This thesis develops methodologies to fabricate complex traditional Japanese timber joints using a three-axis CNC machine; resolving timber to timber connections without being dependent on mechanical fastenings.
The role of carpenter in traditional Japanese architecture is as much an architect as a craftsman. Japanese joinery created by miyadaiku carpenters (carpentry techniques using interlocking wood without nails) allows timber connections to be resolved by sophisticated joints without relying on mechanical fastenings. This approach to timber design has been largely lost with the adoption of mechanical fastenings such as nail or screw connections, especially in the construction of structures with many small timber members. Largely, this is the result of the expensive labour cost associated with making timber joinery, leaving this craft to be the reserve of high-end furniture; no longer being seen in the realm of 21st-century building.
Sophisticated timber joints are still used in structures with large timber members which cost thousands of dollars. Using CNC milling to cut the joints accurately; with timber of this scale, the time and set up of the CNC milling is justified by the cost of the member being cut. However, a gap in the application of this technology exists regarding small members of timber, costing a fraction of what larger members do. Therefore, the cost to set up the CNC milling cannot be justified, and screws are used.
The question focusing the research is ‘How can simple three-axis CNC milling be utilised to fabricate traditional Japanese timber joints, creating viable timber-to-timber connections on small members?’ and then secondly, ‘How might this methodology be applied to a live project?’
Research into this field has been undertaken by previous timber structures supervised by Dr Andrew Barrie such as Dylan Waddell’s Shadow Pavilion (2019) and Kanade Konishi’s Watari-Ago Shelter (2020). Both projects successfully milled one face of the timber to create lapped and cog joints; the issue being the limitation of what type of joints can be fabricated as only one face is cut. In this thesis, a new methodology is devised to cut any face of the timber so that more sophisticated and complex joints can be fabricated, further increasing the scope and application of this technology.
To interrogate and test the methodology, a 12m2 forest classroom constructed from a lattice of small timber members, connected by repeated Kashigi-oire joints has been built for a client in Papamoa. The thesis is largely a story of the fabrication process, with the Pavilion serving as a built example of how the technology can be applied to live projects.
