BA screw sizes

by Russ Elliott
BA
no.
tpi
(threads
per inch)
Tapping
drill size
(mm)
Clearance
drill size
(mm)
0 25.40 5.2 6.1
1 28.22 4.5 5.4
2 31.35 4.1 4.8
3 34.79 3.5 4.2
4 38.48 3.0 3.7
5 43.05 2.65 3.3
6 47.92 2.3 2.85
7 52.91 2.1 2.55
8 59.07 1.8 2.3
9 65.12 1.6 1.95
10 72.57 1.4 1.75
11 81.93 1.2 1.5
12 90.71 1.05 1.3
13 101.60 0.975 1.15
14 110.43 0.80 1.00
15 120.95 0.70 0.90
16 133.68 0.60 0.80

page first published 2000