# Ball-joint cap: Ø40 × 8 ring with an R15 spherical seat and 3 × Ø3.4 holes

> What holds the ball in the socket?

- Category: Hardware › Mechanism parts
- Kind: Modern device
- Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
- Page: https://xemstudio.com/objects/ball-joint-cap-d40-r15/ · JSON: https://xemstudio.com/api/geometry?object=ball-joint-cap-d40-r15 · Plain text: https://xemstudio.com/objects/ball-joint-cap-d40-r15/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 |
|---|---|---|
| 40.0 | 40.0 | 8.0 |

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

## Notes

- Ø40 × 8 ring whose bore is the R15 sphere between z 0 and 8 (opening Ø25.38 at the top, smaller than the Ø30 ball), so screwed down on the socket it holds the ball in; three Ø3.4 holes for M3 screws.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| ring | Ø40 × 8 |
| seat | R15 sphere |
| opening | Ø25.38 |
| holes | 3 × Ø3.4 on Ø32 |

## 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. 249: figure, his text and an animation](https://507movements.com/mm_249.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/tube-ball-and-socket-joint-mechanism/) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/ball-joint-cap-d40-r15/index.json · license: https://xemstudio.com/files/hardware/ball-joint-cap-d40-r15/LICENSE.md

- ball-joint-cap-d40-r15: [STEP](https://xemstudio.com/files/hardware/ball-joint-cap-d40-r15/ball-joint-cap-d40-r15.step) · [STL](https://xemstudio.com/files/hardware/ball-joint-cap-d40-r15/ball-joint-cap-d40-r15.stl) — cap, sphere centre at the origin, z 0..8

## Questions

**What holds the ball in the socket?**

Ø40 × 8 ring whose bore is the R15 sphere between z 0 and 8 (opening Ø25.38 at the top, smaller than the Ø30 ball), so screwed down on the socket it holds the ball in; three Ø3.4 holes for M3 screws.

## Fits with

- [Ball-and-socket joint for tubing](https://xemstudio.com/objects/tube-ball-and-socket-joint-mechanism/)