1-1/4-7 UNC Thread Specifications
Complete dimensions for 1-1/4-7 UNC (Unified National Coarse) thread per ASME B1.1. TPI: 7, Pitch: 0.14286" (3.629 mm).
Thread Dimensions
| Designation | 1-1/4-7 UNC |
| Threads Per Inch (TPI) | 7 |
| Pitch | 0.14286" (3.629 mm) |
| Major Diameter | 1.25" (31.75 mm) |
| Pitch Diameter | 1.1572" (29.393 mm) |
| Minor Diameter (External) | 1.0747" (27.298 mm) |
| Minor Diameter (Internal) | 1.0954" (27.822 mm) |
| Thread Depth | 0.07732" (1.964 mm) |
| Tensile Stress Area | 0.96911 in² (625.2 mm²) |
Tap Drill Size
Recommended tap drill: 1-3/32" (1.0938" / 27.78 mm)
Calculated minor diameter (internal): 1.0954" (27.82 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 | 53,301 | 71,714 |
| Grade 5 | 85,000 | 120,000 | 82,374 | 116,293 |
| Grade 8 | 120,000 | 150,000 | 116,293 | 145,366 |
Same Size, Different Series
Common Applications
- Heavy structural, foundation bolts, large machinery
- Coarse thread applications