Thread type: BL, ST

Tapping screw thread DIN EN ISO 1478 (or DIN 7970)

The table for the ST thread contains the dimensional data for sheet metal screw threads. The values from the ST thread table follow the specifications of the DIN EN ISO 1478 standard and the DIN 7970 standard. Both standards for the ST thread table correspond to each other in essential parts. The self-tapping screw thread is a special thread that is specifically intended for use on self-tapping screws and is sometimes also found on lead screws. Tapping screws whose thread is formed according to the specifications in the ST thread table are designed for screwing sheet metal to other components. The tapping screw thread according to the table forms its own receiving thread when screwed in. When working with self-tapping screws, it is particularly important to ensure the correct core hole size. This can also be found in the ST thread table.

The tapping screw thread has a flank angle of 60°. As you can see from the ST thread table, it is a metric thread. The designation for the sheet metal screw thread according to the table is made up of two components. The first is the abbreviation ST, followed by a numerical value. This numerical value is based on the specifications for the required core hole, which can also be determined using the ST thread table. The thread designation therefore already allows conclusions to be drawn as to how central the correct core hole dimension is for the use of the self-tapping screw thread.

You will find twelve entries in our ST thread table, with nominal dimensions ranging from ST 2.2 to ST 9.5. Another important specification in the ST thread table is the pitch in mm. The sheet metal used must always be thicker than the pitch of the self-tapping screw thread. The ST thread table also contains entries regarding the outer diameter and the required core hole diameter. In both cases, minimum and maximum values are specified in the ST thread table. The diameter actually achieved must therefore be between these two values.

 Pitch P in mmoutside-Ø
in mm
in mm
in mm
in mm
ST 2,20,81,521,632,102,24
ST 2.60,91,801,902,432,57
ST 2.91,12,082,182,762,90
ST 3.31,32,292,393,123,30
ST 3.51,32,512,643,353,53
ST 3.91,32,772,923,733,91
ST 4.21,42,953,104,044,22
ST 4.81,63,433,584,624,80
ST 5.51,83,994,175,285,46
ST 6.31,84,704,886,036,25
ST 82,15,996,207,788,00
ST 9.52,17,597,859,439,65
Cross section of a BL, ST thread