# Bayonet joint: two studs in L-slots, locked by a 30° turn

> How does a bayonet joint lock?

- Category: Mechanisms › Couplings & joints
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 245 (1868)
- Page: https://xemstudio.com/objects/bayonet-joint-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=bayonet-joint-mechanism · Plain text: https://xemstudio.com/objects/bayonet-joint-mechanism/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/)

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

## Notes

- Two studs on the inner tube slide straight into the two L-shaped slots of the socket; a part turn then carries them along the slots' short legs to their closed ends, where they hold the tubes together against being pulled apart. Turning back and pulling releases it.
- Ø20 tube in a Ø20 socket bore (line on line), Ø3 studs, slots 3 wide, 8 mm deep with a 30° turn; drawn locked, each stud seated in the round end of its slot.
- Brown's No. 245 (bayonet joint).
- Parts (each has its own page): bayonet-tube-20x14-studs-3, bayonet-socket-24x20-l-slots, dowel-pins-metric.
- Brown's movement No. 245 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| tube | Ø20 |
| studs | 2 × Ø3 |
| slot | 8 axial + 30° turn, 3 wide |
| lock | 30° turn |

## Where the files are

- Henry T. Brown (1868, public domain): [Five Hundred and Seven Mechanical Movements — scan on archive.org](https://archive.org/details/fivehundredseven00browiala) — web — Publisher's page; dimensions are facts
- 507movements.com: [Brown's movement No. 245: figure, his text and an animation](https://507movements.com/mm_245.html) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

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

- bayonet-joint-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/bayonet-joint-mechanism/bayonet-joint-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/bayonet-joint-mechanism/bayonet-joint-mechanism-assembly.stl) — Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)

## Questions

**How does a bayonet joint lock?**

Two studs on the inner tube slide straight into the two L-shaped slots of the socket; a part turn then carries them along the slots' short legs to their closed ends, where they hold the tubes together against being pulled apart. Turning back and pulling releases it.

## Fits with

- [Bayonet tube Ø20 × Ø14 × 70 with two Ø3 stud holes](https://xemstudio.com/objects/bayonet-tube-20x14-studs-3/)
- [Bayonet socket Ø24 × Ø20 × 40 with two L-slots (8 deep, 30° turn), 3 wide](https://xemstudio.com/objects/bayonet-socket-24x20-l-slots/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)