Common Folding Knife Locking Methods

Everyone loves a good pocket knife. The modern knife industry has yielded vast improvements to both the design and construction of pocket knives. With this innovation came a number of different locking methods. How a knife locks is important, because this feature is the crux of the folding knife. We’ll examine a number of common folding knife locking designs and discuss the pros and cons of each. 

No Lock 

First off, we’ll take a look at some knives that don’t lock. This will be our baseline for folding knife functionality. I do this because I believe almost everyone has at least handled one of these at some point. Folding knives without a lock typically come in the form of a slipjoint. A slipjoint uses bar springs to create pressure and a stop for the blade. They will not lock the blade open. However, they will provide the force needed to keep it open for most cutting tasks. If the blade is pressed forward, the knife will fold closed. This does pose risk of injury for the user under hard use, but it is perfectly safe for most tasks (if properly handled).

The two most popular examples are from Case Knives and Victorinox (or other Swiss Army-style knives). My grandfather always carries one and it’s part of what got me into knives originally, so they’ve secured a special place in my heart. These are great because they are legal almost everywhere. (Obviously, take this with a grain of salt. Any metal detectors and you’ll likely be stopped.) 

Friction folders are another option. These feature a metal tang opposite the blade so that when the knife is folded open, your hand holds down the tang and keeps the blade in the open position via natural pressure as you use the knife. This can be a great workaround if you live or travel in an area where locking knives are prohibited, but be sure to look into the specific laws for your location.

Back Lock

Now, the lock even your grandpa is familiar with, the back lock has been used on knives for over 100 years. One of the most notable examples, the Buck 110, was introduced in 1902 and has been in the pockets of hunters, workers, tradesmen, and everyday people ever since. It is well made at an affordable cost that won’t have you shedding a tear if you drop it, and this tends to be a trademark of most back locks — aside from high-end custom work. They are built to take a beating and keep on working. 

Although with modern knifemaking, back locks have fallen out of style. People want quick access and one-handed closing capability. Sure with practice you can do this with a good back lock — especially one where the lock is locked toward the middle of the handle as opposed to the bottom — but it will never be as easy as any of our next locking methods. 

Liner Lock

Most modern folding knives use what’s called a liner lock, which consists of a thin sheet of metal cut and folded over to support the blade when locked open. This is one of the most common and inexpensive methods to create a locking knife, thus it is used extensively. 

The design is very intuitive for most people. At first glance, it’s easy to see that you simply press the bar over to disengage the lock and close the knife. This may seem unnecessarily mundane, but inexperienced people can hurt themselves by using some of the more complicated locks incorrectly. 

One downside often mentioned in relation to the liner lock, is that you must put your finger in the path of the blade — albeit just for a few seconds — to close the knife. 

Likewise, it is not the strongest lock design. Liner locks rely on lock face geometry to provide you with repeatable and solid lockup. As you open and use your knife, this contact between the lock and the blade will naturally wear down the metal. Depending on the metal, titanium vs. steel, this will happen more or less quickly. Titanium is softer than steel, so it will wear quicker. Eventually, you will reach a point where the lock will fail and need to be replaced, sometimes this means replacing the entire knife. 

Frame Lock

Consider the frame lock like a beefed up liner lock. Instead of a thin sheet, the entire side of the knife handle is crafted from a thicker slab of metal. The same overall premise remains the same, however. This sheet is cut and bent to support the blade in the open position. It simply provides more surface area for the blade to contact the lock face. This makes for a more secure lockup. 

The frame lock design has a few kinks of its own, mainly in the way of what’s called overtravel. Overtravel is when you hyperextend the lock bar outward while disengaging the lock. It takes a fair bit of force, but is possible. This issue is typically mitigated by the addition of an overtravel stop, or lock bar stabilizer. This is some form of guard that prevents the lock bar from traveling too far. 

Another consideration with the design of a frame lock is material. Frame locks are typically constructed of either titanium or stainless steel. The difference is cost and weight. Titanium is lighter and more expensive, while steel is heavier and typically reserved for ‘budget’ knives. 

Since the entire side of the knife handle acts as the locking mechanism, many feature what is called a lock bar insert. This is a bit of hardened steel that screws into the lock face to contact the blade instead of the softer titanium. Additionally, if your lock geometry wears down or changes over time, this part can simply be replaced instead of the entire slab of material. 

Axis/Bar Lock

The Axis lock was originally a hallmark of Benchmade knives. However, after the patent expired, other companies entered the playing field. Now, the generic variation has been deemed the bar lock. The bar lock consists of a sliding bar that is raised and held in the upright position by spring pressure. This creates both the detent and lockup. Pulling down on the bar releases pressure on the blade, allowing it to swing open and close freely. 

This bar contacting and supporting the tang of the blade creates a very strong lockup. My only issue with the bar lock is that you’re relying on springs that can break. fairly easily. Bar part is very strong and that is what is taking force during use, but to keep that bar in place you just have a thin spring. If that spring snaps, your knife is useless. 

Compression Lock

The compression lock is found on Spyderco knives and acts as a sort of reverse liner lock because the lock is located on the back, rather than the front of the knife. I’d say it’s an obvious design improvement as well, because it keeps your fingers out of the path of the blade as you close the knife so you don’t accidentally cut yourself. Because your fingers are safely out of the path of the blade, when you release the lock, the blade can swing freely open or closed. It may also be a bit more secure. I’ve never had a compression lock fail on me, but I’ve had a few liner and frame locks do so. 

Button Lock

The button lock is mostly on automatic, side-opening knives, but it is also popping up on some manuals now. To function, the button is really part of a bar that interfaces with the tang of the blade to click into place with the knife is in the open or closed position. With an auto, you must overcome spring pressure to close the knife; with a manual, the blade will swing feely with the button depressed. 

One common complaint about the button lock is what’s called ‘button stick.’ This occurs because of friction between the button and the blade tang. Usually this works itself out over time, but it is similar to lock stick on liner or frame lock designs. 

Final Thoughts

So, there you have it, all the common locking methods for modern folding knives. They’re all great in their own way, but they all have their weaknesses as well. In the end, a folding knife will never be as strong as a fixed blade, so there is always going to be a compromise for convenience. Pick the one that you like the most and use it well. 

What is your favorite folding knife locking method? How does your knife lock up? Share your answers in the comment section.