Sebenza 31 Lock Rock?!

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I wondered if we'd see evidence of the lock up "settling in," but it looks exactly like the lock face on both my large 31 and my Inkosi, neither of which ever exhibited lock rock.

Edit: Maybe there is a small notch where the ceramic impressed itself into the steel? Hard to say if this accounts for the improvement in lock up that you described earlier. However it happened, I'm glad it happened.
 
My guess from observing the knife through use is that the lockup has broken in from about the 25% mark to what looks like, in the above photo, about 60% of the way. This changes the angle at which pressure is applied from the lock face on the blade to the ceramic ball and into the lock bar.

My problem was always that my blade would flex downward when applying pressure to the spine (because of the lock bar flexing or the ceramic ball rolling farther across the lock face). Perhaps this change in angle allows the lock bar to more directly absorb the force along its strongest axis, and/or leaves less room for the ceramic ball to travel.
 
the lock flex does not bother me that much, I also have Seb 21 that have this characteristics if you insist, the ceramic ball I think has only accentuated the problem being much harder it tends to slip on the blade tang.
I noticed, however, that among my sebenza 31 (small, large) a certain difficulty in finding the right setting when you take it apart to clean it.
In the old 21s when they disassembled there was no need for any kind of adjustment to be made, the screws went tight and there was no need for loctite on pins and screws. on these modern 31 the right compromise must be found from time to time between the two pins (pivot blade, stop pin), they must be registered without tightening them completely and stopped with the thread lock supplied, if you do not operate in this way the blade does a lot struggling to slide or tends to be too braked. I read around that others have encountered this problem, mine did not present it immediately but with the first disassembly and cleaning they started to give trouble.
Has anyone else encountered the problem?
 
I have not disassembled my 31 yet, but I recall the Apostle P waxing eloquent about the shouldered stop pin being machined to less exacting tolerances than the precision lapped stop pin wahser on the 21. I'm grateful for your detailed observations on reassembly.
 
cmfkdragoon said:
Despite such a fiery and impassioned post when I received my less-than-perfect Small Seb 31 (I was quite disappointed), I changed my mind on returning the knife and decided to give it a try. I started carrying the small sebenza 31 regularly, and tried to ignore the lock flex as much as possible.

After several weeks of use, the lock flex remains but has improved markedly. Perhaps the suggestion of a break-in period is valid. Most importantly, the lock flex is completely imperceptible in normal use. It turns out I love this knife so much for all of its others qualities that I hardly care. As well, it gives me a reason not to fuss over imperfections from use.
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I think your post kind of sums up the entire thread in a sense. With any product, if you make it a point to find imperfections, you will find them. If none exist, you will decide something is an imperfection.

The only way to avoid this is to search around until you just happen to find something that matches your idea of perfection
 
Modernflame said:
I have not disassembled my 31 yet, but I recall the Apostle P waxing eloquent about the shouldered stop pin being machined to less exacting tolerances than the precision lapped stop pin wahser on the 21. I'm grateful for your detailed observations on reassembly.
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I think so! the bushing on the stop pin present on the old Seb21 allowed a more precise adjustment than the current system.

this thing does not compromise the functionality of the knife but, my 2 cents, if you want to find a difference (in favor of the old one) between the two models (21-31) this is it. Always having to adjust and find compromise between the two pins can make it long and impractical as well as always using Loctite 222 on the threads to ensure they don't loosen any further, the step back has been made here.
I hope over time they will find a more effective solution or that they will return to the bushing on the stop pin as on the old 21.
 
willy88 said:
there is a certain inconstancy between the various models. 1 in 3 may have this characteristic
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Back to that Apostle P video, he speculated that wear and tear on the tooling bits could account for some variation in the size of the shouldered stop pin. I am no machinist but that sounds plausible to me.
 
Modernflame said:
Back to that Apostle P video, he speculated that wear and tear on the tooling bits could account for some variation in the size of the shouldered stop pin. I am no machinist but that sounds plausible to me.
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Which in turn can be adjust with cutter compensation... It would get seen during inspection of the part at the machine - either adjust the tooling compensation or index the insert or change the endmill - whichever.
 
Modernflame said:
Back to that Apostle P video, he speculated that wear and tear on the tooling bits could account for some variation in the size of the shouldered stop pin. I am no machinist but that sounds plausible to me.
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it can be an inconsistency of the components but also of the final assembly / setting.

if it continues to bother me I will go to grind / polish the bronze washers with DMT 8000 grit so that I can tighten the pivots without loctite and without blade play. all these problems come from small differences in some parts, the only way to correct is to properly adjust the blade bushing and the bronze washers
 
brownshoe said:
CRK recommends just cleaning washers not removing any metal.
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in CRK the grinding of bushings and washers are done manually on very fine abrasive paper, we are talking about a few hundredths of a millimeter to record the sliding of the blade and games.

small update ... as anticipated very small correction on the washers have solved the problem. now, by tightening all the screws, the blade does not lock and slides smoothly without play
 
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