DIN 7991 M20 × 35 Countersunk head (90°)
DIN 7991 M20 × 35 is a socket countersunk head screw with a 35 mm nominal length, on a M20 × 1.5 mm metric thread. Flat head version of the socket screw. The 90° cone seats flush in a matching countersink so nothing protrudes above the surface.
Dimensions
- Standard
- DIN 7991
- Type
- Socket countersunk head screw
- Size
- M20 × 35
- Thread
- M20 × 1.5
- Length L
- 35 mm
- Socket size s
- 14 mm
- Head diameter dk
- 36 mm
- Head height k
- 11 mm
- Thread length b
- 52 mm
- Drive
- Hexagon socket
- Head
- Countersunk head (90°)
Nominal values in millimetres as published in DIN 7991. Estimated weight 140.932 g per piece in steel (141.83 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.
Thread data
Full M20 thread pageOther lengthsDIN 7991 M20
All M20 specificationsInterchangeability
DIN 7991 is catalogued with ISO 10642 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.
Choosing and fitting this size
DIN 7991 M20 × 35 is a countersunk head (90°) in M20, 35 mm long under the head, on a 1.5 mm coarse pitch. Mating threads should be a matching class nut or a tapped hole of the same nominal size.
Common stock grades are 8.8, 10.9 and 12.9 in steel, plus A2-70 and A4-80 in stainless. Class 10.9 and 12.9 carry roughly 1.25 and 1.5 times the proof load of 8.8, but they also need a properly rated mating nut — a class 8 nut under a 12.9 bolt simply moves the failure into the thread. Zinc-plated 10.9 and above should be baked to avoid hydrogen embrittlement.
For a tapped hole, M20 × 1.5 mm takes a 18.5 mm tap drill, and the external thread's minor diameter is 18.16 mm — that is the section carrying the load, not the nominal M20 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.