# Linear guide (HGR, MGN)

A rail of any length, or a block, in HIWIN's public sizes, as an envelope for assemblies. The MGN blocks are in the
`miniature-linear-guide` part.

## Geometry

- **Rail:** a WR × HR bar along X, centred on the origin, base on the XY plane, with counterbored mounting holes at pitch P
  centred along the length (at least E from each end).
- **Block:** a W × L body from H1 above the rail's base up to H, with the rail's section as its channel and four mounting holes
  at B × C (threads drawn at nominal diameter).

Ball tracks, end seals and lubrication fittings aren't modelled.

## Source

- **HG rails and blocks:** HIWIN *Linear Guideways* catalogue (the copy at <https://www.tuli.si/files/HIWIN_celotni_katalog.pdf>),
  Table 1.14 Dimensions of the block HGH (p. 17), Table 1.16 HGW (p. 19), Table 1.17 Dimensions of the rail HGR_R (p. 20).
- **MGN rails:** HIWIN Linear Guideway Technical Information, FORM G99TE24-2410, section 2-4-19 (1), printed p. 88.

| Rail | WR | HR | D | h | d | P | E min |
|---|---|---|---|---|---|---|---|
| HGR15 | 15 | 15 | 7.5 | 5.3 | 4.5 | 60 | 6 |
| HGR20 | 20 | 17.5 | 9.5 | 8.5 | 6 | 60 | 7 |
| HGR25 | 23 | 22 | 11 | 9 | 7 | 60 | 8 |
| MGN7 | 7 | 4.8 | 4.2 | 2.3 | 2.4 | 15 | 5 |
| MGN9 | 9 | 6.5 | 6 | 3.5 | 3.5 | 20 | 7.5 |
| MGN12 | 12 | 8 | 6 | 4.5 | 3.5 | 25 | 10 |
| MGN15 | 15 | 10 | 6 | 4.5 | 3.5 | 40 | 15 |

Every block row is in `part.py` (`BLOCKS`). The HIWIN name identifies the source; this part isn't made by or affiliated with HIWIN.
Preset lengths: step.parts catalogue metadata (MIT, `library/NOTICE.md`).