Suggestion to reduce Sebenza lock wear...

Professor

Professor

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Apr 6, 1999
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Greetings all. I was wondering what would happen if the blade tang-ramp on Sebenza's was ground concave instead of flat?

That is to say, like the tang ramp of the now-discontinued BM Sentinel. The ramp would curve significantly out toward the opposite liner, thus making it nearly impossible for the lock to wear all the way to the opposite liner. I've often wondered why all liner-locking folders were not made this way. Perhaps doing this would make the lock more likely to accidentally disengage with wear, but I can't substantiate that in my mind.

While there could be an unforeseen problem with this design, in theory wouldn't it extend the locking-liner life? It's hard to describe it if you've never seen the Sentinel, but hopefully you get what I mean.

Any thoughts? Thanks.

Professor.
 
On the surface, this seems like a good idea. However, it leaves no accomodation for lock bar wear. When the Ti lock bar does wear, the concave blade tang doesn't let it move over any further, thus making the blade play problem worse.
How bout a tiny, screwed in, replaceable SS insert on the tip of the lock bar? Wonder if this would work.
 
I know what you mean with the end piece, sort of like the original Applegate folder by Gerber (though mine has it's share of accidental lock-disengagement tendencies). Conceivably, when worn out, you could replace the piece, and of course it would be more wear-resistent than the ti alone if it's a hard piece of stainless (as hard or harder than 410).

With the concave tang, again with the visualization of the BM Sentinel in mind, there is still plenty of room for wear. It's just that it wears much slower and at a much steeper angle than the presently-used angle.

Regardless, I think we're onto something here! I just don't like that I can physically (and without a great amount of force) push the locking bar all the way over on my NEW small Sebenza. Seems like there's got to be an alternative.

Professor.
 
I hear ya Professor.
I guess you can send it back to CRK and ask them to look at it. The solution to my problem was to replace the complete lock bar handle slab. But my problem was most likely due to fiddling by me, and not just wear. I wonder if Mr Reeve has given any thought to this situation though.
 
That is why the lock bar is heat treated, so it will wear longer.

I believe that the lock on the Seb series of knives is among the longest lasting locks of any knives made. It has only been one recent post on the wear of the lock bar which prompted this concern. Talk of changing the lock geometry is, to put it mildly, premature.

Remember that Chris Reeve made two phone calls to address this situation (one to the owner of the knife, and another to a poster who questioned the situation). Can you imagine how busy Chris would be on the phone if there were a genuine problem with lock wear? It seems to me that Chris' response was consistant with an UNusual situation, which warranted his personal intervention.

Remember that the knife is designed for the lock bar to travel further across the tang with sideways pressure from a firm grip on the knife; this is what makes the knife so safe. The worn knife in question had both up and down and side to side blade wobble with the lock bar all the way across. This is clearly an abnormal condition, not present in any of my knives.

It is good that posters are eager to suggest solutions to a problem. Better still would be if posters make sure that there is a problem to begin with before making suggestions for fixing it.

Walt
 
Walt,
The user with the Sebenza lock problem was me. It only had side to side play which I really don't understand. I would've thought that the strength of the screwed together handles pressing on the pivot area alone was enough to prevent side play of the blade, regardless of the lock bar wear.
You bring up an interesting point on the heat treatment of the lock bar. Is it just the bar that is heat treated or the whole handle slab?
BTW, so far, the new Sebenza that Mr Reeve sent me has been awesome. The lock bar has settled at 50% travel and that's it.
Lenny
 
The Sebenza Military has a lock surface on the blade with 75% flat and 25% curved or concave surface. It appears like a ski jump ramp, the locking bar however, is very thin and I would estimate .030-.040" thick. This system must be used with stop bushing that is eccentric on outside diameter wrt ID. The early Military design had problems with lock bar traveling across the blade and jamming in position, I beleive this answered that design weakness.

My preference is the present design by Chris, maximum contact of lock and knife ramp and local heat treatment on wear surface of lock bar. When has anyone ever heard of lock failure or slippage on a Sebenza? The stop pin sleeve is not eccentric but can be rotated to present a fresh surface when deformed with hard opening snaps. Simple elegant designs are much more difficult to manufacture due to tolerances, angles and metal to metal contact friction factors. The Sebenza may not be a hand made "custom" knife however, IMHO it is better than 99% of the customs available today.

Regards,
FK
 
I have been carrying my Sebenza for almost 10 years now, and have flicked and clicked open tens of thousands of times ( if not more!)I have never had a single problem, except to retighten the pivot screw after a LONG sesssion of open and close. The way I have used my knife, and I use it alot. I can see myself, God willing, handing this knife to one of my sons and he in turn passing it on. This is a LIFETIME using knife. Unless you abuse it, you should experience no trouble, BUT, if you do. The CRK shop will take of it. THANK YOU...........
IT is a SOLID design, well thought out and executed and has been around long enough to prove it. ENJOY!!!!!
 
I believe one of the reasons for the use of titanium in liner locks is that it "galls" to other metals under pressure, providing a lock that is less likely to slip. Replacing the end of the titanium bar with steel might be longer-lasting, but it might also result in a more "slippery" lock.
 
All due respect, Professor, but I believe you're looking for the solution to a problem that doesn't exist.
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ralph
 
Professor:
Your sugestions are well intensioned but Mr. Reeve has agonized over every minute detail of the knife his small company produces. If there was a better way to make the Sebenza lock, he would not hesitate to incorporate it in its production. His knives have served me well. I think all Sebenzanistas appreciate your thoughts regarding this thread. I gave my son-in-law a silver one-piece mountaineer and a BM 705 (for everyday small stuff) to take with him as he is joining the Navy in a couple weeks. I would have given him my small plain Seb but alas, I'm a southpaw and he's a righty. Thanks for interesting thread!
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Lenny; I stand corrected. Side to side play was indeed what you experienced. Vertical play was mentioned, along with replacement of the stop pin, but this was by people suggesting solutions without completely understanding the situation.

I believe just the lock bar is heat treated, although I am basing this on a picture in American Handgunner, which showed Chris Reeve heating the lock bar to red heat with a propane torch.

Thank you for correcting me about my error. I am delighted that you find your 'new' knife to be functioning perfectly.

Walt
 
Lenny,

While I did not completely follow the problem with your sebenza lock; if the play in your sebenza was side to side it seems you had an overly large pivot bearing which is an easily correctable problem (new bearing). The lock bar only minimally reduces side to side play. And if an overly large pivot bearing truely was the culprit, then a worn lock may have been a seperate incident entirely.
 
JoHnYKwSt,
Good point on the pivot bearing. Mr Reeve never stated exactly what the problem was so we can only surmise. In the thread, someone did some excellent detective work and found a very early review that I had done on my Sebenza. In it I stated that I bent the lock bar outward slightly (when it was disassembled) to make the lock easier to disengage. However, I did this when the knife was 1 month old. The problem didn't crop up till 2.5 years later. Go figure!
I really don't want this whole can of worms opened again, but, ever since my incident, I guess people have naturally been trying to improve on Mr Reeve's design. Looks like mine was the only incident of premature lock wear, and it was traced to "fiddling" by me. So, in reality, the design is probably optimized already.
Lenny
 
Lenny, as the Ti lock bar wears it will move further over. Remember, it has be set memory and is inclined to go over. The only thing that stops it, unless the knife is completely worn, is its contact with he blade. So, as the tolerance between the blade and lockbar oncrease, the lock bar would move further over only to be met by a part of the blade with mare material thereby eliminating the play that would otherwise exist. Browning Citori shotguns have been made this way for decades with a lock thet "wears in, not out" or so their slogan went. It works on shotguns. On knives, however, there is the stree that wants to push the lock bar back over if there were enough of an angle on the mating surfaces to induce the stress in that direction.

Hey, I do what I do, fairly well, I am told and CR does what he does. I wish I did what I do as well as Chris does what he does. Kinda think I'm not alone on this one.
 
Sorry to have seemingly touched a nerve with some. My thinking was that a slightly steeper blade tang ramp would decrease long-term wear. I'm of the opinion too that the Sebenza's about as close to simplistic perfection as can be. However, I also feel that stagnating with "what works" and not venturing to occasionally "fix what ain't broke" can be counterproductive.

Anyhow, I plan to carry the small Sebenza daily with other folders so I'll see firsthand how it wears. Thank you all for the responses!

Professor.
 
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