#3-56 UNF Thread Specifications
Complete dimensions for #3-56 UNF thread per ASME B1.1. TPI: 56, Pitch: 0.01786" (0.454 mm).
Thread Dimensions
| Designation | #3-56 UNF |
| Threads Per Inch (TPI) | 56 |
| Pitch | 0.01786" (0.454 mm) |
| Major Diameter | 0.099" (2.515 mm) |
| Pitch Diameter | 0.0874" (2.22 mm) |
| Minor Diameter (External) | 0.0771" (1.958 mm) |
| Minor Diameter (Internal) | 0.0797" (2.024 mm) |
| Thread Depth | 0.00967" (0.246 mm) |
| Tensile Stress Area | 0.00515 in² (3.3 mm²) |
Tap Drill Size
Recommended tap drill: #47 (0.0785" / 1.99 mm)
Calculated minor diameter (internal): 0.0797" (2.02 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 | 283 | 381 |
| Grade 5 | 85,000 | 120,000 | 438 | 618 |
| Grade 8 | 120,000 | 150,000 | 618 | 772 |
Same Size, Different Series
Common Applications
- Electronics
- Instrument screws
- Precision assemblies
- Avionics