3Dモデル: Hira-isuka-tsugi by thejoinery on Sketchfab
組み立ての要点
Kone Tsugi teaches the fundamentals of lengthening joints. The interlocking shoulders provide mechanical strength while the angled cut increases gluing surface area. This joint bridges the gap between simple edge joints and complex temple-grade tsugite techniques. It is often a student's first mechanically locked scarf.
歴史的背景
Kone Tsugi (腰根継ぎ, root-waist splice) features interlocking shoulders that prevent the two halves from sliding apart—a step beyond glue-only Kiritsuke Tsugi. The name refers to the waist-like narrowing at the joint center. Carpenters use it for beam extensions in house framing and as preparation for advanced scarfs like Kanawa Tsugi and Okkake Daisen Tsugi.
組み立て手順
- Mark the scarf angle and shoulder positions on both timbers using a marking gauge.
- Saw the angled scarf faces, then chisel the interlocking shoulders on each member.
- Cut the mating half to match; test-fit until shoulders seat without gaps.
- Apply adhesive if used; assemble and clamp along the full length.
- Optional: add a draw pin through the shoulders for structural applications.
日本で見られる場所
- Traditional house framing — Rural Japan — beam extensions and repairs
- Woodworking schools — Japan — taught as an intermediate tsugite exercise
バリエーション
Shoulder count and scarf angle vary with timber size. Some versions add a through-key (shachi). For temple work, craftsmen advance to Kanawa Tsugi or Daiwa Tsugi when loads demand greater shear resistance.
用途
- Beam extensions
- Long spans
- Repair work
必要な道具
- Ryoba saw
- Chisels
- Kanna plane
- Marking gauge