*NOTE: This is a transcript of my segment on Assorted Calibers Podcast episode 35*
Welcome to Oddball Corner Pocket. For this week, I thought I’d talk about the different kinds of knife locks, and why you might want to use one over the other. This will probably be another drinking game candidate. This time with the word “lock.” The same warning applies as with the segment on grinds.
The thing that makes pocket knives convenient to carry is also probably there biggest weakness. Namely, the fact that they fold. Sure, it makes them compact, since their close to half the length closed as they are open, but they also can close when you don’t want them. Since your fingers are usually in the path of the blade if it folds while you’re using it, you can hopefully see why this is bad.
The first folding pocket knives were friction folders. As the name implies, the only thing that keeps the knife blade open or closed is friction at the pivot point. Some designs, like the Svord Peasant knife, and old school straight razors get around this by having an exposed tang, or metal extending past the where the blade meets the pivot. You can keep your thumb against the tang while using the knife, and therefor stopping it from closing on you. This design actually works pretty well, but also means that it can open pretty easily when you don’t want it to… like while it’s in your pocket.
There are some other designs that don’t have this feature. This means that they’re less likely to open in your pocket, but it also means that they are much more likely to close on you when you don’t want them to.
Fortunately, most non-locking knives for probably the past couple hundred years have used what’s called a slip joint. A slip joint has a spring along the spine of the knife that causes the blade to want to stay in either the fully open or fully closed position. Most people have used one of these. Your standard Swiss Army knife and old fashioned Case knives use this design. It’s a much safer design than a friction folder. Unfortunately, while I’ve never had one of these open when I didn’t want it to, I have had one close on me.
While there have been locking of various types for centuries, surprisingly, they weren’t really all that popular until the 1960’s, with the famous Buck 110 and it’s back lock. It’s a similar design to the slip joint, except the back bar actually latches into the back of the blade instead of just laying against it. That means that you have to push against it to unlock the blade and close the knife. Depending on where exactly the point that you’re supposed to push on it, this style lock may be referred to as a back lock, mid lock, or spine lock. Oh, and I’m going to include Cold Steel’s “tri-ad” lock in this type of lock, since it’s pretty much the same thing with an added pin to handle some abuse.
This is a very solid locking mechanism, and is probably the strongest out there. The main issue with this lock is that it is difficult to close. Depending on exactly where the divot for you to press is, it can be pretty much impossible, like the Buck 110, or tricky until you figure it out, like the Spyderco Endura.
Push things up to really the 1990’s, and folks started using what are called liner locks and frame locks. Instead of having the locking device on the spine of the handle, runs along the side. When you open the knife, a piece of metal will spring out into the empty part of the handle and wedge itself against the blade. This metal may be part of the liner and covered by a scale on the handle (hence “liner lock”), or the handle may be one piece, and the cut out is exposed (this is typically referred to as a frame lock). In my mind, there really isn’t any difference between these two lock types, but custom knife maker Michael Walker received a patent and trademark on the liner lock in the 80’s, so I’d suspect that the frame lock was a work around. To disengage these locks, you simply push the liner or frame out of the way of the blade, and close the knife.
While this design isn’t as strong as the back lock, it does allow for some things that the back lock won’t. Once you get past the detente spring that holds it closed, a frame or liner lock tends to be a smoother action than the back lock. Since the locking device isn’t running down the spine of the handle, you can use spacers in between the two liners instead of having a solid bar. This is often done to save weight. It also allows for newer design features like flipper openers where you can quickly flick the knife open. Oh, and it is significantly easier to close the knife one handed using this style of lock.
The frame and liner lock designs have become incredibly popular these days, probably to the point of being used more than anything else. I would say that most “modern” locking knives are of this type.
There is a variation on the frame lock called the compression lock. Basically, instead of having the locking device wedge itself near the edge side of the blade, it engages by the spine. For various reasons, it’s generally considered to be a little stronger than frame or liner locks, but I consider these types of locks to be closely related. To my knowledge, Spyderco is the only company that uses this style of lock.
The last type of lock I’m going to talk about is the Axis lock. Until a couple years ago, Benchmade had a patent on this type of lock, and was pretty much the only company to use it. There have been a couple companies, like Spyderco with their “ball lock” that made something very similar, and, since the patent ran out, I know Ganzo has been making knives using the Axis lock.
With this style lock, there is a spring loaded bar that goes across the back of the blade at the pivot, and stops it from closing. This makes for a very strong lock up in most uses, and I’ve seen handles break before the lock failed. To close the knife, you simply pull back on the bar, and shut the blade. Since there is no detente ball or spring applying pressure directly to the blade, this can make for a very smooth action, to the point that all you have to do is pull back on the lock bar, and let gravity do the work for you. While, at the same time, I’ve seen designs where the blade is secure enough, that it’s honestly a little difficult to intentionally deploy the knife without pulling on the lock bar. The one downside that I see to this style of lock is that, as Benchmade designed it, it relies on a small omega spring to work the lock bar. It’s a relatively fragile spring, and has been known to break after a few years of heavy use. Oh, and the design has been known to fail if you’re doing something like batoning, where the knife is struck rather hard.
I hope this helps you guys understand the different locks, and why you might choose one over the other. I will say that whatever lock system you choose, if it’s a decent quality knife, you should be able to rely on it during everyday use. If you’re a bit abusive towards your knife, you might want to choose a back lock of some kind, but I’ve never been worried about a frame lock failing on me during regular cutting jobs. Of course, if you’re the type that like to baton with your knife, use it as a step with it sticking out of a tree, etc… just get a good fixed blade and use that.