When you need Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067) in the M8 size, the controlling values come from GB/T 6171 / ISO 8673. This page lists them in one place — pitch, head geometry, tool size and the matching hole.
M8 Dimensional Row (GB/T 6171 / ISO 8673)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M8 | 1.25 | 13.0 | 14.38 | 6.8 | ISO 4032 / GB/T 6170 |
Spanner & Drive for M8 Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067)
M8 Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067) have a width across flats of 13.0 mm — fit a 13.0 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 M8 Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067)
M8 Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067) are commonly specified for general-purpose joints in machinery, fixturing and equipment frames.
Installation Tips for M8 Hex Nut, Fine Pitch — GB/T 6171 / ISO 8673 (Series 067)
- 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.
Mating Parts for M8
Pair M8 with the matching M8 bolt or screw, plus a M8 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M8
When the joint preload approaches the proof load of M8 class 8.8, step up to M10 class 8.8 (or move to M8 class 10.9). When the joint is over-specified, M6 often saves weight and cost without losing the safety margin.