M2 thread: tap drill, clearance hole and counterbore sizes
The hole sizes and depths for an M2 coarse thread, and how to put it on a drawing.
| Property | Value |
|---|---|
| Nominal diameter | 2 mm |
| Pitch (coarse) | 0.4 mm |
| Tap drill | Ø1.6 mm |
| Clearance hole, fine | Ø2.2 mm |
| Clearance hole, medium | Ø2.4 mm |
| Clearance hole, coarse | Ø2.6 mm |
| Socket head cap screw head Ø (ISO 4762) | 3.8 mm |
| Counterbore Ø (DIN 974-1) | 4.4 mm |
| Counterbore depth (head flush) | about 2.5 mm |
Thread depth
| Material | Full thread engagement |
|---|---|
| Steel, stainless steel | 2–3 mm |
| Aluminium, brass | 3–4 mm |
| Plastics | 4–5 mm or an insert |
Drill the tap hole at least 1.2–1.6 mm (3–4 pitches) deeper than the full thread, plus the drill point. More on this in how deep a tapped thread should be.
How to call it out on a drawing
Tapped blind hole: M2x0.4-6H, thread 3 deep, tap drill Ø1.6 4.6 deep.
Clearance hole with counterbore: Ø2.4 through, counterbore Ø4.4 × 2.5 deep.
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