FASTENER STANDARD
ISO 7050
Cross-recessed countersunk head tapping screws
ISO 7050:2011 specifies the characteristics of cross-recessed countersunk (flat) head tapping screws with thread sizes from ST 2,2 to ST 9,5 inclusive.
2011 · currentISO 7050 dimensional reference
Cross-recessed countersunk head tapping screws
| Thread size | Pitch (mm) | aMax | dkTheoreticalMax | Head diameter dk (mm) | dkMin | Head height k (mm) | rMax | driveNo | driveRefH | driveDepthMaxH | driveDepthMinH | driveRefZ | driveDepthMaxZ | driveDepthMinZ | pointC | pointF | pointR |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ST2.2 | 0.8 | 1.6 | 4.4 | 3.8 | 3.5 | 1.1 | 0.8 | 0 | 1.9 | 1.2 | 0.9 | 2 | 1.2 | 0.95 | 2 | 1.6 | - |
| ST2.9 | 1.1 | 2.2 | 6.3 | 5.5 | 5.2 | 1.7 | 1.2 | 1 | 3.2 | 2.1 | 1.7 | 3 | 2.01 | 1.76 | 2.6 | 2.1 | - |
| ST3.5 | 1.3 | 2.6 | 8.2 | 7.3 | 6.9 | 2.35 | 1.4 | 2 | 4.4 | 2.4 | 1.9 | 4.1 | 2.2 | 1.75 | 3.2 | 2.5 | 2.7 |
| ST4.2 | 1.4 | 2.8 | 9.4 | 8.4 | 8 | 2.6 | 1.6 | 2 | 4.6 | 2.6 | 2.1 | 4.4 | 2.51 | 2.06 | 3.7 | 2.8 | 3.2 |
| ST4.8 | 1.6 | 3.2 | 10.4 | 9.3 | 8.9 | 2.8 | 2 | 2 | 5.2 | 3.2 | 2.7 | 4.9 | 3.05 | 2.6 | 4.3 | 3.2 | 3.6 |
| ST5.5 | 1.8 | 3.6 | 11.5 | 10.3 | 9.9 | 3 | 2.2 | 3 | 6.6 | 3.3 | 2.8 | 6.3 | 3.18 | 2.73 | 5 | 3.6 | 4.3 |
| ST6.3 | 1.8 | 3.6 | 12.6 | 11.3 | 10.9 | 3.15 | 2.4 | 3 | 6.8 | 3.5 | 3 | 6.6 | 3.45 | 3 | 6 | 3.6 | 5 |
| ST8 | 2.1 | 4.2 | 17.3 | 15.8 | 15.4 | 4.65 | 3.2 | 4 | 8.9 | 4.6 | 4 | 8.8 | 4.6 | 4.15 | 7.5 | 4.2 | 6.3 |
| ST9.5 | 2.1 | 4.2 | 20 | 18.3 | 17.8 | 5.25 | 4 | 4 | 10 | 5.7 | 5.1 | 9.8 | 5.64 | 5.19 | 8 | 4.2 | - |
