Recommendation? What should I do with my ZT(framelock issue)?

MSchott said:
This video reminds me of the CS vs CRK videos. Why would you whack your knife on the spine in daily usage? Daily usage puts pressure in the other direction, towards lockup. He discounts this but only because it supports his point IMO.
Click to expand...
I don't care about what he says these knives should not fail on spine whack. Especially because they are advertised as hard use.
 
Last edited:
My 620 was one one the very first runs and has a pretty strong detent and lock engagement, did something change?
 
MSchott said:
This video reminds me of the CS vs CRK videos. Why would you whack your knife on the spine in daily usage? Daily usage puts pressure in the other direction, towards lockup. He discounts this but only because it supports his point IMO.
Click to expand...

Because_Aliens_LOL.jpg


(I don't know either, I like a locking knife so it doesn't close on my fingers, I never understood the spine whacking.)
 
Comeuppance said:
I don’t advise trying to manually adjust lockbar tension as a means to that particular end; what you’re describing is lock slip, which is caused by a combination of lock geometry (both the materials and angles of both the blade tang and lock interfaces) and the tension on the lockbar. I’m not familiar with KAI’s warranty policy, but manual bending of the lockbar sounds like the kind of thing that voids warranties.

ZT warranty service or a return / exhange to the seller are far and away your best options, as those run no risk of voiding a warranty and little risk of getting an unsatisfactory result in the end.
Click to expand...

I wouldn’t normally bend the lockbar to remedy this issue but I had the exact issue with the exact same knife and bending the lockbar to add just abit more tension 100% fixed the problem.
 
mongomondo said:
Yeah I had a black ZT 620 with really weak lock tension. I'm guessing they started doing that because a lot of their older knives were actually built with really strong detents and tension and customers probably started whining how it hurt their fingers to flip the knives constantly.
Click to expand...

I agree, they are coming from the factory tuned for optimal flipping and it suits the needs of the vast majority. I simple tuning of the lockbar would change the lockup strength, as well as better suit it for a spine whack test. This would be the knife equivalent of tuning your car before a race, or studying for a test (albeit a completely stupid test imo, the validity of which has been debated in numerous threads on this forum). In that video it also appears that the source of the "lock rock" could possibly be addressed by adjusting the pivot and handle screw tension, similar to how one would adjust centering. Also, multiple whacks on a surface hard enough to force a fail could end up putting more wear on the lockbar (rounding the normally sharp edge of a lockface), making future fails more likely.

The likelihood of any of those knives failing during any routine, or even "hard" use scenario (even the RAT which he forced a fail on) would be extremely unlikely even without adjusting the lockup. The added natural resistance of your hand grip on a frame lock also helps prevent a lockup fail. If this issue were so prevalent that it was causing failures leading to injury there would be plenty of threads with supporting evidence of such failures, or worse case possibly even force a consumer action such as a recall. To my knowledge Gerber is the only major knife company to issue recalls due to lock failures, and the threads resulting in injury are almost always attributed to user error or explainable circumstance.

To the OP, if you aren't comfortable tuning the lockup I would agree with the others that sending it in makes sense. If you have a knife smith or local maker nearby that could make the adjustments on your behalf that may also be an option.
 
I just tried the big bad ZT 0909 on a roll of tape and it failed like I've seen cheap knives fail. Didn't even hit it hard at all. Brand new knife too.
 
It has no lock rock and looking close at the liner lock it only locks on the inside edge of the liner lock. Can't get it to move at all by hand pressure, my dad who is many times stronger than me couldn't either. I think the shock is just bouncing the lock loose when it's hit.
 
jill jackson said:
It has no lock rock and looking close at the liner lock it only locks on the inside edge of the liner lock. Can't get it to move at all by hand pressure, my dad who is many times stronger than me couldn't either. I think the shock is just bouncing the lock loose when it's hit.
Click to expand...

The test I was doing was purely hand pressure and the framelock was slipping towards disengaging. Thats the thing, I'm not talking about any sort of spine whack test at all, just pure pressure from my hands, no jarring or impact that would cause it to slip.
 
Has any fellow Canadians recently bought or had a knife repaired and ship from the US to Canada?
 
My ZT 0909 lock readily fails with very light taps on the back of a padded office chair. Not whacks, mind you, just taps. However, it is one of my favorite knives. The ergos and blade shape are just perfect for a large utilty/work knife. I just use it like I would a large traditional slipjoint and I don't use it for heavy piercing cuts.

It's too bad really, ZT has the machining skill to make a decent lock. I don't think the lock needs to be up to CS standards, but it shouldn't fail with light taps on a padded surface.
 
  • Like
Reactions: Mo2
AmosPaul said:
My ZT 0909 lock readily fails with very light taps on the back of a padded office chair.
Click to expand...

No way I could live with that. It would drive me crazy. However, I don't spine whack so unless there's play apparent from a vigorous wiggling of the blade, I wouldn't even know. I wonder if your knife has play if gripped by the tip and firmly wiggled.
 
AF said:
No way I could live with that. It would drive me crazy. However, I don't spine whack so unless there's play apparent from a vigorous wiggling of the blade, I wouldn't even know. I wonder if your knife has play if gripped by the tip and firmly wiggled.
Click to expand...

No blade play whatsoever. I really should send the knife in to ZT, but I carry it so much I would miss it. By the way, I'm not spine whacking, just lightly tapping on the top of a padded office chair.

The lock doesn't fail with medium hand pressure on the back of the blade (I haven't tried hard pressure; I'm a little afraid to do that).

Only the very edge of the lock bar contacts the blade tang. It is an extremely small contact area compared to other liner locks.
 
  • Like
Reactions: AF
AmosPaul said:
Only the very edge of the lock bar contacts the blade tang. It is an extremely small contact area compared to other liner locks.
Click to expand...

Oh, in that case I would be aware of an issue. I always inspect for lock geometry. Send it in! I imagine you'd love it even more without that issue.
 
Sure wish i could bend my Lionsteel Ti-Spine lock bar... the thing barely keeps locked... with the clip pushing on the lock...

My previous one had the same problem
 
AF said:
Oh, in that case I would be aware of an issue. I always inspect for lock geometry. Send it in! I imagine you'd love it even more without that issue.
Click to expand...

Mine is the exact same. Liner lock only contacts the inside corner. It too is easy to tap and make fail. Spyderco Military has full contact on it's liner and won't be spine whacked to failure. I have a number of ZTs and I'm afraid almost to try to see how they fare after seeing the video where all of that guy's did.
 
You must log in or register to reply here.
Back
Top