umnum test from poland

[ipm]

i doubt the bending back of the lock bar would loosen it that much. it does not look that extreme, at least to my eyes.

lets wait for the CRK reply before speculating.

perhaps the Polish guys can send it in to CRK for an examination in the factory.

 

[rybak]

Thanks for appearing here and adding some background.

Be my guest.

Whether or not the test methodology is valid or realistic is certainly a question. Contacting CRK is obviously a very constructive idea, and we'd probably all love to hear his views.

Of course it can being discussed, if the methodology is realistic / some trials are rational.

That's why I wrote, those are just tests - like Diabelek (tester) has imagined them.

If You'll read the translated description (it's not soo bad, I'm surprised, the translator is getting better and better ), You'll see, that it was not pure pleasure of destruction, or something like that, he has his own reason for every "test", and also references to his daily routine.

I have to add that, if you try "not to publish anything from PA before all potential ... problems are clarified," you will (1) probably never get anything published

Our users test everything, from no-name knives from China, through more or less "normal" or premium European or American brands (like Buck, SOG, Kershaw, Spyderco, Benchmade, Böker, and many more), up to CRK

Cases, when some technical problems occur, and contacting the manufacturer/dealer seems necessary, are very rare.

It's not THAT bad

An example - Diabelek has done similar things with Microtech SOCOM.
No failures AFAIR.

I spent some time poking around on your site - it looks like a great resource.

Thanks, we try to do our best.
Feel free to ask anything, many users speak English.
We have also English forum descriptions.

I wish my Polish were as good as your English.

It's Your andvantage - all the world speaks more or less English, You don't need to waste Your valuably time to learn any foreign languages

I need two.

 

[TLR]

I don't own an umnum so I can't speak to the strength of the lock bar; however I've tweaked a number of Sebenza's lock bars to that level of deflection, if not slightly more, to make minor adjustments in blade opening tension. In each case the titanium has proven is VERY resilient in that the lock bar easily returned to the opposite scale with tension to spare once the blade was removed. I cant imagine the titanium lock bar on the umnum to be any less durable than the Sebenza.

What I did find interesting was the video where he depressed the lock bar down several times with the blade extended. I couldn't do that on a Sebenza if I tried, does the interface between the blade tang and the ball on an umnum lock bar make that movement possible?

Like I said I don't own or have experience with the umnum, I just want to know if that movement is normal prior to the ball having caused the slight ding in the blade lock tang?

I can push down on my sebenzas lock bar in the open position like that. It's very easy if there is any lateral movement as your thumb presses down which seems to tend to happen.

 

[BobP63]

I can push down on my sebenzas lock bar in the open position like that. It's very easy if there is any lateral movement as your thumb presses down which seems to tend to happen.

I didn't consider motion in two planes; introducing lateral movement would allow at least a partial unlock condition which would substantially reduce resistance to downward force. :thumbup:

I approached it from a solid lock up condition with only linear motion being applied to the lock bar.

It's hard to tell from the video if lateral movement was being applied as well.

 

[rybak]

It's hard to tell from the video if lateral movement was being applied as well.

If You look into google translation, You can read the description:

"An additional problem is too narrow leaf lock, which works with a strong grip in both planes."

I would maybe say "moves in both directions", but yes, the Polish text says, that if You apply the pressure to the frame, it moves in both directions, in the plane of the handle width (from front to spine), and in plane of handle thickness (from plate to plate).

On two photos following this sentence, You can see marks on tang left by the ceramic ball, so there should be no more doubts.

 

[JNewell]

Another thing that I'm curious about, as I keep thinking about this, is how the tang got so dented by the ceramic ball. The tang appears to be a lot softer than the ceramic ball?

 

[TLR]

Another thing that I'm curious about, as I keep thinking about this, is how the tang got so dented by the ceramic ball. The tang appears to be a lot softer than the ceramic ball?

Well ceramic IS harder then the steel. Steel tends to deform. Ceramic is so hard it will either shatter or crack if to much force is applied. This is actually a worry that I've had about having a ceramic ball in the locking mechanism. That under extreme force it would crack or break. Guess that won't happen I would assume that the tang is hardened. I hadn't really thought that deformation to that degree would occur.

Looking at that picture more however I would have thought that as the steel deformed it would be smoother then it looks. In other words, one smooth depression. Could it be possible that in the mud grit and or a tiny rock caused that damage? Or that part of the ceramic ball chipped and gouged that out?

BobP63:
If you try it you'll find that your thumb naturally induces some lateral movement when trying to move it up and down. My small will still move slightly even without lateral movement however. I don't have a large to compare it to which is likely more an apples to apples comparison.

 

[JNewell]

Here's a post from another recent post by Sal Glesser on using ceramics and steel together, fwiw.

Alumina ceramic and zirconia ceramic can be polished to a very high degree so wearing into the blade can be minimal if at all.

I know a custom maker that gold plates the ball on his linerlocks.

Is there a measurable difference in performance?

sal

 

[TLR]

Here's a post from another recent post by Sal Glesser on using ceramics and steel together, fwiw.

I may be making to big of an assumption but I would think that Sal is talking about the ball for the detent on the side of the blade. That application would see very little actual force or pressure versus the lock face. I don't know what happens on the lock face under force.

Does anyone know of any other framelocks that uses the umnum's locking method or is this a new and original application?

 

[bigmark408]

I just checked a couple of my user Zaans and they both have wear on the lock face of the blade....one is substantial (IMO)...looks very similar to the pics above...lock up is still fine with no blade play.

I ain't trippin but i was surprised to see it....i'm gonna play this one out over time and see what happens.

 

[xzhang]

Another thing that I'm curious about, as I keep thinking about this, is how the tang got so dented by the ceramic ball. The tang appears to be a lot softer than the ceramic ball?

maybe these dents did not form in the test?
a firend of mine handled two Umnumzan's, one of them came from the first or second batch. it was brand new, but it had dents like this.
if (only if) these dents were caused by the force, then I have to say that maybe using the ceramic ball was not a good idea.

 

[xzhang]

I just checked a couple of my user Zaans and they both have wear on the lock face of the blade....one is substantial (IMO)...looks very similar to the pics above...lock up is still fine with no blade play.

I ain't trippin but i was surprised to see it....i'm gonna play this one out over time and see what happens.

the wear on the lock face of the blade came from CRK, my friend told me that the wear made it easier to open the knife;
newborn Umnumzan's have similar but less wear.

 

[JNewell]

I may be making to big of an assumption but I would think that Sal is talking about the ball for the detent on the side of the blade. That application would see very little actual force or pressure versus the lock face. I don't know what happens on the lock face under force.

Does anyone know of any other framelocks that uses the umnum's locking method or is this a new and original application?

You're definitely right - I thought the basic concept might be applicable, but I appreciate the point you're making about why it might not be.

 

[JNewell]

I just checked a couple of my user Zaans and they both have wear on the lock face of the blade....one is substantial (IMO)...looks very similar to the pics above...lock up is still fine with no blade play.

I ain't trippin but i was surprised to see it....i'm gonna play this one out over time and see what happens.

Good advice. Thank you very much for both the report on what the tangs look like and how the knives are working.

 

[on_the_edge]

the wear on the lock face of the blade came from CRK, my friend told me that the wear made it easier to open the knife;
newborn Umnumzan's have similar but less wear.

Mine is very new and also has similar wear. Regardless, I have no intention of getting rid of mine based on this test, nor do I have any fear that mine would fail in a spine whack test. Despite not knowing the exact cause for this particular knife failing a spine whack test, I do feel that a spine whack test failure is more the exception than the rule. In any event, one knife of a mass-produced model does not and cannot provide a statistically significant result (regardless of whatever that result may be).

 

[xzhang]

Mine is very new and also has similar wear. Regardless, I have no intention of getting rid of mine based on this test, nor do I have any fear that mine would fail in a spine whack test. Despite not knowing the exact cause for this particular knife failing a spine whack test, I do feel that a spine whack test failure is more the exception than the rule. In any event, one knife of a mass-produced model does not and cannot provide a statistically significant result (regardless of whatever that result may be).

cannot agree you more. it is still unknown what caused these dents. so let's wait for the answer.

 

[TLR]

bigmark and xzhang-

Thaks for the pics. They really have a lot to say about all of this. It seems to just keep getting more interesting
So bgmark you say that yours has the (for lack of a better word) "gouging" like the one in the user test from poland?
xzhang's picture is what I'd expect to see. I mean a ceramic ball is certainly going to mark and lightly smooth the lock face some. I was just surprised at the amount of deformation that the other picture seemed to have.
With that said I'm far from any kind of expert on metallurgy and I trust CRK pretty implicitly so I'm not saying this is bad I'm just a little surprised.

JNewell-
Sorry if I came off dismissive. I was thinking this out via typing Actually after thinking about the quote you provided, the lubricity, if that's the right word??, of the ceramic ball against a compressed area on the tang might make a difference in this case. Kind of like the ramp on a gun barrel. I would think that the ball under pressure could create a "ramp-like" effect which would almost be polished by the compression??? Kind of like staking the screws on an AR. I had a liner lock that suffered from a similar issue with engagement. The tang was to steep of an angle and after some use it would fail the spine-whack test as the liner would simply slide aside.

I don't know. I'm also really tired so I may be talking out of my butt.

 

[JNewell]

bigmark and xzhang-

Thaks for the pics. They really have a lot to say about all of this. It seems to just keep getting more interesting
So bgmark you say that yours has the (for lack of a better word) "gouging" like the one in the user test from poland?
xzhang's picture is what I'd expect to see. I mean a ceramic ball is certainly going to mark and lightly smooth the lock face some. I was just surprised at the amount of deformation that the other picture seemed to have.
With that said I'm far from any kind of expert on metallurgy and I trust CRK pretty implicitly so I'm not saying this is bad I'm just a little surprised.

JNewell-
Sorry if I came off dismissive. I was thinking this out via typing Actually after thinking about the quote you provided, the lubricity, if that's the right word??, of the ceramic ball against a compressed area on the tang might make a difference in this case. Kind of like the ramp on a gun barrel. I would think that the ball under pressure could create a "ramp-like" effect which would almost be polished by the compression??? Kind of like staking the screws on an AR. I had a liner lock that suffered from a similar issue with engagement. The tang was to steep of an angle and after some use it would fail the spine-whack test as the liner would simply slide aside.

I don't know. I'm also really tired so I may be talking out of my butt.

No offense taken at all. If there is a hardness difference, or maybe even if there isn't, it does seem logical that there would be some kind of marking on the tang, if only due to the difference in the size of the contact area? A normal RIL lockbar could have a lot more surface area engaged on the tang than the Umnumzaan system with its small ceramic contact point?

 

[GigOne]

I have a Umnumzaan and it was purchased in Jun 08. The tang on my Umnumzaan shows a very light, lateral mark where the ceramic ball has made contact with the tang (similar to xzhang’s picture), as a result of the lock engaging and disengaging the tang. I expected this when purchasing the knife, knowing the ceramic ball being harder than the tang material.

I would be curious to know when the deep galling was first noticed. If we follow the sequence of the vids and pictures, it would appear it developed during kamilpoi’s exercise in stabbing the refrigerator, keeping in mind he’s introduced numerous shock loads. Pushing the blade forward, to remove the knife from the refrigerator, is also another key factor. Where is the bearing surface or critical area during each stabbing and blade removal? Tang and ceramic ball. The primary task of a knife is for cutting. Anytime a shock load (as in this case, all steps involved in the repeated stabbing to the refrigerator and removing the blade from the object) is applied, the probably of damage or malfunction increases.

The galling shown on kamilpoi’s tang is severe. It runs lateral, but also tapers downward. It doesn’t surprise me a light “spine whack” caused the lock to disengage. Simply, the ceramic ball has minimal to no bearing surface on the tang and follows the galling when minimal force to the spine is applied.

 

[JNewell]

I have a Umnumzaan and it was purchased in Jun 08. The tang on my Umnumzaan shows a very light, lateral mark where the ceramic ball has made contact with the tang (similar to xzhang’s picture), as a result of the lock engaging and disengaging the tang. I expected this when purchasing the knife, knowing the ceramic ball being harder than the tang material.

I would be curious to know when the deep galling was first noticed. If we follow the sequence of the vids and pictures, it would appear it developed during kamilpoi’s exercise in stabbing the refrigerator, keeping in mind he’s introduced numerous shock loads. Pushing the blade forward, to remove the knife from the refrigerator, is also another key factor. Where is the bearing surface or critical area during each stabbing and blade removal? Tang and ceramic ball. The primary task of a knife is for cutting. Anytime a shock load (as in this case, all steps involved in the repeated stabbing to the refrigerator and removing the blade from the object) is applied, the probably of damage or malfunction increases.

The galling shown on kamilpoi’s tang is severe. It runs lateral, but also tapers downward. It doesn’t surprise me a light “spine whack” caused the lock to disengage. Simply, the ceramic ball has minimal to no bearing surface on the tang and follows the galling when minimal force to the spine is applied.

Good thoughts - follow the dots...? Does this lead you to question whether using the ceramic ball is appropriate and/or better than the traditional RIL approach?

I was looking around on CRK's website and didn't see any explanations for the change to the ceramic ball. (?)