Choosing a rivet
A riveted joint depends on three choices: the diameter, the length and the layout of the rivets. The rules of thumb below come from sheet metal and aircraft practice, and give a good starting point for workshop projects.
Diameter
A common rule sets the rivet diameter at about three times the thickness of the thickest sheet. Two sheets of 0.040 in and 0.063 in call for about 3 × 0.063 ≈ 0.19 in, so a 3/16 in rivet. In metric, 1 mm and 1.5 mm sheets call for about 4.5 mm, so a 4.8 mm blind rivet.
Length and grip
The grip is the total thickness of material being joined.
- Solid rivets: length = grip + 1.5 × diameter. The extra length forms the shop head, which should end up about 1.5 D wide and 0.5 D high.
- Blind (pop) rivets: manufacturers sell each length for a grip range. Choose the rivet whose range includes your total thickness. Too short a rivet will not set properly; too long a rivet leaves a loose, bulky head.
Hole size
The hole should be just larger than the rivet, typically about 0.004 in or 0.1 mm over:
| Rivet | Usual drill |
|---|---|
| 1/8 in | #30 (0.1285 in) |
| 5/32 in | #20 (0.161 in) |
| 3/16 in | #11 (0.191 in) |
| 4 mm | 4.1 mm |
| 4.8 mm | 4.9 mm |
Layout
| Rule | Minimum | Typical |
|---|---|---|
| Edge distance (center of rivet to edge of sheet) | 2 D | 2 to 2.5 D |
| Spacing between rivets (pitch) | 3 D | 4 to 8 D |
| Distance between rows | 2.5 D | 3 to 4 D |
Too close to the edge, the rivet tears out; too close together, the sheet weakens between the holes.
Example
Joining 0.040 in and 0.063 in aluminum with a 3/16 in solid rivet: grip = 0.103 in, rivet length = 0.103 + 1.5 × 0.1875 ≈ 0.384 in, so a 3/8 in rivet. Keep at least 0.375 in from the edge and 0.5625 in between rivets.
Materials
Use rivets of the same or a compatible material as the sheets: aluminum on aluminum, stainless or Monel on stainless. Mixing metals such as aluminum and steel causes galvanic corrosion outdoors. For structural or aircraft work, follow the drawings and the applicable standard rather than these rules of thumb.