DIN 915 M8 × 20 Headless
DIN 915 M8 × 20 is a socket set screw, dog point with a 20 mm nominal length, on a M8 × 1 mm metric thread. A cylindrical dog point that drops into a drilled hole in the shaft. It locks the position without damaging the shaft surface.
Dimensions
- Standard
- DIN 915
- Type
- Socket set screw, dog point
- 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 DIN 915. 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 lengthsDIN 915 M8
All M8 specificationsInterchangeability
DIN 915 is catalogued with ISO 4028 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
DIN 915 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.