15. Bored hole size before tapping ( for thread cutting ) Unit : mm Production data Size Minor diameter of internal threads (D1) Bored hole size Size Minor diameter of internal threads (D1) Bored hole size ( ref.) ( ref.) 18.1 36.6 18.6 35.1 19.09 36.1 19.6 37.1 20.1 37.6 20.6 37.1 21.09 38.1 21.1 38.6 22.1 37.6 22.6 38.1 23.09 39.1 23.1 40.1 23.6 40.6 24.09 40.6 24.6 41.1 24.1 42.1 25.1 43.1 25.6 43.6 26.09 43.1 26.1 44.1 26.6 45.1 27.09 46.1 26.6 46.6 27.1 47.1 28.1 48.1 28.6 48.6 29.09 M52×5 47.297 46.587 47.1 30.1 M52×4 48.270 47.670 48.1 30.6 M52×3 49.252 48.752 49.1 29.6 M52×2 50.210 49.835 50.1 30.1 M52×1.5 50.676 50.376 50.6 31.1 M55×4 51.270 50.670 51.1 31.6 M55×3 52.252 51.752 52.1 33.6 M55×2 53.210 52.835 53.1 32.1 M55×1.5 53.676 53.376 53.6 33.1 M56×5.5 50.796 50.046 50.6 34.1 M56×4 52.270 51.670 52.1 34.6 M56×3 53.252 52.752 53.1 • D1: Minor diameter of 6H internal thread. M56×2 54.210 53.835 54.1 M56×1.5 54.676 54.376 54.6 Information Technical Technical-36 807