攻丝底孔直径 = 螺纹公称直径 - 螺距
这是一个基础公式，但实际应用中会根据材料、螺纹深度要求和经验进行微调，以达到约75%的螺纹深度（在大多数应用中提供了强度与攻丝难度的平衡）。
使用建议
首选查表：对于常见规格，直接使用推荐值非常可靠。
试切验证：对于新材料或关键工件，建议先用废料试攻，检查螺纹配合松紧和丝锥负荷。
参考权威手册：在关键设计或大批量生产前，务必查阅新的国家标准（如GB/T）或丝锥制造商提供的详细技术资料。
公制 ISO 粗牙螺纹M
| 螺纹 | 牙距 | 最小D1 mm | 最大D1 mm 5H/6H |
建议钻头直径 mm |
|---|---|---|---|---|
| M1* | 0.25 | 0.729 | 0.785 | 0.75 |
| M1.1* | 0.25 | 0.829 | 0.885 | 0.85 |
| M1.2* | 0.25 | 0.929 | 0.985 | 0.95 |
| M1.4* | 0.3 | 1.075 | 1.142 | 1.1 |
| M1.6 | 0.35 | 1.221 | 1.321 | 1.25 |
| M1.7 | 0.35 | 1.321 | 1.421 | 1.35 |
| M1.8 | 0.35 | 1.421 | 1.521 | 1.45 |
| M2 | 0.4 | 1.567 | 1.679 | 1.6 |
| M2.2 | 0.45 | 1.713 | 1.838 | 1.75 |
| M2.3 | 0.4 | 1.813 | 1.938 | 1.85 |
| M2.5 | 0.45 | 2.013 | 2.138 | 2.05 |
| M2.6 | 0.45 | 2.113 | 2.238 | 2.15 |
| M3 | 0.5 | 2.459 | 2.599 | 2.5 |
| M3.5 | 0.6 | 2.85 | 3.01 | 2.9 |
| M4 | 0.7 | 3.242 | 3.422 | 3.3 |
| M4.5 | 0.75 | 3.688 | 3.878 | 3.7 |
| M5 | 0.8 | 4.134 | 4.334 | 4.2 |
| M6 | 1 | 4.917 | 5.153 | 5 |
| M7 | 1 | 5.917 | 6.153 | 6 |
| M8 | 1.25 | 6.647 | 6.912 | 6.8 |
| M9 | 1.25 | 7.647 | 7.912 | 7.8 |
| M10 | 1.5 | 8.376 | 8.676 | 8.5 |
| M11 | 1.5 | 9.376 | 9.676 | 9.5 |
| M12 | 1.75 | 10.106 | 10.441 | 10.2 |
| M14 | 2 | 11.835 | 12.21 | 12 |
| M16 | 2 | 13.835 | 14.21 | 14 |
| M18 | 2.5 | 15.294 | 15.744 | 15.5 |
| M20 | 2.5 | 17.294 | 17.744 | 17.5 |
| M22 | 2.5 | 19.294 | 19.744 | 19.5 |
| M24 | 3 | 20.752 | 21.252 | 21 |
| M27 | 3 | 23.752 | 24.252 | 24 |
| M30 | 3.5 | 26.211 | 26.771 | 26.5 |
| M33 | 3.5 | 29.211 | 29.771 | 29.5 |
| M36 | 4 | 31.67 | 32.27 | 32 |
| M39 | 4 | 34.67 | 35.27 | 35 |
| M42 | 4.5 | 37.129 | 37.799 | 37.5 |
| M45 | 4.5 | 40.129 | 40.799 | 40.5 |
| M48 | 5 | 42.587 | 43.297 | 43 |
| M52 | 5 | 46.587 | 47.297 | 47 |
| M56 | 5.5 | 50.046 | 50.796 | 50.5 |
| M60 | 5.5 | 54.046 | 54.796 | 54.5 |
| M64 | 6 | 57.505 | 58.305 | 58 |
| M68 | 6 | 62.505 | 62.305 | 62 |
*5H 最大
公制 ISO 细牙螺纹MF
| 螺纹 | 牙距 | 最小D1 mm | 最大D1 mm 6H |
建议钻头直径 mm |
|---|---|---|---|---|
| M2×0.25 | 0.25 | 1.729 | 1.785 | 1.75 |
| M2.2×0.25 | 0.25 | 1.929 | 1.985 | 1.95 |
| M2.3×0.25 | 0.25 | 2.029 | 2.085 | 2.05 |
| M2.5×0.35 | 0.35 | 2.121 | 2.221 | 2.15 |
| M3×0.25 | 0.25 | 2.729 | 2.785 | 2.75 |
| M3×0.35 | 0.35 | 2.621 | 2.721 | 2.65 |
| M3.5×0.35 | 0.35 | 3.121 | 3.221 | 3.15 |
| M4×0.35 | 0.35 | 3.621 | 3.721 | 3.65 |
| M4×0.5 | 0.5 | 3.459 | 3.599 | 3.5 |
| M4.5×0.5 | 0.5 | 3.959 | 4.099 | 4 |
| M5×0.35 | 0.35 | 4.621 | 4.721 | 4.65 |
| M5×0.5 | 0.5 | 4.459 | 4.599 | 4.5 |
| M5×0.75 | 0.75 | 4.188 | 4.378 | 4.2 |
| M6×0.5 | 0.5 | 5.459 | 5.599 | 5.5 |
| M6×0.75 | 0.75 | 5.188 | 5.378 | 5.25 |
| M7×0.5 | 0.5 | 6.459 | 6.599 | 6.5 |
| M7×0.75 | 0.75 | 6.188 | 6.378 | 6.25 |
| M8×0.5 | 0.5 | 7.459 | 7.599 | 7.5 |
| M8×0.75 | 0.75 | 7.188 | 7.378 | 7.25 |
| M8×1 | 1 | 6.917 | 7.153 | 7 |
| M9×0.75 | 0.75 | 8.188 | 8.378 | 8.25 |
| M9×1 | 1 | 7.917 | 8.153 | 8 |
| M10×0.5 | 0.5 | 9.459 | 9.599 | 9.5 |
| M10×0.75 | 0.75 | 9.188 | 9.378 | 9.25 |
| M10×1 | 1 | 8.917 | 9.153 | 9 |
| M10×1.25 | 1.25 | 8.647 | 8.912 | 8.75 |
| M11×1 | 1 | 9.917 | 10.153 | 10 |
| M12×0.5 | 0.5 | 11.459 | 11.599 | 11.5 |
| M12×1 | 1 | 10.917 | 11.153 | 11 |
| M12×1.25 | 1.25 | 10.647 | 10.912 | 10.75 |
| M12×1.5 | 1.5 | 10.376 | 10.676 | 10.5 |
| M13×1 | 1 | 11.917 | 12.153 | 12 |
| M14×0.75 | 0.75 | 13.188 | 13.378 | 13.2 |
| M14×1 | 1 | 12.917 | 13.153 | 13 |
| M14×1.25 | 1.25 | 12.647 | 12.912 | 12.75 |
| M14×1.5 | 1.5 | 12.376 | 12.676 | 12.5 |
| M15×1 | 1 | 13.917 | 14.153 | 14 |
| M15×1.5 | 1.5 | 13.376 | 13.676 | 13.5 |
| M16×0.75 | 0.75 | 15.188 | 15.378 | 15.2 |
| M16×1 | 1 | 14.917 | 15.153 | 15 |
| M16×1.25 | 1.25 | 14.647 | 14.912 | 14.8 |
| M16×1.5 | 1.5 | 14.376 | 14.676 | 14.5 |
| M17×1 | 1 | 15.917 | 16.153 | 16 |
| M18×1 | 1 | 16.917 | 17.153 | 17 |
| M18×1.5 | 1.5 | 16.376 | 16.676 | 16.5 |
| M18×2 | 2 | 15.835 | 16.21 | 16 |
| M20×1 | 1 | 18.917 | 19.153 | 19 |
| M20×1.5 | 1.5 | 18.376 | 18.676 | 18.5 |
| M20×2 | 2 | 17.835 | 18.21 | 18 |
| M22×1 | 1 | 20.917 | 21.153 | 21 |
| M22×1.5 | 1.5 | 20.376 | 20.676 | 20.5 |
| M22×2 | 2 | 19.835 | 20.21 | 20 |
| M24×1.5 | 1.5 | 22.376 | 22.676 | 22.5 |
| M24×2 | 2 | 21.835 | 22.21 | 22 |
| M25×1 | 1 | 22.917 | 23.153 | 23 |
| M25×1.5 | 1.5 | 23.376 | 23.676 | 23.5 |
| M26×1.5 | 1.5 | 24.376 | 24.676 | 24.5 |
| M27×1 | 1 | 25.917 | 26.153 | 26 |
| M27×1.5 | 1.5 | 25.376 | 25.676 | 25.5 |
| M27×2 | 2 | 24.835 | 25.21 | 25 |
| M28×1.5 | 1.5 | 26.376 | 26.676 | 26.5 |
| M28×2 | 2 | 25.835 | 26.21 | 26 |
| M30×1 | 1 | 28.917 | 29.153 | 29 |
| M30×1.5 | 1.5 | 28.376 | 28.676 | 28.5 |
| M30×2 | 2 | 27.835 | 28.21 | 28 |
| M32×1.5 | 1.5 | 30.376 | 30.676 | 30.5 |
| M32×2 | 2 | 29.835 | 30.21 | 30 |
| M33×1.5 | 1.5 | 31.376 | 31.676 | 31.5 |
| M33×2 | 2 | 30.835 | 31.21 | 31 |
| M34×1.5 | 1.5 | 32.376 | 32.676 | 32.5 |
| M35×1.5 | 1.5 | 33.376 | 33.676 | 33.5 |
| M36×1.5 | 1.5 | 34.376 | 34.676 | 34.5 |
| M36×2 | 2 | 33.835 | 34.21 | 34 |
| M36×3 | 3 | 32.752 | 33.252 | 33 |
| M38×1.5 | 1.5 | 36.376 | 36.676 | 36.5 |
| M39×1.5 | 1.5 | 37.376 | 37.676 | 37.5 |
| M39×2 | 2 | 36.835 | 37.21 | 37 |
| M39×3 | 3 | 35.752 | 36.252 | 36 |
| M40×1.5 | 1.5 | 38.376 | 38.676 | 38.5 |
| M40×2 | 2 | 37.835 | 38.21 | 38 |
| M40×3 | 3 | 36.752 | 37.252 | 37 |
| M42×1.5 | 1.5 | 40.376 | 40.676 | 40.5 |
| M42×2 | 2 | 39.835 | 40.21 | 40 |
| M42×3 | 3 | 38.752 | 39.252 | 39 |
| M45×1.5 | 1.5 | 43.376 | 43.676 | 43.5 |
| M45×2 | 2 | 42.835 | 43.21 | 43 |
| M45×3 | 3 | 41.752 | 42.252 | 42 |
| M48×1.5 | 1.5 | 46.376 | 46.676 | 46.5 |
| M48×2 | 2 | 45.835 | 46.21 | 46 |
| M48×3 | 3 | 44.752 | 45.252 | 45 |
| M50×1.5 | 1.5 | 48.376 | 48.676 | 48.5 |
| M50×2 | 2 | 47.835 | 48.21 | 48 |
| M50×3 | 3 | 46.752 | 47.252 | 47 |
| M52×1.5 | 1.5 | 50.376 | 50.676 | 50.5 |
| M52×2 | 2 | 49.835 | 50.21 | 50 |
| M52×3 | 3 | 46.587 | 47.087 | 49 |
| M56×1.5 | 1.5 | 54.376 | 54.676 | 54.5 |
| M56×2 | 2 | 53.835 | 54.21 | 54 |
| M56×3 | 3 | 52.752 | 53.252 | 53 |
| M58×1.5 | 1.5 | 56.376 | 56.676 | 56.5 |
| M60×1.5 | 1.5 | 58.376 | 58.676 | 58.5 |
| M60×2 | 2 | 57.835 | 58.21 | 58 |
| M60×3 | 3 | 56.752 | 57.252 | 57 |