Unified Imperial Threads (UNC / UNF)

#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.

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#4-40 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1120 inches (2.845 mm) and 40 threads per inch (TPI). Requiring a #43 (0.0890 inch) tap drill, it is the worldwide computing standard for D-subminiature connector jackscrews (VGA, DVI, RS-232 serial ports).

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#6-32 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1380 inches (3.505 mm) and 32 threads per inch (TPI). Requiring a #36 (0.1065 inch) tap drill, it is the universal standard for desktop PC case covers, power supplies, 3.5-inch hard drive mounting, and North American electrical wall outlet boxes.

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#8-32 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1640 inches (4.166 mm) and 32 threads per inch (TPI). Requiring a #29 (0.1360 inch) tap drill, it is the standard fastener for North American electrical ceiling junction boxes, light fixtures, and kitchen cabinet hardware knobs.

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#10-24 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1900 inches (4.826 mm) and 24 threads per inch (TPI). Requiring a #25 (0.1495 inch) tap drill, it provides high clamping torque for household appliances, outdoor power equipment, and light mechanical assemblies.

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1/4"-20 UNC is a fractional Unified Coarse machine screw thread with a major diameter of 0.2500 inches (6.350 mm) and 20 threads per inch (TPI). Requiring a #7 (0.2010 inch) tap drill, it is the universal global standard under ISO 1222 for camera tripod mounting sockets, studio light stands, and general machinery bolting.

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3/8"-16 UNC is a fractional Unified Coarse machine screw thread with a major diameter of 0.3750 inches (9.525 mm) and 16 threads per inch (TPI). Requiring a 5/16 inch (0.3125 inch) tap drill, it is the international standard for professional photography tripod-to-head mounting studs, cinema camera baseplates, and stage microphone stands.

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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.

7 specs