ZT 0200: Lock not making full contact vertically.

Macchina

Macchina

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Apr 7, 2006
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I got a Kershaw ZT 0200 about a month ago. I've carried it for about 5 days and have used it to open a few boxes. I've opened it under 100 times. The lock bar started out engaging about half of it's width, perfect for a nice long wear-in. After opening it about 80 times, the lock bar is now a little more than fully engaged, a little faster than I'd normally expect from a liner lock "settling". I was looking it over yesterday and noticed that the liner lock does not engage along its entire height, but instead only at a single point! It is a little hard to see in the picture, but the liner lock touches only on the very top corner. I can see light both along the height and width of the liner lock. The rest of the contact surface angles away to allow about a 0.020" gap at the bottom. I added a rudimentary sketch to demonstrate what I mean. I don't if I should send it in to have it replaced, or use it and risk premature wear-out (Maybe it will wear in, but it looks like the liner lock will go to the far side before the bottom touches the blade). I compared it to my other liner locks from benchmade, Spyderco, and Kershaw and they all show full contact with the lock bar. I have never sent anything into Kershaw, but have been scorned by other knife companies for sending in expensive knives with bent blades and blade play. If anybody else has a ZT 0200, could you check this out and see if it is how they all are?
Thanks,
Michaelmcgo
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I have seen similar on other knives..
but that does seem a little extreme..?
I would like to know too
 
Give em a call, Im sure they will replace it with one that fully seats. I would imagine a gap like that surely would have been noticed by others (and we probably would have read about it) if that is in fact how they are suposed to be.

Just curious, are you having blade play with it or is still solid?
 
IIRC thats the only part that should touch.
 
My 0205 has a very small gap at the bottom of the liner lock, but nothing as significant as yours.
 
Ive heard someone say.. two contact points are good .. And others say one...?
I think once it wears in.. It will sit more flush and tighter over time..?
 
Same as mine. As it wears the contact surface increases in area in my case. I personally prefer a larger contact area and maybe a more circular blade cut-out so that it'll significantly increase the time it takes for the lockbar to travel to the other liner.

No worries, it'll get better with use. As the surface increases (as you wear it down) then the time taken to further make the lockbar travel will take longer cause you have a larger area to wear out. Something like it's not a linear time vs lockbar travel but more like a exponential relationship.

I still think a straight and flat cutout shape on the blade is not as good as a partially circular one though.
 
Kershaw customer service is fantastic. Just shoot them an email or call them, and I'm sure they'll get you taken care of.
 
The one I had made contact the exact same way. It's liner was not cut at an angle, instead it was cut straight across so the first edge only made contact.
I brought this up here over a year ago.
http://www.bladeforums.com/forums/showthread.php?t=492105
I was told not to worry about it because an other's 0200 was the same and they'd had no problems.
I thought it was a little strange all the rest of my cheaper Kershaws with liner-locks had regular flush lock-up.
 
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I sent them an email.
Weird that their premium line has this "problem" when they obviously have quite a lot of experience with liner locks. I'll see what they say.

The gap is so large that I do not believe the bottom of the lock bar will ever touch the blade contact surface. I do really like the design of the knife, and the liner lock is very secure, I just want something that is going to last a while and not develop blade play quickly.
 
I wasn't comfortable having a liner only making contact on the edge.
It would have to grip less hard, compared to a well fitted lock-up. (I don't see how it would ever wear in by use being it didn't fit well in the first place)
The knife is made very nicely other than that one very annoying factor.
My JYD II composite blade cost nearly half as much and it's liner is well fitted and it's about the same thickness as the 0200.
 
Easier to make it this way.

If contact surface has small or no gap then imagine that if manufacturing variations may result in the contact surface being in the 'deeper' part instead of the more ideal 'outer' part.

Why is the 'deeper' part less ideal is cause it's close to the pivot and because of physics (moment calculation) it will be less resistant to closing forces.

This is why I personally do not see this small contact area in front as being problematic. Though I prefer large contact area I like the fact that it will become larger in time due to use/wear as lockbar travels deeper.

I prefer a slightly circular profile to the blade cutout instead of the straight (like for ZT0200) cause it will very significantly increase the service life. Meaning it takes much much longer to travel. Plus under impact the lockbar will not slide and become unlock (just stating possibility and my own actual experiance with the ZT0200). A straight cutout/profile can result in lockbar moving into the 'unlock' position when for example under spinewhack.

PS: I will try to explain better, picture/concept is in head but having difficulty in expressing/explaining you know :)
 
Mine is the same way. I fully expect that it is an intentional design. With the way strain is applied to a liner lock, even with the lock above, the entire locking system is holding the knife open. That small portion of contact wont flatten out or "flow" from pressure before the liner itself has tried to fold in half.
 
If you break the lock width into thirds you have a window of 'foot print' in this style of folder in the bottom third part of the lock for making a contact. No lock of this type should contact fully, no lock of this type should contact in the middle or at the top. Note the top is the part closest to the stop pin. Bottom is by the thumb grooves. The bottom third part of the lock needs to connect to the blade. This can be clear at the bottom, the bottom 2/3rds if we take that bottom third and break it in to thirds again or the full bottom third of the lock width providing it isn't enough to allow blade movement. Ones like this I've seen on Sebenza models to make the lock wear more even and so it sticks less and also to wear longer combined with a good heat treat to put some good anodizing going on deep inside and out are the ones I use as the standard to judge by.

Anodized parts are near ceramic in hardness so that helps to wear better for the lock also. Technically speaking a correctly made integral lock should contact at the two farthest points from the midline of the pivot point to allow for a good solid lock up 'tripod' for strength. One point is the lock contact, the other is the stop pin. The ones that connect in the middle or fully allow what we call 'blade roll' and you can see that in some that although come with a good lock up that appears solid when the blade spine is put under a load it allows the blade to lift up momentarily from the stop pin just enough to bug you. A lot of the Buck Strider 880 and 881 models had blade roll. This was why. I fixed many of them by taking contact out of the middle and adjusting the bottom to come out further with a quick peen using a flat end punch and ball peen hammer. They left here rock solid by adjusting it. That is done by many makers and manufacturers as well so its quite common to see even in new knives on occasion.

Your lock is made right. Use it and enjoy. If it contacted fully you'd be writing about blade movement up and down verically from noticed blade roll trust me..

STR
 
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If there's no blade play, I'd say no problem. I'd worry about it developing play when and if it does. Then send it in. Either way, I'd be highly surprised if you were "scorned" by Kershaw/ZT CS.
 
J_Curd said:
Mine is the same way. I fully expect that it is an intentional design. With the way strain is applied to a liner lock, even with the lock above, the entire locking system is holding the knife open. That small portion of contact wont flatten out or "flow" from pressure before the liner itself has tried to fold in half.
Click to expand...

No offense, but that doesn't make much sense. The entire liner is made of the same material. When pressure is applied to a system, the system fails at the weakest point. By definition, the point of contact receives the most direct pressure. Because the sectional area is also at is lowest point there, that area will deform before any other part does. I design machines for a living. Metal will always wear when it moves against metal. The best way to prevent wear is to add a bearing, when that is not possible you add material to prevent the area from wearing as quickly.
 
There is no way to make it connect fully to where its hitting evenly on each part of the lock contact. Many tried its just not feesible. You look at the mark put on the blade from a typical stop pin that slams it over and over again. The contact foot print is not that big. The lock whether it be stainless or titanium wears fine against the blade and is designed to self correct with wear from the spring action. Sure they wear. Thats what an integral lock does from the moment its first opened. Sure the thinner and even some of the thicker ones can be indented if you spine whack it. Thats abuse. Its not designed to be slammed against the lock that way. Its not considered normal use to do that. Most all including myself would call that abusive and if the blade develops vertical play after someone does that well, they get what they deserve.

Used as its designed the system comes together well enough to function effectively in most uses to keep the blade secure long enough to make a cut and then fold it away. No lock is perfect. Some wear better than others. By some definitions the integral, IE, frame and liner locks begin self destruction from the moment you start using one. It is of little concern though since most wear as they are designed for quite a while even with the design flaws inherent in the lock up and overall function.

STR
 
michaelmcgo, between what STR has said, along with the info from the Strider link, you've got two concurring answers. My 0200 is the same way, and after talking with others about this I was told it's the best way to make the strongest lock up. I've had my 0200 since they first came out, and I've opened it and used it hard thousands of times. No failure, and the lockup is still 100% rock solid.

Return it if you wish, as that is what the CS department is for. But I'd be willing to bet they will tell you it's right the way it is.

Let us know what they say.
 
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