B.A. THREAD SERIES
B.A. threads are used for fine fastening, especially in instruments.
Basic Dimensions : B.S. 93 – 1956. Gauging Practice : B.S 919 Part II - 1971
B.A. No
Dia MM
Pitch MM
0
6.00
1.000
1
5.3
0.900
2 *
4.7
0.81
3
4.1
0.73
4 *
3.6
0.66
5
3.2
0.59
6 *
2.8
0.53
7
2.5
0.48
8
2.2
0.43
9
1.9
0.39
10
1.7
0.35
Plug Gauges – Only one class i.e. NORMAL (N) Ring Gauges – NORMAL (N) and CLOSE (C)
2 B.A (N)
Before Coating
After coating or Uncoated finish threads
Internal threads (Plug gauges)
Over Size by 0.001"/ 0.025mm
Medium, Normal Class
External threads (Ring gauges)
Under size by 0.001"/0.025mm
Close, Medium, Free class.
