Average life of a liner lock(liner)

Scarman · Oct 14, 1999

I am trying to get an idea of life expectancy on liner lock liners.
I have read of some(mostly titanium) liners moving all the way over to the other end of the knife in, what seems to me, a relatively short time.
Is this normal and if so what would be a better material to look for?
I have the BM975 and a Military and both locks are well over to the originating side but lock up solid. I do not flick knives and I do not open/close all day as some do.
I have noticed the liner on the Military is Stainless, but the 975 is Titanium. I have also noted that the tang on the Military is concave while the 975 is flat but angled.
Is stainless better/stronger than titanium for liners and if so who else uses it?
What is the average user to expect out of the liners?
Help.....!!!

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The greatest thought that has ever entered my mind is that one day I will have to stand before a Holy God and give an account of my life.
*Daniel Webster

Rev 20:12

JoHnYKwSt · Oct 14, 1999

The life expectancy is quite broad. I've heard Ti liner locks that lasted from less than a month to a couple of years and still going strong. If you ask me, the life of liner locks are all too short! Just more reason to stay away from them. Stainless liners will last longer than Titanium liners because they're harder. If I were forced to buy a liner lock, it would definetively be stainless. Titanium does have it's advantages however, the main one being that it will gall against steel and give a more secure lockup.

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Johnny
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bald1 · Oct 14, 1999

Scarman,

This is an interesting thread

! I'm hoping you'll get a lot of input regarding different liner materials. The most criticized has been titanium for galling and wear which is interesting considering that it is always touted for its strength... never hear much about wear.

But as for real world wear to the point where a liner lock mechanism can not be adjusted for secureness, I've no clue.

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-=[Bob Allman]=-

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JoHnYKwSt · Oct 14, 1999

Bob,

Titanium is touted for it's strength. It is about the same stregnth as steel, but this isn't the problem. It's the inadequate hardness, which is why it wears quicker (sometimes much quicker) than a stainless liner. I don't know if production companys heat treat the face of their liners, but if they did this would help considerably. I know Chris Reeve heat treats the lock bar face of his sebenzas with a blow torch. In liner locks galling is a good thing--more secure lockup.

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Johnny
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bald1 · Oct 14, 1999

Johnny,

Thanks for the clarification. I needed help here as I'm no metallurgist and could only recall vague comments about titanium problems.

I also fully agree with you about CRK Sebenzas. Mine has been flawless and is a great workhorse of a folder! Hadn't even thought about my 'Benza when I posted above. I was strictly thinking about the thin liners used and not Chris' integral lock.

Again, thanks for helping out

!!!

-=[Bob]=-

takao · Oct 14, 1999

I've had my ti for about 2 years no problem yet very sturdy lock up. BM 975 series.

Corduroy · Oct 14, 1999

I've been carrying the same AFCK for over 4 years. It's been through a fair amount, including some modifications and other "abuse" (you can see it on my site). Lockup falls just a hair past dead center, its state when I bought it. I've seen other Benchmades with Ti liners wear in very fast over their first few weeks, but I once they find their "spot" the ones I know have held up very well.

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-Corduroy
"Why else would a bear want a pocket?"

Little Bear Knives
Drew Gleason:
adg@student.umass.edu

sirgrumps · Oct 15, 1999

From what I remember from school. The "strength" of Titanium is the high tensile strength and low weight as compared to steel. When comparing stiffness (resistance to bending) Titanium is not much better than aluminum (roughly 1/3 of steel). But Titanium is very hard, difficult to cut or mill. The lower grade Ti are easier cot cut and work, but you give up hardness. This is a very misunderstood material. The metalurgist are still learning hoe to use it. Both steel and Al are at the upper limits of the ability to tweak the material. All of the improvements are going to be incremental. Ti still has a way to go. Personally, I think using Ti in most applications is marketing hype. A reason to charge more, it's "high tech". Just use Al unless you need to shave every little bit of weight. Like for Olympic class athletes.

I do not like liner locks. I think the best is the axis lock or the top lock use on a Spyderco Goddard.

The reason Ti liners gall is that TI is very similar in hardness to steel and at the microscopic level it is not very smooth. You get a very similar situation when you have two pieces of stainless rubbing against each other. Just ask anyone who owns a stainless semi-auto pistol.

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sirgrumps@earthlink.net

JoHnYKwSt · Oct 15, 1999

Sirgrumps,

Please refer to my posts in this thread http://www.bladeforums.com/ubb/Forum1/HTML/004963.html

The reason Titanium is hard to mill isn't because it is hard, it is because of it's properties are different than that of aluminum and steel.

Stainless liners are harder than titanium ones. Mission's titanium MPK maxes out at ~45Rc, this is after heat treat, and Stainless Steel knives are usually around 56-60Rc.

Improvements must be taken as a whole for the purpose intended, then its benefits won't be incremental.

Just use Al unless you need to shave every little bit of weight.

Just for reference, the density of Steel, Aluminum, and Titanium are as follows: 0.29lbs per cubic inch, 0.12lbs per cubic inch, and 0.16 per cubic inch. Please forgive me if these numbers are off as I am taking them from memory. Aluminum is lighter than titanium.

The reason Ti liners gall is that TI is very similar in hardness to steel and at the microscopic level it is not very smooth.

I'm not sure about this. From my understanding, Titanium will gall with any other metal.

When comparing stiffness (resistance to bending) Titanium is not much better than aluminum (roughly 1/3 of steel).

I recall someone doing chin ups with a MPK titanium blade. And the blade suffered no damage. I know if this were an aluminum blade, there would be no way it would support a man doing chin ups. Maybe we should change the word to flexibility, titanium is more flexible than steel but it will bend and then come back to true.

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Johnny
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mjjbecker · Oct 15, 1999

I will still be using my trusty lockbacks when all you gents are running around with your fingers missing! Ha Ha, only joking.
I can remember when liner locks were being touted as the answer to all our knife problems. It does show that there are pros and cons to all systems.
An important point though-what about the guarantees regarding lifetime coverage for materials and workmanship? If titanium liners are flawed, then some companies in the future will have one hell of a repairs liability in the making!

Scarman · Oct 15, 1999

I appreciate the wealth of information you gentlemen have brought to the subject. Certainly more than I could find.
I must say the while I have heard Titanium is tough, I do feel more comfortable with my Military's lock than with the 975(referring to wear)
I was not sure about the Sebenza. I do know it is Titanium, and I had heard that the lock face was heat treated to some degree. I have also seen that it is much thicker than the other Ti liners I have seen and therefore gives me a warm fuzzy in the wear department. I am also wondering if the fact that the contact surface on the tang has something to do with it. The Sebenza's is smoother than all the rest, thus leading me to believe, less abrasive to the lock face.
I do know that all I have read or seen on that particular knife gives me great confidence in every aspect of it.
Thanks again and please keep the information flowing.

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The greatest thought that has ever entered my mind is that one day I will have to stand before a Holy God and give an account of my life.
*Daniel Webster

Rev 20:12

Walt Welch · Oct 16, 1999

I have dozens of knives of the liner lock persuasion. I think that this is a style that is on its' way out, but not due to wear considerations. Accidental lock release, while rare on a properly designed knife, is a much more pertinent consideration.

Frame locks, such as the Sebenza and Darrel Ralph Apogee, are much stronger, and the harder you grip the knife, the more the lock is squeezed closed.

Stainless or Ti in a liner lock? They both work, and work well. The ONLY problem I have had from a liner lock wearing was in a Kit Carson #18. I loaned (groan) the knife to a friend's wife, my hostess at the time, and she flipped it for about 30 min. This flatted the stop pin, and the knife would no longer lock up solidly. I shamfacedly called up Kit and told him what had happened; he chuckled, and had me return it for free refurbishment. It is still my daily carry knife, and works perfectly.

FWIW, I have a few dozen BM's, and the liner locks on the BM 97X series (the Emerson knock-offs) were the most variable of any of the BM models. Some were fine, but others were sticky, and nothing I tried would fix it (disassembly, polishing metal surfaces, high tech lubricants- I tried them all).

Hope this helps, Walt

DonL · Oct 15, 1999

I've noticed no movement in the locking bar stop point on my small Sebenza in the 1-1/2 years or so that I've owned it. While the end of the locking bar may be heat treated, let's also keep in mind that the bar is so wide, that any conditions or forces that would create wear in a thinner "leaf-type" liner is spread over a much greater area in the Sebenza. Also, the stop pin sleeve can be adjusted or rotated, or even replaced and "tuned" to reduce the amount of locking bar travel across the locking face of the blade.

As for aluminum use in folders, use for handle scales should be fine, but aluminum has a much lower "cyclic fatigue strength" than either steel or titanium. This would lead to a relatively short service life of a liner leaf, as it would accomodate much fewer locking and unlocking flex cycles before it fractures. This is one reason why bicycles, for example, made of aluminum are overbuilt and stiff, they can't afford to flex as much as a steel or titanium frame would. In addition, aluminum tends to act much "softer" than most steels, and while hard surface anodizing may help the wearing of an aluminum liner against a steel blade, stainless and titanium liners will tend to outperform those made of Al. Trying to make an aluminum liner on the lock side would produce a short term advantage (saving a portion of an ounce or so) while reducing the number of times a lock can flex to an unsatisfactory level. There are always trade offs, but I've come to trust titanium locking bars and stainless liners, or toher locking mechanisms altogether.

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Don LeHue

The pen is mightier than the sword...outside of arm's reach. Modify radius accordingly for rifle.

JoHnYKwSt · Oct 15, 1999

mjjbecker:

If titanium liners are flawed, then some companies in the future will have one hell of a repairs liability in the making!

Many companies and makers are moving away from titanium liners towards stainless steel just because they were getting tired of having liner locks return due to wear.

DonL,

I dont think we could use aluminum as a liner material even if we tried. It would wear way to quickly. Saving weight really isnt' a consideration when we are talking about liners--a stainless steel liner wouldn't weigh much more than a titanium one, which is why I believe stainless steel is the better material to use for liners.

When we are talking about integral lock folders, however, other things become more important than others. Steel if it were lighter, would be fine in these applications. But titanium has everything steel has to offer except it's softer and it's more expensive. The softness issue can be solved if the lock bar face were heat treated. Integral folders have the lock as a part of the handle, if an integral folder were to be made out of steel it would be very heavy. Titanium for these folders are the best choice.

FWIW, I've been opening and closing my sebenza about 50 times a day (bad habit), for about 5 months already. I'll let you know when the lock wears out.

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Johnny
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mjjbecker · Oct 15, 1999

Putting aside my comment about lockbacks, I wish I had seen this thread before I shelled out on three liner locks myself! All have titanium liners.
I had bought a Boker Brend for heavy duty use but I may go and get an SOG Tomcat instead.

storyville · Oct 15, 1999

a similar thread just recently opened in the new CRK forum, FYI. i mentioned there that i've had my sebenza for about 2 yrs now w/o any problems w/lock wear. i also asked to hear from folks who may have had wear problems, however... we'll see what folks post in the next few days.

Scarman,
RE the "warm fuzzy" feeling you get "seeing" the Sebenza integral lock -- wwwwell, please find a local retailer who carries them, and *feel* the warm fuzzies to your heart's delight! got mine right here... whoa, starting to feel...

Glen

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The piano has been drinking -Tom Waits

Scarman · Oct 15, 1999

Glen,

It looks like I might get lucky this weekend.
I will be off all weekend, but I hope to come back the proud owner of a Sebenza.
Keep your fingers crossed for me.
Y'all have a good weekend.

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The greatest thought that has ever entered my mind is that one day I will have to stand before a Holy God and give an account of my life.
*Daniel Webster

Rev 20:12

Mark Schmitt · Oct 15, 1999

Corduroy's analogy of "finding its spot" is
dead on, IMHO. I have many linerlock folders
and all of them have behaved the same,
regardless of Ti or SS liners. They will
"wear in" to a certain point and then stop.

The two most-used folders I have (both
Benchmades) have been cycled probably 10-20
times a day since I bought them. This was
back when the Benchmade 975 was first
released. There was initial wear, then
virtually none. Lockup is still solid.

My sample size may be low, but maybe we can
come to a consensus...

Mark

Walt Welch · Oct 16, 1999

Regarding the 'cyclic fatigue strength' of Al, and the problems thereof, see the article,'Why Things Break' in the latest (Oct. '99) issue of 'Scientific American.'

It explains why the Al roof of the 747 of Aloha Airlines flight unzipped in April, 1988. Further, the author explains a new theory of chemical bonds, and how this theory is leading to development of extremely high strength, yet ductile, alloys for hypersonic aircraft.

For the first time, alloys for extreme conditions can be chosen by theoretical models. Interesting and easy to read article.

Perhaps an Fe doped Ni aluminide blade in a Sebenza..... Walt

A T Barr · Oct 16, 1999

The reason that the majority of Liner Locks use Titanium for the spring is, 6al-4v Titanium does not lose its memory, or
fatigue ,ever. The only spring material that will not fatigue fairly quickly is made with carbon steel. When you make a spring out of any steel, first you have to bend it to the exact angle needed and then you have to heat treat it to a very exact hardness. A spring made of stainless stell will fatigue much quicker than one made with a carbon steel. All locks have their plus and minuses.