1-3/8-6 UNC Thread Specifications
Complete dimensions for 1-3/8-6 UNC (Unified National Coarse) thread per ASME B1.1. TPI: 6, Pitch: 0.16667" (4.233 mm).
Thread Dimensions
| Designation | 1-3/8-6 UNC |
| Threads Per Inch (TPI) | 6 |
| Pitch | 0.16667" (4.233 mm) |
| Major Diameter | 1.375" (34.925 mm) |
| Pitch Diameter | 1.2668" (32.175 mm) |
| Minor Diameter (External) | 1.1705" (29.731 mm) |
| Minor Diameter (Internal) | 1.1946" (30.342 mm) |
| Thread Depth | 0.09021" (2.291 mm) |
| Tensile Stress Area | 1.15488 in² (745.1 mm²) |
Tap Drill Size
Recommended tap drill: 1-7/32" (1.2188" / 30.96 mm)
Calculated minor diameter (internal): 1.1946" (30.34 mm)
Proof Loads by SAE Grade
| Grade | Proof Stress (psi) | Tensile Strength (psi) | Proof Load (lbf) | Tensile Load (lbf) |
|---|---|---|---|---|
| Grade 2 | 33,000 | 60,000 | 38,111 | 69,293 |
| Grade 5 | 74,000 | 105,000 | 85,461 | 121,263 |
| Grade 8 | 120,000 | 150,000 | 138,586 | 173,232 |
Same Size, Different Series
Common Applications
- Heavy structural, foundation bolts, large machinery
- Coarse thread applications