DIN 931Hexagon headExternal hexagon
DIN 931 M8 × 40 Hexagon head
DIN 931 M8 × 40 is a hexagon head bolt with a 40 mm nominal length, on a M8 × 1 mm metric thread. Same head as DIN 933 but with an unthreaded shank under the head. The plain shank carries shear load, which is why these are preferred for structural steelwork and machinery frames.
Diameter8 mm
Length40 mm
Pitch1 mm
Socket size s13 mm
Head height k5.3 mm
HeadHexagon head
DriveExternal hexagon
Dimensions
- Standard
- DIN 931
- Type
- Hexagon head bolt
- Size
- M8 × 40
- Thread
- M8 × 1
- Length L
- 40 mm
- Socket size s
- 13 mm
- Head height k
- 5.3 mm
- Drive
- External hexagon
- Head
- Hexagon head
Nominal values in millimetres as published in DIN 931. Estimated weight 15.783 g per piece in steel (15.884 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M8 thread pageDesignationM8 × 1 fine
Pitch1 mm
Major Ø8 mm
Pitch Ø7.35 mm
Minor Ø ext6.77 mm
Tap drillØ 7 mm
Other lengthsDIN 931 M8
All M8 specificationsInterchangeability
DIN 931 is catalogued with ISO 4014 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.