# Lower block for a pitch-Ø20 sheave with a standing-end arm (tackle rove to advantage)

> What is the lower block for a pitch-ø20 sheave with a standing-end arm (tackle rove to advantage)?

- 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/tackle-block-10-advantage/ · JSON: https://xemstudio.com/api/geometry?object=tackle-block-10-advantage · Plain text: https://xemstudio.com/objects/tackle-block-10-advantage/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 |
|---|---|---|
| 68.7 | 13.0 | 43.2 |

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

## Notes

- Block frame: two 2 mm cheeks either side of the sheave (Ø4 pin holes), joined by bridges that carry Ø3 stems (into the beam, the floor plate or a weight's socket) and Ø3 rope-end sockets; every bridge sits clear of the rope's path. The arm carries the rope's standing end 50 mm to the side, so the hauling part can come off the moving block.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| sheaves | pitch Ø20 at (0, 0) |
| cheeks | 2 mm, 9 mm apart (8 mm sheaves) |
| pins | Ø4 |
| stems | Ø3 × 8 at x = -16.67 down |
| rope sockets | Ø3 × 5 at x = -50 |

## 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. 12: figure, his text and an animation](https://507movements.com/mm_012.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/tackle-rove-to-advantage-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/tackle-block-10-advantage/index.json · license: https://xemstudio.com/files/hardware/tackle-block-10-advantage/LICENSE.md

- tackle-block-10-advantage: [STEP](https://xemstudio.com/files/hardware/tackle-block-10-advantage/tackle-block-10-advantage.step) · [STL](https://xemstudio.com/files/hardware/tackle-block-10-advantage/tackle-block-10-advantage.stl) — frame, sheave plane y = 0, coordinates as in the mechanism

## Questions

**What is the lower block for a pitch-ø20 sheave with a standing-end arm (tackle rove to advantage)?**

Block frame: two 2 mm cheeks either side of the sheave (Ø4 pin holes), joined by bridges that carry Ø3 stems (into the beam, the floor plate or a weight's socket) and Ø3 rope-end sockets; every bridge sits clear of the rope's path. The arm carries the rope's standing end 50 mm to the side, so the hauling part can come off the moving block.

## Fits with

- [Two single blocks rove to advantage (3 : 1)](https://xemstudio.com/objects/tackle-rove-to-advantage-mechanism/)