# Keyed mitre joint (feather keys)

> How do keys reinforce a mitre joint?

- Category: Joinery › Mitre joints
- Kind: Hardware
- Basis: Xem Studio design — geometry computed in the generator from traditional proportions
- Page: https://xemstudio.com/objects/keyed-mitre-joint/ · JSON: https://xemstudio.com/api/geometry?object=keyed-mitre-joint · Plain text: https://xemstudio.com/objects/keyed-mitre-joint/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 |
|---|---|---|
| 80.0 | 80.0 | 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).
- Thin keys across the outside corner of a mitre (as on picture frames) lock it and show as stripes.

## Sizes

| dimension | value |
|---|---|
| stock | 20 × 20 mm square |
| parts | part a, part b, key 1, key 2 |
| mitre | 45° |
| keys | two, 2.5 mm thick, 12 mm legs, across the outside corner |
| assembles | close the mitre, slide the keys into the kerfs |
| holds | the mitre against opening |

## 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 (5 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/keyed-mitre-joint/index.json · license: https://xemstudio.com/files/hardware/keyed-mitre-joint/LICENSE.md

- keyed-mitre-joint-part-a: [STEP](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-part-a.step) · [STL](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-part-a.stl) — Mitred member A with two key kerfs
- keyed-mitre-joint-part-b: [STEP](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-part-b.step) · [STL](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-part-b.stl) — Mitred member B with two key kerfs
- keyed-mitre-joint-key-1: [STEP](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-key-1.step) · [STL](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-key-1.stl) — Triangular key, 2.5 mm thick
- keyed-mitre-joint-key-2: [STEP](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-key-2.step) · [STL](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-key-2.stl) — Triangular key, 2.5 mm thick
- keyed-mitre-joint-assembled: [STEP](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-assembled.step) · [STL](https://xemstudio.com/files/hardware/keyed-mitre-joint/keyed-mitre-joint-assembled.stl) — All parts in their assembled position (each part its own solid)

## Questions

**Where do mitre keys go?**

Across the outside corner, square to the frame face, one or two per corner.

## Fits with

- [Splined mitre joint (hidden spline)](https://xemstudio.com/objects/splined-mitre-joint/)
- [Butterfly key (bow-tie, dutchman)](https://xemstudio.com/objects/butterfly-key-joint/)