M3 is one of the standard coarse-thread sizes for thin hex nut under GB/T 6172.1 / ISO 4035. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M3 Dimensional Row (GB/T 6172.1 / ISO 4035)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 1.8 | ISO 4035 / GB/T 6172 |
Spanner & Drive for M3 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055)
M3 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055) have a width across flats of 5.5 mm — fit a 5.5 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Common Applications for M3 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055)
M3 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055) are commonly specified for paired with the same-size screws on PCB hardware, light enclosures and small-scale assemblies.
Installation Tips for M3 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055)
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
- At M3 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
Mating Parts for M3
Pair M3 with the matching M3 bolt or screw, plus a M3 flat washer where required to distribute load on softer materials.