A hex socket flat point set screw — gb/t 77 / iso 4026 (series 021 in M12: this guide pulls the row from the standard, adds the assembly numbers an engineer actually uses, and links you straight to a quote.
M12 Dimensional Row (GB/T 77 / ISO 4026)
| Size | Pitch (mm) | Length L (mm) | Hex socket s (mm) | Engagement depth t min (mm) | Point diameter dp (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M12 | 1.75 | 18 | 6.0 | 6.0 | 8.5 | ISO 4026-4029 / GB/T 77-79 |
Spanner & Drive for M12 Hex Socket Flat Point Set Screw — GB/T 77 / ISO 4026 (Series 021)
The hex socket for M12 Hex Socket Flat Point Set Screw — GB/T 77 / ISO 4026 (Series 021) is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). A T-handle Allen key gives the best feel for setting preload by feel; for production work use a torque-controlled driver.
Hole Sizes for M12
| Coarse-thread pitch (ISO 724) | 1.75 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 13.5 mm |
| Tapping drill, coarse thread | 10.2 mm |
Tightening Torque for M12
| Class 8.8 (dry, ~µ 0.125) | ≈ 85 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 120 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 145 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Common Applications for M12 Hex Socket Flat Point Set Screw — GB/T 77 / ISO 4026 (Series 021)
M12 Hex Socket Flat Point Set Screw — GB/T 77 / ISO 4026 (Series 021) are commonly specified for heavier machine assembly and equipment mounting.
Installation Tips for M12 Hex Socket Flat Point Set Screw — GB/T 77 / ISO 4026 (Series 021)
- Use a quality Allen key fully seated in the socket — partial engagement is the most common cause of stripped sockets at this size.
- For countersunk and button-head variants, chamfer the through-hole to seat the head flush without preloading the head/shank fillet.
Mating Parts for M12
For M12, pair with a M12 hex nut (ISO 4032 / DIN 934) and, where used, a M12 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.