15. Bored hole size before tapping ( for thread cutting ) Production data ■ for Helical Coil Wire Thread Inserts, Metric Threads Unit : mm ■ for Helical Coil Wire Thread Inserts, Unified Threads unit: mm Bored hole size Bored hole size Minor diameter of internal threads (D1) Bored hole size Nominal size ( ref.) Size ( ref.) Max. Min. STI M2 ×0.4 2.15 STI No. 2 - 56 UNC 2.440 2.284 2.40 STI M 2.5×0.45 2.66 STI No. 4 - 40 UNC 3.180 2.985 3.13 STI M 2.6×0.45 2.76 STI No. 4 - 48 UNF 3.121 2.962 3.08 STI M 3 ×0.5 3.18 STI No. 5 - 40 UNC 3.487 3.315 3.44 STI M 4 ×0.7 4.27 STI No. 6 - 32 UNC 3.878 3.678 3.83 STI M 5 ×0.8 5.29 STI No. 6 - 40 UNF 3.817 3.645 3.77 STI M 6 ×1 6.38 STI No. 8 - 32 UNC 4.523 4.339 4.48 STI M 8 ×1.25 8.47 STI No. 8 - 36 UNF 4.498 4.321 4.45 STI M10 ×1.5 10.56 STI No. 10 - 24 UNC 5.283 5.055 5.23 STI M10 ×1.25 10.47 STI No. 10 - 32 UNF 5.184 4.999 5.14 STI M10×1 10.38 STI No. 12 - 24 UNC 5.943 5.715 5.89 STI M12×1.75 12.66 STI 1/4 - 20 UNC 6.868 6.625 6.81 STI M12×1.5 12.56 STI 1/4 - 28 UNF 6.720 6.546 6.68 STI M12×1.25 12.47 STI 5/16 - 18 UNC 8.488 8.243 8.43 STI M14×2 14.75 STI 5/16 - 24 UNF 8.351 8.167 8.31 STI M14×1.5 14.56 STI 3/8 - 16 UNC 10.126 9.868 10.06 STI M14×1.25 14.47 STI 3/8 - 24 UNF 9.931 9.754 9.89 STI M16×2 16.75 STI 7/16 - 14 UNC 11.783 11.507 11.71 STI M16×1.5 16.56 STI 7/16 - 20 UNF 11.584 11.387 11.53 STI M18×2.5 18.93 STI 1/2 - 13 UNC 13.393 13.122 13.33 STI M18×1.5 18.56 STI 1/2 - 20 UNF 13.172 12.975 13.12 STI M20×2.5 20.93 STI 5/8 - 11 UNC 16.672 16.376 16.60 STI M20×1.5 20.56 STI 5/8 - 18 UNF 16.385 16.180 16.33 STI M22×2.5 22.93 STI 3/4 - 16 UNF 19.608 19.393 19.55 STI M22×1.5 22.56 STI M24×3 25.11 STI M24×1.5 24.56 • The figures listed above are according to the data provided by helical coil wire insert manufacturers. Technical Information Technical-39 810