Min Min Min Max 外螺纹 External 内螺纹 Internal Nominal Sine,Threads per Inch,and Series Designation 级别 Class 公差 Allowanc 大径MajorDiameter 中径Pitch Diameter 小径UNR Minor Diam. Max(Ref.)级别 Class 小径Minor Diameter Max 0.50.4886 0.4459 0.4419 0.4008 3B 0.41 0.4223 1A 0.0015 0.4985 0.4822 0.4485 0.4411 0.4069 1B 0.417 0.434 1/2 UNC 2A 0.0015 0.4985 0.4876 0.4822 0.4485 0.4435 0.4069 2B 0.417 0.434 3A 0.50.4891 0.45 0.4463 0.4084 3B 0.417 0.4284 1/2-14 UNS 2A 0.0015 0.4985 0.4882 0.4521 0.4471 0.4135 2B 0.423 0.438