The M20 size of Cap (Acorn) Nuts is dimensioned by DIN 1587. The tables below give the dimensional row from the standard, the drill and spanner sizes that go with it, and the assembly torque per property class. The technical drawing on this page redraws to the exact values selected.
M20 Dimensional Row (DIN 1587)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Total height m (mm) | Dome diameter (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M20 | 2.5 | 30.0 | 33.53 | 34.0 | 30.0 | DIN 1587 | Closed-end domed cap nut, decorative / protective |
Spanner & Drive for M20 Cap (Acorn) Nuts
Drive geometry for M20 Cap (Acorn) Nuts is given by the row above; match the tool to the listed values.
Common Applications for M20 Cap (Acorn) Nuts
M20 Cap (Acorn) Nuts are commonly specified for structural joints, flange connections and heavy equipment foundations.
Installation Tips for M20 Cap (Acorn) Nuts
- At M20 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
When to Step Up or Down from M20
When the joint preload approaches the proof load of M20 class 8.8, step up to M24 class 8.8 (or move to M20 class 10.9). When the joint is over-specified, M16 often saves weight and cost without losing the safety margin.