Daiwa Tsugi 台輪継ぎ

Assembly insights

Daiwa Tsugi belongs to the family of complex lengthening joints developed by miyadaiku for structural applications. The stepped or scalloped profile increases shear resistance and provides mechanical interlock beyond simple oblique scarfs. Layout follows centerline-based methods similar to Kanawa Tsugi, with precise story sticks guiding the angled faces and shoulder cuts. Used historically in shrine and temple construction.

Historical context

Daiwa Tsugi emerged alongside other sophisticated tsugite during the Edo period, when advances in toolmaking allowed carpenters to execute increasingly complex joinery. The stepped geometry distributes stress across multiple shoulders, making it suitable for wall plates and eave purlins where loads are significant. It remains a hallmark of skilled structural joinery.

Construction steps

1. Establish a centerline on both pieces; use a story stick for consistent layout.
2. Mark the stepped shoulders and angled scarf faces on both members.
3. Saw the primary scarf angles, then chisel the stepped profile.
4. Cut the mating half to match; test-fit and adjust for a snug assembly.
5. Lock with draw pins (komisen) or keys if the design calls for it.

Where to see this joint in Japan

• Historic shrines and temples — Japan — wall plates and eave framing

Variations

Daiwa Tsugi shares characteristics with Okkake Daisen Tsugi and Kanawa Tsugi. Some variants use a single large key (shachi) while others rely on friction fit. The number and shape of steps can vary depending on timber size and structural requirements.