DIN 661 Countersunk Head Rivet
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.
Where it is used
Countersunk head rivets are chosen when the joint face has to stay flat: aircraft skin, panels that slide over one another, hinge leaves, and any surface where a proud head would catch or show. The 75° head sits in a matching countersink and finishes flush, so the load path runs through the sheet rather than through a head standing above it. The trade is that the countersink removes material from the sheet, and the head must be deep enough to fill it — which is why the head depth k is the dimension that matters most on this page.
How to choose it
The shank, the hole and the setting method are identical to DIN 660: same nominal diameters, same H12 hole, same cold upset. Only the head differs, and it differs in two ways that both matter. The countersunk head is 0.1 mm wider at 1.4 mm and at 3.5 mm nominal — the only two cells where the two tables disagree — and its depth k is one step smaller than the round head's height at every size. A countersunk rivet dropped into a joint drilled for a round head will not fill the countersink, and a round head cannot be made to sit flush at all.
Dimensions13 sizes · millimetres
| Nominal diameter d1 (mm) | Head diameter d2 (mm) | Shank diameter d3 min. (mm) | Head depth k (mm) | Hole diameter dH12 (mm) |
|---|---|---|---|---|
| 1 | 1.8 | 0.93 | 0.5 | 1.05 |
| 1.2 | 2.1 | 1.13 | 0.6 | 1.25 |
| 1.4 | 2.5 | 1.33 | 0.7 | 1.45 |
| 1.6 | 2.8 | 1.52 | 0.8 | 1.65 |
| 2 | 3.5 | 1.87 | 1 | 2.1 |
| 2.5 | 4.4 | 2.37 | 1.2 | 2.6 |
| 3 | 5.2 | 2.87 | 1.4 | 3.1 |
| 3.5 | 6.3 | 3.37 | 1.8 | 3.6 |
| 4 | 7 | 3.87 | 2 | 4.2 |
| 5 | 8.8 | 4.82 | 2.5 | 5.2 |
| 6 | 10.5 | 5.82 | 3 | 6.3 |
| 7 | 12.2 | 6.82 | 3.5 | 7.3 |
| 8 | 14 | 7.76 | 4 | 8.4 |
Nominal dimensions in millimetres as published in DIN 661. Tolerances, material requirements and marking are defined separately by the issuing body.
Available sizeslinked to individual specification pages
Fitting and interchange notes
Because the head is flush, the countersink angle has to match: 75° is the DIN 661 head angle, and a 90° countersink — the commonest in general sheet metal — will leave the head standing proud at its rim while the centre bottoms out. The length l on this page is measured from the top face of the head, not from under it, which is the opposite of DIN 660; ordering a length by the DIN 660 convention gives a rivet that is one head-depth short. Grip lengths in the standard's Table 3 are guidance only, as with DIN 660.