# Constant-diameter cam for two Ø10 rollers 44 mm apart, 4 thick, Ø8 bore

> What is a constant-diameter cam?

- 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/constant-diameter-cam-c22-a6-b1-bore8/ · JSON: https://xemstudio.com/api/geometry?object=constant-diameter-cam-c22-a6-b1-bore8 · Plain text: https://xemstudio.com/objects/constant-diameter-cam-c22-a6-b1-bore8/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 |
|---|---|---|
| 34.42 | 34.0 | 4.0 |

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

## Notes

- Plate cam whose roller-centre (pitch) curve is r = 22 + 6 sin θ − sin 3θ: opposite radii always add up to 44 mm, so two rollers 44 mm apart on one yoke touch it at every angle and the yoke is driven both ways with no spring. The profile is the pitch curve offset inward by the 5 mm roller radius (no undercut). Stroke 14 mm.
- Only odd harmonics are allowed in such a curve (r(θ) + r(θ + 180°) = constant); the sin 3θ term flattens the ends of the motion.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| pitch curve | r = 22 + 6 sin θ − sin 3θ |
| roller centres | 44 mm apart |
| rollers | Ø10 (623 bearings) |
| stroke | 14 mm |
| thickness | 4 mm |
| bore | Ø8 |

## 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. 117: figure, his text and an animation](https://507movements.com/mm_117.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/cam-between-rollers-yoke-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/constant-diameter-cam-c22-a6-b1-bore8/index.json · license: https://xemstudio.com/files/hardware/constant-diameter-cam-c22-a6-b1-bore8/LICENSE.md

- constant-diameter-cam-c22: [STEP](https://xemstudio.com/files/hardware/constant-diameter-cam-c22-a6-b1-bore8/constant-diameter-cam-c22.step) · [STL](https://xemstudio.com/files/hardware/constant-diameter-cam-c22-a6-b1-bore8/constant-diameter-cam-c22.stl) — cam, z 0..4, θ from +X

## Questions

**What is a constant-diameter cam?**

Plate cam whose roller-centre (pitch) curve is r = 22 + 6 sin θ − sin 3θ: opposite radii always add up to 44 mm, so two rollers 44 mm apart on one yoke touch it at every angle and the yoke is driven both ways with no spring. The profile is the pitch curve offset inward by the 5 mm roller radius (no undercut). Stroke 14 mm.

## Fits with

- [Constant-diameter cam between two rollers in a yoke](https://xemstudio.com/objects/cam-between-rollers-yoke-mechanism/)