Tuning lockup on my ZT0551

00ChevyScott

00ChevyScott

Basic Member
Joined
Dec 3, 2010
Messages
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Before anyone says to send it in for warranty work, this is a blem given to me by Thomas W and carries no warranty.

I love the knife, it's basically the only thing that has kept me from spending $400 on a strider. But sadly I haven't used it much lately because it has developed some up/down blade play that I cannot fix. I have taken the knife apart multiple times, adjusted the pivot and handle screws, bent in the lock bar (this helped for a week or two), but there is still play if you put pressure on the blade. I want to use the knife, and could handle some blade play if it was left/right, but up/down play just ruins it for me.

Is there anything else I can do to fix this? I cannot bend the lock bar over anymore and even putting pressure on it while gripping it doesn't really help all that much. It also doesn't have a stop pin to adjust as it uses the thumb studs as part of the lock. To me it feels as if the thumb studs are placed a hair too far forward on the blade and aren't putting enough pressure against the lock bar. When I received this knife, it had zero play. After a few months of light use, but a fair amount of playing with, it developed some play.

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Maybe this video could help you out. However, this guy seems to be using his method to decrease lock bar engagement, although it can be used to adjust lockup either way. So, I'm not entirely sure it will do anything for you, but maybe give it a try. Can't hurt...
 
Watch from 1:50-2:20
[youtube]2Yauqhx7Akg[/youtube]

He basically put an O-ring on the thumstud to stop the movement.


He also carbodized the lock bar but that was just to stop the wear. I guess just making the titanium harder, although I've never seen another maker use this method for a lock bar.
 
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From what I can see in the photos, you may need to have somebody with experience to grind down the tang on the knife slightly so that the angle of the lock-bar matches the angle of the tang on the knife for perfect contact.

Basically, the only way I've seen to fix this is to have a belt sander with a surface perpendicular to the sanding area and to lightly brush the tang to correct the angle.

If you can't find somebody, I can point you in the right direction to get your issue fixed, just PM me.

-M
 
Thanks knivesandguns. Ya when I take the blade out of the knife and look at the tang it almost looks concaved.
 
And how will you solve the problem of vertical play after filing/grinding down the tang and creating a larger gap? Not trolling here but perhaps there are smaller steps 1st likke the 1st video to be tried first. It'd only take about 10 minutes.

BTW, Hinderer carbidizes his lock bars, maybe others two. CRK come with some soot on the lock bar but don't know what he calls his method of hardening.
 
cziv said:
And how will you solve the problem of vertical play after filing/grinding down the tang and creating a larger gap? Not trolling here but perhaps there are smaller steps 1st likke the 1st video to be tried first. It'd only take about 10 minutes.

BTW, Hinderer carbidizes his lock bars, maybe others two. CRK come with some soot on the lock bar but don't know what he calls his method of hardening.
Click to expand...

It's not creating a larger gap, per se. It's merely slightly re-shaping so that the angle matches. You're not removing that much material, only brushing the tang on the sander for brief moments.
 
knivesandguns said:
It's not creating a larger gap, per se. It's merely slightly re-shaping so that the angle matches. You're not removing that much material, only brushing the tang on the sander for brief moments.
Click to expand...

Granted you have the skills to just "touch it up" a bit. There's still going to be removal of metal and it could translate to an ocean of play - maybe.

I'm no expert but I've "tuned" two lock bars and boy it wouldn't take much to mess one up and I've just bent a couple of them a hair, not increasing the already critical space needed for stopping vertical movement. Once you have play up & down I can't see how you'd get rid of it by removing stock. I still recommend trying to slide the ti slab up & the other down as in the video #1.
 
The video trick did not seem to make any noticeable difference. I tried it twice and it still looks/feels exactly the same as before.
 
Sorry to hear that. I guess that's why some of them come with 4 XXXXs. I see them on the exchange every week for around the same price they were sold for and they're either new or like new. Maybe you should score one under warranty and then play with the blem. If I love a folder I always buy a couple - but that's just me. Good luck man!
 
You guys do realize the lock face is supposed to be concave right? Putting a straight angle on it will cause the lockbar to walk off the face, especially if you carbodize the lock bar face as it will be less prone to sticking/galling.

Why not just adjust where the lockbar bends to a spot slightly farther down towards the butt of the handle? I've done this on two Emersons (liner locks) and one Kershaw (framelock) with success to get earlier and most positive lock up, as it basically extends the lockbar a hair. Liner locks can also have the lock bars peined slightly to gain some extra length but doing that to a framelock would be a really messy solution.

The best solution in a standard framelock is putting in a bigger stop pin, so why not look at that type of solution here, by finding ways to widen the thumbstuds, Orings, jb weld, epoxy, all are better solutions to modifying the blade face angle, this is Kershaw/ZT here, do you really think they got that wrong?
 
00ChevyScott said:
The video trick did not seem to make any noticeable difference. I tried it twice and it still looks/feels exactly the same as before.
Click to expand...

Both of mine have vertical "play" if I grab the blade and really tug up and down. Matter of fact, all 8 0551s that I've held have had that.

I don't think you're experiencing play, especially since the oring trick did not work for you. I think you are experiencing VERY slight lock rock, which is just unfortunately a result of the design of frame locks. It is inevitable that MOST frame locks will have some "give", especially if you are looking for it.

Hold the handle, the handle alone. (with the blade in the open position) Now shake the knife up and down. Do you hear clicking from the blade moving back and forth? If not, then you don't have "play", you have some slight movement in the locking system, which is just going to happen. VERY few frame locks can avoid this. Strider and CRK are the only ones that I know of, and the way Strider fixes it is by having the lock meet at such an extreme angle that it wears out in 6 months. Stop obsessing over a TINY amount of movement and use the knife, it's not going to affect anything.
 
CrimsonTideShooter said:
Both of mine have vertical "play" if I grab the blade and really tug up and down. Matter of fact, all 8 0551s that I've held have had that.

I don't think you're experiencing play, especially since the oring trick did not work for you. I think you are experiencing VERY slight lock rock, which is just unfortunately a result of the design of frame locks. It is inevitable that MOST frame locks will have some "give", especially if you are looking for it.

Hold the handle, the handle alone. (with the blade in the open position) Now shake the knife up and down. Do you hear clicking from the blade moving back and forth? If not, then you don't have "play", you have some slight movement in the locking system, which is just going to happen. VERY few frame locks can avoid this. Strider and CRK are the only ones that I know of, and the way Strider fixes it is by having the lock meet at such an extreme angle that it wears out in 6 months. Stop obsessing over a TINY amount of movement and use the knife, it's not going to affect anything.
Click to expand...

The O-ring trick may have worked if I found on small enough to fit just right.

And not trying to sound like a jerk but I'm not buying that. Why do none of my liner lock knives have play like this? It's practically the same style of lock.
 
00ChevyScott said:
The O-ring trick may have worked if I found on small enough to fit just right.

And not trying to sound like a jerk but I'm not buying that. Why do none of my liner lock knives have play like this? It's practically the same style of lock.
Click to expand...

It looks the same, but they aren't as similar as you think.


But, the reason your liner locks don't have play like that is because the liners are made of steel. They don't wear NEARLY as fast. Steel vs steel acts a LOT differently than Ti vs steel.


You can choose not to believe me. Doesn't change a thing.
 
CrimsonTideShooter said:
It looks the same, but they aren't as similar as you think.


But, the reason your liner locks don't have play like that is because the liners are made of steel. They don't wear NEARLY as fast. Steel vs steel acts a LOT differently than Ti vs steel.


You can choose not to believe me. Doesn't change a thing.
Click to expand...

If the Ti in my 0551 wore that fast in the 2 months I used it, why the hell would anyone use it....?
 
Maybe you could try gently bending the lock bar up vertically to try to get the angle to match better? Not sure if that might run the risk of tearing or stress fracturing the thin part of the Ti lock bar where it meets the frame though... If any of that makes sense... :) Definitely be careful though, I wouldn't blame you if you didn't want to chance it...

Also, how 'bout another even more off the wall suggestion? Take some fine copper wire and wrap a few coils, or more depending on the size of the wire, tightly around the thumb studs. Then a drop of super glue to hold the wire... This would just be an alternative (probably a less ideal one) to the o-ring trick in the absence of properly sized o-rings...

Sorry if those suggestions are kinda crappy, best I could come up with so far... :o
 
The stop pin/thumb studs measure out to .250. You might try some small sections of stainless thinwall tubing placed over the studs. Then grind or file them down till a good tight fit is reached. It might work. You could also possibly pay a knife modder/maker on BF to fix it for you
 
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