DIN 1587 domed cap nut (acorn nut): dimensions
Tall hexagon cap nut with a closed dome, used to cover the end of a bolt, from M4 to M24. Pick a size to get its dimensions and CAD files.
DIN 1587 acorn nut dimensions
| Size | Pmm | snom, mm | emin, mm | hmax, mm | dkmax, mm | mmax, mm | tmin, mm |
|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 7 | 7.66 | 8 | 6.5 | 3.2 | 5.26 |
| M5 | 0.8 | 8 | 8.79 | 10 | 7.5 | 4 | 7.21 |
| M6 | 1 | 10 | 11.05 | 12 | 9.5 | 5 | 7.71 |
| M8 | 1.25 | 13 | 14.38 | 15 | 12.5 | 6.5 | 10.65 |
| M10 | 1.5 | 16 | 17.77 | 18 | 15 | 8 | 12.65 |
| M12 | 1.75 | 18 | 20.03 | 22 | 17 | 10 | 15.65 |
| M14 | 2 | 21 | 23.35 | 25 | 20 | 11 | 17.65 |
| M16 | 2 | 24 | 26.75 | 28 | 23 | 13 | 20.58 |
| M18 | 2.5 | 27 | 30.14 | 32 | 26 | 15 | 24.58 |
| M20 | 2.5 | 30 | 33.53 | 34 | 28 | 16 | 25.58 |
| M22 | 2.5 | 34 | 37.72 | 39 | 33 | 18 | 28.58 |
| M24 | 3 | 36 | 39.98 | 42 | 34 | 19 | 30.5 |
Where DIN 1587 (older s) differs from DIN 1587
| Size | sDIN 1587 | sDIN 1587 (older s) |
|---|---|---|
| M10 | 16 | 17 |
| M12 | 18 | 19 |
| M14 | 21 | 22 |
DIN 1587 (older s) is withdrawn but parts to it are still sold. Only the sizes listed here differ; in every other size both standards give the same part. Pick the standard in the selector above to get the matching CAD files.
Dimensions in millimetres unless stated. Select a row to load its CAD files above.
DIN 1587 width across flats
The main table uses the widths across flats of the current edition (16, 18 and 21 mm in M10, M12 and M14). Older stock may still have 17, 19 and 22 mm; those versions have their own files under the table.
Acorn nut dimensions: thread depth and bolt length
The dome closes the end, so the bolt must not reach it. The depth t is the minimum usable thread from the bearing face. At M10 the nut is up to 18 mm high, with at least 12.65 mm of thread inside. Choose the bolt length so that its end stays within that depth once the nut is tight.
DIN 1587 acorn nuts: common questions
- How long can the bolt be under an acorn nut?
- The protruding part of the bolt must be shorter than the thread depth t of the nut, for example 12.65 mm at M10. Any longer and the bolt hits the dome before the nut is tight.