Metric fine
Tap drill 30 mm for a M33 × 3.0 thread — major Ø 33 mm, pitch 3 mm (8.47 TPI).
Profile
| Designation | M33 × 3.0 |
|---|---|
| Major (outside) diameter | 33 mm · 1.2992" |
| Pitch | 3 mm · 8.47 TPI |
| Pitch diameter | 31.052 mm · 1.2225" |
| Minor diameter (external) | 29.319 mm · 1.1543" |
| Minor diameter (internal) | 29.753 mm · 1.1714" |
| Recommended tap drill | 30 mm · ≈77% thread |
| Clearance hole | Close 34 · Normal 36 · Loose 38 mm |
| Hex head (across flats) | 50 mm |
| Socket key (across flats) | 24 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 | 715.6 mm² | 311.3 kN | 2054.6 N·m |
| Class 10.9 | 715.6 mm² | 445.47 kN | 2940.1 N·m |
| Class 12.9 | 715.6 mm² | 520.62 kN | 3436.1 N·m |
For a M33 × 3.0 thread, drill the hole with a 30 mm tap drill (30 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 33 mm and a pitch of 3 mm (8.47 TPI).
To pass a M33 × 3.0 bolt through a part rather than thread it, use a clearance hole: Close 34 · Normal 36 · Loose 38 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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