DIN 7991Countersunk head (90°)Hexagon socket

DIN 7991 M14 × 80 Countersunk head (90°)

DIN 7991 M14 × 80 is a socket countersunk head screw with a 80 mm nominal length, on a M14 × 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.

DIN 7991 M14 × 80 — Countersunk head (90°)Nominal dimensions in mm · Not to scale

Diameter14 mm

Length80 mm

Pitch1.5 mm

Socket size s10 mm

Head Ø dk27 mm

HeadCountersunk head (90°)

DriveHexagon socket

Dimensions

Standard: DIN 7991
Type: Socket countersunk head screw
Size: M14 × 80
Thread: M14 × 1.5
Length L: 80 mm
Socket size s: 10 mm
Head diameter dk: 27 mm
Head height k: 8.4 mm
Thread length b: 40 mm
Drive: Hexagon socket
Head: Countersunk head (90°)

Nominal values in millimetres as published in DIN 7991. Estimated weight 119.167 g per piece in steel (119.926 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.

Thread data

Full M14 thread page

DesignationM14 × 1.5 fine

Pitch1.5 mm

Nominal Ø14 mm

Pitch Ø13.03 mm

Minor Ø ext12.16 mm

Tap drillØ 12.5 mm

Other lengthsDIN 7991 M14

All M14 specifications

M14 × 25 M14 × 30 M14 × 35 M14 × 40 M14 × 50 M14 × 60 M14 × 80 M14 × 100

Interchangeability

DIN 7991 is catalogued with ISO 10642 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.

Equivalent standardISO 10642Hexagon Socket Countersunk Head Screw ComparisonDIN 7991 vs ISO 10642Field-by-field differences and a substitution verdict

Choosing and fitting this size

DIN 7991 M14 × 80 is a countersunk head (90°) in M14, 80 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, M14 × 1.5 mm takes a 12.5 mm tap drill, and the external thread's minor diameter is 12.16 mm — that is the section carrying the load, not the nominal M14 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.