六角穴付きボルト加工穴寸法（参考値）
2級
| ねじの呼び（d） | M3 | M4 | M5 | M6 | M8 | M10 | M12 | M14 | M16 | M20 | M24 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| ds | 3 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 20 | 24 |
| d′ | 3.4 | 4.5 | 5.5 | 6.6 | 9 | 11 | 14 | 16 | 18 | 22 | 26 |
| dk | 5.5 | 7 | 8.5 | 10 | 13 | 16 | 18 | 21 | 24 | 30 | 36 |
| D | 6.5 | 8 | 9.5 | 11 | 14 | 17.5 | 20 | 23 | 26 | 32 | 39 |
| K | 3 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 20 | 24 |
| H1 | 2.7 | 3.6 | 4.6 | 5.5 | 7.4 | 9.2 | 11 | 12.8 | 14.5 | 18.5 | 22.5 |
| H2 | 3.3 | 4.4 | 5.4 | 6.5 | 8.6 | 10.8 | 13 | 15.2 | 17.5 | 21.5 | 25.5 |
引用：https://www.nbk1560.com/resources/other/article/technical-22-dimensions-of-holes-for-hexagon-socket-cap-screws/?SelectedLanguage=ja-JP
引用：https://www.nbk1560.com/~/media/PDF/ja-JP/products/pdf/20_Diameter_of_Clearance_Holes_and_Counterbores_for_Bolts_and_Screws.ashx%3Fla%3Dja-JP
