# Train arm 64 × 14 × 5 with three Ø6 holes at 25 mm (Ferguson's paradox)

> What is the arm of Ferguson's paradox?

- 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/paradox-arm-25-25-b6/ · JSON: https://xemstudio.com/api/geometry?object=paradox-arm-25-25-b6 · Plain text: https://xemstudio.com/objects/paradox-arm-25-25-b6/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 |
|---|---|---|
| 64.0 | 14.0 | 5.0 |

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

## Notes

- 14 × 5 mm arm with Ø6 holes at 0, 25 and 50 mm: it turns on the fixed sun's Ø6 stud and carries the thick idler on the middle pin and the three paradox wheels on the end pin.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| holes | 3 × Ø6 at 0 / 25 / 50 mm |
| section | 14 × 5 mm |

## 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. 504: figure, his text and an animation](https://507movements.com/mm_504.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/fergusons-paradox-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/paradox-arm-25-25-b6/index.json · license: https://xemstudio.com/files/hardware/paradox-arm-25-25-b6/LICENSE.md

- paradox-arm-25-25-b6: [STEP](https://xemstudio.com/files/hardware/paradox-arm-25-25-b6/paradox-arm-25-25-b6.step) · [STL](https://xemstudio.com/files/hardware/paradox-arm-25-25-b6/paradox-arm-25-25-b6.stl) — arm, z 0..5, stud hole at the origin

## Questions

**What is the arm of Ferguson's paradox?**

14 × 5 mm arm with Ø6 holes at 0, 25 and 50 mm: it turns on the fixed sun's Ø6 stud and carries the thick idler on the middle pin and the three paradox wheels on the end pin.

## Fits with

- [Ferguson's mechanical paradox (19 / 20 / 21 tooth wheels on one pin)](https://xemstudio.com/objects/fergusons-paradox-mechanism/)