|
Recommended tapping and clearance drill sizes
 |
| UNC Unified Course Thread |
| d1 |
TPI |
d2 mm |
d3 mm |
|
d1 |
TPI |
d2 mm |
d3 mm |
| No 1 |
64 |
1.55 |
1.95 |
|
1/4 |
20 |
5.10 |
6.50 |
| No 2 |
56 |
1.85 |
2.30 |
|
5/16 |
18 |
6.60 |
8.10 |
| No 3 |
48 |
2.10 |
2.65 |
|
3/8 |
16 |
8.00 |
9.70 |
| No 4 |
40 |
2.35 |
2.95 |
|
7/16 |
14 |
9.40 |
11.30 |
| No 5 |
40 |
2.65 |
3.30 |
|
1/2 |
13 |
10.80 |
13.00 |
| No 6 |
32 |
2.85 |
3.60 |
|
9/16 |
12 |
12.20 |
14.50 |
| No 8 |
32 |
3.50 |
4.30 |
|
5/8 |
11 |
13.50 |
16.25 |
| No 10 |
24 |
3.90 |
4.90 |
|
3/4 |
10 |
16.50 |
19.25 |
| No 12 |
24 |
4.50 |
5.60 |
|
7/8 |
9 |
19.50 |
22.50 |
|
|
|
|
|
1 |
8 |
22.25 |
25.75 |
|
|
|
|
|
1 1/8 |
7 |
25.00 |
29.00 |
|
|
|
|
|
1 1/4 |
7 |
28.00 |
32.00 |
|
|
|
|
|
1 3/8 |
6 |
30.75 |
35.50 |
|
|
|
|
|
1 1/2 |
6 |
34.00 |
38.50 |
|
|
|
|
|
1 3/4 |
5 |
39.50 |
45.00 |
|
|
|
|
|
2 |
4.5 |
45.00 |
51.00 |
The above information is for guidence only and should not be used when working to stringent specifications.
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