ISO 290130° flank
Trapezoidal Threads
The metric power thread. A 30 degree flank carries thrust far better than a 60 degree V, which is why lead screws, jacks and machine feeds use it. Sizes are written Tr followed by diameter × pitch. 16 designations are listed here, all quoted in millimetres.
Dimensions
mm| Designation | Pitch (mm) | Major (mm) | Pitch Ø (mm) | Minor ext (mm) | Tap drill (mm) |
|---|---|---|---|---|---|
| Tr8 × 1.5 | 1.5 | 8 | 7.25 | 6.95 | 6.5 |
| Tr10 × 2 | 2 | 10 | 9 | 8.5 | 8 |
| Tr10 × 1.5 | 1.5 | 10 | 9.25 | 8.95 | 8.5 |
| Tr12 × 3 | 3 | 12 | 10.5 | 10 | 9 |
| Tr12 × 2 | 2 | 12 | 11 | 10.5 | 10 |
| Tr14 × 3 | 3 | 14 | 12.5 | 12 | 11 |
| Tr16 × 4 | 4 | 16 | 14 | 13.5 | 12 |
| Tr16 × 2 | 2 | 16 | 15 | 14.5 | 14 |
| Tr18 × 4 | 4 | 18 | 16 | 15.5 | 14 |
| Tr20 × 4 | 4 | 20 | 18 | 17.5 | 16 |
| Tr24 × 5 | 5 | 24 | 21.5 | 21 | 19 |
| Tr24 × 3 | 3 | 24 | 22.5 | 22 | 21 |
| Tr28 × 5 | 5 | 28 | 25.5 | 25 | 23 |
| Tr30 × 6 | 6 | 30 | 27 | 26 | 24 |
| Tr36 × 6 | 6 | 36 | 33 | 32 | 30 |
| Tr40 × 7 | 7 | 40 | 36.5 | 35.5 | 33 |