M30 thread: tap drill, clearance hole and counterbore sizes
The hole sizes and depths for an M30 coarse thread, and how to put it on a drawing.
| Property | Value |
|---|---|
| Nominal diameter | 30 mm |
| Pitch (coarse) | 3.5 mm |
| Tap drill | Ø26.5 mm |
| Clearance hole, fine | Ø31 mm |
| Clearance hole, medium | Ø33 mm |
| Clearance hole, coarse | Ø35 mm |
| Socket head cap screw head Ø (ISO 4762) | 45 mm |
| Counterbore Ø (DIN 974-1) | 48 mm |
| Counterbore depth (head flush) | about 30.5 mm |
Thread depth
| Material | Full thread engagement |
|---|---|
| Steel, stainless steel | 30–45 mm |
| Aluminium, brass | 45–60 mm |
| Plastics | 60–75 mm or an insert |
Drill the tap hole at least 10.5–14 mm (3–4 pitches) deeper than the full thread, plus the drill point. More on this in how deep a tapped thread should be.
How to call it out on a drawing
Tapped blind hole: M30x3.5-6H, thread 45 deep, tap drill Ø26.5 59 deep.
Clearance hole with counterbore: Ø33 through, counterbore Ø48 × 30.5 deep.
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