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M8 set / grub screw size
4 mm Allen key
hex key size for M8 set screw
M8 set screw — Heavy shaft collars, pulleys, gears.
Full specification
| System | Metric coarse |
| Nominal diameter | 8 mm |
| Thread pitch | 1.25 mm |
| Allen key / hex socket | 4 mm |
| Tap drill | 6.8 mm |
| Clearance hole | 9 mm |
| Common grade / class | 12.9 |
| Typical torque | 18 Nm (13.3 ft·lb) |
About M8 set screws
Heavy shaft collars, pulleys, gears.
Set screws (also called grub screws) are headless screws with a hexagonal socket. They are used to secure an object within or against another object. Common applications include securing pulleys, gears, and collars to shafts.
Grade 12.9 indicates high-strength alloy steel for demanding applications.
Frequently asked questions
- What size Allen key fits M8 set screw?
- M8 set screw uses a 4 mm Allen key.
- What is the torque for M8 set screw?
- Typical torque for M8 set screw in 12.9 is about 18 Nm (13.3 ft·lb).
- What are set screws used for?
- M8 set screws are used in heavy shaft collars, pulleys, gears.