Metric coarse
Tap drill 58 mm for a M64 × 6.0 thread — major Ø 64 mm, pitch 6 mm (4.23 TPI).
Profile
| Designation | M64 × 6.0 |
|---|---|
| Major (outside) diameter | 64 mm · 2.5197" |
| Pitch | 6 mm · 4.23 TPI |
| Pitch diameter | 60.103 mm · 2.3663" |
| Minor diameter (external) | 56.639 mm · 2.2299" |
| Minor diameter (internal) | 57.505 mm · 2.264" |
| Recommended tap drill | 58 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 | 2676 mm² | 1164.05 kN | 14899.8 N·m |
| Class 10.9 | 2676 mm² | 1665.79 kN | 21322.1 N·m |
| Class 12.9 | 2676 mm² | 1946.77 kN | 24918.6 N·m |
For a M64 × 6.0 thread, drill the hole with a 58 mm tap drill (58 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 6 mm (4.23 TPI).
To pass a M64 × 6.0 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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