# Hex standoff (Würth WA-SBRII / WA-SBRIE, Harwin R25 / R30 / R40)

Hexagonal brass spacers M2 to M4, female/female and male/female, at any body length. Presets cover the catalogue's
generic hex standoffs at the lengths the makers sell.

## Geometry

A hex prism, width across flats **AF** (the maker's maximum), corners along X, from z = 0 to the body length **L**,
centred on the origin. Internal threads are drawn as plain bores at the nominal diameter: through where the maker's
part is tapped through, otherwise to the maker's minimum full thread length (from both ends of a female/female
standoff; the tap drill's run-out beyond it is not modelled). The male stud, a plain cylinder at the nominal
diameter, runs from z = 0 down by its length. Threads, chamfers and the stud's undercut are not modelled.

## Parameters

| Parameter | Meaning |
|---|---|
| `thread` | M2, M2.5, M3, M4 |
| `gender` | `female-female` or `male-female` |
| `length` | Body length L, mm (the stud is extra) |
| `material` | `brass-nickel` (CW614N, nickel plated) |

## Sources

- **M2**: Würth Elektronik, WA-SBRII brass spacer, internal/internal (order codes 970LL0244) and WA-SBRIE,
  internal/external (971LL0244), datasheets per order code, revisions 001.003 / 001.004, 2020-07-28
  (`https://www.we-online.com/components/products/datasheet/<order code>.pdf`; read: 970050244, 970060244, 970080244,
  970100244, 970120244, 970150244, 971050244, 971080244, 971100244, 971150244, 971200244, 971250244, 971300244), and the
  product pages listing the lengths
  (https://www.we-online.com/en/components/products/SBRII_BRASS_SPACER_STUD_METRIC_INTERNAL_INTERNAL,
  https://www.we-online.com/en/components/products/SBRIE_BRASS_SPACER_STUD_METRIC_INTERNAL_EXTERNAL).
- **M2.5, M3, M4**: Harwin customer information sheets (sheet 2 of 2), brass CW614N, nickel finish, L1 ± 0.10 up to
  12 mm, ± 0.15 over: R25-100XX02 (DRG-01991, issue 4), R30-100XX02 (DRG-01994, issue 14, 10.03.21), R40-100XX02
  (DRG-02016, issue 6), R25-300XX02 (DRG-01992, issue 11, 02.11.22), R30-300XX02 (DRG-01997, issue 22, 17.03.25),
  R40-300XX02 (DRG-02019, issue 6, 03.11.22), from `https://content.harwin.com/asset/<id>/DRG-0xxxx-Technical-Drawing-Datasheet-<series>-pdf.pdf`
  (linked from each series' page on harwin.com).

| Thread, gender | Series | AF | Stud | Female thread |
|---|---|---|---|---|
| M2 F/F | Würth WA-SBRII | 4 | – | through (Tli = L), L 5, 6, 8, 10, 12, 15 |
| M2 M/F | Würth WA-SBRIE | 4 | M2 × 5 (Tlo) | Tli 2.5 (L 5), 5 (L 8, 10), 6 (L 15–30) |
| M2.5 F/F | Harwin R25-100 | 5.00 max | – | through, except L 25 and 33: at least 10 from both ends |
| M2.5 M/F | Harwin R25-300 | 5.0 max | M2.5 × 5.00 | L2 min 1.90 (L 3), 2.50 (4, 5), 3.50 (6), 4.50 (7), 5.00 (8–20) |
| M3 F/F | Harwin R30-100 | 5.00 / 4.80 | – | through up to 21; 22–28 not through but at least 10 from both ends; over 28: at least 10 (hole 14 max) |
| M3 M/F | Harwin R30-300 | 5.0 / 4.8 | M3 × 6.00 | L3 min 2.00 (L 4), 2.50 (5), 3.00 (6), 4.50 (7), 5.50 (8), 6.00 (9 and over) |
| M4 F/F | Harwin R40-100 | 7.00 / 6.80 | – | as M3 F/F |
| M4 M/F | Harwin R40-300 | 7.00 / 6.80 | M4 × 8.00 | L3 min 2.50 (L 6), 3.50 (7), 4.50 (8), 5.50 (9), 6.50 (10), 8.00 (11 and over) |

Body lengths sold: Würth M2 F/F 5, 6, 8, 10, 12, 15; M2 M/F 5, 8, 10, 15, 20, 25, 30; Harwin per the drawings' tables
(R25-100: 4–18, 20, 25, 33; R25-300: 3–18, 20; R30-100: 4–18, 20–22, 24, 25, 28, 30, 32, 34–36, the 39 and 40 marked
obsolete; R30-300: 4–22, 24–26, 30, 32, 34, 35, 38, 40, 45, 50, 60, 80; R40-100: 5–16, 18, 20, 25, 26, 30, 36, 60;
R40-300: 6–16, 18, 20, 25, 30, 35, 40, 46, 63). Catalogue lengths a maker does not sell are not presets.

Not covered: round standoffs (no maker table for round male/female; the round female/female table found, RS PRO
https://docs.rs-online.com/46b8/A700000007872806.pdf, does not state the thread depth of its short parts).

Preset list: sizes of the step.parts catalogue (MIT), see `library/NOTICE.md`.