12x28 UNJF - 3B HSS Ground Thread Tap

Specification Product: 12-28" UNJF Straight Flute Hand Taps Size: 12x28 UNJF Tolerance: 3B Material: High Speed Steel Options: Bottom, Second, Taper Leads and Set of 3 see option box UNJF. "J" threads are supplied in both external and internal forms. The external thread has a much larger root radius than the corresponding UNC, UNF or UNS threads. This radius is mandatory and its inspection is required, whereas no root radius is required on UNC, UNF, or UNEF threads. Since the larger root radius increases the minor diameter, a UNJF fastener has a larger net tensile area than a corresponding UNF fastener. This root radius also gives a smaller stress concentration factor in the threaded section. Therefore, high strength bolts usually have "J" threads. Part Number ES-14737