大径=1/4英寸=6.35mm螺距=25.4/36=0.7056mm小径=大径-1.0825*螺距=6.35-1.0825*0.7056*0.7056≈5.586mm。
小径是？你知道怎么算的吗螺距是25.4/36=0.706螺纹大径是1/4*25.4=6.35螺纹小径是6.35-1.0825*0.706=5.585
