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ZT 0550 lock issue

TkSteve

TkSteve

Joined
Dec 1, 2013
Messages
333
Hello,

I bought a ZT 0550 on ebay and used it for a day and started noticing it was getting stuck in the open position after a hard/solid deployment. The more I opened it the worse it got. It got to the point where if I wanted to close the knife I had to use something to pry the frame lock back out. I returned the knife to the seller and they said it was a manufacturing defect and they sent me out another. The first day it was fine and I had no issues. It is now my second day and I am starting to get the same problem. It is not as severe but it is very difficult to pull the frame lock back and close the knife and it seems to be getting worse. The harder the deployment the more "stuck" it is. The lock surfaces that touch when the knife is open seem to be smooth with no abnormalities.

Just curious if anyone else has experienced this. If so, did the problem work its self out in time or am I just very unlucky and got two bad blades?

Thanks
 
It sounds like it needs to break in. Take a sharpie and color the area on the blade where the lock hits.
 
Dry the contact area on the blade tang. Then color it with a pencil. People say a sharpie works as well or better, but I've never tried it.

And yes this is very common with titanium frame locks, but it will break in after one or two applications of pencil lead.
 
It is common, I notice it happens more if the blade is stressed - haven't noticed it during solid lockup as much as after copious amounts of solid use.
 
Also make sure that the pivot is adjusted properly and loc-tited.
A loosening pivot will directly affect lock engagement.
 
When you say hard deployment are you wrist flipping it? I wouldnt recommend that on any knife, sure it will take it but its going to wear it out faster and can make a sticky lock problem worse.
 
Wrist flicking is only second to spine whacking as one of the worst things you can do to a folding knife.
 
fsatsil said:
I'm guessing because they think it looks cool?
Click to expand...

Its what non-knife folk do, Like when I let a co worker use my 0561. Which most certainly is the last knife you need to add wrist movement to when flipping or flicking!

To the OP,
Just relax and let it work itself, Mine stuck for a day or two and i kept using a credit card with a paper towel around it to dry the oil off the lock bar and also cleaned the blade tang with a Q-tip. That said I could still unlock it easily with my man thumb. It just grabbed alot.
Just be nice to it and give it time. Use a sharpie even.
I have since broken my 0561 down once and used loc-tite on the pivot. Even if the knife is layered in rem oil it will still just grab a little. Just remember the lock bar is strong. If you are comfortable remove some bend if your thumbs are weak?
It has broken in perfect, you just need to be patient with it and or learn to adjust the knife to your liking... If this was a bit of a ramble ive had alot of coffee while keeping up with the babies..
 
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Thanks for all the great info. As far as the wrist flicking goes. The detent on the ZT 0550 is very strong. So much so I actually need to give it a little momentum with my wrist if I want to be certain it's going to deploy. I think with time the detent will give a little as well and not be so strong. I actually did not know that it was harmful to the knife, glad I now know!

What does adding sharpie/pencil actually do to help solve the problem?
 
TkSteve said:
Thanks for all the great info. As far as the wrist flicking goes. The detent on the ZT 0550 is very strong. So much so I actually need to give it a little momentum with my wrist if I want to be certain it's going to deploy. I think with time the detent will give a little as well and not be so strong. I actually did not know that it was harmful to the knife, glad I now know!

What does adding sharpie/pencil actually do to help solve the problem?
Click to expand...

It serves as a type of dry lubricant. Titanium will gall since it is softer than the steel tang, and the pencil lead allows it to glide smoothly as well as break in after a period.
 
My detent was really hard when I got it too. After several hundred openings its smooth and just takes a flick of the stud to snap it open. Also dont press on the lockbar when you open it.
 
Yea I was having problem of pushing down on the lock bar when I first got it. I have since changed my grip when opening. Just was fooling with it and I can absolutely open it without any wrist flick. I was mistaken to think I needed to do that to deploy the blade. I think I was opening it to hard and it was exasperating the lock issue.
 
What causes this? I understand that different metals can gall on each other, but I've owned many Ti liner knives and most do not exhibit lock sticking and are locked up very secure. Is it a problem with the tang/lock bar alignment/angle? Too much mating surface contact, not finishing the tang/lock bar face smooth enough, etc? I've always felt when I've handled a knife if the lock bar was sticky it was simply poor design/quality control.

As others have said pencil lead or graphite is a good dry lube, and wrist flicking is super hard on most liner/frame lock knives, people do it because it looks cool trying to emulate an auto knife, whats more sad is that manufacturers have started to reduce detent strength and compromise the knife's resistance to opening inadvertently in the users pocket to try an cater to this consumer trend.
 
It just happens. If it goes away it is clearly the surfaces are working out. If not there could be an issue.
Also My zt has a stronger lock bar than many other frame locks ive owned and it still does not stick. It has a perfect angle mating to the tang face. So my best assumption is that it is the angle and the surface finish wearing in at the beginning. Also, oil or a dirty lock can cause this.
 
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