The origins of kigumi 

Kigumi refers to the craft of making wooden joints without nails or metal fittings. The most primitive kigumi technique involved tying logs together with rope or string. Although this method was convenient because it did not require processing the logs, it lacked durability. Over time, joinery techniques were developed by carving and notching the wood, increasing the strength of the connection. Typically, the interlocking surfaces were made flat because gaps reduced load resistance. However, during the Edo period (1603–1868), ambitious design aesthetics led to techniques where even curved surfaces could be precisely fitted together without gaps. Despite appearing similar from the outside, the underlying techniques and aesthetics used to create kigumi joints can vary significantly.
 

捻子組

1. Neji-gumi 

Twisted joint with a two-stop tenon

The neji-gumi joint is considered to be the pinnacle of log craftsmanship. It is used where eave beam logs intersect a post at a building’s corners. Once assembled, it is nearly impossible to discern how the pieces fit together. The precise fit of the individual components creates a unique sense of tension that cannot be achieved with metal fasteners.
 

縛る木組

2. Shibaru kigumi

Rope-tied wood joinery

This wood joinery technique is still employed today in Indonesia, using the sturdy leaves of the Lontar palm.
 

込栓

1. Komi-sen

Draw pin

This technique involves driving a wooden pin through a hole made in the side of a post, precisely at the location where the tenon of the joining tie beam is inserted. The pin passes through a matching hole in the tenon and secures the tie beam in place. While this method effectively fixes the post and tie beam, it requires precise drilling to align the holes. It is a technique used in many parts of the world, but it is particularly widespread in the European and American tradition, where drills were developed.
 

下げ鎌

2. Sage-kama

Wedged-through half-dovetail joint

Technique for connecting a tie beam to a column at the end of the structure. Though called sage-kama (literally meaning “lowered goose neck”), it is shaped like a dovetail and is therefore also called kata-sage-ari (meaning “partially lowered dovetail”).
 

渡り腮

3. Watari-ago

Cogged lap joint

A simple jointing technique used since ancient times, in which the upper and lower pieces of wood are carved and overlapped. The model shows its use in a connection between a column and a tie beam. To compensate for the absence of weight at the top, the joint is secured by wedges inserted on both sides.
 

鼻栓

4. Hana-sen

Nose pin or external draw pin

A hole is drilled in the tip (nose or hana) of a long tenon that passes through a post, and a peg is then inserted to secure it. This method is primarily used to resist tensile forces. It is easier to construct than a draw pin (komi-sen), and can be found worldwide. In this model, the joint features a slight housing trench to reduce the stress on the tenon. 
 

隅留め

1. Sumi-dome

Corner mitre tenon joint

A sumi-dome joint is often used at the adjoining corners of foundation beams or floor framing. In this joint, the members are connected together at a 45-degree angle giving a clean appearance. This precision is difficult to achieve.
 

大入れ蟻掛け 

2. Ōire-arikake

Dadoed, half-lapped, half-blinded dovetail with full mortise and tenon joint

This technique is used when building a foundation or floor frame. The central mortise is designed for inserting a post. As the joint is relatively shallow, it employs a dovetail joint (arikake or ari-otoshi) with a housing to increase its strength.