BRITISH ASSOCIATION THREADS (BA) TAPPING DRILL SIZES If you have been pointed directly to this text file by a search engine, please also see:- http://homews.co.uk/page29.html and http://homews.co.uk/ SIZE OUT CORE PITCH TAP DEP DIA. DIA. DRILL TH mm mm mm mm % 0 6.00 4.80 1.00 5.30 58 0 6.00 4.80 1.00 5.20 67 0 6.00 4.80 1.00 5.10 75 1 5.30 4.22 0.90 4.70 56 1 5.30 4.22 0.90 4.60 65 1 5.30 4.22 0.90 4.50 74 2 4.70 3.73 0.81 4.20 51 2 4.70 3.73 0.81 4.10 62 2 4.70 3.73 0.81 4.00 72 3 4.10 3.22 0.73 3.60 57 3 4.10 3.22 0.73 3.50 68 3 4.10 3.22 0.73 3.40 80 4 3.60 2.81 0.66 3.15 57 4 3.60 2.81 0.66 3.10 63 4 3.60 2.81 0.66 3.05 69 5 3.20 2.49 0.59 2.80 56 5 3.20 2.49 0.59 2.75 64 5 3.20 2.49 0.59 2.70 71 6 2.80 2.16 0.53 2.45 55 6 2.80 2.16 0.53 2.40 63 6 2.80 2.16 0.53 2.35 71 7 2.50 1.92 0.48 2.20 52 7 2.50 1.92 0.48 2.15 61 7 2.50 1.92 0.48 2.10 69 8 2.20 1.68 0.43 1.90 58 8 2.20 1.68 0.43 1.85 68 8 2.20 1.68 0.43 1.80 78 9 1.90 1.43 0.39 1.65 53 9 1.90 1.43 0.39 1.60 64 9 1.90 1.43 0.39 1.55 75 10 1.70 1.28 0.35 1.50 48 10 1.70 1.28 0.35 1.45 60 10 1.70 1.28 0.35 1.40 71 11 1.50 1.13 0.31 1.30 54 11 1.50 1.13 0.31 1.25 67 11 1.50 1.13 0.31 1.20 81 12 1.30 0.96 0.28 1.15 45 12 1.30 0.96 0.28 1.10 60 12 1.30 0.96 0.28 1.05 74 13 1.20 0.90 0.25 1.05 50 13 1.20 0.90 0.25 1.00 67 13 1.20 0.90 0.25 0.98 73 14 1.00 0.72 0.23 0.85 54 14 1.00 0.72 0.23 0.82 65 14 1.00 0.72 0.23 0.80 72 15 0.90 0.65 0.21 0.78 48 15 0.90 0.65 0.21 0.75 60 15 0.90 0.65 0.21 0.72 71 16 0.79 0.56 0.19 0.68 48 16 0.79 0.56 0.19 0.65 61 16 0.79 0.56 0.19 0.62 75 17 0.70 0.50 0.17 0.60 49 17 0.70 0.50 0.17 0.58 59 17 0.70 0.50 0.17 0.55 74 18 0.62 0.44 0.15 0.52 56 18 0.62 0.44 0.15 0.50 67 18 0.62 0.44 0.15 0.48 78