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M27 x 3 tap drill size
Use a 24 mm drill to tap M27 x 3 (coarse pitch). The rule is major diameter minus pitch: 27 − 3 = 24 mm. Closest inch drill: 15/16 (23.81 mm).
M27 x 3 thread specifications
| Thread | M27 x 3 ISO metric coarse |
|---|---|
| Major (nominal) diameter | 1.0630 in / 27.00 mm |
| Pitch | 3 mm (≈ 8.5 threads per inch) |
| Recommended tap drill | 24 mm = .9449 in |
M27 clearance hole (ISO 273)
| Fit | Hole diameter |
|---|---|
| Fine (close) | 28 mm |
| Medium (normal) | 30 mm |
| Coarse (loose) | 32 mm |
A clearance hole lets the M27 bolt pass through freely. Drill the tap-drill size only in the part that gets threaded.
Tips for tapping M27 x 3
- 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 (12.0 mm here).
- Thread engagement of 1–1.5 × the diameter (27.0–40.5 mm) is enough for most steel parts. Softer materials need more.