Komisen-tsugi-shikuchi-no-sanpousashi

The Komisen-tsugi-shikuchi-no-sanpousashi is a traditional Japanese wooden joining method used to make strong mitered connections at intersecting angles, typically 90 degrees.

Some key aspects of this joint:

Komisen refers to cutting the wood along the grain direction to form interlocking tapered shapes.

Tsugi means to adjoin pieces together sequentially.

Shikuchi translates to intersecting at an angle, such as two pieces meeting at a corner.

Sanpou means three sides, with sashi referring to interlocking.

To create this joint, the ends of both wood pieces are miter cut at 45 degrees. Tapered cuts following the grain are then made on three sides of each piece.

This forms triangle-shaped interlocking tabs that securely engage when the miters are joined, reinforcing the connection.

The joint achieves strength through the intricate three-sided tapers that engage the wood fibers. It allows robust assemblies without other fasteners.

Traditionally used in Japanese carpentry and architecture, it provides durable L-shaped intersections that can be joined and disassembled as needed. Today it remains useful for high-quality wooden structural joining.