The bokken, the aikidoka's sword
The bokken is a wooden sword that replicates the length, shape and feel of a Katana.
Why a wooden saber?
For security reasons. Indeed, when the samurai were training they initially used real swords (katanas). Unfortunately the mortality of the pupils increased, so much so that we gradually decided to adopt the bokken. This also allowed samurai of lower conditions to access schools since the purchase of a bokken was less expensive than that of a katana. Little by little, the samurais no longer held back their blows so much so that the fractures multiplied again and that many samurais were crippled which again caused the number of koryus (= old schools of saber) to fall again.
Many schools made the bokken a specific weapon and not a simple substitute for the katana, because the bokuto (= bokken) is very resistant. Thus the mythical Myamoto MUSASHI used bokkens rather than katanas.
The bokken usually has a length of 105 cm but this varies according to the schools (like the length of the katanas for the rest).
It is made in a non-resinous hardwood such as: red (Akagashi) or white (Shirakashi) oak, evergreen oak, Holme oak, medlar (Biwa), ebony (Kokutan), Sunuke ...
There are thus different categories:
AA Class Natural white oak
AA Class Natural red oak
A Class Natural white oak
Stained red oak
Brown stained oak
Painted black oak
High quality bamboo
In the manufacture of a bokken, the trunk is first cut into longitudinal slices, and then left to air dry for a year. Some manufacturers employ mechanical drying processes, which shorten this time to fifteen days, at the cost of greater shrinkage of the wood fibers, producing bokken more sensitive to humidity and more brittle. A pattern then makes it possible to mechanically cut the silhouette of the bokken in the slice of wood, to cut the point and the edge (ha). Once the shape is rough, the bokken is cut by hand by successive planing using around twenty models of planers with different angles and curvature. The finish is done with fine sandpaper.
Finally, there are different shapes and curvatures: Koshi-zori bokken have their curvature closer to the handle. the Torii-zori bokken have their curvature more in the center. Saki-zori bokken have their curvature closer to the tip. but in aikido there is no specific curvature, so no need to look for one in particular.
As part of a kata work alone or cutting work, it is about getting closer to the sensations of the sword. The bokken used must then have a balance and a hanger similar to those of a katana. For muscle strengthening, there are bokken (suburito, "sabers for cutting") with a thickened blade, reproducing the weight (but more the balance) of a saber. As part of a work with two armed partners (each of a bokken, or a jō in the case of the jōdō), impact resistance becomes an important parameter. The wood of the bokken must settle in the face of an impact, without producing splinters or sharp angles that could injure the two protagonists. To do this, the quality bokken are cut in the length of the trunk, so that the fibers go from one end of the bokken to the other.
The part of the bokken representing the blade (ha) is cut according to the use to be made of it. In the case of the arts based on armed confrontation, the blade is smooth, ending in a sharp angle, to reproduce the same type of contact and hiss as the steel blades of sabers. In the case of Aikido, where one of the partners can be bare-handed, the blade is rounded and the tip flattened in order to limit the risk of injury and to guarantee better resistance to shocks.
Likewise, the position of the focus of curvature, which determines the center of gravity of the weapon, is chosen according to a trade-off between maneuverability and power of the weapon.
The use of the bokken in aikido
In aikido the bokken is used to work the maai (= distance). In other words, we don't really do what many call the saber (we speak of diaido) but we use this instrument to work on our aikido techniques. Indeed, O Sensei in his synthesis of aikido, was inspired by techniques practiced saber So using the bokken is to find and therefore clarify the basic techniques in the mind of the practitioner.
It is also learning to manage your distance from others. Often the inaccuracies are increased with the practice of the bokken and what seemed right with bare hands are found wanting with the weapons. We speak of daiki-ken to designate this practice. Finally, note that there are also katas ken against ken (= kumi ken) and ken techniques against bare hands from 3rd dan. In fact, it is said that the use of the katana during training increased the death rate in sword schools!
There are variations of the bokken, either intended for specific types of technical work, or representing blades of different length than the katana. Among the most common are:
The suburi bokken or suburitō. To reproduce the weight (but more then the balance) of the katana within the framework of a work of the straight strike (shomen), the suburitō presents a thicker blade, allowing to develop the musculature, but being able to be at the origin tendonitis.
The shoto, a wooden wakizashi. It is used in the kata of the koryu under the term of kodachi. It is also used in the practice of the two swords present in several koryu (Hyoho Niten Ichi Ryu, Suio Ryu, Tenshin Shōden Katori Shintō-ryū) and in the Aikido school of Mitsugi Saotome senseï.
Using the Bokken in Kendo
In the practice of Kendō, the bokken is used for kata.
The koryu use the bokken for their kenjutsu practice. They use it in kata with bokken against bokken, bokken against two bokken (one large and one small), bokken against naginata, bokken against kusarigama and even bokken against arrows.
Using the Bokken in Iaido
Iaido is a martial art geared towards the use of the saber. At a very high level, it is possible to practice it with a sharp blade, that is to say a real Katana.
To start practicing Iaido, the student will start with a Bokken.
It has a plastic guard (Tsuba) and a scabbard (Saya).