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M8 socket cap screw size
6 mm hex key
Allen / internal hex key size for M8 socket cap
M8 socket cap screw — machinery and mould tooling.
Full specification
| System | Metric (12.9) |
| Nominal diameter | 8 mm |
| Thread pitch | 1.25 mm |
| Hex key (Allen) | 6 mm |
| Tap drill | 6.8 mm |
| Clearance hole | 9 mm |
| Common grade / class | 12.9 |
| Typical torque | 40 Nm (30 ft·lb) |
| Closest other-system size | ~5/16 inch |
🔧 Torque unit converter
Pre-filled with the typical torque for M8 socket cap (12.9, dry). Edit any field to convert.
⚠️ Torque values here are general references for 12.9 on clean, dry threads. Lubrication, coatings, and the joint material change the figure significantly. For structural, automotive, or safety-critical work, always use the torque specified by the manufacturer or engineer.
About M8 socket cap
M8 socket caps hold machine bases, moulds and heavy fixtures.
A 6 mm hex key drives M8 — use a quality key, as torque is significant.
Frequently asked questions
- What size Allen / hex key fits M8 socket cap?
- M8 socket cap screw uses a 6 mm hex (Allen) key with an internal hex drive.
- What is the torque for M8 socket cap?
- A typical tightening torque for M8 socket cap screw in 12.9 on dry threads is about 40 Nm (30 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does M8 socket cap use?
- M8 socket cap screw has a thread pitch of 1.25 mm and uses a 6.8 mm tap drill, with a 9 mm clearance hole.