1-11/16-18 UNEF Thread Specifications
Complete dimensions for 1-11/16-18 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 18, Pitch: 0.05556" (1.411 mm).
Thread Dimensions
| Designation | 1-11/16-18 UNEF |
| Threads Per Inch (TPI) | 18 |
| Pitch | 0.05556" (1.411 mm) |
| Major Diameter | 1.6875" (42.862 mm) |
| Pitch Diameter | 1.6514" (41.946 mm) |
| Minor Diameter (External) | 1.6193" (41.131 mm) |
| Minor Diameter (Internal) | 1.6274" (41.335 mm) |
| Thread Depth | 0.03007" (0.764 mm) |
| Tensile Stress Area | 2.09537 in² (1351.9 mm²) |
Tap Drill Size
Recommended tap drill: 1-5/8" (1.625" / 41.27 mm)
Calculated minor diameter (internal): 1.6274" (41.34 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 | 115,245 | 155,057 |
| Grade 5 | 85,000 | 120,000 | 178,106 | 251,444 |
| Grade 8 | 120,000 | 150,000 | 251,444 | 314,306 |
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings