15. Bored hole size before tapping ( for thread cutting ) Production data ■ for Metric Threads Unit : mm Size Minor diameter of internal threads (D1) Bored hole size Size Minor diameter of internal threads (D1) Bored hole size ( ref.) ( ref.) 0.77 6.33 0.81 6.56 0.87 6.85 0.91 7.09 0.97 7.33 1.01 7.56 1.13 7.85 1.21 8.09 1.30 8.33 1.41 8.60 1.40 8.85 1.51 9.09 1.50 9.33 1.61 9.56 1.65 9.60 1.77 10.10 1.81 10.33 1.97 10.56 1.95 10.4 2.07 10.6 2.11 10.85 2.20 11.09 2.21 11.56 2.30 12.1 2.56 12.6 2.70 13.09 2.97 13.60 3.20 14.09 3.38 14.1 3.56 14.6 3.83 15.09 4.06 15.60 4.28 16.09 4.56 15.6 M5.5×0.5 5.099 4.959 5.06 16.1 5.09 16.6 5.33 17.09 5.56 17.6 6.09 The recommended bored hole sizes indicated above are for 6H Metric Threads. • D1: Minor diameter of 6H internal thread. The Minor diameters D1 shown in ( ) are of 5H for coarse threads and of 4H • 5H for fine threads. Technical Information Technical-35 806