Sebenza 25 lock stick

B

Bcamos

Joined
Mar 7, 2013
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My Sebenza 25 has developed pretty bad/consistent lock stick. I've cleaned it up and scrubbed the mating surfaces. There's a small divot on the tang where the ceramic ball meets the lock face. This knife if definitely a user, as I don't baby it at all. It's used as a tool. I certainly plan on sending it off to the spa to get checked out, but I'm wondering if anyone else has experienced this with their 25/Umnum.

I'll try to grab a video later.
 
https://vimeo.com/136941232

Here's a video. Turn up the volume and you can definitely hear the "click" when the ball snaps out of the divot.

211b0eb1b4c9fee07fd36b78eb4ddc35.jpg


Picture of the divot
 
Depending on how badly it sticks, I might be inclined to want to keep it that way - a "lock-detent" actually sounds pretty cool.
 
Nope, don't have that problem on any of my 25's.
That looks like a deep divot, cant say I've ever seen that before.
Looks like you need to send it in.
 
A slight stick is normal and desireable as it seems more secure. The divot in your pic is definitely not normal at least in my experience.
 
Mine is a very early one with the press fit stop pin, and it has had very deep lockup and a tiny bit of stick since new. CRK did a clean and tune when I stopped by a couple years ago, and they said it was fine.

That said, that is the deepest intent/groove that I have ever seen in a 25/Umnumzaan. (Not that I am any kind of expert...)
 
The mark on your lock face does look more pronounced than you would normaly see, there is usually more of a track to the point where it stops rather than just a dimple so that is probably why you are felling the action more. You can try working the lock to flaten out that edge of the dimple. There is also the after market LS carbonfiber scale you have on the knife that could be throwing things off. :)
 
Haze said:
The mark on your lock face does look more pronounced than you would normaly see, there is usually more of a track to the point where it stops rather than just a dimple so that is probably why you are felling the action more. You can try working the lock to flaten out that edge of the dimple. There is also the after market LS carbonfiber scale you have on the knife that could be throwing things off. :)
Click to expand...

I'm pretty positive the scale had nothing to do with it. It really is a user. And I don't mean cutting open boxes and sandwiches. This knife cuts anything and everything I need it to. Cut through roots, de limb small trees, processing game, scrape grout, cut drywall and open freeze pops for my daughter.
 
I have no doubt the knife cuts, I know mine does. :D

The issue with lock stick is coming from somewhere so the possible issues need to be highlighted untill they can be discounted. That is an unusal working mark on the blade tang so I have to wonder where that came from. :)
 
Quick question, do you flick the knife open with either thumb or wrist action???
 
Haze said:
I have no doubt the knife cuts, I know mine does. :D

The issue with lock stick is coming from somewhere so the possible issues need to be highlighted untill they can be discounted. That is an unusal working mark on the blade tang so I have to wonder where that came from. :)
Click to expand...

Certainly. Though it definitely didn't come from a scale. My explanation was a suggestion that it came from a long life of hard use.
 
I have had an Umnumzaan that has been my main user for about 5 years. The tang mark on that knife is quite different to yours. :)
 
I'm with Haze on this one The lack of a track from the detent ball is unusual at the very least.

To me it almost looks like it had to be a homemade mod or something. I have a hard time seeing how the ball could have just "made" a deep divot like that with no track. Is there any up and down blade play at all?
 
Corskin said:
I'm with Haze on this one. The lack of a track from the detent ball is unusual at the very least.

To me it almost looks like it had to be a homemade mod or something. I have a hard time seeing how the ball could have just "made" a deep divot like that with no track. Is there any up and down blade play at all?
Click to expand...

I'm going to assume there is a track on the knife, but it is washed out in the photo. You can see a bit of it on the left side of the dent.
 
There is a very pronounced and obvious dimple on the lock face and that is unusual. That dimple seems to be acting like a "detent" and is causing the lock stick. How it got there is the obvious question. :)
 
Tripton said:
I'm going to assume there is a track on the knife, but it is washed out in the photo. You can see a bit of it on the left side of the dent.
Click to expand...

Wouldn't the track be coming from the ti side with the lockbar? The lockup looks way early which also is why I thought it may be a mod.
 
Corskin said:
Wouldn't the track be coming from the ti side with the lockbar? The lockup looks way early which also is why I thought it may be a mod.
Click to expand...

Ah, indeed you are correct sir. I don't know what the hell I was thinking. :D

Now that you point that out, it is a REALLY early place for a dent like that. Very, very strange.
 
No worries Tripton. I thought the same thing as i followed the thread all day; right up until the time I made my first post on this tonight.


Anyhow, OP - I have a few questions as it seems some of us are intrigued by this. It does seem unique.

- did you buy this knife new?
- is the divot the same size as the detent ball? Can you provide side by side pictures of the tang and detent ball?
- is the back of the tang (around the divot) polished or can you see some grind marks on it?
- is there any vertical blade play?
- has this knife been subject to hacking or jabbing? Any super hard blows, batoning, etc?
- do you flick it open? if so, how hard do you snap it open?
 
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My 25 has seen "real work" as well. It has a definite track to where the ball stops, and what you might call a slight divot. Nothing pronounced like that.

My best guess is the thicker-than-normal (or so it appears to me) aftermarket scale is preventing the pivot from screwing in all the way, or maybe from being held firmly. Also, the factory bevel on the back of the pivot screw precisely matched the factory bevel on the slab. I could see that if there is any mismatch, it could introduce play in this assembly. This play may be almost unnoticeable, but create a situation that as the knife is opened, the ball sips off the end of the tang, takes up the slight slack in the assembly, than slams back into the tang, creating the divot.

I would sand the divot flush, with very fine sandpaper, and swap out the CF scale and see if the problem comes back. Or just live with it. Might be the price you pay if you like that scale.

Just my two bits.
 
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