Pivot loosening by itself..

Django606

Django606

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Jul 22, 2005
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My NIB Large Micarta came Thursday, and on two different occasions since then, the pivot has become unscrewed enough so that the pivot and bushing can be pushed from side to side in the pivot hole. I realized it once while washing off the blade and again just now after I pulled it out of my pocket.

Can anyone help me? It says in the papers that LocTite should not and does not need to be used. Why is this, and why is my pivot coming loose? I was thinking it might have to do with me opening and closing the knife alot today, but I would not expect this to be a problem considering the way the Sebenza is built.
 
Hmm… I don’t know what could be causing the pivot to loosen. Maybe a washer is slightly pinched by the bushing? It can be hard to tell when that happens. You may want to take the knife apart and put it back together a couple of times. Or, you could just try tightening the pivot down a bit a more than usual and see if that helps.

With most folders, when you tighten the pivot screw, you’re bringing the two halves of the handle closer together. In the Sebenza though, the bushing acts as a spacer that keeps the two handle slabs at a set distance from each other. If the tolerances are right, you should be able to tighten down the pivot screw as tight as it will go, and still be able to open the blade without much resistance.
 
Hi,
I thought you mentioned in your other post that you have already dis-assembled the knife at least once.

Could it be you are not tightening it enough on re-assembly ?
 
In the papers it says to tighten to "hand tightness" and not "super tightness."

After reassembling, I tightened all the screws fairly tight, to the point where I was afraid to tighten them any more (because of the precautions in the paperwork)
 
There were several threads, over the years, that discussed this problem extensively.

It doesn't take much for one of the bronze washers to be slightly out of position, which can cause the pivot bushing to not be perfectly centered.

Take the knife apart, clean all of the old lube off, relube, and reassemble. . . .making sure that all of the parts in their proper position.

The pivot screw should be tight, but not to the point where the allen wrench is twisting under the torque. :D

On a new Sebbie, the blade action should be smooth ~ not fast. Once everything is seated and all of the mating surfaces "break in". . . .you'll begin seeing/feeling the action quicken.
 
I had the same problem on a wood inlay annual edition. In fact, it got sent back a few times too to no avail so eventually I just had the whole thing exchanged. It's the only Sebenza I've had problems with.
 
I reassembled it this morning, and all day it has not loosened. We'll see if it holds up though.

Does anyone know why these screws [are supposed to] stay tight without LocTite?
 
From my understanding it has everything to do with close tolerances and the pivot bushing acting as both bearing and spacer. The precision fit keeps the handles properly spaced. . . .so. . . tightening or loosening of the pivot screw should not have much affect on the blade action. In effect, it's a metal to metal bond ~ pivot screw threads to pivot barrel threads.

Keep in mind, the Sebbie was designed with the user in mind. In that, the user is able to break the knife down in any condition and by only using an allen wrench. If LocTite is used (i.e., blue), you would need a heating device (i.e., hair dryer, soldering iron, etc.) to heat the screws so that the bond could be broken.


On a side note. . .to give you an example of CRK's close tolerances (I believe it was Anne that posted the info) ~ the clearance in the pivot area is 0.0006", which is the right amount of space for the lubricant. :eek:
 
Django606 said:
I reassembled it this morning, and all day it has not loosened. We'll see if it holds up though.

Does anyone know why these screws [are supposed to] stay tight without LocTite?
Click to expand...

Most knives can't be tightened fully since they don't use a bushing, so the they need loctite to fix them on the desired pivot action.
A Sebenza can be tightened 'all the way' without affecting smoothness, therefore you can tighten it pretty strong, and the 'friction' from steel-on-steel and steel-on-titanium will keep the screw in place.
 
I understand. So the tolerances are so tight that there is no room for movement, anything that would loosen a screw in a lesser knife.

Thanks guys. Still hasn't loosened, let's hope it holds up.
 
Ted Voorde said:
Most knives can't be tightened fully since they don't use a bushing, so the they need loctite to fix them on the desired pivot action.
A Sebenza can be tightened 'all the way' without affecting smoothness, therefore you can tighten it pretty strong, and the 'friction' from steel-on-steel and steel-on-titanium will keep the screw in place.
Click to expand...

That's how I understand it. Maybe you didn't tighten it enough? I don't understand how it can come undone by itself if it is tightened all the way.
 
Like GigOne said, one of the washers could have been slightly out of place on the bushing. Yes, the screw was very tight. Most likely tighter than CRK advises.

So with repeated opening and closing, the screw began to loosen.

That is why other knives have pivots that loosen without loctite, because their tolerances are not as low as CRKs.
 
I had this problem with mine. It cleared up after a good cleaning and tightening. Just put a bit more torque on it than you have been. It will work out fine!
 
Make sure the pivot screw and the threaded hole in the pivot pin aren’t contaminated with oil or grease. You could use 99% rubbing alcohol to degrease these parts. Lubricate the normal areas when you reassemble the knife.
 
I belive some people do not tighten them tight enough.
I have gotten two in trades where the pivot screw was loose when I took them apart but after cleaning and reassemble they never loosened up again.
 
It's been about 4 days, so I don't think it is going to loosen anymore. I'll just have to be more careful when reassembling from now on.
 
Django606 said:
It's been about 4 days, so I don't think it is going to loosen anymore. I'll just have to be more careful when reassembling from now on.
Click to expand...


Good to hear !


Now. . .go forth and make you Sebbie gathering multiply. :D
 
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