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M1.6 x 0.35 tap drill size
Use a 1.25 mm drill to tap M1.6 x 0.35 (coarse pitch). The rule is major diameter minus pitch: 1.6 − 0.35 = 1.25 mm. Closest inch drill: 3/64 (1.19 mm).
M1.6 x 0.35 thread specifications
| Thread | M1.6 x 0.35 ISO metric coarse |
|---|---|
| Major (nominal) diameter | .0630 in / 1.60 mm |
| Pitch | 0.35 mm (≈ 72.6 threads per inch) |
| Recommended tap drill | 1.25 mm = .0492 in |
M1.6 clearance hole (ISO 273)
| Fit | Hole diameter |
|---|---|
| Fine (close) | 1.7 mm |
| Medium (normal) | 1.8 mm |
| Coarse (loose) | 2 mm |
A clearance hole lets the M1.6 bolt pass through freely. Drill the tap-drill size only in the part that gets threaded.
Tips for tapping M1.6 x 0.35
- 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 (1.4 mm here).
- Thread engagement of 1–1.5 × the diameter (1.6–2.4 mm) is enough for most steel parts. Softer materials need more.