M4 is one of the standard coarse-thread sizes for slotted long dog point set screw under GB/T 75 / ISO 7435. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M4 Dimensional Row (GB/T 75 / ISO 7435)
| Size | Pitch (mm) | Length L (mm) | Hex socket s (mm) | Engagement depth t min (mm) | Point diameter dp (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M4 | 0.7 | 6 | 2.0 | 2.0 | 2.5 | ISO 4026-4029 / GB/T 77-79 |
Spanner & Drive for M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041)
The hex socket for M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041) 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 M4
| Coarse-thread pitch (ISO 724) | 0.7 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 4.5 mm |
| Tapping drill, coarse thread | 3.3 mm |
Tightening Torque for M4
| Class 8.8 (dry, ~µ 0.125) | ≈ 2.9 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 4.1 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 4.9 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.
Proof Load & Strength for M4
| Tensile stress area As (ISO 898-1) | 8.78 mm² |
|---|---|
| Proof load, class 8.8 | 5.1 kN |
| Proof load, class 10.9 | 7.3 kN |
| Proof load, class 12.9 | 8.5 kN |
| Min. ultimate tensile, class 8.8 | 7 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041) Weight
A steel M4 slotted long dog point set screw at the listed 6 mm length weighs approximately 0.2 g each — about 0.2 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Common Applications for M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041)
M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041) are commonly specified for electronics, PCB hardware, optical mounts and small-scale machinery.
Installation Tips for M4 Slotted Long Dog Point Set Screw — GB/T 75 / ISO 7435 (Series 041)
- 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.
- At M4 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 M4
For M4, pair with a M4 hex nut (ISO 4032 / DIN 934) and, where used, a M4 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.