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M2 x 0.4 tap drill size
Use a 1.6 mm drill to tap M2 x 0.4 (coarse pitch). The rule is major diameter minus pitch: 2 − 0.4 = 1.6 mm. Closest inch drill: #52 (1.61 mm).
M2 x 0.4 thread specifications
| Thread | M2 x 0.4 ISO metric coarse |
|---|---|
| Major (nominal) diameter | .0787 in / 2.00 mm |
| Pitch | 0.4 mm (≈ 63.5 threads per inch) |
| Recommended tap drill | 1.6 mm = .0630 in |
M2 clearance hole (ISO 273)
| Fit | Hole diameter |
|---|---|
| Fine (close) | 2.2 mm |
| Medium (normal) | 2.4 mm |
| Coarse (loose) | 2.6 mm |
A clearance hole lets the M2 bolt pass through freely. Drill the tap-drill size only in the part that gets threaded.
Tips for tapping M2 x 0.4
- Use cutting fluid, and with a hand tap back off about half a turn every turn or two to break the chip. Aluminium and soft materials are the exception: they tap cleanly with spiral-point taps.
- For blind holes, drill deeper than the thread you need. Allow at least 3–4 pitches beyond the last full thread for a plug tap (1.6 mm here).
- Thread engagement of 1–1.5 × the diameter (2.0–3.0 mm) is enough for most steel parts. Softer materials need more.