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British Association (B.A.)
Thread Form
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- p = Pitch
- h = Basic Depth of Thread = 0.6p
- r = Basic Radius = 0.1808346p
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Thread Tables
| BA No. |
Pitch |
Basic Thread Depth |
Basic Major Diameter |
Basic Effective Diameter |
Basic Minor Diameter |
Tapping Drill |
Clearance Drill |
| (n/a) |
(inch) |
(inch) |
(inch) |
(inch) |
(inch) |
(mm) |
(mm) |
| 0 |
0.0394 |
0.0236 |
0.2362 |
0.2126 |
0.189 |
5.1 |
6.1 |
| 1 |
0.0354 |
0.0213 |
0.2087 |
0.1874 |
0.1661 |
4.5 |
5.4 |
| 2 |
0.0319 |
0.0191 |
0.185 |
0.1659 |
0.1468 |
4 |
4.8 |
| 3 |
0.0287 |
0.0172 |
0.1614 |
0.1441 |
0.1268 |
3.4 |
4.2 |
| 4 |
0.026 |
0.0156 |
0.1417 |
0.1262 |
0.1106 |
3 |
3.7 |
| 5 |
0.0232 |
0.0139 |
0.126 |
0.112 |
0.098 |
2.65 |
3.3 |
| 6 |
0.0209 |
0.0125 |
0.1102 |
0.0976 |
0.085 |
2.3 |
2.9 |
| 7 |
0.0189 |
0.0113 |
0.0984 |
0.087 |
0.0756 |
2.06 |
2.6 |
| 8 |
0.0169 |
0.0102 |
0.0866 |
0.0764 |
0.0661 |
1.8 |
2.25 |
| 9 |
0.0154 |
0.0092 |
0.0748 |
0.0656 |
0.0563 |
1.55 |
1.95 |
| 10 |
0.0138 |
0.0083 |
0.0669 |
0.0587 |
0.0504 |
1.4 |
1.75 |
| 11 |
0.0122 |
0.0073 |
0.0591 |
0.0518 |
0.0445 |
1.2 |
1.6 |
| 12 |
0.011 |
0.0066 |
0.0512 |
0.0445 |
0.0378 |
1.05 |
1.4 |
| 13 |
0.0098 |
0.0059 |
0.0472 |
0.0413 |
0.0354 |
0.98 |
1.3 |
| 14 |
0.0091 |
0.0054 |
0.0394 |
0.0339 |
0.0283 |
0.8 |
1.1 |
| 15 |
0.0083 |
0.005 |
0.0354 |
0.0306 |
0.0256 |
0.7 |
0.98 |
| 16 |
0.0075 |
0.0046 |
0.0311 |
0.0266 |
0.022 |
0.6 |
0.88 |
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