# Koshikake ari tsugi (lapped dovetail splice)

> What is a koshikake ari tsugi joint?

- Category: Joinery › Japanese joinery
- Kind: Hardware
- Basis: Xem Studio design — geometry computed in the generator from traditional proportions
- Page: https://xemstudio.com/objects/koshikake-ari-tsugi-lapped-dovetail-splice/ · JSON: https://xemstudio.com/api/geometry?object=koshikake-ari-tsugi-lapped-dovetail-splice · Plain text: https://xemstudio.com/objects/koshikake-ari-tsugi-lapped-dovetail-splice/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 130.0 | 20.0 | 20.0 |

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

## 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 dovetail splice with a seat (koshikake): the female member's lower part runs under the tenon and carries the male member's load — the most common sill and beam splice in Japanese carpentry.

## Sizes

| dimension | value |
|---|---|
| stock | 20 × 20 mm square |
| parts | male, female |
| dovetail | 8 → 13 mm, 15 mm long, upper 14 mm |
| seat (koshikake) | 6 mm thick ledge under the tenon |
| assembles | the male drops in from above onto the seat |
| holds | pulling apart lengthwise; the seat carries load downward |

## Where the files are

- Xem Studio: [Joinery design (geometry computed in the generator from traditional proportions)](https://xemstudio.com/) — web — Xem Studio design

## Free STEP/STL (3 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/index.json · license: https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/LICENSE.md

- koshikake-ari-tsugi-lapped-dovetail-splice-male: [STEP](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-male.step) · [STL](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-male.stl) — Male member: dovetail tenon in the upper 14 mm
- koshikake-ari-tsugi-lapped-dovetail-splice-female: [STEP](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-female.step) · [STL](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-female.stl) — Female member: dovetail socket plus the 6 mm seat it rests on
- koshikake-ari-tsugi-lapped-dovetail-splice-assembled: [STEP](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-assembled.step) · [STL](https://xemstudio.com/files/hardware/koshikake-ari-tsugi-lapped-dovetail-splice/koshikake-ari-tsugi-lapped-dovetail-splice-assembled.stl) — All parts in their assembled position (each part its own solid)

## Questions

**What is the koshikake?**

The seat: a ledge on the female member that the male member's dovetail rests on.

## Fits with

- [Ari tsugi (Japanese dovetail splice)](https://xemstudio.com/objects/ari-tsugi-dovetail-splice/)
- [Koshikake kama tsugi (lapped gooseneck splice)](https://xemstudio.com/objects/koshikake-kama-tsugi-lapped-gooseneck-splice/)