M30×3.5 Thread Specifications
Complete dimensions for M30×3.5 coarse pitch thread per ISO 724. Pitch: 3.5mm (7.3 TPI equivalent).
Thread Dimensions
| Designation | M30×3.5 |
| Thread Series | ISO Metric Coarse |
| Pitch | 3.5 mm (7.3 TPI) |
| Major Diameter (d) | 30 mm (1.1811") |
| Pitch Diameter (d₂) | 27.7267 mm (1.0916") |
| Minor Diameter — External (d₁) | 25.7058 mm (1.012") |
| Minor Diameter — Internal (D₁) | 26.2112 mm (1.0319") |
| Thread Depth | 1.8944 mm |
| Tensile Stress Area | 560.59 mm² |
| Fundamental Triangle Height (H) | 3.0311 mm |
Tap Drill Size
Recommended tap drill: 26.0 mm
Calculated minor diameter (D₁): 26.21 mm. Closest standard metric drill: 26.0 mm.
Closest inch drill: 1-1/32" (1.0312" / 26.19 mm)
Proof Loads by Property Class
| Class | Proof Stress (MPa) | Tensile Strength (MPa) | Proof Load (kN) | Tensile Load (kN) |
|---|---|---|---|---|
| 4.6 | 225 | 400 | 126.1 | 224.2 |
| 4.8 | 310 | 420 | 173.8 | 235.4 |
| 5.8 | 380 | 520 | 213.0 | 291.5 |
| 8.8 | 580 | 800 | 325.1 | 448.5 |
| 9.8 | 650 | 900 | 364.4 | 504.5 |
| 10.9 | 830 | 1040 | 465.3 | 583.0 |
| 12.9 | 970 | 1220 | 543.8 | 683.9 |
Proof load = stress area × proof stress. Per ISO 898-1.
Related Thread Sizes
Common Applications
- Structural steel
- Bridge construction
- Heavy industrial equipment
- Foundation bolts
How M30×3.5 Dimensions Are Calculated
All dimensions on this page are calculated from ISO 724 formulas using the nominal diameter (30 mm) and pitch (3.5 mm):
- Fundamental triangle height: H = (√3/2) × P = 3.0311 mm
- Pitch diameter: d₂ = d − 0.6495 × P = 27.7267 mm
- Minor diameter (external): d₁ = d − 1.2269 × P = 25.7058 mm
- Minor diameter (internal): D₁ = d − 1.0825 × P = 26.2112 mm
- Thread depth: 5H/8 = 1.8944 mm
- Tensile stress area: Aₛ = (π/4) × ((d₂ + d₃)/2)² = 560.59 mm²