Side-by-Side Comparison
Imperial Threads (UNC/UNF)
1/2"-13 UNC vs. #2-56 UNC
Comparing 2 standards across 8 specifications. 8 key differences identified.
Comparing:
1/2"-13 UNC
#2-56 UNC
1/2"-13 UNC is a heavy fractional Unified Coarse bolt thread with a major diameter of 0.5000 inches (12.700 mm) and 13 threads per inch (TPI). Requiring a 27/64 inch (0.4219 inch) tap drill, it is the standard structural fastener for automotive engine cradles, trailer hitches, and building timber connections.
2-56 UNC is a numbered miniature Unified Coarse machine screw thread with a major diameter of 0.0860 inches (2.184 mm) and 56 threads per inch (TPI). Requiring a #50 (0.0700 inch) tap drill, it is widely used in precision model engineering, musical instrument pickups, and micro-electromechanical assemblies.
Specification Comparison Table
8 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Major Diameter
|
0.5000 in (12.700 mm) | 0.0860 in (2.184 mm) |
|
Threads Per Inch (TPI)
|
13 TPI (Coarse pitch: 1.954 mm) | 56 TPI (Coarse pitch: 0.454 mm) |
|
Fine Pitch Equivalent
|
1/2"-20 UNF (1.270 mm pitch — standard automotive wheel lugs) | #2-64 UNF (0.397 mm pitch) |
|
Recommended Tap Drill Size
|
27/64 in drill bit (0.4219 in / 10.72 mm) | #50 drill bit (0.0700 in / 1.78 mm) |
|
Minor Diameter (Internal)
|
0.4167 in (10.584 mm) | 0.0667 in (1.694 mm) |
|
Tensile Stress Area
|
0.1419 in² (91.5 mm²) | 0.00370 in² (2.39 mm²) |
|
Common Drive Size
|
3/4" Hex (19.05 mm) / 3/8" Allen | — |
|
Thread Profile Angle
|
— | 60 degrees |