack from another angle, showing where it goes up the scale

6751C4DC-4B02-46D9-B8E4-81378BB164DC_zps80scnhsu.jpg


Highlighted for clarity

0071A52F-B693-4561-98B0-9C6F42042FFA_zps96ftqz2r.jpg


Bought directly from ZT on 9/30/14, and was not this way out of the box. Knife was used and carried, but never dropped on any hard surface.

That could become a problem...
 
I read your whole post, I agree it does not make sense to purposely push the lock bar in to see when it stops, but on my 0450 it travels to 100% when I'm cutting cardboard. I think it's a combination of pressure from the index finger pushing on the lock bar (95%) and also leeway of the pivot while the blade pushes against the stop pin relieving pressure of the tang on lock bar (5%). Neither problem was resolved by tightening the pivot to a reasonable degree while still maintaining the signature flip-happiness of the knife. I think it's a design flaw, but I'm resolved not to "use" this knife...sadly. It'll do pocket time out to dinner, at weddings and events, etc, but will certainly not be an EDC in the conventional sense.

I have some knives from other manufacturers that go to 100% engagement (or almost that much) when used to cut forcefully.
I just use them. :)

If the lock is failing, then sure, don't use it.
If it just engages a bunch, use it anyway.
 
I have some knives from other manufacturers that go to 100% engagement (or almost that much) when used to cut forcefully.
I just use them. :)

If the lock is failing, then sure, don't use it.
If it just engages a bunch, use it anyway.

I guess it's worth asking then if 100% lockup can cause the knife to fail and cut you?
 
I guess it's worth asking then if 100% lockup can cause the knife to fail and cut you?

Nope. :)

I have seen knives where the lock-bar ended up touching the non-locking side, and the worst that happened was some slight vertical wiggle after years of being that way.
They didn't care, because the lock kept the blade open. :thumbup:

That said, I do prefer my knives to not go to 100% engagement, but that is just due to being an obsessive knife knut. :D
 
when the lock goes to 100% engagement, does it require two hands to disengage? if no, it woyld be less of a problem.
 
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