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Unified Fine
Thread Form
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- p = Pitch = 1/TPI
- hn = Height of internal thread = 0.54127p
- hs = Height of external thread = 0.61344p
- r = Basic Radius = 0.1443p
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Thread Tables
| Nominal Size |
T.P.I. |
Basic Major Diameter |
Basic Effective Diameter |
Basic Minor Diameter of External Threads |
Basic Minor Diameter of Internal Threads |
Tapping Drill |
Clearance Drill |
| (n/a) |
(n/a) |
(inch) |
(inch) |
(inch) |
(inch) |
(mm) |
(mm) |
| No. 0 |
80 |
0.06 |
0.0519 |
0.0447 |
0.0465 |
1.25 |
1.6 |
| No. 1 |
72 |
0.073 |
0.064 |
0.056 |
0.058 |
1.55 |
1.96 |
| No. 2 |
64 |
0.086 |
0.0759 |
0.0668 |
0.0691 |
1.9 |
2.3 |
| No. 3 |
56 |
0.099 |
0.0874 |
0.0771 |
0.0797 |
2.15 |
2.65 |
| No. 4 |
48 |
0.112 |
0.0985 |
0.0864 |
0.0894 |
2.4 |
2.95 |
| No. 5 |
44 |
0.125 |
0.1102 |
0.0971 |
0.1004 |
2.7 |
3.3 |
| No. 6 |
40 |
0.138 |
0.1218 |
0.1073 |
0.1109 |
2.95 |
3.6 |
| No. 8 |
36 |
0.164 |
0.146 |
0.1299 |
0.1339 |
3.5 |
4.3 |
| No. 10 |
32 |
0.19 |
0.1697 |
0.1517 |
0.1562 |
4.1 |
4.9 |
| No. 12 |
28 |
0.216 |
0.1928 |
0.1722 |
0.1773 |
4.7 |
5.6 |
| 1/4 |
28 |
0.25 |
0.2268 |
0.2062 |
0.2113 |
5.5 |
6.5 |
| 5/16 |
24 |
0.3125 |
0.2854 |
0.2614 |
0.2674 |
6.9 |
8.1 |
| 3/8 |
24 |
0.375 |
0.3479 |
0.3239 |
0.3299 |
8.5 |
9.7 |
| 7/16 |
20 |
0.4375 |
0.405 |
0.3762 |
0.3834 |
9.9 |
11.3 |
| 1/2 |
20 |
0.5 |
0.4675 |
0.4387 |
0.4459 |
11.5 |
13 |
| 9/16 |
18 |
0.5625 |
0.5264 |
0.4943 |
0.5024 |
12.9 |
14.5 |
| 5/8 |
18 |
0.625 |
0.5889 |
0.5568 |
0.5649 |
14.5 |
16.25 |
| 3/4 |
16 |
0.75 |
0.7094 |
0.6733 |
0.6823 |
17.5 |
19.25 |
| 7/8 |
14 |
0.875 |
0.8286 |
0.7874 |
0.7977 |
20.4 |
22.5 |
| 1 |
12 |
1 |
0.9459 |
0.8978 |
0.9098 |
23.25 |
25.75 |
| 1, 1/8 |
12 |
1.125 |
1.0709 |
1.0228 |
1.0348 |
26.5 |
29 |
| 1, 1/4 |
12 |
1.25 |
1.1959 |
1.1478 |
1.1598 |
29.5 |
32 |
| 1, 3/8 |
12 |
1.375 |
1.3209 |
1.2728 |
1.2848 |
32.75 |
35.5 |
| 1, 1/2 |
12 |
1.5 |
1.4459 |
1.3978 |
1.4098 |
36 |
38.5 |
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