Strongest, most reliable (and more) folder locks

Hummmmm...I've tried to avoid posting here, but...
smile.gif


A well designed and manufactured liner lock will stay on the tang. If not, it's defective and should be returned to the manufacturer for repair/replacement.

Regarding buckling (and I'm NOT an a pro here), and if the lock is not defective, I understand that it should buckle.

Anyone with a liner lock slipping off the tang should get that back to the manufacturer ASAP! That should not happen.

Ron@SOG

------------------
Website: www.sogknives.com
Email: ron@sogknives.com
 
Sorry, all, for editing my posts, but I can't stand being misquoted and misconstrued. I probably should have done this when dealing with a certain self-appointed knife tester, but I didn't, and the results were not good, so I'm not going to let that happen again.

Again, sorry to any who may take objection, but I did not do this lightly, and I really think it's for the best.

--JB

------------------
e_utopia@hotmail.com
 
e_utopia:

I can concieve of no way in which your left hand applies different pressure to the lock bar than your right.
Click to expand...

Your fingers when will drive the bar towards your palm in a tight grip. In a right handed grip on a right handed Integral lock this tightens the lock. In a left handed grip on the same right handed lock this opens it. The opposite is true as well.

For example, I can fault both versions of the Gunting's (cause the lock to disengage) with a tight grip, but I require a different hand to do it with each one as the liners are on opposite sides of the scales on the two models.

The solution to this of course is to buy the correct version for your hand. However having a lock which radically changes security depending on which hand you use it in is not ideal for emergency situations nor if people other than you are using it.

Physics by the way is not just theory, there is a fairly significant experimental branch which is fundamental to its development and evolution.

Concerning the behavior of well made liner locks under extreme force, the only actual example I have seen described was by Nemo and Fred who viced a Military and applied an extreme torque, using a bar I think. Basically what happened was exactly as what John has described in the above.

-Cliff

[This message has been edited by Cliff Stamp (edited 09-18-2000).]
 
Thanks for the explanation, Cliff. That was much cleared that my attempt earlier.

------------------
Knowledge without understanding is knowledge wasted.
Understanding without knowledge is a rare gift - but not an impossibility.
For the impossible is always possible through faith. - Bathroom graffiti, gas station, Grey, TN, Dec, 1988

AKTI Member #A000831
 
Here's Steve Harvey on his liner-lock soap-box again:

My experience is that liner-locks are unreliable by nature. If every unreliable liner-lock were sent back to the manufacturer, it would ruin the production and handmade folder business that is the mainstay of the high-tech folder boom going on today (no disrespect intended, just my personal opinion). I would estimate that about 60% of liner locks that I have handled would release-fail with either hand closing pressure or a moderate blow to the spine. Practically all of the rest would fail when they were dirty, or worn, or if the handle were twisted. The better ones will lock up fine when clean and dry, but after grime from a couple dozen openings and some pocket lint get on the mating surfaces, they slip.

When closing pressure is placed on a liner lock, the tang exerts force only at the outside of the radius of the tang ramp, reducing the friction surface. Also the lock bar flexes (assuming that it holds even that well) again reducing the area of the lock bar contacting the tang. Then twist the handle and bwang, release. There are some good liner-locks, I've got an M-2 AFCK that has never released on me, but it is just a matter of time until the right combination of factors comes together, wear, dirt, force, and it will let go.

The new locks are better designs. They may not be perfect, but they are better.

By the way, on my Apogee frame lock folder it seems to me that my grip squeezes the lock closed, no matter which hand it's in.

[This message has been edited by Steve Harvey (edited 09-18-2000).]
 
E_utopia,
Thank you for going through the trouble to post this. I have three REKATS and a couple of linerlocks. I like the REKATS best,
why, they fit in my hand better than my other knives. The Rolling Lock slidebar release is convenient, and I just like the designs. The fact the Rolling Lock is fairly
strong and reliable is just frosting on the cake.
 
Steve :

I would estimate that about 60% of liner locks that I have handled would release-fail with either hand closing pressure or a moderate blow to the spine.
Click to expand...

A large number of people consider both of those tests to be flawed. I have seen the first described as improper technique (should not happen during correct use) and the second as outright abuse. If as a whole both of these were accepted as some kind of necesary standard then there would be a reason for the industry to adapt and produce folders that would fit these requirements, until then there really isn't, monetary wise anyway.

Practically all of the rest would fail when they were dirty, or worn, or if the handle were twisted. The better ones will lock up fine when clean and dry, but after grime from a couple dozen openings and some pocket lint get on the mating surfaces, they slip.
Click to expand...

I think this is a critical point. Far too much testing is done on locks (and blades in general) when they are close to or at NIB condition. For a using blade it will only be in this state for a very short period of time. It would be very useful to see how the lock behaved (and anything else for that matter) after a break-in period.

-Cliff
 
Steve - We have found that a properly made linerlock with an offset arc ramp will not defeat with a spine wack, even if dirty. The offset provides a "hook. that prevents the lock from sliding off of the ramp.

To say that something will eventually fail is moot. Everything eventually fails, even you and me.

sal
 
Originally posted by JoHnYKwSt:
This is false. A properly made liner lock has a blade tang angle which will square perfectly with the liner. When this happens the liner will not slip no matter how much force is applied. Also when force is applied friction is caused and this lessens slippage further.
Click to expand...

I wonder about this statement. When I look at my Sebenza, the base of the tang is canted to precisely the angle assumed by the lockbar once it's moved over.

However, this means that a force applied directly against the spine of the blade, will result in a two-part force vector against the lockbar. A small percentage (I don't know the exact amount) will go straight outward, while the much larger remainder will go straight downward. Since the lockbar is not straight, I would assume that most of the force goes into straining its weakest point, namely the cut-out. Meanwhile, the sideways vector will act to try to push aside the locking bar, increasing friction as it does so.

Last week there was a posting by somebody who took a large ax handle against the spine of a Sebenza. He reported that twice the lock disengaged, but there was no noticeable impairment of the lock. My guess is that either the locking bar deformed and then sprang back (very possible with titanium), or that the immediacy of the blow (F = ma) was sufficient enough to overcome the static friction and push the locking bar open.

These were just my thoughts upon looking at the Sebenza's tang, and thinking, 'Wow, they even thought to cant the tang so it would be a full-surface lockup'. Maybe everybody's integral lock does that. But it also made me think right away: Hey wait, any angle creates a two-part force vector, which means that some part of any direct spine pressure is going to want to push that locking bar out of the way... I'm glad my hand's grip works directly against that smaller vector.
 
There is a lot of misconception on how the Walker-Liner lock works. A proper liner lock will not exhibit full contact on the blade tang with the face of the spring. The angles of the blade tang and the spring face should be the same.

As for reliability, this turns into a huge problem with improperly made liner locks. Also, how can a liner lock be tested? I don't believe in the spine whack test, instead, I open the knife, and exert pressure on the back of the blade, using the edge of a table, and keeping my fingers out of the way. A good liner lock will not close, and will not stick when closed. Any perceptable movement of the lock spring while doing this is grounds to be concerned.

I do think the linerlock is safer, as failure is gradual, not sudden like other locks. Is it the strongest? That's unknown to me, but the pressure needed to break any quality lock would be extreme, and out of the boundries of normal knife usage.

--dan

------------------
pint1.gif


Co-Moderator of the General Flashlight, Lantern, & Headlamp Discussion Board at www.candlepowerforums.com
In Memoriam, JKM...
 
When discussing ultimate lock strength, we are usually talking about constant pressure as opposed to shocks. The forum member who disengaged the sebenza's frame lock imposed a sudden force as opposed to a constant force. If the force applied was constant the lock bar would have bent as opposed to slipped.
 
A Walker linerlock is very difficult to make. Made correctly, it is very safe. Bob Terzuola's new book goes into detail on how Spyderco makes it's lineerlocks in production. Most of these were Vince's developments and have patents or patents pending.

Though we feel ours ranks with the best, we are still always testing and seeking new tricks. When we do have a problem, it is an R&D project to determine the EXACT reason why and correct that possibility.

Micheal Walker knows a great deal about this type of lock and has them classified into 2nd generation, 3rd, etc. There are many facets of this type of lock that we have yet to learn about.

The interface of the lock / tang is critical. If the lock slips, all of the values are lost.

Made well, they are very reliable. In our testing, ultimate strength has not been as high as some other lock types. This is primarily because most of the forces are ultimately directed to prying the knife apart as opposed to some type of vertical shear.

Non catastrophic failure is nice. non failure is best.

just some opinions to share.

sal
 
You must log in or register to reply here.
Back
Top