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Kawai tsugite (four-way dovetail joint)

How does the Kawai tsugite joint go together? · Hardware · basis: Xem Studio design — geometry computed in the generator from traditional proportions

Also called: kawai tsugite, kawai tsugite joint, impossible dovetail, four way dovetail, 4 way dovetail joint, japanese impossible joint, 河合継手, cola de milano imposible, unmögliche Schwalbenschwanzverbindung

Exact dimensions. True size, with no printing tolerance added.

length
20.0 mm
width
20.0 mm
height
120.0 mm

Notes

  • Woodworking joint drawn for 3D printing: the parts lock together by shape, so a print can be joined without glue or screws. Drawn at true size with the parts line to line (zero gap) in their assembled position — add your printer's fit allowance to the mating faces (your AI or slicer can do this).
  • The joint that looks impossible: a dovetail shows on all four faces. Both pieces are straight prisms along the diagonal of the square section, so they slide together diagonally — the trick that makes it work.
  • Kiyoshi Kawai's joint, made famous as the "impossible dovetail". Prints well: the faces are straight along the slide direction.

Kawai tsugite size chart

dimensionvalue
stock20 × 20 mm square
partspart a, part b
dovetails6 → 10 mm in the diagonal section, 12 mm long (appear √2 wider on the faces)
assemblesthe two pieces slide together along the diagonal of the square section
holdspulling apart lengthwise and bending in every direction

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Xem StudioJoinery design (geometry computed in the generator from traditional proportions)webXem Studio design

Free files

★ Free files 3 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

kawai-tsugite-joint-part-aPiece A: dovetails on two faces, sockets on the other twoSTEP · STL
kawai-tsugite-joint-part-bPiece B: the mirrorSTEP · STL
kawai-tsugite-joint-assembledAll parts in their assembled position (each part its own solid)STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=kawai-tsugite-joint

Kawai tsugite (four-way dovetail joint), isometric render of a generated part
Render of kawai-tsugite-joint-assembled from the free STEP; not to scale.

Fits with

Ari tsugi (Japanese dovetail splice), isometric render of a generated part
Ari tsugi (Japanese dovetail splice)130.0×20.0×20.0 mm★ 3 files
Through dovetail joint, isometric render of a generated part
Through dovetail joint90.0×60.0×90.0 mm★ 3 files
Kama tsugi (Japanese gooseneck splice), isometric render of a generated part
Kama tsugi (Japanese gooseneck splice)130.0×20.0×20.0 mm★ 3 files

Questions

How does the Kawai tsugite assemble?

Diagonally: both pieces slide together along the diagonal of the square section.

Can it be 3D printed?

Yes — both pieces print standing on their ends; add your fit allowance to the dovetail faces.