Description of productsTechnical Information 15. Bored hole size before tapping ( for thread cutting ) ■ for Helical Coil Wire Thread Inserts, Metric Threads Unit:mm ■ for Helical Coil Wire Thread Inserts, Unified Threads Unit:mm Nominal size Bored hole size Bored hole sizeMax.Min.( ref.) Size Minor diameter of internal threads (D1) Bored hole sizeMax.Min.( ref.) STI M2.6 × 0.45 2.798 2.698 2.77 STI No. 4 - 40 UNC 3.180 2.985 3.13 STI M 3 × 0.5 3.221 3.109 3.19 STI No. 4 - 48 UNF 3.121 2.962 3.08 STI M 4 × 0.7 4.291 4.151 4.26 STI No. 5 - 40 UNC 3.487 3.315 3.44 STI M 5 × 0.8 5.333 5.173 5.29 STI No. 6 - 32 UNC 3.878 3.678 3.83 STI M 6×1 6.406 6.216 6.36 STI No. 6 - 40 UNF 3.817 3.645 3.77 STI M 8 × 1.25 8.483 8.271 8.43 STI No. 8 - 32 UNC 4.523 4.339 4.48 STI M10 × 1.5 10.561 10.325 10.50 STI No. 8 - 36 UNF 4.498 4.321 4.45 STI M10 × 1.25 10.483 10.271 10.43 STI No. 10 - 24 UNC 5.283 5.055 5.23 STI M10 × 1 10.406 10.216 10.36 STI No. 10 - 32 UNF 5.184 4.999 5.14 STI M12 × 1.75 12.644 12.379 12.6 STI No. 12 - 24 UNC 5.943 5.715 5.89 STI M12 × 1.5 12.561 12.325 12.50 STI 1/4 - 20 UNC 6.868 6.625 6.81 STI M12 × 1.25 12.483 12.271 12.43 STI 1/4 - 28 UNF 6.720 6.546 6.68 STI M14 × 2 14.733 14.433 14.7 STI 5/16 - 18 UNC 8.488 8.243 8.43 STI M14 × 1.5 14.561 14.325 14.50 STI 5/16 - 24 UNF 8.351 8.167 8.31 STI M14 × 1.25 14.483 14.271 14.43 STI 3/8 - 16 UNC 10.126 9.868 10.06 STI M16 × 2 16.733 16.433 16.7 STI 3/8 - 24 UNF 9.931 9.754 9.89 STI M16 × 1.5 16.561 16.325 16.50 STI 7/16 - 14 UNC 11.783 11.507 11.7 STI M18 × 2.5 18.897 18.542 18.8 STI 7/16 - 20 UNF 11.584 11.387 11.53 STI M18 × 1.5 18.561 18.325 18.50 STI 1/2 - 13 UNC 13.393 13.122 13.3 STI M20 × 2.5 20.897 20.542 20.8 STI 1/2 - 20 UNF 13.172 12.975 13.12 STI M20 × 1.5 20.561 20.325 20.50 STI 5/8 - 11 UNC 16.672 16.376 16.60 STI M22 × 2.5 22.897 22.542 22.8 STI 5/8 - 18 UNF 16.385 16.180 16.33 STI M22 × 1.5 22.561 22.325 22.50 STI 3/4 - 10 UNC 19.908 19.599 19.8 STI M24 × 3 25.049 24.649 24.9 STI 3/4 - 16 UNF 19.608 19.393 19.55 STI M24 × 2 24.733 24.433 24.7 STI M24 × 1.5 24.561 24.325 24.50 • The figures listed above are according to the data provided by helical coil wire insert manufacturers. Technical-40