Sebenza 21 Detent Ball Flat Spot?

M

MatthewSB

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Feb 1, 2013
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I've been using my micarta inlaid '21 daily for months now, the longest I've used any single knife in years. I had it apart for cleaning and noticed a flash of light, looking closer I could see that there is a small flat spot on the detent ball. I wasn't aware that ceramic detent balls could develop flat spots, as they're harder than the blade steel. The detent functions fine, I'm more curious how ceramic flattens against steel, or if it's from some kind of abrasive (silica, dust, whatever?) getting inbetween?

I'm guessing that it will flatten slightly, then stay that way forever? Anyone ever had a CRK ceramic detent ball flatten to the point where they had to have the knife repaired?
 
Matthew, it might be worth giving CRK a call about your issue. They've been very responsive to any questions that I've had.
 
I could be wrong Matthew, but I am pretty sure that 21's have steel detent balls and 25's have ceramic detent balls. That being said, any detent ball made out of steel will wear some and that's what we call its "breaking in" stage.
 
Both the 21 and 25 have ceramic detent balls. The one on the 25 doubles as the lockface and is much larger. It is normal for a small flat spot to appear on the 21 ceramic ball as it seats itself. All my user 21s exhibit this, but it does not seem to change after the initial wearing in.
 
kidcongo said:
Both the 21 and 25 have ceramic detent balls. The one on the 25 doubles as the lockface and is much larger. It is normal for a small flat spot to appear on the 21 ceramic ball as it seats itself. All my user 21s exhibit this, but it does not seem to change after the initial wearing in.
Click to expand...

This is what I was looking for, thanks!
 
When metals rubs against each other, definitely wear will show up. And depending on the metals, it would be sooner or later. I have a SmF which I bought in 2008 and its detent ball is almost flat (flush) with the lock bar. I have inspected my L21 just a few days ago and I couldn't detect any wear on its detent ball but there is a circular grove around the pivot were the detent contacts the blade tang. As the ball is so minute, and so is the grove line. As far as I am concern, if the issue does not affect its function, then your good to go. An I do envy those members who lives in the continent as they can send in their knives for servicing at any time.
 
I don't know when CRK started using ceramic balls on Sebenza detents, but it was a long time ago, at least as early as the mid-2000s.
 
My large 2002 regular Sebenza that I purchased the same month it was made has a ceramic detent ball.

Jim
 
Yeah. At one point I sent in a 1996 and a 2006 and they replaced the steel detent in the '96 and noted that the '06 was already a ceramic ball. Your 2002 date helps narrow that down. :thumbup:
 
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