M3×0.5 thread
M3×0.5 tap drill
2.5 mm
Clearance hole 3.2 mm · 5.5 mm hex
M3×0.5 is a coarse metric thread with a 3 mm (0.118") major diameter and 0.5 mm pitch. Tap it with a 2.5 mm drill; drill 3.2 mm to pass a bolt through.
The numbers
- Designation
- M3×0.5
- Major diameter
- 3 mm / 0.118"
- Minor diameter
- 2.459 mm
- Pitch
- 0.5 mm pitch
- Tap drill (75% thread)
- 2.5 mm — 2.5 mm
- Clearance hole (close fit)
- 3.2 mm / 0.126"
- Hex across flats
- 5.5 mm
How to measure what you have
- Measure across the thread crests with calipers. A used M3×0.5 reads a little under 3 mm — the crests are truncated by the standard, then worn and plated, so anything from about 2.6 mm up is consistent with this size.
- Measure the pitch: put a rule against the threads and count the distance over ten crests, then divide by ten. This one should give 0.5 mm.
- A thread pitch gauge settles it in seconds and costs very little. Guessing between a coarse and a fine thread of the same diameter is the usual way a thread gets stripped.
Tightening torque
Typical torque
1.1–1.5 N·m
0.8–1.1 lb·ft
Plain steel property class 8.8 or SAE grade 5, dry threads, tightened to about 65% of yield. Lubricated threads reach the same preload at 20-30% less torque. Where the manufacturer publishes a figure — spark plugs, wheel nuts, cylinder heads — use theirs.
Where this size turns up
- 2.5-inch SATA drive and SSD mounting screws
- 3D printer hot-end, carriage and bed screws
- DIN-rail terminal blocks
- Quadcopter frame and motor screws
Common questions
- What size drill for an M3×0.5 tap?
- 2.5 mm (2.5 mm), which gives about 75% thread engagement.
- What clearance hole for M3×0.5?
- 3.2 mm for a close fit — enough to pass the bolt without slop.
- What spanner fits M3×0.5?
- 5.5 mm across the flats on a standard hex head.
Related pages
Sources
- Official vendor product documentation — At One Place
- Typical range compiled from manufacturer specifications — At One Place