1、常 用 螺 纹 底 径 对 照 表公制螺纹 美制螺纹 管螺纹规格 螺距 底孔(钻头直径) 规格 螺距 底孔(钻头直径) 规格 螺距 底孔(钻头直径)M2.50.45 0.45 2.1 NO.4-40UNC 0.635 2.4 RC1/16-28 0.907 6.6M30.5 0.5 2.6 NO.4-48UNF 0.529 2.4 RC1/8-28 0.907 8.5M40.7 0.7 3.3 NO.5-40UNC 0.635 2.7 RC1/4-19 1.337 11.5M50.8 0.8 4.2 NO.5-44UNF 0.577 2.7 RC3/8-19 1.337 14.7M61 1 5
2、.1 NO.6-32UNC 0.794 2.9 G1/16-28 0.907 6.8M81.25 1.25 6.8 NO.6-40UNF 0.635 3 G1/8-28 0.907 8.8M101.5 1.5 8.6 NO.8-32UNF 0.793 3.5 G1/4-19 1.337 11.8M121.75 1.75 10.3 NO.8-36UNC 0.705 3.6 G3/8-19 1.337 15.3M142 2 12.2 NO.10-24UNF 1.058 3.9M162 2 14.2 NO.10-32UNF 0.794 4.1M182.5 2.5 15.8 NO.12-24UNC 1
3、.058 4.6 NPT 1/16-27 0.941 6.4M202.5 2.5 17.7 NO.12-28UNC 0.907 4.7 NPT 1/8-27 0.941 8.6M222.5 2.5 19.8 1/4-20UNC 1.27 5.2 NPT 1/4-18 1.411 11.5M243 3 21.2 1/4-28UNC 0.907 5.5 NPT 3/8-18 1.411 14.7M303.5 3.5 26.8 5/16-18UNC 1.411 6.7 NPT 1/2-14 1.814 18.15/16-24UNC 1.058 73/8-16UNF 1.587 8.13/8-24UNF 1.058 8.67/16-14UNC 1.814 9.57/16-20UNC 1.27 101/2-13UNC 1.854 111/2-20UNC 1.27 11.69/12-12UNC 2.117 12.5
