攻丝底孔直径

攻螺纹前底孔直径的确定

（1）普通螺纹攻螺纹前底孔的钻头直径

（2）非螺纹密封的管螺纹攻螺纹前钻底孔的钻头直径

（3）英制锥管螺纹和英制锥螺纹攻丝前钻底孔的钻头直径

丝锥用底孔钻头直径表

(螺纹牙型高度为75%时的推荐钻头尺寸)

准备攻丝的螺纹钻头规格代码(最接近的英制分数规格) 英制小数规格

0-80UNF 3/64" 3/64" .0469

1-64UNC #53 - .0595

1-72UNF #53 1/16" .0595

2-56UNC #50 - .0700

2-64UNF #50 - .0700

3-48UNC #47 5/64" .0785

3-56UNF #45 - .0820

4-36UNS #44 - .0860

4-40UNC #43 3/32" .0890

4-48UNF #42 3/32" .0935

M3×0.60 2.5mm - .0984

1/8-40UNS #38 - .1015

5-40UNC #38 - .1015

5-44UNF #37 - .1040

6-32UNC #35 7/64" .1100

6-36UNS #34 - .1110

6-40UNF #33 - .1130

6-48UNS #31 - .1200

M4×0.70 3.4mm - .1338

M4×0.75 3.4mm - .1338

8-32UNC #29 - .1360

8-36UNF #29 9/64" .1360

8-40UNS #28 - .1405

3/16"-24UNS #26 - .1470

10-24UNC #25 5/32" .1495

3/16"-32UNS #22 - .1570

10-32UNF #21 5/32" .1590

M5×0.90 4.2mm - .1653

M5×0.80 4.3mm - .1693

12-24UNC #16 11/64" .1770

12-28UNF #14 3/16" .1820

12-32NEF #13 - .1850

14-20UNS #10 - .1935

1/4"-20UNC #7 13/64" .2010

14-24UNS #7 - .2010

M6×1.00 5.2mm - .2047

1/4"-24UNS #4 - .2090

1/4"-28UNF #3 7/32" .2130

1/4"-32NEF 7/32" 7/32" .2188

1/4"-40UNS #1 - .2280

M7×1.00 6.1mm 15/64" .2401

5/16"-18UNC 字母F 17/64" .2570

M8×1.25 6.9mm 17/64" .2716

5/16"-24UNF 字母I - .2720

M8×1.00 7.1mm - .2795

5/16"-32NEF 9/32" 9/32" .2812

M9×1.2 7.9mm - .3110

3/8"-16UNC 5/16" 5/16" .3125

M9×0.75 8.3mm - .3268

M9×1.00 8.1mm - .3189

*该螺纹仅用于火花塞

准备攻丝的螺纹钻头规格代码(最接近的英制分数规格) 英制小数规格3/8"-24UNF 字母Q 21/64" .3320

M10×1.50 8.7mm - .3425

M10×1.25 8.9mm 11/32" .3503

M10×1.00* 9.1mm - .3583

7/16"-14UNC 字母U 23/64" .3680 M11×1.50 9.7mm - .3818

7/16"-20UNF 25/64" 25/64" .3906

M12×1.75 10.5mm - .4133

M12×1.50 10.7mm 27/64" .4212

1/2"-13UNC 27/64" 27/64" .4219

M12×1.25* 10.9mm 27/64" .4291

1/2"-20UNF 29/64" 29/64" .4531

1/2"-24UNS 29/64" 29/64" .4531

M14×2.00 12.2mm - .4803

9/16"-12UNC 31/64" 31/64" .4844

M14×1.50 12.7mm - .4999

M14×1.25* 12.8mm - .5039

9/16"-18UNF 33/64" 33/64" .5156

5/8"-11UNC 17/32" 17/32" .5312

M16×2.00 14.2mm 35/64" .5590

5/8"-18UNF 37/64" 37/64" .5781

M16×1.50 14.7mm - .5787

11/16"-11UNS 19/32" 19/32" .5938

M18×2.50 15.8mm 39/64" .5220

11/16"-16UNS 5/8" 5/8" .6250

3/4"-10UNC 21/32" 21/32" .6562

M18×1.50* 16.8mm - .6614

3/4"-16UNF 11/16" 11/16" .6875

M20×2.50 17.8mm 11/16" .7008

7/8"-9UNC 49/64" 49/64" .7656

7/8"-14UNF 13/16" 13/16" .8125

M22×1.50 20.9mm - .8228

7/8"-18UNS* 53/64" 53/64" .8281

M24×3.00 21.4mm 53/64" .8425 1"-8UNC 7/8" 7/8" .8750

M24×2.00 22.3mm - .8779

1"-12UNF 59/64" 59/64" .9219

1"-14UNS 15/16" 15/16" .9375

11/8"-7 UNC 63/64" 63/64" .9844

11/8"-12 UNF 13/64" 13/64" 1.0469 11/4"-7 UNC 17/64" 17/64" 1.1094 11/4"-12 UNF 111/64" 111/64" 1.1719 13/8"-6 UNC 17/32" 17/32" 1.2188 13/8"-12 UNF 119/64" 119/64" 1.2969 11/2"-6 UNC 111/32" 111/32" 1.3438 11/2"-12 UNF 127/64" 127/64" 1.4219