There are a plethora of pocket knife lock types available today, and in this article I’ll give you my comparative opinions of them. I think that which lock is best for you depends on several factors: your intended use, your hand shape / size, your aesthetic preferences, etc. So this article is not intended to point to any particular lock being the objective best, but rather to give my thoughts having carried and used and pondered them for years.
Back Lock
The back lock is one of the most recognizable and well known locks available. From the tail lock of the Buck 110 to the Triad Lock from Demko Knives & Cold Steel, the back lock has earned its place as a classic. It works by having a bar or rod spring press a rocking lock bar on the spine side of the knife’s handle down into a cutout on the blade tang once opened. A well made back lock can withstand heavy use, and has a particularly strong bias for close compared to other locks. The downside is that you almost always have to have your hand in the path of the blade to unlock the knife. Also, the pressure that the rocking bar applies to the blade tang often results in back locks requiring more constant positive pressure to open them than other locks. Still, the back lock is reliable and simple to use.
Liner Lock / Frame Lock
Liner locks and frame locks are also one of the most commonly used lock styles. I lump these together because they work essentially the same. They both have a leaf spring that bends inward toward the blade and interfaces with a ramp cut into the tang. The difference is in that a liner lock is cut from a thin liner and a frame lock is cut from the handle itself (the knife pictured below, a Jack Wolf Knives Primo Jack, is technically a bolster frame lock). These locks rarely break from wear and tear due to the large leaf spring involved, but they can have or develop lock rock (meaning the lock bar slides on the tang ramp). Some claim that your grip helps hold the frame lock (but not the liner lock) closed, but I don’t find this to be commonly applicable in normal use. The liner lock and frame lock require you to put your thumb in the path of the blade to unlock the knife. Also, these locks use a detent ball in the lock bar and a divot in the blade to hold the knife closed, and they sometimes can have too much or too little strength in the bias toward closed. Some of the most premium knives are liner and especially frame locks, and they’re great locks when done well.
Compression Lock
I decided to separate out the Spyderco Compression Lock into its own subcategory within this class of locks because it functions very similar to the typical style of this lock but without some of the downsides. The compression lock is placed on the spine side of the handle, rather than the blade well side, and this takes away the need to put your hand in the way of the blade when closing. It also places the lock bar between the blade tang and a stop pin, which purportedly increases the strength. While the compression lock requires you to use your index finger to unlock, which can take some getting used to, I think it is a general upgrade over the typical liner lock.
Cross Bar Lock
The cross bar lock has exploded in prevalence recently due to the patent on the Benchmade Axis Lock expiring, allowing many more companies to use this lock style. It involves, you guessed it, a BAR that goes aCROSS the tang of the blade to hold it open. The access on both sides of the handles to the cross bar makes this one of the most ambidextrous locks, working just as well for right and left hand use. The cross bar lock doesn’t require your hand to be in the way of the blade when closing, which makes injuries less likely. One downside of the cross bar lock is that it often uses a (relative to other styles of spring) thin wire form torsion spring that some find to be prone to breaking. That said, some locks that are in roughly the same category as a cross bar lock, such as the Spyderco Caged Ball Bearing Lock or the Microtech RAM-LOK, use different types of springs. The cross bar lock stands out for its inherent ambidextrous nature and ease of use.
Button Lock
The button lock is probably more well known on out the side automatics, but is also available on manual opening knives. The button lock uses a compression spring to push a cone shaped piece against a ramp on the blade tang. Button locks are as simple to use as it gets; push the button, blade closes. They don’t require your hand to be in the path of the blade and anyone can use them. In my opinion they’re usually relatively easy to use left handed also. The compression spring is unlikely to wear out, but if the angles of the cone and tang are off they can sometimes slip if heavy pressure is applied to the blade tang. Some highest value budget friendly knives, such as the Sencut Serene below, use button locks.
Plunge Lock / Spine Lock
Spine or Plunge Locks are a newer type of lock that have created a lot of excitement in the pocket knife enthusiast community. These locks work by forcing a bar on the spine side of the handle forward to block the blade tang from rotating closed. If it sounds similar to a cross bar lock, that’s because it is similar in how it actually holds the blade open. The main place where plunge locks differ from cross bar locks is in how you actuate the lock. Plunge locks, also sometimes called spine locks, are disengaged with one finger pulling down on a ramped part of the lock bar that protrudes from the spine side of the handle between the two sides, rather than by pulling on a part of the cross bar on the handle slabs. These locks offer much the same advantages of a cross bar lock, but I think sometimes suffer in ergonomics. Two well known examples of spine locks are the SnecX Super Lock and the Demko Shark Lock. I think these locks have a lot of potential, but I haven’t been win over completely yet.
Summary
Now, at the beginning of this article I said the purpose was not to suggest a “best” lock… but I am going to go against that in a way. It might not be the best lock for everyone, but if you’re looking to get your first (or only) modern pocket knife I would recommend looking at knives with a button lock. Why? The button lock is super simple and intuitive to operate, doesn’t require your hand to be in the path of the blade, is reliable and secure, and doesn’t interfere with the ergonomics or aesthetics as much as some locks.
