Page 312 - Mechanical Engineer's Data Handbook

300 MECHANICAL ENGINEER’S DATA HANDBOOK

8.2.5 Clearance holes for bolts 8.2.6 British Association (BA) screw
threads
Clearance holes for metric bolts
Bolt Clearance hole diameter, (mm) Area at
size, D Major Core bottom
(mm) Fine Medium Coarse diameter Pitch diameter of thread
No. (mm) (mm) (mm) (mm2)
1.6 1.7 1.8 2
2 2.2 2.4 2.6 0 6.0 1 .o 4.80 18.10
2.5 2.7 2.9 3.1 1 5.3 0.9 4.22 13.99
3 3.2 3.4 3.6 2 4.7 0.81 3.73 10.93
4 4.3 4.5 4.8 3 4.1 0.73 3.22 8.14
5 5.3 5.5 5.8 4 3.6 0.66 2.81 6.20
6 6.4 6.6 7 5 3.2 0.59 2.49 4.87
7 7.4 7.6 8 6 2.8 0.53 2.16 3.66
8 8.4 9 10 7 2.5 0.48 1.92 2.89
10 10.5 11 12 8 2.2 0.43 1.68 2.22
12 13 14 15 9 1.9 0.39 1.43 1.61
14 15 16 17 10 1.7 0.35 1.28 1.29
16 17 18 19 11 1.5 0.3 1 1.13 1 .OO
18 19 20 21 12 1.3 0.28 0.96 0.72
20 21 22 24 13 1.2 0.25 0.90 0.64
22 23 24 26 14 1.0 0.23 0.72 0.41
24 25 26 28 15 0.9 0.21 0.65 0.33
27 28 30 32 16 0.79 0.19 0.56 0.25
30 31 33 35 17 0.70 0.17 0.50 0.20
33 34 36 38 18 0.62 0.15 0.44 0.15
36 37 39 42 19 0.54 0.14 0.37 0.1 1
39 40 42 45 20 0.48 0.12 0.34 0.09 1
21 0.42 0.1 1 0.29 0.066
22 0.37 0.10 0.25 0.049
23 0.33 0.09 0.22 0.038
24 0.29 0.08 0.19 0.028
25 0.25 0.07 0.17 0.023