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M24 x 3 tap drill size
Use a 21 mm drill to tap M24 x 3 (coarse pitch). The rule is major diameter minus pitch: 24 − 3 = 21 mm. Closest inch drill: 53/64 (21.03 mm).
M24 x 3 thread specifications
| Thread | M24 x 3 ISO metric coarse |
|---|---|
| Major (nominal) diameter | .9449 in / 24.00 mm |
| Pitch | 3 mm (≈ 8.5 threads per inch) |
| Recommended tap drill | 21 mm = .8268 in |
M24 clearance hole (ISO 273)
| Fit | Hole diameter |
|---|---|
| Fine (close) | 25 mm |
| Medium (normal) | 26 mm |
| Coarse (loose) | 28 mm |
A clearance hole lets the M24 bolt pass through freely. Drill the tap-drill size only in the part that gets threaded.
Tips for tapping M24 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 (24.0–36.0 mm) is enough for most steel parts. Softer materials need more.