ZT0301 Bronze washer eroding

D

diversionmary

Joined
Sep 27, 2006
Messages
320
I've had my Kershaw/ZT0301 for a little over a week now, and it appears that the larger bronze washer is eroding from the blade's motion when closing. Where the framelock and the blade meet when open, that piece of the blade is scraping by the washer when closing and slowly carving a 'scoop' out of it.

It's hard to explain, I need to take better pics of it:

485600565_ab854d2c85.jpg


10 o'clock on the large washer. Do all bronze washer/framelocks have this problem? Should I worry about it?

Edit:
You should be able to see the washer thinning right here:
afg.sized.jpg


Click for bigger
 
You should call Kershaw customer service. They are great! And you may discuss your option - the new washers or new knife. For this price you may ask for perfection and I am sure they will deliver it to you.

I hope Tomas will see this post and replay. Looking forward to see another example of excellent customer complain handling from him...

Thanks for sharing this with us, I will check it in my ZT302. So far it was just perfect.

Thanks, Vassili.
 
That doesn't look normal. Vassili is right, call up Kershaw and they'll take care of you, their customer service is top notch.
 
Yeah I linked to this thread in the main Kershaw Knives thread. I've seen Thomas go above and beyond and I'm not worried about it if it is a warranty issue. What I am worried about is if it's a design flaw with the knife or model itself. You can see bronze scrapings and dust on the washer side of the blade lock above. The glinty bits next to the worn washer = bronze filings.

I took it by a knife store after work to see it vs. a display model, but they don't carry zt, nor had they seen one before. :) It got passed around a lot and I received some condolences regarding the washer. The other knife store in town does carry zt so this weekend I'll go compare I think.
 
Well, I tell ya. I'v switched to teflon washers in all my knives due to similar observations. I used to use nothing but PB washers in all my custom folders and rebuilds. Here in the last year I've had a few come back to me for other work. One was a custom I did about two years ago. The customer decided he wanted a low rider pocket clip on it now and it didn't have a clip at all before. I got it took the clip side scale off and got inside the folder as I normally would to do a clip for tip up right hand carry and the pivot looked horrible. I didn't document that one, just cleaned it up and did the work sending it home. Then it happened again with other knives.

Recently I got a Stretch in that I redid in titanium liners, PB washers, and of course reused the original blade. He wanted new handle scales on it to replace the old Micarta ones I did. Here is what I saw when I got inside it in these two pictures. This knife was used for food prep, rinsed under the sink, and treated as it had always been treated. It didn't show this the last time I took it apart when it was still the factory set up and had no washers.

Alls I can figure is that its some kind of beginning stages of galvanic corrosion taking place. The other thing I now know is that by replacing the washers with Teflon the problem goes away. I have four knives I know of now that I've replaced the washers in and kept up with over time. None have had this reoccur after replacing the PB washers with Teflon washers.

So, what does this mean? Well, sometimes you have to go where the facts lead you I guess. I'm not saying I know for sure but for me the path of least resistance and the easiest cure was swapping the washers. It seems to me PB washers are no good on kitchen use, food prep use, tactical or outdoors folders or survival folding knives. I'd measure the washers thickness using a good digital caliper and find some the same thickness from Texas Knifemaker supply, Jantz supply, Knife and Gun finishing supply, or Sheffield supply that will fit your pivot diameter and swap them if you are seeing this in your folders. Its cheap and easy to do.

STR
 

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Oh yeah. Here is some info I found when researching it. Just a quick paste.

"What causes galvanic corrosion?

For galvanic or dissimilar or electrolytic corrosion to occur, three conditions must be met:

the metal join must be wet with a conductive liquid
there must be metal to metal contact
the metals must have sufficiently different potentials

So, look at your particular situation. Does the product have the above going on? If so make the necessary changes to insulate the metal to metal contact or reduce the risk of wet conditions or both."
Or carry Spyderco H1 blades. :D

STR
 
STR, thanks for your observations. Now I don't know whether to request for PB on my customs or just plain old teflon. Tom Mayo uses teflon - I love his knives. But I love my HInderer - it uses PB.
 
I thought PB washers walked on water for many years. I'm now using Teflon whenever I can. FWIW

If you note the Stretch picture above of the full knife you can also see very small signs of rusting taking place on other areas away from the pivot. This indicates there may be issues going on between stainless and titanium that have nothing to do with the washers. So it is possible that some minor effects could be seen if there are metal to metal, with water contact between any dissimilar metals I guess. Live and learn. I've heard some say that anodizing the titanium helps but I have my doubts about that. Its just best to replace the spacer/spring holder with a same metal material and do the best you can to keep the other areas dry where two different metals meet.

STR
 
Anodize for things like aluminum and titanium are electrically built up layers of oxide. Many metals are corrosion resistant due more to the oxide layer than the metal itself.This is true of stainless steel and there is a 'passivation ' treatment to build up an oxide layer on stainless but I don't know how often it's used on knives..The will be a difference in the electric potential between a bare metal and one with an oxide layer and a good galvanic series table will show this ....With the very short life of the knife shown by diversionmary I would conclude it's just wear not a galvanic corrosion problem .I would look for dimension problems and/or rough surfaces.
 
It was easier to just replace the washers. :D

But its good to have a metal guy chime in. I don't recall rough surfaces. I do know that I took the knife apart, rebuilt it and got it back about one year later. (above pictured knife I mean) So, whatever caused it did so in a year or less.

Thanks

STR
 
Hey Mete. Is that process to build up an oxide layer on stainless something that can easily be done or set up in a shop?

STR
 
I have putting in PB washers like a madman the last year or so and now I see STR's pic.... doh.


Is there not a firmer alternative than mushy teflon ? I mean I have a few knives with teflon washers that are rock solid but I fear over time teflon will poop out since it's a plastic.

Also , did the folks that had thier PB washers corrode the pivot area like that , did they take care of thier knives like most of us on here do ?
I mean if I use mine in any sort of moisture (vegetables , fish cleaning etc ) it gets a thorough drying before being stowed in my pocket or wherever.
 
A lot of it is maintainance related, or I should say lack of, but unfortunately the majority of the buyers of knives don't have the word maintain in their vocabulary. I've not had problems with teflon washers wearing out. I should have documented the condition of most of the PB washers I've replaced though. They looked worse than the blade. It is evident to me that the majority of the rusting took place around the most electrically conductive componet, that being the PB washers but if the blades were dried out with a hair dryer or blast of air and a clean cloth it would probably prevent a lot of that rusting from occuring in the first place.

STR
 
Looking at your photograph and hearing about the "chips" and such, it seems the prime culprit would be the edge of the blade that bears on the cut out portion. As this is the "high side" of the lock, I would lightly chamfer the edge where it bears on the washer to avoid any further cutting of the washer . . . I'd also ask Kershaw for a new washer.

Just lightly break the edge with a stone or some 1000 grit paper then polish it a bit so it no longer cuts at the washer.

Of course, it could be a design flaw in which case I would recommend purchasing a couple dozen washers and simply replacing one when it shows wear.
 
Rebeltf, Mushy teflon ?? I thought it was like many plastics - however - they're building a bridge here and I've been photographing it. When large girders expand and contract with heat and cold they used rollers on one end so the girder could move. Not any more . They are using a very hard rubber pad with a thin layer of teflon on the support. On the bottom of the girder there is a stainless steel layer with extremely smooth finish. So it's stainless steel to teflon to see movement !!!.....STR, I'm not sure. The usual treatment was with nitric acid but now due mostly to environmental things they are using citric acid more. Maybe you could find something on google. Otherwise you could find a stainless steel processer who would do it.
 
mete said:
Rebeltf, Mushy teflon ?? I thought it was like many plastics - however - they're building a bridge here and I've been photographing it. When large girders expand and contract with heat and cold they used rollers on one end so the girder could move. Not any more . They are using a very hard rubber pad with a thin layer of teflon on the support. On the bottom of the girder there is a stainless steel layer with extremely smooth finish. So it's stainless steel to teflon to see movement !!!.....STR, I'm not sure. The usual treatment was with nitric acid but now due mostly to environmental things they are using citric acid more. Maybe you could find something on google. Otherwise you could find a stainless steel processer who would do it.
Click to expand...

Yea , mushy. What I mean is take a teflon washer and bite down on it , what happens ? I'm not saying teflon is not strong but it is mushy. :D
 
I have never seen PB washers or pivot areas like that. Of course I take care of my knives. :p
 
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