2-1/4-4.5 UNC Thread Specifications
Complete dimensions for 2-1/4-4.5 UNC (Unified National Coarse) thread per ASME B1.1. TPI: 4.5, Pitch: 0.22222" (5.644 mm).
Thread Dimensions
| Designation | 2-1/4-4.5 UNC |
| Threads Per Inch (TPI) | 4.5 |
| Pitch | 0.22222" (5.644 mm) |
| Major Diameter | 2.25" (57.15 mm) |
| Pitch Diameter | 2.1057" (53.484 mm) |
| Minor Diameter (External) | 1.9774" (50.225 mm) |
| Minor Diameter (Internal) | 2.0094" (51.04 mm) |
| Thread Depth | 0.12028" (3.055 mm) |
| Tensile Stress Area | 3.24769 in² (2095.3 mm²) |
Tap Drill Size
Recommended tap drill: 2-1/64" (2.0156" / 51.2 mm)
Calculated minor diameter (internal): 2.0094" (51.04 mm)
Proof Loads by SAE Grade
| Grade | Proof Stress (psi) | Tensile Strength (psi) | Proof Load (lbf) | Tensile Load (lbf) |
|---|---|---|---|---|
| Grade 2 | 55,000 | 74,000 | 178,623 | 240,329 |
| Grade 5 | 85,000 | 120,000 | 276,054 | 389,723 |
| Grade 8 | 120,000 | 150,000 | 389,723 | 487,154 |
Common Applications
- Industrial and structural applications
- Coarse thread applications