How Knives Open

One of the ways that knives are often categorized as is how they open. There are six different ways that knives can open. These are automatic, out the front, butterfly, spring assist, folding, and fixed blades. Today we are going to discuss what each of these are, how they are most often used, and some advantages and disadvantages of each kind.


Automatic Knives:

Automatic knives are known as a variety of different names, one of the most popular being a switchblade. Some of the other names that an automatic knife is known by are pushbutton knife, ejector knife, springer, flick knife, and flick blades. An automatic knife is a folding or sliding blade that is contained in the handle of the knife, which can then be opened automatically by a spring. This is triggered by a button, lever, or switch on the handle. Many automatic knives include a locking blade, which adds a safety element to the knife. This safety is when the blade is locked against closure. The safety button is usually a manual button that allows it to be locked in an open or closed position. Automatic knives are grouped into two categories: folding and out the front. Some people enjoy automatic knives because of how quickly and efficiently they can be opened, usually with just one hand. However, automatic knives are highly regulated in the states, because they can be dangerous. Unfortunately, automatic knives can have mechanical failure, thus ruining the knife. Some people are hesitant with automatic knives because they can open without meaning to open, but like earlier stated, most of the automatic knives have a safety feature. This style of knife can also be a more expensive option than others. This style of knife is not an ideal knife for heavy duty tools, because a fixed blade would stand up better to heavy use.

Advantages of an automatic knife:

  • Can be opened very quickly.
  • Can be opened with one hand.
  • Most feature a safety mechanism.
  • Can be speedy for using as a self-defense weapon.

Disadvantages of an automatic knife:

  • High regulations and laws that limit the ability to own one, so you have to check into your local laws.
  • More expensive than some of the other options.
  • Not ideal for heavy duty use.
  • If your automatic knife doesn’t feature a safety, it can be accidentally opened when you didn’t want it to be opened.


Out-the-Front Knife

Similarly, to an automatic knife, out-the-front knives are known by a few names. Some of these other names include sliding knife and telescoping knives. An out-the-front knife got its name because it is a knife that opens and closes through a hole in one end of the handle. This is unique because many other knives open with the blade coming out of the side, rather than the front. An out-the-front knife is one grouping of an automatic knife, because you can get this style as an automatic style. However, you can get a manual out-the-front knife. There are a few different styles of out-the-front knives, some of the popular ones are automatic knives, gravity knives, and spring assisted.

Automatic out-the-front knives:

This style of out-the-front knife is where the blade is connected to a track on the inside of the handle. This grouping is also categorized into two groupings: single action and double action. Single action deploys the blade automatically, but they must first be cocked or retracted to close. Double-action is when the blade deploys and retracts with a button and spring design.

Gravity out-the-front knives:

This style of out-the-front knives are never known as a sliding knife, because the blade is ejected by gravity. This style does not have a spring inside the handle, unlike the other kinds. The blade gets locked inside the handle with a lever, which creates tension to hold the blade in place. To eject the blade, you have to first release the lever and then turn the knife upside down, the blade will fall right out. Then, this lever also creates tension to lock the blade to hold it open.

Spring assisted out-the-front knives:

This style is a newer style. This style works because when the blade is retracted, it is under constant pressure from a compressed spring that rests inside the handle. When you push the button, it releases the spring, which then pushes the blade out of the handle. To pull the blade back into the handle, you press a release button, which is usually the same button, and manually retract the blade.

Advantages of an out-the-front knife:

  • Variety of styles, so you can get what you prefer.
  • Some are automatic, so they are quick.
  • Since the blade comes out the front, you cannot close the blade on your hand.
  • This style is a good option for self-defense.

Disadvantages of an out-the-front knife:

  • Since many are automatic, they fall under the same strict laws that other automatic knives do.


Butterfly Knives

Like the previous two knives, butterfly knives go by a couple of different names, such as a fan knife or a balisong knife, the latter being one of the most popular name options for this style. A butterfly knife is a folding pocket knife, what makes it unique is that it has two handles that hug the blade when it is close. When it is open, the two handles fall to the bottom and there is a small clip that connects the two handles to keep them open and together. This style of knife was very commonly used by Filipino people, especially in the Tagalog region. A balisong knife is primarily used for stabbing or slashing. This knife is not ideal used for chopping because it doesn’t carry the weight to actually carry through with any of the chopping. Butterfly knives rarely sport a serrated edge. However, many people have trained themselves to perform the art of “flipping” or “fanning”. This art is when people can perform by flipping the knife in a series of movements.

Advantages of a butterfly knife:

  • This style of knife has a unique look to it, so it has an awe factor to it.
  • The handles of this knife can be used as a blunt weapon.
  • Can use this knife for an art form, instead of just tactical uses.
  • Butterfly knives are good for stabbing and slashing.
  • This can be a cheap option.

Disadvantages of a butterfly knife:

  • While this is good for stabbing, since the blade is so thin, it makes a smaller wound than other knives would.
  • This style cannot be used for chopping.
  • The typical size is a lot larger than other styles of knives.


Spring-assisted knives:

Spring-assisted knives are also commonly called assisted-opening knives. This style is often confused with an automatic style knife, but they differ slightly. This style is a kind of folding knife that has an internal mechanism of a torsion spring and a track that the blade is resting on. This mechanism helps finish opening the blade once the user has already partially opened it. The user will partially open the knife by using a flipper or thumb stud that is attached at the bottom of the blade. When the knife is closed, the blade will be held in place by torsion springs. You can also get an additional blade lock on the knife. While an automatic knife has strict laws, assisted knives are usually legal. Another benefit of spring-assisted knives are that they are less likely to have some of its mechanisms broken, unlike an automatic knife. This is because an automatic knife has constant pressure on the spring the whole time that the knife is closed. In a spring-assisted knife, the spring only has this tension placed on it when the blade is being deployed, at other times, the spring has no pressure and can be relaxed. Because spring assisted knives are partially automatic, they can open much quicker than a regular folding knife would be able to.

Advantages of a spring-assisted knife:

  • They are legal in more places than a fully automatic knife would be.
  • Because they are legal in more areas, they make for a great every day carry knife and a great self-defense weapon.
  • Less likely to break than a fully automatic knife.
  • Much quicker to open than a regular folding knife.

Disadvantages of a spring-assisted knife:

  • This style is not as quick to open as a fully automatic knife.
  • Not great for heavy duty work.
  • Over time, the inner mechanisms can wear down and the “assisted” mechanism loses its “snap”.


Manual folding knives:

A manual folding knife is a style of knife that requires the user to physically open the blade. The user will do this by using either a thumb stud or a cut out. The cut out style of opening mechanism is commonly found on traditional pocket knives and also on Swiss Army knives. The cut out is a small groove in the blade that you can put your nail in to get a grip on the blade and open it up. The thumb stud mechanism is a small protrusion that sits on the blade that allows you to get a grip on the blade. This is usually done by placing your thumb on the stud and pulling the blade out of the handle of the knife. A manual folding knife was the first style of pocket knife before any of the newer knife technology was developed. This style of knife is a very popular knife because they fit nicely in your pocket and can also be carried easily in a pack.

Advantages of a manual folding knife:

  • This style of knife offers a very classic style.
  • Opens slower than an automatic knife, so it can be much safer than an automatic or assisted knife.
  • Since it doesn’t rely on a spring to open, it is less likely to break than an automatic or assisted knife.
  • Legal in many more areas than an automatic knife—but make sure to always check your local laws before buying and carrying a knife.

Disadvantages of a manual folding knife:

  • Opens very slowly, so it is not a good self-defense weapon.


Fixed blade knife:

A fixed blade is any knife that doesn’t have a folding or sliding blade. They are sometimes called sheath knives because to close them, you just place a sheath over the blade. This style of knife is usually stronger and sturdier than the other styles because the blade is directly connected to the handle and you remove any moving and inner parts. You can also purchase fixed blade knives in a large variety of sizes—you can get them small and you can get them huge. But, fixed blades are usually harder to conceal than the previous styles of knives. They are also harder to carry, since they are usually larger and don’t fit in pockets as well or at all. Fixed blade knives are also very easy to maintain because you don’t have to worry about springs or mechanisms. Fixed blade knives often have a larger blade than the previously mentioned styles, making them ideal for heavy duty work. This style of knife is also an idea survival tool because they can manage so many different tasks and they will last.

Advantages of a fixed blade knife:

  • Sturdier than other options of knives.
  • Last longer than the other styles of knives because they don’t have moving parts that can break.
  • Longer/bigger blade.
  • Great option for a survival tool.
  • Great option for heavy duty work.
  • Large variety of sizes.
  • Easy to maintain.

Disadvantages of a fixed blade knife:

  • Harder to conceal than other styles of knives.
  • Harder to carry, since they are usually bigger than the other styles of knives.



There are many different styles of knives and one of the biggest ways to categorize them is how they open. We have now discussed the six most popular categories of how knives open. When choosing the perfect knife for you always keep in mind the task at hand.