# Nut, inch (ASME B18.2.2)

Hex nuts, hex jam nuts and square nuts for Unified inch threads (UNC and UNF) #0-80 to 1/2-20. Presets cover the
catalogue's hex, jam and square nuts.

## Geometry

Envelope for assemblies: a hexagonal or square prism, width across flats **F**, thickness **H** (corner chamfers and
bearing-face washers are not modelled), with a plain bore at the basic major diameter **D**; the thread is not
modelled. The nut sits on the XY plane, centred on the origin; a hexagon's corners point along X, a square's sides
are parallel to X and Y.

## Parameters

| Parameter | Meaning |
|---|---|
| `size` | Thread, #0-80 to 1/2-20 (UNC and UNF) |
| `style` | `hex`, `jam` (1/4 to 1/2 in only) or `square` |
| `material` | `steel` (carbon steel, zinc plated), `stainless-18-8` (304), `stainless-316` |

## Sources

- **D**, basic major diameter: ASME B1.1-1989 (R2001), *Unified Inch Screw Threads*, external thread table, column
  "Major Diameter Basic", as reproduced at <https://www.engineersedge.com/screw_threads_chart.htm>.
- **#0 to #10**, square and hex machine screw nuts: ASME B18.2.2, *Nuts for General Applications: Machine Screw Nuts,
  Hex, Square, Hex Flange, and Coupling Nuts (Inch Series)*, Table 1-1 (2010 edition; Table 1.1.1-1 in the 2022
  edition): F **basic**, thickness H **max** (the table gives the thickness as min / max only). Read from
  <https://www.fasten.it/Norms/Norm/ASME_B18.2.2_TABLE_1-1> ("Publication date: 2010"), checked against
  <https://www.engineersedge.com/hardware/hexagon_machine_screw_nuts_14062.htm> (ANSI B18.6.3-1991, the earlier home of
  these nuts; same values, F basic as fractions). Machine screw nuts moved from B18.6.3 to B18.2.2; B18.6.3-2013 has
  no nut table. There is no machine screw jam nut, so the catalogue's numbered-size jam nuts are left out.
- **1/4 to 1/2**, hex nuts and hex jam nuts: ASME B18.2.2, F **basic**, H **basic**:
  <https://www.engineersedge.com/hex_nut.htm>, <https://amesweb.info/Fasteners/Nut/Hex-Nut-Sizes-Dimensions-Table.aspx>
  (B18.2.2-2010 via Machinery's Handbook 30th ed.), jam nuts also
  <https://www.aftfasteners.com/hex-jam-nuts-dimensions-technical-information/> (ANSI/ASME B18.2.2-1987).
- **1/4 to 1/2**, square nuts: ASME B18.2.2-2010 (via Machinery's Handbook 30th ed.), F **basic**, H **basic**:
  <https://amesweb.info/Fasteners/Nut/Square-Nuts-Dimensions.aspx>.

The values are the same in the 1987, 2010 and 2022 editions as far as these reproductions show; the citation is
ASME B18.2.2-2022 (Tables 1.1.1-1, 1.1.1-3 and 1.1.1-5, numbering from ASME's table of contents
<https://www.asme.org/getmedia/a5d59a0e-7d26-4b87-aa17-d45e8fcf48e4/B18-2-2_2022_ToC.pdf>). Inch values as printed
in the tables; the model converts them to millimetres (1 in = 25.4 mm).

| Size | D | Hex F × H | Jam F × H | Square F × H |
|---|---|---|---|---|
| #0 | 0.06 | 0.15625 × 0.050 | – | 0.15625 × 0.050 |
| #1 | 0.073 | 0.15625 × 0.050 | – | 0.15625 × 0.050 |
| #2 | 0.086 | 0.1875 × 0.066 | – | 0.1875 × 0.066 |
| #3 | 0.099 | 0.1875 × 0.066 | – | 0.1875 × 0.066 |
| #4 | 0.112 | 0.25 × 0.098 | – | 0.25 × 0.098 |
| #5 | 0.125 | 0.3125 × 0.114 | – | 0.3125 × 0.114 |
| #6 | 0.138 | 0.3125 × 0.114 | – | 0.3125 × 0.114 |
| #8 | 0.164 | 0.34375 × 0.130 | – | 0.34375 × 0.130 |
| #10 | 0.19 | 0.375 × 0.130 | – | 0.375 × 0.130 |
| 1/4 | 0.25 | 0.4375 × 0.21875 | 0.4375 × 0.15625 | 0.4375 × 0.21875 |
| 5/16 | 0.3125 | 0.5 × 0.265625 | 0.5 × 0.1875 | 0.5625 × 0.265625 |
| 3/8 | 0.375 | 0.5625 × 0.328125 | 0.5625 × 0.21875 | 0.625 × 0.328125 |
| 7/16 | 0.4375 | 0.6875 × 0.375 | 0.6875 × 0.25 | 0.75 × 0.375 |
| 1/2 | 0.5 | 0.75 × 0.4375 | 0.75 × 0.3125 | 0.8125 × 0.4375 |

Corrected in this audit: the #0 to #10 thicknesses were "basic" fractions no edition of the table gives
(3/64, 1/16, 3/32, 7/64, 1/8); they are now the table's H max (0.050, 0.066, 0.098, 0.114, 0.130), and the
#0 to #10 presets cite ASME B18.2.2 instead of B18.6.3.

Not covered (no sourced table): nylon-insert and all-metal lock nuts, flange nuts, acorn nuts.

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