Not all knives are the same. Occasionally some bright knifemaker/designer will come up with a new idea to open or lock the blade in a way that’s never been seen before. Or maybe just a simple addition or removal of material in the handle that makes your life so much easier. It’s constantly evolving and every time you think “this is it, now we’ve seen everything”, another one comes along. It's one of the many elements that keeps the hobby fun.
I’ll start of by saying this: there are a lot of smart designs and technology out there. So this isn’t the complete list. Just some highlights worth mentioning. I’ll update the list every once in a while to try and make it more complete. I will also add pictures in due time, to further explain these systems visually.
One of the simplest and (possibly therefore) most common locking systems in the modern pocket knife is the liner lock. Liners are thin pieces of (mostly) steel, placed on the inside of the handle scales, or rather: the handle scales are mostly fixed onto the liners. The liners make up the skeleton of the knife giving it stability and weight.
In the case of a liner lock, one of the liners has a part of it cut out and slightly bent. So when you open the knife, the bent piece of liner slides under the blade, locking it in place. When you want to fold the knife back to closed position, you simply bend the liner back and fold the knife.
R.I.L. / framelock
The framelock, originally called the Reeve Integral Lock by its inventor Chris Reeve, is actually a lot like the liner lock. With the framelock you also have to bend a piece of steel back to close the knife. Only in this case it’s not the liner, but a piece of the frame itself. Sometimes the non-lock side of the knife handle will have a handle scale, but mostly framelock knives have full steel/titanium/aluminium handles. Framelock knives are often thought to be stronger, since the handle frame of usually thicker than a line, thus having more material locking the blade in place.
With some activities, people want all the strength and stability of a fixed blade, but in a folding knife package. This is the reason locking blades were invented of course. But even still, sometimes people have trouble trusting locking blades and want a secondary lock. The Rotoblock is such a secondary lock. The Rotoblock is a system owned and patented by LionSteel, a knife manufacturer from Maniago, Italy.
It’s essentially a small wheel placed in the cut-out of a framelock. When you open the knife, the framelock slides into place. Then you can turn the wheel clockwise, locking the framelock (what?!) into place. So it’s a backup to the already tremendously powerful framelock. To disengage, turn the wheel counter-clockwise and press the framelock outwards to fold the knife.
LAWKS and Auto LAWKS
While on the subject of secondary locks, it’s interesting to bring these up. The LAWKS (Lake And Walker Knife Safety) system is a secondary aid to back up the liner lock. It consists of an extra piece of steel around the pivot, which emerges as a switch on the spine of the blade, which can be manually engaged or disengaged to lock the liner in place, making it impossible to slide it aside.
The Auto LAWKS system is similar, only in this case the secondary switch is spring powered. The latch is always pushed towards the locking direction. So when you open the knife, it automatically engages both the linerlock and the LAWKS lock.
Often viewed as an upside-down version of the liner lock, the compression lock allows you to unlock the blade on the back of the knife. The big upside to this, is that you don’t have to put your thumb in the way of the blade, like a regular liner lock. This minimalizes the risk of the user. The compression lock is one of the many brilliant inventions of Spyderco.
The AXIS lock is an invention from Benchmade. Until recently, the AXIS lock was patented technology.
Contrary to liner- and framelocks, the AXIS lock is an ambidextrous solution for folding knives. The locks relies on the AXIS bar, which is visible in the handle of the knife. A so called ‘Omega spring’ (named after its Ω shape) forces the AXIS bar forward, which locks into a notch in the blade when opened, making it unable to fold back again. Until, of course, you pull the AXIS bar backwards again.
Possibly one of the oldest locking mechanisms in the knife world, the back lock is still one of the strongest and most reliable systems out there. These days they’re slightly less popular, because they’re not as easy to use with one hand. The Buck 110 is one of the most common knives in the world and has represented this lock for over half a century.
The spine of the handle is essentially the lock. It’s a bar which pivots on a pin. When the knife is opened, the lock bar catches a notch in the blade. When the back lock is pressed, the spine raises slightly towards the pivot and gives the blade freedom of motion again.
Knife designer Andrew Demko took the old fashioned back lock and perfected it for Cold Steel. He named it the Tri-Ad lock. In this case they’ve added a stop pin between the blade and the lockbar. The blade is notched where it touches the stop pin. The lock bar is kept in place by a pin. The hole that this pin runs through is given some extra space left and right of the pin, so the bar can correct itself during hard use. Cold Steel isn’t shy about showing how strong this lock is. There are plenty of videos of them torturing their knives to prove its strength.
The best known Ring lock in the world is probably from the French company Opinel. They call it the Virobloc system. A ring around the pivot allows the user to optionally engage/disengage the lock either in open or closed position. A very intuitive and user friendly solution, even for children.
A less spectacular, but super efficient addition to a knife is a nail nick. It’s basically a small groove in the blade, which allows you to open a pocket knife using your nail to catch or pinch the nick. You’ll fine nail nicks on most Victorinox Swiss army knives, for example. When people speak of a two hand opening knife this is a common factor.
Simple but effective. Back when they patented this in 1981, Spyderco drilled a big hole in the blade, allowing for easy, one-handed opening. It’s ambidextrous and does not interfere with cutting or sharpening, the way a thumb disc or stud might. It has become so popular and instantly recognizable, that you can often spot a Spyderco from a distance, just because it has a round hole in it.
The thumb stud is possibly one of the earliest ways of deploying a folding knife with one hand. It’s a stud, mostly screwed on to the side of the blade, allowing you to place your thumb behind it and push the blade outwards to open it. Sometimes the stud is placed on both sides of the blade, making it ambidextrous. You’ll also find knives where it’s fitted on one side, but is reversible.
Much like a thumb stud, but a different construction. The thumb disc is a small (mostly) steel disc placed on the spine of the blade. It’s wider than the spine, allowing you to place your thumb under it to push the blade outwards. This automatically means it’s an ambidextrous solution. In some cases, the disc is fastened with a small bolt. In that case, you can unscrew it and remove the disc. This is nice, if you want to take your knife somewhere you’re not allowed to carry a one hand opening knife.
A flipper is part of the blade that protrudes out of the back of the handle when the knife is folded closed. By applying pressure on the flipper with the index finger, the knife pops outwards into open position when the detent gives way.
The front flipper works the same as a “regular” flipper, except that is protrudes from the front of the handle in stead of the back. This is sometimes regarded as more difficult to use, because the thumb is used in stead of the index finger. If you have long fingers, you might be able to use your index finger for some front flipper knives.
This leaves little to the imagination, but it’s a piece of steel attached to the knife handle, allowing it to be carried on the edge of a pocket. This way, the knife isn’t ‘floating’ around loosely in the pocket and can’t fall out in a seated position, for example. Most pocket knives these days have pocket clips, but it was Spyderco who came up with this solution.
Often found on linerlock/framelock mechanisms, the detent keeps the knife closed in you pocket. A small ball is placed on the piece of the liner/frame which falls into a dent in the blade. That way it keeps the blade in place, until a sufficient amount of pressure is applied to release it. In flippers, this is what really can make them pop.