Testing the Sebenza integral lock

P

Protein

Joined
Mar 25, 1999
Messages
54
Hi there guys!

No, this is actually not me posting about the test. In fact, I've only briefly handled a small Sebenza; I'm not a current owner. What I'd like to do is solicit test results from all the Sebenza owners out there about the one facet of the integral lock that concerns me.

Much has been said about the strength and reliable lock-up of the Sebenza. A major difference between the integral lock, and the liner-lock, is that since the integral lock uses the entire handle scale as a lock-bar, gripping the knife hard actually reinforces the lock-up. The force applied by your grip augments the tension of the lock-bar in springing across the blade tang.

However, liner-locks as a class are very vulnerable to torquing-type stresses on the lock that push aside the liner-lock bar, and allow the blade to swing closed. I believe this is the one situation where the force of the user's grip is in the opposite direction of the lock-bar tension. Since the user's gripping force is greater than the lock-bar tension, the lock defeats, and the knife closes up.

So, here's how I traditionally test this. The test described is for a right-handed Sebenza, held in the right hand in the saber grip, which is a forward "hammer" grip with the thumb placed on the blade's thumb ramp.

Thrust the blade of the Sebenza (fully immersed) into a few layers of folded-over corrogated cardboard, so the blade is solidly anchored. Grip the knife firmly in the forward saber grip. Rotate the knife counter-clockwise, while putting pressure on the handle as if to close the handle. See if the knife closes. Be careful!

i call this the torquing foos-ball test, as the torquing motion is similar to the wrist action required in playing a game of foos-ball.

I can flunk many liner-locks, particularly the non-recessed locks using the above protocol. Torquing forces like above could potentially occur when yanking a knife out, if it is lodged and stuck in the object to be cut.

Please post here if your Sebenza passes or fails the above test.

Thanks guys!

Ian
 
I have tried a similar test using different materials, as well as some others. The closest to your “torque test” involved a bench vice and a pair of 2x4’s. Similar pressure as described above was applied, with only slight movement of the lock bar.

It seems that “white knuckle” liner lock failure is caused when the locking liner is squeezed against the scale of the handle and slips off of the tang. With the integral lock there is no scale to squeeze against, only your hand, witch is squeezing back. Rather central to the design.

The “bolster lock” that is used on Spark’s new Janus (thanks for the picks!) seems to be a liner lock with the scale over the pivot and lock portion of the handle removed. This should allow your grip to re-enforce the lock in a similar fashion, and is what gives the knife its “bolster” appearance. Sweet idea.


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James
 
stjames,

Thatnks for reporting back. You mentioned that the lock-bar did shift slightly? The reason I make a big deal of this is that using the above test, I've popped the lock on another integral lock folder.

Above that, consider the dangerous reports on the CRKT KISS knife. I'm among several people who've mentioned that this knife routinely fails any torquing pressure. This is a dangerous knife.

The obvious reply is that the KISS knife only has one scale. The locking bar is exposed and not protected, so of course the torquing force will be transmitted from the user's hand into unlocking the lock-bar.

Well, the Sebenza lock bar isn't protected either. And neither is the other integral lock that I popped. See here, at the top of the Chris Reeve site. The lock-bar on the old-style Sebenza is particularly exposed.

http://www.chrisreeve.com/article.html

What I'm saying is that when I put my integral lock knife through the aforementioned test, yes, my fingers are still pressing the lock bar closed, but the torquing force is trying to release the lock-bar.

In other words, the two forces are going in the opposite direction. And since the torquing force is generated by my arms, which are stronger than my fingers generating the grip force, the torquing force is likely to win out and unlock the knife. The fact that your lock bar moved when tested is an indication that there was a net unlocking force with a magnitude greater than zero.

It's a really simple test. Stick the knife into 2-3 layers* of cardboard. Torque the knife counter-clockwise. See if the lock bar moves or the knife closes.

* If you only use 1 layer of cardboard, the knife tends to rotate and gouge a hole through the cardboard. You want enough layers of cardboard that the knife blade is immobilized. More layers is obviously better.

Ian

PS: I'm not trying to start a stink. This is a genuine question that's been bothering me for a while. Please prove me wrong, because that benefits us all. Many things sound bad in theory but work great in the field.

PPS: Heya Spark, wanna test that bolster-lock and report here? It's a completely non-destructive test.
 
When I first read the topic for this thread I got real excited.
smile.gif
But now that I know what it's about, it wasn't what I was expecting. I've wondered about this for a long time also. Long before I ever even got my sebenza. But since, it was never mentioned on the forums I thought it was no big deal. After I got my sebenza I never tested it. Well, I just tested it a moment ago and I think I got the bar to move a little bit, but that was it. And plus my finger hurts now. I was torquing it pretty hard couldn't get it to budge. Maybe some other (stronger) people could make the lock fail.

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Johnny
[]xxxxxx[]=============>
 
Ian, by very slight I mean that the bar did budge, but not any measurable amount. I am fairly strong and applied as much pressure as was possible. Only slight movement, no where near enough to make the lock fail.

I will try the test with my old handle profile Sebenza today and see if there is a difference.

I would also love to see a few test results from the "Bolster Lock". I would be interesting to know how the Damasteel performs.

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James
 
The following are the results of a little test I performed this week. This is edited from an Email I sent to Ian directly on the subject, but I have decided to go public with the finding for general interest:

On to the Tests and Results. I decided to go with the multiple layers of cardboard to get a more exact simulation. I never applied a "white knuckle" grip, just a normal grab by a stagehand. I tested both with and without gloves on, with various finger positioning. The knives tested;

Large Sebensa, new handle profile
Small Sebenza, new profile
Large Sebenza, old profile
Small Sebenza, old profile
4.25" Apogee
3.9" Apogee
3" Apogee

The only one I was able to get to fail was the 3.9" Apogee.

As in my previous test the New Large Sebenza just budged. I had a co-worked helping me eyeball the knives, and his expression, pardon my language, was that it moved "just a **** hair". (colorful fellows, stagehands.) The same held true for the Large with the old handle profile, despite the fact that there is more of the locking bar exposed.

Both styles of small Sebenza moved even less. "I could say it moved, but I might be wrong. No, I am never wrong. It moved. Half a **** hair."

The 4.25" Apogee budged but held firm. The 3" DID NOT MOVE. It is still a little tough to unlock in cold weather, so I will re-test when broken in.

The 3.9" failed in much the same way you have described. Not every time, but I could make it fail at will. Reaction: "What the f---!"

After some examination and further testing, I believe we have found the reason. On the Large Apogee, the cut out in the handle that forms the locking bar is 3" long (on a handle of over 5.5") On the Medium Apogee, the cut out is 3.5" (on a handle of just over 5"). I believe the extra 1/2" of the lock bar makes it a long enough lever to defeat the spring formed by the cutouts in the handle. (The pilot hole for the medium is also about twice the diameter as on the large and small). For reference, the cutout on the Large Sebenza is also 3" long.

Also, the medium Apogee's locking bar is the only one on any of these knives that could be flexed past true, or away from the blade past the original plane of the handle scale. This seems to confirm the hypotheses.

I would like to conclude by stating that I was able to make the 3.9" Apogee fail, but I had to try and MAKE it fail deliberately to do so. I still have a very high degree of confidence in the knife, and the workmanship is excellent. This is by no means a rub on Darrel or in any way meant to fan the flames of the current “why not spend the money on a Custom Knife instead” debates going on. It is simply my testing of a few different types of knives that use similar materials and mechanisms.

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James
 
Folks
I am currently subtracting 1/2 in off the med apogee lock length to correct this problem. I will also check the thickness of the spring grooves to make sure the right amount of torque is being applied to the lock surface. Im glad I have this forum for feedback.
I dont think ANY lock is perfect. I have went over the lock on the apogee many times to make sure it is as good as it gets. This will be just another revision!

On another note for you automatic fans
I have developed the first (I THINK) DA action intergal locking knife. It has a hidden release that cannot be detected.
It works fantastic in all the testing I have done. The knife looks just like the regular apogee except that is is a da auto.
This sound impossible but it is true. I have designed the release to NOT dig into the spring as in most other DA type releases do also.
This causes the spring to become weak and fail on some knives after hard use. The release I have design DOES NOT dig into the spring. It is very solid and reliable.
The purpose of a DA auto IMHO is to have a stealth release . This is so it (the release) cannot be detected. I guess thats the way I think. What use is a DA auto if the release
is not hidden? Well It is done ! IT works great !

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Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!


[This message has been edited by Darrel Ralph (edited 22 August 1999).]

[This message has been edited by Darrel Ralph (edited 22 August 1999).]
 
I'm right handed, but just out of curiosity, how is the Sebenza's lock affected by left handed use?
 
As some of you may know, I broke my folder and have been in the market for a new one since. Since I own a Project 1, I decided to check out the Sebenza.

Well, like it's name implies, the Sebenza is a purpose-built worker. I think it was also intentionaly designed to be less functional as a weapon, but only to the degree that it doesn't impair functionality as a tool.

So anyway, irregardless of lock, the Sebenza is out of the running. Since this is a knife that won't work for what I want anyway, and because I'm a big fan of Chris Reeve Knives, I hope you will see this as the unbiased and impartial evaluation without an agenda that it is.

I did the torquing test, and I found that the lock can and will disengage when you twist so hard your grip starts to slip.

It takes a lot of force, it's not something that comes up much, but it can and will happen.
 
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