KUMIKI THE KNOW-HOW
The basis of all kumiki types pursuing pure, simple beauty. Tsukitsuke pieces do not connect by themselves. It is a quite primitive form of kumiki, but is used for locations where no forces are applied, aiming for a beautiful design derived from its simplicity.
A kumiki, which supplements other elements. Koshikake is used as splice, away from structural underpinning. As the name indicates (koshikake means “a stool”), two parts just sit on each other. It is used with other kumiki types in horizontal elements.
Halved joint type kumiki which fits each other. It can be used as splice, just like Koshikake does, but proves its merit at the intersection of two parts. When orthogonally joining two parts in the same height, the finished surface at the joint becomes flat.
Ryakukama (mortise and tenon joint) is said to be named after the shape of Kama (sickle) divided into two pieces. The strength significantly increases when combined with Mechigai to form Okkake-tsugi, and additionally with Sento to form Kanawa-tsugi
Mechigai (tongue and groove joint) is a functional kumiki created by a small tongue and a groove. It could be used on its own, but is often applied to other kumiki, to provide a structural support or to prevent warping of parts.
Ari (dovetail joint) withstands against tensile forces by the inverted trapezoid shapes fitting together. Although tensile strength is weaker than that of Kama’s, it can be used for locations where joint length is insufficient since Ari requires short length for joint part.
Kama (mortise and tenon joint) is a typical kumiki that has been used since ancient times. It has a greater tensile strength than Ari, while it has a drawback of requiring longer joint length. Kama can be commonly found in old buildings as a joint for structural members.
A versatile kumiki with excellent strength and easy application, while it can be easily pulled apart. It is favorable for locations where compression forces are constantly applied. It can also be used when disassembly and reassembly are required, since it can be easily pulled apart.
Sen (pin/ plug/ key) is a part that secures all types of kumiki and transforms them into unified structural members. It is used to improve the strength of the joint, or completely fix it by inserting a Sen into a designed gap of the joint part.
This kumiki is a combination of Ari and Koshikake, which will be secured once fitted together. This example uses Mechigai as conjunction. This joint represents the ultimate functional beauty of kumiki, improving details of the joint by the combination of kumiki.