Metric coarse
Tap drill 21 mm for a M24 × 3.0 thread — major Ø 24 mm, pitch 3 mm (8.47 TPI).
Profile
| Designation | M24 × 3.0 |
|---|---|
| Major (outside) diameter | 24 mm · 0.9449" |
| Pitch | 3 mm · 8.47 TPI |
| Pitch diameter | 22.052 mm · 0.8682" |
| Minor diameter (external) | 20.319 mm · 0.8" |
| Minor diameter (internal) | 20.753 mm · 0.817" |
| Recommended tap drill | 21 mm · ≈77% thread |
| Clearance hole | Close 25 · Normal 26 · Loose 28 mm |
| Hex head (across flats) | 36 mm |
| Socket key (across flats) | 19 mm |
ISO 273 clearance holes (fine / medium / coarse).
Target preload is 75% of proof load; torque is estimated from T = K · F · d.
| Grade / class | Stress area | Preload | Torque |
|---|---|---|---|
| Class 8.8 | 352.5 mm² | 153.34 kN | 736 N·m |
| Class 10.9 | 352.5 mm² | 219.43 kN | 1053.3 N·m |
| Class 12.9 | 352.5 mm² | 256.45 kN | 1230.9 N·m |
For a M24 × 3.0 thread, drill the hole with a 21 mm tap drill (21 mm — the standard D − P rule) before tapping. That produces roughly 77% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 24 mm and a pitch of 3 mm (8.47 TPI).
To pass a M24 × 3.0 bolt through a part rather than thread it, use a clearance hole: Close 25 · Normal 26 · Loose 28 mm.
All values are generated from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables — not hand-entered. See the full reference.
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