# Neodymium block magnets: 30 × 10 × 4 mm

> What size is a 30 × 10 × 4 block magnet?

- Category: Hardware › Magnets & seals
- Kind: Hardware
- Basis: Nominal size as sold; magnetised through the 4 mm dimension
- Page: https://xemstudio.com/objects/neodymium-block-magnets/ · JSON: https://xemstudio.com/api/geometry?object=neodymium-block-magnets · Plain text: https://xemstudio.com/objects/neodymium-block-magnets/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- A rectangular neodymium block 30 × 10 × 4 mm, magnetised through its 4 mm thickness, a stock size. Drawn at the nominal size with square edges.
- On the free-piston mover 48 of them sit on the 12 flats of the core in four rows, alternately N and S outward.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| inner face | 30 × 10 | mover-core flat (bonded) | designed | all |
| outer face to sleeve | r 22.66 (corners r 23.2) under the Ø47.00 sleeve bore | mover sleeve (no contact) | designed | all |

## Sizes

| length_mm | width_mm | thickness_mm | magnetised |
|---|---|---|---|
| 30 | 10 | 4 | through 4 |

## Where the files are

- Xem Studio: [tools/gen_ta_power.py: the network model and every dimension on this page](https://xemstudio.com/) — code — CC BY 4.0
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/neodymium-block-magnets/index.json

- magnet-block-30x10x4: [STEP](https://xemstudio.com/files/hardware/neodymium-block-magnets/magnet-block-30x10x4.step) · [STL](https://xemstudio.com/files/hardware/neodymium-block-magnets/magnet-block-30x10x4.stl) — block magnet 30 × 10 × 4, magnetised through the 4 mm thickness

## Questions

**Which way is it magnetised?**

Through the 4 mm thickness, so one 30 × 10 face is N and the other S.

## Fits with

- [Neodymium disc magnets, common sizes](https://xemstudio.com/objects/neodymium-disc-magnets/)
- [Free-piston mover for a 2 in honed spool: piston and alternator magnets in one, Ø48.00 × 130](https://xemstudio.com/objects/free-piston-mover-2in/)