Lock face tolerance’s

SubaruSTi

SubaruSTi

Joined
Nov 28, 2005
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Chris Reeve is famous for the tolerance but many knives have a different lockup distance. Some are around what looks to be 70% and for a new knife this seems odd. I wonder if the tooling that cuts the face is a factor here or what. I’m speaking to newer models like 31 and Inkosi. These have the ceramic ball and should maintain the lockup for a long time. Thoughts?

I did have a 2007 annual that went all the way over right out of the box, I was livid but that’s another story from long ago. My 2006 was perfect.

https://flic.kr/p/2mU1Ewn

https://imgur.com/a/b29VUAP
 
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All four of my CRKs with the ceramic ball land around 60% or so. I'm not sure how that geometry is applied, whether by a CNC machine or whether it is hand fitted like the old 21 precision lapping. I agree that the interface should last a very long time, as the ceramic ball would have to work "uphill" against the tall side of the lock face. Seems like you'd sooner wear out your blade from use and sharpening.
 
I have an observation and also a question. The following two photos are of the lock face on my new small 31. The first image shows what looks like a wide swath cut by the ceramic ball. The second image shows the same knife after cleaning the lock face. Turns out it was dirty. The ceramic ball is wearing a normal track onto the lock face. I have not had the knife in my pocket enough for the schmutz to have been pocket lint. I suspect it's steel debris, removed by the harder ceramic. My large PJ 31 did the same thing, but it doesn't seem to happen any more. I'm hypothesizing that this is the result of the lock "settling in." Do you guys think that makes sense? Could this be the basis for the user observations that lock flex decreases as the knife breaks in?

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I wouldn’t think much wear would accrue at all since one side is 97rc and the other is 61. The titanium is way softer.
 
I’ve learned that with the ceramic ball interface, the lock bar looks like it has late lock up. But, when you look at the ball tract on the blade, it’s earlier than what the lock bar shows. My 25’s, Inkosi’s are what I consider normal which is around 50/60 %. Now, the Umnumzaan has considerably early lock up, around 30 %
 
Modernflame said:
I have an observation and also a question. The following two photos are of the lock face on my new small 31. The first image shows what looks like a wide swath cut by the ceramic ball. The second image shows the same knife after cleaning the lock face. Turns out it was dirty. The ceramic ball is wearing a normal track onto the lock face. I have not had the knife in my pocket enough for the schmutz to have been pocket lint. I suspect it's steel debris, removed by the harder ceramic. My large PJ 31 did the same thing, but it doesn't seem to happen any more. I'm hypothesizing that this is the result of the lock "settling in." Do you guys think that makes sense? Could this be the basis for the user observations that lock flex decreases as the knife breaks in?

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it is normal soiling due to carrying it in your pocket. I have noticed that these blocks remain like this for a long time and do not need adaptations or running in periods. the oldest ceramic sphere I have is a Zaan from 2008 and it's still like when I get there. the dirt you see is probably due to grease, however it tends to attract dirt once saturated with dust it will attract much less dirt.

returning to the discourse of the flexible block .... it does not depend on the use or other factors (small or large), as explained by Tim it is a characteristic that the old 21 also had but which was less noticeable due to the different geometry, the The titanium blade / bar interface point was much wider than the blade / ball contact point. Reeve has never mounted an LBS on his classic models just to keep them "classic" and because it doesn't do much good, but if there was a bar it wouldn't have the flex. when you do your lock flex test on the table, notice that the bar moves towards the rest of the titanium folder.
but as mentioned an LBS is useless, a pocket knife, as I see it, must remain such, it must not replace a fixed blade or must not do unthinkable things or beyond its capabilities but must have good cutting performance (geometry of good blade and edge thickness). I have many other pocket knives that promise abuse but the compromise between cutting capacity and good resistance is too biased towards resistance so that after some sharpening the thickness at the edge becomes too generous and they are only good as a chisel. I think CRK has a good compromise instead and I can guarantee you that you will use your blades for a long time, I have CRKs that are almost 20 years old and they are still like when they were taken more I know that the SPA is always available.
 
Lock bar stabilizer. I’m a mountain biker so I always read that as local bike shop lol.

I’m not talking about lock rock with this thread, I’m speaking to the locking interface distance on the lock face. I’ve seen a few new knives at 80% my new Inkosi might have the shortest distance I’ve seen.
 
SubaruSTi said:
Lock bar stabilizer. I’m a mountain biker so I always read that as local bike shop lol.

I’m not talking about lock rock with this thread, I’m speaking to the locking interface distance on the lock face. I’ve seen a few new knives at 80% my new Inkosi might have the shortest distance I’ve seen.
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the answer is in the previous post. there has been much discussion in the past about how and how much a blocking bar should engage the blade, there are those who claim 20% other 50% appure as CRK over 60%. the right answer lies in the construction, if you have a good geometry and execution you will not have to worry about the advance due to consumption. there are hard use knives that reach 20% engagement but advance with use until you attack the other folder and at that point you will have to increase the stop pin. the ceramic ball guarantees the non-wear of the block, so why worry if it is at 80%? maybe it could happen on some model but there is always the SPA
 
Because Chris is all about the tolerance and the extreme difference in one knife to the next is odd. I would think 50% is ideal since it’s not going to wear.
 
for what I noticed in non-CRK execution, having a lock bar that engages a large part of the blade makes everything more stable and safe.
however I wouldn't worry too much about where the bar sits
 
I have an early unnumzaan, that if you look at the lockbar the lockup seems to be too “deep”. However, the ball track is only about 60% of the way across the tang and has never moved. This knife has been carried a tonne. I don’t worry about it because, barring the unforeseen, if the lock bar runs out of travel CRK will deal with it.
 
The later the lockup the safer IMO.

But, the market generally wants early lockup.

.01 of a mm or 0.0039 of an inch can make a huge difference in lockup percentage in my experience.

And you have three to four facets to consider when grinding a lock, one human slip of the hand and you need to start over/change a part or such.
 
Watching the videos for how they are made, the lock is fitted by hand so some variability is inevitable, unlike the other parts of the knife. When I received mine (2nd hand), it was probably around 75% lockup. I wasn’t worried about it. Totally solid. When I disassembled, cleaned, lubed and reassembled its lock up was more like 50-60%. Noticeably less, still rock solid, and didn’t change after that. I disassembled and reassembled again to put the lanyard in, same result. 50-60%. Not sure what was different with my assembly vs prior owner but I imagine this is another variable that impacts lockup when we are talking about tolerances measured in 10 thousandths for the mating parts. I should note this is a 21 so no ball.

Sure there is some variability. I guess I’m not worried about it.
 
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