1-1/4-12 UNF Thread Specifications
Complete dimensions for 1-1/4-12 UNF (Unified National Fine) thread per ASME B1.1. TPI: 12, Pitch: 0.08333" (2.117 mm).
Thread Dimensions
| Designation | 1-1/4-12 UNF |
| Threads Per Inch (TPI) | 12 |
| Pitch | 0.08333" (2.117 mm) |
| Major Diameter | 1.25" (31.75 mm) |
| Pitch Diameter | 1.1959" (30.375 mm) |
| Minor Diameter (External) | 1.1478" (29.153 mm) |
| Minor Diameter (Internal) | 1.1598" (29.459 mm) |
| Thread Depth | 0.04511" (1.146 mm) |
| Tensile Stress Area | 1.07295 in² (692.2 mm²) |
Tap Drill Size
Recommended tap drill: 1-11/64" (1.1719" / 29.77 mm)
Calculated minor diameter (internal): 1.1598" (29.46 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 | 35,407 | 64,377 |
| Grade 5 | 74,000 | 105,000 | 79,398 | 112,659 |
| Grade 8 | 120,000 | 150,000 | 128,753 | 160,942 |
Same Size, Different Series
Common Applications
- Heavy structural, foundation bolts, large machinery
- Fine thread applications