ISO 10511Nylon insert lock nutExternal hexagon

ISO 10511 M3 Nylon insert lock nut

ISO 10511 M3 is a nylon insert lock nut, on a M3 × 0.5 mm metric thread. ISO equivalent of DIN 985. Reuse is limited — the prevailing torque drops each time the insert is run over the thread.

Dimensioned drawing — ISO 10511 M3s 5.5m 4
ISO 10511 M3 — Nylon insert lock nutNominal dimensions in mm · Not to scale
Diameter3 mm
Pitch0.5 mm
Socket size s5.5 mm
Thickness h4.5 mm
Height m4 mm
DriveExternal hexagon

Dimensions

Standard
ISO 10511
Type
Nylon insert lock nut
Size
M3
Thread
M3 × 0.5
Socket size s
5.5 mm
Height m
4 mm
Total height h
4.5 mm
Drive
External hexagon

Nominal values in millimetres as published in ISO 10511. Estimated weight 0.395 g per piece in steel (0.397 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.

Thread data

Full M3 thread page
DesignationM3 × 0.5
Pitch0.5 mm
Nominal Ø3 mm
Pitch Ø2.68 mm
Minor Ø ext2.39 mm
Tap drillØ 2.5 mm

Other lengthsISO 10511 M3

All M3 specifications
M3

Interchangeability

ISO 10511 is catalogued with DIN 985 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.

Equivalent standardDIN 985Prevailing Torque Hexagon Nut with Nylon InsertComparisonISO 10511 vs DIN 985Field-by-field differences and a substitution verdict

Choosing and fitting this size

ISO 10511 M3 is a M3 nut, on a 0.5 mm coarse pitch. Mating threads should be a matching class nut in the same property class.

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, M3 × 0.5 mm takes a 2.5 mm tap drill, and the external thread's minor diameter is 2.39 mm — that is the section carrying the load, not the nominal M3 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.