Metric fine
Tap drill 60 mm for a M64 × 4.0 thread — major Ø 64 mm, pitch 4 mm (6.35 TPI).
Profile
| Designation | M64 × 4.0 |
|---|---|
| Major (outside) diameter | 64 mm · 2.5197" |
| Pitch | 4 mm · 6.35 TPI |
| Pitch diameter | 61.402 mm · 2.4174" |
| Minor diameter (external) | 59.093 mm · 2.3265" |
| Minor diameter (internal) | 59.67 mm · 2.3492" |
| Recommended tap drill | 60 mm · ≈77% thread |
| Clearance hole | Close 66 · Normal 70 · Loose 74 mm |
| Hex head (across flats) | 95 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 | 2850.8 mm² | 1240.09 kN | 15873.1 N·m |
| Class 10.9 | 2850.8 mm² | 1774.61 kN | 22715 N·m |
| Class 12.9 | 2850.8 mm² | 2073.94 kN | 26546.5 N·m |
For a M64 × 4.0 thread, drill the hole with a 60 mm tap drill (60 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 64 mm and a pitch of 4 mm (6.35 TPI).
To pass a M64 × 4.0 bolt through a part rather than thread it, use a clearance hole: Close 66 · Normal 70 · Loose 74 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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