framelock vs. linerlock

[offbyone]

I might be missing something, but can someone tell me the difference between framelocks and linerlocks? To me, the only difference is that a linerlock has a scale on the side of the knife with the lock. The locking mechanism seems identical.

thanks!

edited to change 'bolster' to 'scale' - eek!

[Bernez]

Hi,

I think the difference is in the placement of the lock. Correct me if I'm wrong.
By a Frame Lock, is the lock made as part of frame/handle. Therby it's much thicker than a liner (? 1/8" - 3/16").
By a Liner Lock is the lock made as part of the Liner and not of the frame or scales. Usualy .040"/.050".

Edited by Bernez:
How do you explain this in plain English

Bernez

[Ray Rogers]

OK, plain English:

A liner lock consists of two handle slabs and a separate piece of liner material from which the lock bar is cut. Another popular design for liner locks is two thin liners upon which are mounted the bolsters and the scale material. The lock bar is cut from one of these liners. In both these cases, the lock bar would likely be anywhere from .040 to .062 in thickness depending on the size of the knife and the preference of the maker.

A frame lock consists of the two handle slabs and no extra piece for a liner. In models like the Sebenza (which popularized the frame lock) the lock bar is cut directly from the handle slab and therefore would likely be in the .125 to .187 range of thickness. A plain framelock looks about like this:



Another design for the framelock allows a scale to be mounted on top of the handle slab or for part of the slab to be milled away and replaced by a scale, like this:



It is easy to recognize a framelock because the end of the lock bar has been cut from the bolster and is therefore visible whereas a liner lock's locking bar is inside the knife.

The next question you will ask, once you understand these design issues, is 'which is stronger?'. Most likely, the frame lock is stronger but it is my opinion that it is not as much stronger as one would assume at first. In order for these heavier locks to be moved by ordinary mortal hands, a small portion of the bar must be milled away until it is thin enough to bend easily. It is still stronger than a thinner piece but I'm not convinced that it is all that much better. It does put a wider support behind the blade though, and that may be where most of its advantage truly lies .....

[Bernez]

Ray,

It's exactly what I mean. Thanks

Bernez

[chris caban]

The question about the liner locks and which is stronger can be answered by looking at a knife that untill about 2 years ago was unknown to most. The Karambit has become a fad with Tactical knife makers after 2001, the Champion of the blade and its unique training methods shopped his design of a folding Karambit, prior they were only fixed blades, to many companies, all refused. After sending him away they all began their own Karambit programs, with one fatal flaw, they never really looked at his design. Now Karambits are everywhere, '03 Blade show in Atlanta hosted at least 15 folding models, '02 there were none. The companies that were crumb snatching the Idea of these exotic design missed the fact that the Karambit works in two directions, which places a lot of stress on the back of the blade. If the knife has a liner lock, watch your fingers. You can look around and find the knife that the one in the know created, it has a spine lock, all of the others are poor copies.

[Frank J Warner]

Also, from a maker's point of view, your basic framelock goes together about twice as fast as a locking liner. There are no scales or bolsters to match up, drill, tap or contour. Just the frame itself. Fewer parts.

I've heard (and am inclined to believe) that framelocks have a more secure locking mechanism. This is due in part to the thickness of the lock itself, but more because, when in use, the hand squeezes the lock tighter against the blade tang lock face.

One difficulty with the framelock is that it needs a limiter on the lock itself, so that the user doesn't spring the lock too far open when closing the knife. A well-designed pocket clip can solve this problem, or a tab milled on the inside of the lock.

Framelocks are a joy to make, IMO. Two slabs, a blade, two screws, a stop pin and a pivot. Everything else is embellishment.

-Frank J Warner

[AUBE]

Originally posted by Frank J Warner
A well-designed pocket clip can solve this problem, or a tab milled on the inside of the lock.

-Frank J Warner [/B]

hmm im having trouble picturing the milled tab, can u describe how it works please?

thanks

-Jason Aube

[offbyone]

Frank,

thanks!
Having been even more of a newbie than I am now when I started this thread, frame and liner locks seemed pretty much identical to me, at least mechanically. Obviously, there are more parts to the liner lock, since you need 'handles', but I have seen knives designated as 'framelocks' which have some sort of scale/embellishment bolted to parts of the frame. Originally it just seemed to me that the difference was simply whether or not the knife had scales. Especially since framelocks often have relieved locks, which means the springiness (technical term, heh) is about the same.

However, I didn't think about the fact that thicker face on the lock does indeed engage more of the blade. I also didn't think about the fact that squeezing the lock strengthens the lock. This also answers for me why I have seen some frame/linerlocks (call it what you will) with a split scale over the lock side of the handle. That is to say there is a separate piece of handle/scale over the lock. I guess this allows the hand squeeze pressure on the handle to be transferred to the lock.

I am also curious about the milled tab as a lock stop; I'm not picturing it. I also guess I'm not really sure why pushing the lock too far when disengaging it is a problem. Is the problem simply that the user may inadvertenly unbend the spring by opening the lock too far? Having tried bending some thin titanium myself, I'd think it would have to be done with more than a thumb in order to have enough pressure to actually change the nature of the spring. I guess I'm probably wrong.

Anyway, thanks for the most informative response. The other responses were good too, but they didn't really answer my (perhaps poorly articulated) question.

[AUBE]

Originally posted by offbyone

I also guess I'm not really sure why pushing the lock too far when disengaging it is a problem. Is the problem simply that the user may inadvertenly unbend the spring by opening the lock too far[/B]

yup your right

[Frank J Warner]

I am also curious about the milled tab as a lock stop; I'm not picturing it. I also guess I'm not really sure why pushing the lock too far when disengaging it is a problem.

There are no bolsters or scales on a simple framelock to prevent the lock from opening too far. While this would generally not be a problem, it is possible to spring the lock if there is no mechanism to prevent it.

I've been scouring the Internet trying to find examples of what I mean by a lock limiter. Turns out there's a perfect example right here at CKD in this thread:

Framelock safety stops

The clips shown in this thread also act as lock limiters. The same principle would apply if you're not using clips or if your clip is mounted for tip-up carry. You'd need a tab or other limiter to prevent the lock from being sprung.

It should be noted that this is a nice fail-safe device and not required on every knife. If your frame is beefy enough or heat treated to the right springiness, springing the lock is next to impossible except for the most heavy-handed users.

-Frank J Warner

[Kevin Wilkins]

Originally posted by Ray Rogers
SNIP

In models like the Sebenza (which popularized the frame lock)
SNIP

I think it's important to point out, Chris Reeve INVENTED the framelock and incorporated it into his Sebenza which was the first knife ever to use this lock. I believe he developed it after looking at the liner lock, which was designed and first used by Michael Walker. As neither Walker nor Reever ever sought or obtained a patent for their designs, they have been widely taken over by everyone and his dog... including me, but credit goes to them for having created the designs in the first place.

A properly made frame- or liner lock doesnt need any limiter to prevent over bending. Chris Reeve Knives has been making Sebenzas for years without one, and if you take apart a Sebenza and study the geometry, you'll see why! BTW 6al4v titanium doesnt respond to heat treating, it just oxidizes on the surface.

[Ray Rogers]

Well, OK, I stand correvted re the frame lock and Chris Reeve. If you say he was the first to use it I really can't argue.

On Michael Walker though, I will beg to differ. Mr Walker did us all a great service by popularizing and refining the liner lock as it is known today but locking liners seem to go way back. At least, that's what I've read......

[AUBE]

Originally posted by Kevin Wilkins


BTW 6al4v titanium doesnt respond to heat treating, it just oxidizes on the surface.

6al4v Ti. does respond to heat treating...just not as much as a heat treatable steel etc...
6al4v is known as a alpha-beta alloy of titanium and heat treating can improve strength by 30-40%

-Jason Aube

[Kevin Wilkins]

Well Ray, no reason to believe me! :-) you can ask Chris Reeve over on his forum and he will give you the low down. I've spoken to him at shows in the past about the whole thing. He said getting a patent woud have cost too much and continued costing money, time and energy every time he went to court to defend it. :-) I think the Sebenza still sets standard too.

Chris also gives Michael Walker credit for the liner lock, as does Bob Terzuola (in print) in his book on making tactical folders. Ron lake has been pretty vocal on the subject as well. I dont think Michael Walker has ever made enough knives to "popularize" his design. What's made it popular is the fact that everyone and his brother started using it! Why? Because it's a #### good idea. I wish I'd thought of it, but I'm just a popularier myself. :-)

There were indeed some similiar ideas around before Walker's linerlock such as the old Linesman's knife, but they work substantially different from Walker's design. Walker's design is unique in using the liner as a spring which not only locks the blade open, but prevents the blade from opening when it's closed (ball detent.) In this way the back spring is eliminated. The unique, triangulated geometry and angled contact surface on the back of the blade are also from Walker, as is useing the galling properties of titanium when combined with steel to help the lock work.

Regarding titanium:

If you have any heat treating tables or information, I'd like to see them. I have information from many industrial suppliers of (Grade 5) titanium with pages of technical regarding everthing the rec'd. free angle and composition of the optimal cutter for a lathe when working the stuff to detailed welding and physical properties tables... but the only information on heat treating is regarding stress relievng of complicated components after welding.

No heat treater I've ever heard of will touch the stuff.

So I dont know where you get figures of 30-40% increases in strength... I'd like to hear about it however!

If you're telling me that heating titanium up with a torch till it glows makes it 30-40% stronger... well I guess I'm from Missouri on that one!! :-)

[Frank J Warner]

I want to note that the heat treating I was refering to was in reference to steel frames, not titanium.

I also want to stress again that a lock limiter is NOT required. 90% of the framelocks out there don't have them and don't need them.

I put them on mine because it's a nice touch.

-Frank J Warner