Specifications of International Thread Standards

British Association Standard Thread. Used for instruments and clocks. Replaced by the metric ISO thread and the ISO fine thread.
The flank angle is 47.5°.

BA Thread No.Diameter
mm
Tapping Drill Size
mm
Pitch
mm
BA No. 06.004.801.00
BA No. 15.304.220.90
BA No. 24.703.730.81
BA No. 34.103.220.73
BA No. 43.602.810.66
BA No. 53.202.490.59
BA No. 62.802.160.53
BA No. 72.501.920.48
BA No. 82.201.680.43
BA No. 91.901.430.39
BA No. 101.701.280.35
BA No. 111.501.130.31
BA No. 121.300.960.28
BA No. 131.200.900.25
BA No. 141.000.720.23
BA No. 150.900.650.21
BA No. 160.790.650.19
BA No. 170.700.500.17
BA No. 180.620.440.15
BA No. 190.540.370.14
BA No. 200.480.340.12
BA No. 210.420.290.11
BA No. 220.370.250.098
BA No. 230.330.220.090
BA No. 240.290.190.080
BA No. 250.250.160.072
BA-Thread