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M3 set screw size
1.5 mm hex key
Allen / internal hex key size for M3 grub
M3 set screw — securing small knobs and collars.
Full specification
| System | Metric (45H) |
| Nominal diameter | 3 mm |
| Thread pitch | 0.5 mm |
| Hex key (Allen) | 1.5 mm |
| Tap drill | 2.5 mm |
| Clearance hole | n/a (threaded) |
| Common grade / class | 45H |
| Typical torque | 0.7 Nm (0.5 ft·lb) |
| Closest other-system size | ~#5 imperial |
🔧 Torque unit converter
Pre-filled with the typical torque for M3 grub (45H, dry). Edit any field to convert.
⚠️ Torque values here are general references for 45H 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 M3 grub
M3 grub screws lock small knobs, gears and collars onto shafts.
A 1.5 mm hex key drives M3 grubs — a tiny, easy-to-lose tool, so keep spares.
Frequently asked questions
- What size Allen / hex key fits M3 grub?
- M3 set screw uses a 1.5 mm hex (Allen) key with an internal hex drive.
- What is the torque for M3 grub?
- A typical tightening torque for M3 set screw in 45H on dry threads is about 0.7 Nm (0.5 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does M3 grub use?
- M3 set screw has a thread pitch of 0.5 mm and uses a 2.5 mm tap drill, with a n/a (threaded) clearance hole.