umnum test from poland

If you removed the ceramic ball the lock bar would travel all the way over to the other side and not give a secure lock up.
It would be like grinding a mm or 2 off the face of a regular frame lock. (No, I'm not going to take mine apart to test it :p)
 
Biginboca said:
Shing,

Not trying to get base here, but comments like these and the look of the knife on your site make me believe that you have no idea what you are talking about.

How are 2 rough edges going to wear against each other in the long run as the knife is cycled over the years? They will wear in and then wear out, imo. Your comments and knives pictured seem to point to a lack of experience.

And coming to the factory forum of CRK to publicly reengineer and/or challenge your knives against the knives of the most reknowned, respected manufacturer in the world is just poor tastes. If you think you have great ideas quietly implementing them on your own forum or submitting them to Chris in private would be much more respectable, IMO.

Based on the behavior here I will not be considering one of your knives and I think I am not alone...

I hope everyone can learn from this thread.
Click to expand...

This an open forum to discuss CR knives. I have seen plenty of threads asking for different options on CRK products like Wharncliff blades and different steels to make CRK products better or more acceptable and comparing them to other products like Striders and Lochsas.

I see no point being wound up by it and if you don't understand what I am talking about, you should ask for clarification rather than criticism.

I really like CR knives and have used them as a basis for my designs. What I would not do is copy the ball bearing system for locking the blade open because it does not work as well as the Sebenza system.

By the way, does anyone know if the bearing in the Ummy rotates in its housing?
 
Shing said:
By the way, does anyone know if the bearing in the Ummy rotates in its housing?
Click to expand...

The cearamic ball for the lock contact does not rotate, it's been "peened in" at 3 points.

There are pictures on here some where in one of the takedown threads.

:thumbup:
 
Shing said:
What I would not do is copy the ball bearing system for locking the blade open because it does not work as well as the Sebenza system.
Click to expand...


I'll give you a "user" perspective. I've owned and used many Sebbies. After using the Umnumzaan, I believe the lock on the Umnumzaan lock works as well as the lock on the Sebenza.

Your comment is based on?
 
Haze said:
The cearamic ball for the lock contact does not rotate, it's been "peened in" at 3 points.

There are pictures on here some where in one of the takedown threads.

:thumbup:
Click to expand...

Its peened but how strong is the grip on the ball? I think another mode of failure is the ball rotating in its housing and reducing the friction required for the lock to work.
 
Last edited:
GigOne said:
I'll give you a "user" perspective. I've owned and used many Sebbies. After using the Umnumzaan, I believe the lock on the Umnumzaan lock works as well as the lock on the Sebenza.

Your comment is based on?
Click to expand...

Based on the Polish vids, I haven't seen a sebenza with the same problem.
 
Shing said:
Its peened but how strong is the grip on the ball?
Click to expand...

Strong enough IMO, if the knife is damaged to the extent that ball could
"fall out" for eg. you have bigger problems to worry about, thats for sure.
 
Shing said:
Its peened but how strong is the grip on the ball? I think another mode of failure is the ball rotating in its housing and reducing the friction required for the lock to work.
Click to expand...

strong enough, http://www.bladeforums.com/forums/showthread.php?t=685111
btw, the thumbstud only came out because of an early tolerance issue, and was almost immediately fixed, and then months later replaced with an entirely different, single piece, thumbstud design
 
STR - do you think that overextending locking bar weakens the lock significantly?
Because in that case a "frame-stop" would be a MUST in frame lock knife. Cause we all overextend it a little from time to time while closing the knife.
 
stabman said:
I still don't see it as a roll.
Sliding, sure. Rolling, no.
Click to expand...

to me, since the lockbar bends, if you visualize the movement of the ball with the lockbar and then take away the lockbar, it's basically rolling.

idaho, if you mean a hinderer lockbar stabilizer, the umnumzaan doesn't really need it. the lockbar cut out is much different from strider and hinderer knives, and the lockbar requires much more force to move. it would be very hard to overextend the lockbar
 
Shing said:
Its peened but how strong is the grip on the ball? I think another mode of failure is the ball rotating in its housing and reducing the friction required for the lock to work.
Click to expand...

Totally n/a. In the lockup position, there is for practical purposes only straight line pressure on the ball. You could perhaps, possibly (but unlikely), blow the ceramic ball right out of its detent, with enough pressure. However, if the Polish Stab-The-Refrigerator test didn't put enough pressure on the ball to cause the peening to fail, I don't see what you could do that would...well, maybe stab the sidewalk? :rolleyes: BTW, that may be why the blade tang shows a fairly prominent indent in the "after" pictures in that test.

No offense and not trying to join the pile-on, but you may need to look more carefully at the tear-down pictures or get your hands on one of these to make sure you understand how it was designed.
 
Let's stay focused on here to discuss the real problem that could be related with this lock-up system, and that is the ceramic ball being harder than the steel and wearing away or grooving-out the tang-- thereby loosening the lock-up.

I really don't care if my Umnum fails a spine-whack test after stabbing a refrigerator or frozen side of beef, or what not.

If I want an indestructible folder I will put a pivot pin in one of my Busses after dissecting it in 2 pieces. Just kidding. :)
 
komondor said:
Let's stay focused on here to discuss the real problem that could be related with this lock-up system, and that is the ceramic ball being harder than the steel and wearing away or grooving-out the tang-- thereby loosening the lock-up.

I really don't care if my Umnum fails a spine-whack test after stabbing a refrigerator or frozen side of beef, or what not.

If I want an indestructible folder I will put a pivot pin in one of my Busses after dissecting it in 2 pieces. Just kidding. :)
Click to expand...

I thought that the carbide layer put on the lockbar face of some maker's knives is very very hard (i'm not sure if it's harder than the ceramic ball) but the fact that a ball is used on the umnumzaan should mean there's less wear than on the knives with carbides on the lockbar. does anyone know how these two materials compare in terms of hardness?
 
You must log in or register to reply here.
Back
Top