# Oblong endless rack, module 1: two 4π racks joined by 20-tooth half-gear ends

> What is a mangle rack?

- 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/oblong-endless-rack-m1-20t-ends/ · JSON: https://xemstudio.com/api/geometry?object=oblong-endless-rack-m1-20t-ends · Plain text: https://xemstudio.com/objects/oblong-endless-rack-m1-20t-ends/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 |
|---|---|---|
| 34.56 | 22.0 | 8.0 |

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

## Notes

- Closed toothed outline: two straight module 1 racks 12.57 mm long (4 pitches) joined by the two halves of a 20-tooth gear, so a pinion can roll right round it; 8 mm thick, Ø3.4 centre hole. Tooth pitch is continuous (π mm on the straights, 18° on the ends) because the end radius is the gear's pitch radius, 10 mm.
- The pinion's centre runs on the parallel curve 10 mm outside the pitch line; at each end the pinion changes sides, so the rack's direction reverses while the pinion keeps turning the same way.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| module | 1 |
| straights | 12.57 mm (4 pitches) |
| end radius (pitch) | 10 mm |
| teeth on each end | 10 |
| thickness | 8 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. 119: figure, his text and an animation](https://507movements.com/mm_119.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/mangle-rack-oblong-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/oblong-endless-rack-m1-20t-ends/index.json · license: https://xemstudio.com/files/hardware/oblong-endless-rack-m1-20t-ends/LICENSE.md

- oblong-endless-rack-m1: [STEP](https://xemstudio.com/files/hardware/oblong-endless-rack-m1-20t-ends/oblong-endless-rack-m1.step) · [STL](https://xemstudio.com/files/hardware/oblong-endless-rack-m1-20t-ends/oblong-endless-rack-m1.stl) — rack, end centres at (0, 0) and (12.57, 0), z 0..8

## Questions

**What is a mangle rack?**

Closed toothed outline: two straight module 1 racks 12.57 mm long (4 pitches) joined by the two halves of a 20-tooth gear, so a pinion can roll right round it; 8 mm thick, Ø3.4 centre hole. Tooth pitch is continuous (π mm on the straights, 18° on the ends) because the end radius is the gear's pitch radius, 10 mm.

## Fits with

- [Oblong endless rack and pinion (mangle rack)](https://xemstudio.com/objects/mangle-rack-oblong-mechanism/)