ISO 4029 M8 × 20 Headless
ISO 4029 M8 × 20 is a socket set screw with a 20 mm nominal length, on a M8 × 1 mm metric thread. ISO equivalent of DIN 916, same cup point geometry and socket sizes.
Dimensions
- Standard
- ISO 4029
- Type
- Socket set screw
- Size
- M8 × 20
- Thread
- M8 × 1
- Length L
- 20 mm
- Socket size s
- 4 mm
- Drive
- Hexagon socket
- Head
- Headless
Nominal values in millimetres as published in ISO 4029. Estimated weight 7.892 g per piece in steel (7.942 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M8 thread pageOther lengthsISO 4029 M8
All M8 specificationsInterchangeability
ISO 4029 is catalogued with DIN 916 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
ISO 4029 M8 × 20 is a headless in M8, 20 mm long under the head, on a 1 mm coarse pitch. Mating threads should be a matching class nut or a tapped hole of the same nominal size.
Set screws are rated by surface hardness rather than tensile class — the common stock grade is 45H, which is hard enough to bite into a hardened shaft. Stainless set screws are not through-hardened and will not bite the same way, so they are a poor substitute where the point has to grip.
For a tapped hole, M8 × 1 mm takes a 7 mm tap drill, and the external thread's minor diameter is 6.77 mm — that is the section carrying the load, not the nominal M8 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.