DIN 661 7 × 25 Countersunk head (75°)
DIN 661 7 × 25 is a countersunk head rivet with a 25 mm nominal length, 7 mm shank diameter. A solid rivet with a 75° countersunk head that finishes flush with the surface. Same shank and same hole as DIN 660 — only the head differs, and the head is where the two tables part company: the countersunk head is 0.1 mm wider at 1.4 mm and at 3.5 mm nominal, and its depth k is one step smaller than the round head's height at every size. That difference is the whole reason a countersunk rivet cannot be substituted where a round head was specified, and vice versa: the head is what carries the load into the sheet.
Dimensions
- Standard
- DIN 661
- Type
- Countersunk head rivet
- Size
- 7 × 25
- Diameter
- 7
- Length L
- 25 mm
- Head diameter d2
- 12.2 mm
- Shank diameter d3 min.
- 6.82 mm
- Head depth k
- 3.5 mm
- Hole diameter dH12
- 7.3 mm
- Head
- Countersunk head (75°)
Nominal values in millimetres as published in DIN 661. Estimated weight 8.533 g per piece in steel (8.587 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Other lengthsDIN 661 7
All 7 specificationsChoosing and fitting this size
DIN 661 7 × 25 is a countersunk head (75°) with a 7 mm shank, 25 mm long overall, measured from the top face of the head. The hole is drilled 7.3 mm — slightly larger than the shank, so the rivet drops in without force. Setting upsets the protruding end into a second head, which makes the joint permanent: there is no way to take it apart without destroying the rivet.
Rivets carry no property class. The standard sets a minimum tensile strength per material group instead of a single grade, and the material is part of the designation — St for steel, A2 or A4 for stainless — so the strength of a rivet is a property of the wire it was made from rather than of a marking on the head. Cold setting work-hardens the shank as it upsets, which is why a properly set joint is stronger than the annealed rivet that went into it; it also means the rivet cannot be straightened and re-used after a bad set.