Metric fine
Tap drill 31.5 mm for a M33 × 1.5 thread — major Ø 33 mm, pitch 1.5 mm (16.93 TPI).
Profile
| Designation | M33 × 1.5 |
|---|---|
| Major (outside) diameter | 33 mm · 1.2992" |
| Pitch | 1.5 mm · 16.93 TPI |
| Pitch diameter | 32.026 mm · 1.2609" |
| Minor diameter (external) | 31.16 mm · 1.2268" |
| Minor diameter (internal) | 31.376 mm · 1.2353" |
| Recommended tap drill | 31.5 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 | 783.9 mm² | 341 kN | 2250.6 N·m |
| Class 10.9 | 783.9 mm² | 487.98 kN | 3220.7 N·m |
| Class 12.9 | 783.9 mm² | 570.29 kN | 3763.9 N·m |
For a M33 × 1.5 thread, drill the hole with a 31.5 mm tap drill (31.5 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 1.5 mm (16.93 TPI).
To pass a M33 × 1.5 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.
Same diameter
Nearby sizes