Butterfly knife


A balisong, also known as a fan knife, butterfly knife or Batangas knife, is a folding pocketknife from the Philippines. Its distinct features are two handles counter-rotating around the tang such that, when closed, the blade is concealed within grooves in the handles. A balisong typically has the latch on the handle facing the cutting edge, and is commonly called the bite handle.
The balisong was commonly used by Filipinos, especially those in the Tagalog region, as a self-defense and pocket utility knife. Hollow-ground balisongs were also used as straight razors before conventional razors were available in the Philippines. In the hands of a trained user, the knife blade can be brought to bear quickly using one hand. Manipulations, called "flipping", are performed for art or amusement. Blunt versions of these knives, called "trainers", are for sale to practice tricks without the risk of injury.
The knife is now illegal or restricted in some countries, often under the same laws and for the same reasons that switchblades or concealed weapons are restricted, and in their country of origin they are no longer as common in urban areas as they were.

Etymology

The name "balisong" is derived from barangay Balisong, part of the municipality of Taal, Batangas province, which along with the neighboring barangay Pandayan, were the original manufacturing centers of the knives in the Philippines. The two barangays were home to a blacksmith industry that also produced other bladed implements such as bolo knives. It is also claimed that the meaning of the term balisong is derived from the Tagalog words baling sungay as the hilt of the blade were traditionally made from carved carabao and deer horn, as well as bones. The traditional balisong is also known as veinte y nueve, or "twenty-nine," in the Philippines, because they are long when opened. Other names for the knives in English include "fan knives" and "butterfly knives" from the motion, and "click clacks" from the sound they make when they are opened and closed.

History

The origin of the knives is unclear. Oral histories claim that the knives were first created in the Philippines in 800 AD. However, there is no documentation or archeological evidence to back this. Balisong mass production in the Philippines can only be attested to the early 1900s. Another claim is that balisong were originally an adaptation of a French measuring tool called the pied du roi, invented between the 1500s to the late 1700s. However, how it was introduced to the Philippines is unknown. There are theories that it may have been introduced by sailors in the Spanish Empire, which was then allied to France.
Regardless of the origin, the modern balisong was perfected in the Philippines, where it became much larger and were predominantly used as a weapon and not just a tool. The quick opening techniques were also developed in the Philippines. In contrast, the French pied du roi was primarily a folding ruler, with the knife only included in some specimens as a novelty. They were cumbersome to open and unlikely to be used for self-defense, especially since they also commonly included a metal tang at a right angle from the end of the handle to aid in measuring. There were also very similar designs to the balisong produced in England in the late 19th century, presumably also derived from the pied du roi. But like the latter they were primarily utilitarian tools.

Construction

There are two main types of balisong construction: "sandwich construction" and "channel construction".
Sandwich constructed balisong knives are assembled in layers that are generally pinned or screwed together though may sometimes use a ball-bearing system. They allow the pivot pins to be adjusted more tightly without binding. When the knife is closed, the blade rests between the layers.
For a channel constructed balisong, the main part of each handle is formed from one piece of material. In this handle, a groove is created in which the blade rests when the knife is closed. This style is regarded as being stronger than sandwich construction.
Some of the blades of traditional butterfly knives in the Philippines were made from steel taken from railroad tracks thus giving them a decent amount of durability and hardness, while others are made from the recycled leaf springs of vehicles.
Some balisongs, such as the Benchmade 51, do not use Tang Pins. Instead, it uses "Zen Pins", which are two small pins embedded in the handles of the balisong which make contact with the bottom of the blade. A balisong with zen pins negates the problem of having the tang pin fall out.

Parts

; Bite handle: The handle that closes on the sharp edge of the blade, and will cut the user if they are holding the handle when they go to close it. It's the handle that usually has the latch on it.
; Choil: The unsharpened portion of the blade just above the kicker, that makes it easier to sharpen the blade.
; Kicker : Area on the blade that prevents the sharp edge from touching the inside of the handle and suffering damage. This is sometimes supplanted by an additional tang pin above the pivots.
; Latch: The standard locking system, which holds the knife closed. Magnets are occasionally used instead. Also keeps it from opening up when the user doesn't want it to.
; Latch, Batangas: A latch that is attached to the bite handle.
; Latch, Manila: A latch that is attached to the safe handle.
; Latch, Spring: A latch that utilizes a spring to propel the latch open when the handles are squeezed.
; Latch gate : A block inside the channel of the handles stopping the latch from impacting the blade.
; Pivot joint: A pin about which the Tang/Blade/Handle assemblies pivot.
; Safe handle: The handle that closes on the non-sharpened edge of the blade.
; Swedge: Unsharpened spine of the blade. Some balisongs are also sharpened here or on both sides with either a more traditional look or wavy edges similar to a Kris sword.
; Tang: The base of the blade where the handles are attached with pivot pins.
; Tang Pin: Pin meant to hold the blade away from the handle when closed to prevent dulling; and, in some cases, a second pin to keep the handles from excessively banging together while the butterfly knife is being manipulated.
; Zen Pins: Screws mounted inside the handles that collide with the kicker mounted on the tang to prevent the blade from moving around while in the open or closed position.
; Blade: The blade is the piece of steel that runs down the center of the knife that is secured by both handles when closed. One edge of the blade is sharp and will cut the user if they are not careful, especially when flipping the knife. The other edge, called the swedge, is blunt and won't cut the user. The swedge commonly impacts the user's hand when flipping.

Legal status

The balisong has been outlawed in several countries.
Balisong trainers feature a special blunt and unsharpened "blade" and are legal in some areas where balisongs are not.

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