Umnumzaan Detent Ball

W

whw

Joined
Aug 15, 2008
Messages
21
Received my Umnumzaan today! Despite some concerns after going through the 'umnum test from poland' thread, I pulled the trigger and am extremely happy with my decision! I'm new to collecting knives, so I'm really excited and pleased with this purchase.

I took some pictures of the detent ball for those of you who are interested. Do note that I used an old 5 mega pixel camera and a magnifying glass to take the pictures, and I took the pictures at night, so the picture quality is not razor sharp (unlike my Umnumzaan :thumbup:).

Picture of my engaged framelock. You can see the side of the detent ball here.
P1080731.jpg


Can you spot that slight bronze curve in the pic below? That's the pivot washer (if I am not mistaken).
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The detent ball. The detent ball is in full contact with the blade tang.
P1080739.jpg


P1080740.jpg


The framelock has been disengaged:
P1080744.jpg


Yes, the detent ball does leave a 'mark' on the tang. The picture below is not that clear, and it looks like a scratch. Actually, it more like a polished surface on my knife with no indentation. Then again my knife is new and has only been opened a few times by me.
P1080749.jpg


Knife is almost fully closed. Notice the small round indentation on the blade for the detent ball to 'fit-in' giving a nice solid lock-up when the blade is closed. The 'line' marks you see in the picture are not scratches! They are actually lubricant/grease that has been smeared. In real-life, the lubricant looks whitish in colour. The picture is deceiving as the lighting is poor.
P1080752.jpg


The knife is perfect! My only minor peeve, is that my blade is not PERFECTLY in the center. It's out by like 0.5mm! But that's being anal!
P1080760.jpg


Hope you enjoyed the pictures! Thanks for looking.
P1080722.jpg
 
Nice knife. The ball is ceramic? Is there any concern that the ball could crack if the knife is snapped open? (I'm sure CR did their R&D on the knife, but it still seems like its possible in theory.)
 
I think there is a much greater risk (which is still extraordinarily small, if not non-existent) that you'd knock the ball out of the lockbar before you cracked or shattered the ceramic ball. This is the same stuff that is used as armor plates on modern tanks. If it can take direct AP/HE hits, it's good for a knife. :D The Umnu is a very substantial, very well-engineered piece of work from a designer with more than 30 years (I think) in the tool & die and cutlery fields.

To the OP - nice pics. FWIW, I'd say that blade is centered. Framelocks and linerlocks often don't do better than that - a fair percentage don't even do that well. :)

Slightly to one side of the topic, and I hesitate to go here, but I'm on the verge of concluding that the Polish lock failure the OP mentions in this thread was either a fabrication or the result of some beyond-abuse scenario. In real life, I don't cut the sidewalls out of truck tires (as the Polish tester did), but I can see someone doing that and I can see lateral and reverse pressure on a lock that could unlock it or cause a failure - and it didn't happen in his video. In real life, I don't stab fridges with a knife, not even an Emerson ;), but the Polish tester did and the lock didn't fail. And I'm then supposed to believe that he can make the lock fail doing a spine-whack on a twig, or on his finger? I'm sorry, I don't believe that what we're seeing in that video represents reality.
 
Great Pics. The umnumzaan is a great knife, your going to love using it !
 
whw said:
Received my Umnumzaan today! Despite some concerns after going through the 'umnum test from poland' thread, I pulled the trigger and am extremely happy with my decision! I'm new to collecting knives, so I'm really excited and pleased with this purchase.
Click to expand...

Told ya so...;)
 
Now if we can only get Cotherion to come along...:p

VERY few people are disappointed by the Um, and even fewer truly dislike it.

Oh, and for the record, if any believers of that test thread are willing to let me do it, I'd be more than happy to use my Um on their finger for a spine whack test! :eek:;):foot:
 
Goldistheanswer said:
Nice knife. The ball is ceramic? Is there any concern that the ball could crack if the knife is snapped open? (I'm sure CR did their R&D on the knife, but it still seems like its possible in theory.)
Click to expand...

the lockbar will bend in ward toward the knife before there's anywhere near enough pressure to crack the ceramic ball. that's assuming that the blade wouldn't break before the ball cracks. folding knives have many possible modes of failure, but I don't think the ceramic ball cracking is one of them.
 
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I have had my Umnumzaan for almost two months now and love it. I have carried it everyday since. Really nice pics.
 
on_the_edge said:
Now if we can only get Cotherion to come along...:p

VERY few people are disappointed by the Um, and even fewer truly dislike it.

Oh, and for the record, if any believers of that test thread are willing to let me do it, I'd be more than happy to use my Um on their finger for a spine whack test! :eek:;):foot:
Click to expand...

You won't have a problem :)

Though my first buy will be a Sebbie. The proper order is a Sebbie then the Zaan. And all this gotta wait till my finances recover from the "ambitious folder".

I appreciate the pictures. Didn't realize how big the ball was. Basically IMO the bigger the ball the more durable is the wear (in this design). This is due to the assumption that the surface area of a ball increases exponentially compared to first initial contact. Which means contact is improved when it wears.

Sebbie then Zaan, walk then run. That's the natural order of things to enable max appreciation IMO ;)
 
on_the_edge said:
Now if we can only get Cotherion to come along...:p

VERY few people are disappointed by the Um, and even fewer truly dislike it.

Oh, and for the record, if any believers of that test thread are willing to let me do it, I'd be more than happy to use my Um on their finger for a spine whack test! :eek:;):foot:
Click to expand...

You won't have a problem :)

Though my first buy will be a Sebbie. The proper order is a Sebbie then the Zaan. And all this gotta wait till my finances recover from the "ambitious folder".

I appreciate the pictures. Didn't realize how big the ball was. Basically IMO the bigger the ball the more durable is the wear (in this design). This is due to the assumption that the surface area of a ball increases exponentially compared to first initial contact. Which means contact is improved when it wears.

Sebbie then Zaan, walk then run. That's the natural order of things to enable max appreciation IMO ;)

PS: IMO (again, got lotsa opinion lately...) the thing that would cause a crack in the ceramic ball* is velocity upon impact. The way it is now in the blade methink even with max distance** available the is not enough velocity to shatter/crack this ball. I could be wrong but I'm fairly certain with this. That's why the ball integrity is not my major concern now :)


*(assuming ceramic ball is homogenous and has no distortion of materials)
**(needed to generate speed with constant acceleration (which in turn is generated from the lockbar stiffness which is actually reducing not maintained during movement from disengaged to engaged))
 
Cotherion said:
You won't have a problem :)

Though my first buy will be a Sebbie. The proper order is a Sebbie then the Zaan. And all this gotta wait till my finances recover from the "ambitious folder".

I appreciate the pictures. Didn't realize how big the ball was. Basically IMO the bigger the ball the more durable is the wear (in this design). This is due to the assumption that the surface area of a ball increases exponentially compared to first initial contact. Which means contact is improved when it wears.

Sebbie then Zaan, walk then run. That's the natural order of things to enable max appreciation IMO ;)
Click to expand...

sorry, I don't think I understand what you're saying in the bolded portion.

the ball won't crack, it's not really even slamming into the tang of the blade. the ball, although stationary with respect to the lock bar, essentially rolls into place (some people disagree with my language there, replace rolls with slides if so). any extreme force on the ceramic ball would first go into pushing the lock bar inward toward the slab, which takes much less force to do than cracking the ball. i have yet to notice this even happening, so the event of the ball cracking seems even more unlikely.
 
Ok, well imagine a new Zaan, imagine the contact area.

Then imagine a much much older Zaan. Imagine the contact area then.

Assume the BB "eats into" the tang over time. Being a ball in shape the increase in area (contact area of BB to tang) is not linear in relationship as we gradually increase the depth of how much the BB eats/wears in. This is especially true as we consider larger balls. It's more than a gradual/linear increase over constant rate of wear depth.

Reality is that the rate of wear is more like gradually decreasing over time as the contact area increases and the forces reduce cause the lockbar will in time travel deeper and at a different position (deeper in) the stiffness is less (may not be easily felt but it's definitely the logical assumption).

Sorry if I'm not good with explanations, English is my 2nd language so it's bit wonky. I've been doing lots of analyzing the Zaan cause I'm interested in the design.
 
Ive had my umnun about 6-7 wks.Ive edc it all but a day or 2.Opening and

closing you umnun several hundred times is the best way smoooth it.It will

grow on you ....mine has!
 
Cotherion said:
Ok, well imagine a new Zaan, imagine the contact area.

Then imagine a much much older Zaan. Imagine the contact area then.

Assume the BB "eats into" the tang over time. Being a ball in shape the increase in area (contact area of BB to tang) is not linear in relationship as we gradually increase the depth of how much the BB eats/wears in. This is especially true as we consider larger balls. It's more than a gradual/linear increase over constant rate of wear depth.

Reality is that the rate of wear is more like gradually decreasing over time as the contact area increases and the forces reduce cause the lockbar will in time travel deeper and at a different position (deeper in) the stiffness is less (may not be easily felt but it's definitely the logical assumption).

Sorry if I'm not good with explanations, English is my 2nd language so it's bit wonky. I've been doing lots of analyzing the Zaan cause I'm interested in the design.
Click to expand...

I think the first order of business is for you to actually get a Zaan in your possesion...do all your testing and hit us back in about 10 years and tell us you were wrong.:D

You better layoff the God shots, there makin you think to much. :)
 
I think I understand what you're saying, but consider that whatever dimension changes occur through dimpling of the blade tang is likely to be much less than what's inherent in the traditional linerlock and framelock design.

Cotherion said:
Ok, well imagine a new Zaan, imagine the contact area.

Then imagine a much much older Zaan. Imagine the contact area then.

Assume the BB "eats into" the tang over time. Being a ball in shape the increase in area (contact area of BB to tang) is not linear in relationship as we gradually increase the depth of how much the BB eats/wears in. This is especially true as we consider larger balls. It's more than a gradual/linear increase over constant rate of wear depth.

Reality is that the rate of wear is more like gradually decreasing over time as the contact area increases and the forces reduce cause the lockbar will in time travel deeper and at a different position (deeper in) the stiffness is less (may not be easily felt but it's definitely the logical assumption).

Sorry if I'm not good with explanations, English is my 2nd language so it's bit wonky. I've been doing lots of analyzing the Zaan cause I'm interested in the design.
Click to expand...
 
bigmark408 said:
I think the first order of business is for you to actually get a Zaan in your possesion...do all your testing and hit us back in about 10 years and tell us you were wrong.:D

You better layoff the God shots, there makin you think to much. :)
Click to expand...

I gotta cut down, go decaf. Drink more tiger beer...

10 years? Here's hoping, gravity as well as time ain't my friends :p
 
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