Metric fine
Tap drill 44 mm for a M48 × 4.0 thread — major Ø 48 mm, pitch 4 mm (6.35 TPI).
Profile
| Designation | M48 × 4.0 |
|---|---|
| Major (outside) diameter | 48 mm · 1.8898" |
| Pitch | 4 mm · 6.35 TPI |
| Pitch diameter | 45.402 mm · 1.7875" |
| Minor diameter (external) | 43.093 mm · 1.6966" |
| Minor diameter (internal) | 43.67 mm · 1.7193" |
| Recommended tap drill | 44 mm · ≈77% thread |
| Clearance hole | Close 50 · Normal 52 · Loose 56 mm |
| Hex head (across flats) | 75 mm |
| Socket key (across flats) | 36 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 | 1537.7 mm² | 668.88 kN | 6421.3 N·m |
| Class 10.9 | 1537.7 mm² | 957.2 kN | 9189.1 N·m |
| Class 12.9 | 1537.7 mm² | 1118.65 kN | 10739 N·m |
For a M48 × 4.0 thread, drill the hole with a 44 mm tap drill (44 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 48 mm and a pitch of 4 mm (6.35 TPI).
To pass a M48 × 4.0 bolt through a part rather than thread it, use a clearance hole: Close 50 · Normal 52 · Loose 56 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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