螺纹攻丝底孔表

（1）、普通螺纹攻螺纹前底孔的钻头直径螺纹公称直径D螺 距p钻头直径d铸铁、青铜、黄铜钢、可锻铸铁、紫铜20.40.251.61.61.751.752.50.450.352.052.052.152.1530.50.352.52.52.652.6540.70.53.33.33.53.550.80.54.14.24.54.5610.754.955.25.281.2510.756.66.76.977.17.2101.58.48.51.258.68.718.980.759.19.2 （续）螺纹公称直径D螺 距p钻头直径d铸铁、青铜、黄铜钢、可锻铸铁、紫铜121.7510.110.21.510.410.51.2510.610.7110.91114211.8121.512.412.5112.91316213.8141.514.414.5114.915182.515.315.5215.8161.516.416.5116.917202.517.317.5217.8181.518.418.5118.919 （续）螺纹公称直径D螺 距p钻头直径d铸铁、青铜、黄铜钢、可锻铸铁、紫铜222.519.319.5219.8201.520.420.5120.92124320.721221.8221.522.422.5122.923攻米制螺纹：P1mm；d0dP P1mm；d0d（1.04-1.06）P式中P螺距（mm）D0钻头直径（mm）D螺纹公称直径（mm）攻不通孔螺纹钻孔深度=所需螺孔深度+0.7P，另外也可以查上表。 （2）、非螺纹密封的管螺纹攻螺纹前钻孔的钻头直径螺纹公称直径/()每25.4 mm内的牙数钻头直径/mm1/8288.81/41911.73/81915.21/21418.9 （续）螺纹公称直径/()每25.4 mm内的牙数钻头直径/mm3/41424.411130.611139.211141.611145.1(3)、英制锥管螺纹和英制锥螺纹攻丝前钻底孔的钻头直径英制锥管螺纹英制锥螺纹公称直径/()每25.4 mm内的牙数钻头直径/mm公称直径/()每25.4 mm内的牙数钻头直径/mm1/8288.41/8278.61/41911.21/41811.13/81914.73/81814.51/21418.31/21417.93/41423.63/41423.211129.711129.211138.311137.911144.111143.921155.821156