The diameter of the drill bit selected in this table is aimed at easily knowing the diameter of the drill bit during tapping processing . It is selected based on the standard drill bit sold in the market.
When using the drill bit, due to the shape, size and accuracy of the drill bit, The material being drilled, etc., has a great influence on the size and accuracy of the drilled hole. Therefore, use the drill diameter in this table. If there is any improper point, the drill diameter should be changed appropriately in the actual situation.
 
This table is based on the level 2 tooth Formulate.
 
Metric coarse thread
specification Standard diameter
Grade 2 teeth drilling diameter
maximum
The smallest
M1.0×0.25 0.75
0.785
0.729
M1.1×0.25 0.85
0.885
0.829
M1.2×0.25 0.95
0.985
0.929
M1.4×0.3 1.10
1.142
1.075
M1.6×0.35 1.25
1.321
1.221
M1.7×0.35
1.35
1.421
1.321
M1.8×0.35
1.45
1.521
1.421
M2.0×0.4
1.60
1.679
1.567
M2.2×0.45
1.75
1.838
1.713
M2.3×0.4
1.90
1.979
1.867
M2.5×0.45
2.10
2.138
2.013
M2.6×0.45
2.20
2.238
2.113
M3.0×0.5
2.50
2.599
2.459
M3.0×0.6
2.40
2.44
2.280
M3.5×0.6
2.90
3.010
2.850
M4.0×0.7
3.30
3.422
3.242
M4.0×0.75
3.25
3.326
3.106
M4.5×0.75
3.80
3.878
3.688
M5.0×0.8
4.20
4.334
4.134
M5.0×0.9
4.10
4.170
3.930
M6.0×1.0
5.00
5.153
4.917
M7.0×1.0
6.00
6.153
5.917
M8.0×1.25
6.80
6.912
6.647
M9.0×1.25
7.80
7.912
7.647
M10×1.5
8.50
8.676
8.376
M11×1.5
9.50
9.676
9.376
M12×1.75
10.30
10.441
10.106
M14×2.0
12.00
12.210
11.735
M16×2.0
14.00
14.210
13.835
M18×2.5
15.50
15.744
15.294
M20×2.5
17.50
17.744
17.294
M22×2.5
19.50
19.744
19.294
M24×3.0
21.00
21.252
2.752
M27×3.0
24.00
24.252
23.752
M30×3.5
26.50
26.771
26.211

 

Metric fine thread
specification Standard diameter
Grade 2 teeth drilling diameter
maximum
The smallest
M1.0×0.2 0.80
0.821
0.783
M1.1×0.2 0.90
0.921
0.883
M1.2×0.2 1.00
1.021
0.983
M1.4×0.2 1.20
1.221
0.183
M1.6×0.2 1.40
1.421
1.383
M1.7×0.2
1.45
1.500
1.460
M1.8×0.2
1.60
1.621
1.583
M2.0×0.25
1.75
1.785
1.729
M2.2×0.25
1.95
1.985
1.929
M2.3×0.25
2.05
2.061
2.001
M2.5×0.35
2.20
2.221
2.121
M2.6×0.35
2.20
2.246
2.186
M3.0×0.35
2.70
2.721
2.621
M3.5×0.35
3.20
3.221
3.121
M4.0×0.5
3.50
3.599
3.459
M4.5×0.5
4.00
4.099
3.959
M5×0.5
4.50
4.599
4.459
M5.5×0.5
5.00
5.099
4.959
M6.0×0.75
5.30
5.378
5.188
M6.0×0.5
5.50
5.550
5.400
M7.0×0.75
6.30
6.378
61.88
M7.0×0.5
6.50
6.550
64.00
M8.0×1.0
7.00
7.153
6.917
M8.0×0.75
7.30
7.378
7.188
M8×0.5
7.50
7.520
7.400
M9×1.0
8.00
8.153
7.917
M9×0.75
8.30
8.378
8.188
M10×1.25
8.80
8.912
8.647
M10×1.0
9.00
9.153
8.917
M10×0.75
9.30
9.378
9.188
M10×0.5
9.50
9.520
9.400
M11×1.0
10.00
10.153
9.917
M11×0.75
10.30
10.378
10.188
M11×1.5
10.50
10.676
10.376
M12×1.25
10.80
10.912
10.647

 

Metric fine thread
specification Standard diameter
Grade 2 teeth drilling diameter
maximum
The smallest
M12×1.0 11.00
11.153
10.917
M12×0.5 11.50
11.520
11.4
M14×1.5 12.50
12.676
12.376
M14×1.0 13.00
13.153
12.917
M15×1.5 13.50
13.676
13.376
M15×1.0
14.00
14.153
13.917
M16×1.5
14.50
14.676
14.376
M16×1.0
15.00
15.153
14.917
M17×1.5
15.50
15.676
15.376
M17×1.0
16.00
16.153
15.917
M18×2.0
16.00
16.210
15.835
M18×1.5
16.50
16.670
16.376
M18×1.0
17.00
17.153
16.917
M20×2.0
18.00
18.210
17.835
M20×1.5
18.50
18.676
18.376
M20×1.0
19.00
19.153
18.917
M20×2.0
20.00
20.210
19.835
M22×1.5
20.50
20.676
20.376
M22×1.0
21.00
21.153
20.917
M24×2.0
22.00
22.210
21.835
M24×1.5
22.50
22.676
22.376
M24×1.0
23.00
23.153
22.917
M25×2.0
23.00
23.210
22.835
M25×1.5
23.50
23.676
23.376
M25×1.0
24.00
24.153
23.917
M26×1.5
24.50
24.676
24.376
M27×2.0
25.00
25.210
24.835
M27×1.5
25.50
25.676
25.376
M27×1.0
26.00
26.153
25.917
M28×2.0
26.00
26.210
25.835
M28×1.5
26.50
26.676
26.376
M28×1.0
27.00
27.153
26.917
M30×3.0
27.00
27.252
26.752
M30×2.0
28.00
28.210
27.835
M30×1.5
28.50
28.676
28.376
M30×1.0
29.00
29.153
28.917
M32×2.0
30.00
30.210
29.835
M32×1.5
30.50
30.676
30.376
M33×3.0
30.00
30.252
29.752
M33×2.0
31.00
31.210
30.835
M33×1.5
31.50
31.376
31.376
M35×1.5
33.50
33.676
33.376
M36×3.0
33.00
33.252
32.752
M36×2.0
34.00
34.210
33.835
M36×1.5
34.50
34.676
34.376

 

American fine thread
Specification (UNF) Standard diameter
Grade 2 teeth drilling diameter
maximum
The smallest
Number of teeth outside diameter      
NO.0-80(1.524)
1.25
1.305
1.182
NO.1-72(1.854)
1.55
1.612
1.474
NO.2-64(2.184)
1.85
1.912
1.756
NO.3-56(2.515)
2.10
2.197
2.025
NO.4-48(2.845)
2.40
2.458
2.271
NO.5-44(3.175) 2.70 2.740 2.551
NO.6-40(3.505) 2.90 3.022 2.820
NO.8-36(4.166) 3.50 3.606 3.404
NO.10-32(4.826) 4.10 4.165 3.963
NO.12-28(5.846) 4.60 4.724 4.496
1/4 -28 5.50 5.588 5.360
5/16 -24 6.90 7.035 6.782
3/8 -24 8.50 8.636 8.382
7/16 -20 9.90 10.033 9.729
1/2 -20 11.50 11.607 11.329
9/16 -18 12.90 13.081 12.751
5/8 -18 14.50 14.681 14.351
3/4 -16 17.50 14.678 17.323
7/8 -14 20.50 20.675 20.270
1 -12 23.20 23.571 23.114
1-1/8 -12
26.50
 26.746 26.289
1-1/4 -12
29.50
 29.921 29.464
1-3/8 -12
32.80
 33.096 32.464
1-1/2 -12
36.00
 36.270 35.814

 

Chipless wire tap drilling diameter
specification
Accuracy class
RH4.5.6
RH7.8
RH9
M1.0×0.25 0.86
0.88
 –
M1.1×0.25 0.96
0.98
 –
M1.2×0.25 1.06
1.08
 –
M1.4×0.3 1.24
1.25
 –
M1.6×0.35 1.41
1.43
 –
M1.7×0.35
1.51
1.53
 –
M1.8×0.35
1.61
1.63
 –
M2.0×0.4
1.78
1.80
 –
M2.2×0.45
1.95
1.98
 –
M2.3×0.4
2.08
2.10
 –
M2.5×0.45
2.25
2.28
–
M2.6×0.45
2.35
1.38
–
M3.0×0.5
2.73
2.75
–
M3.0×0.6
3.17
3.20
–
M4.0×0.7
3.62
3.65
3.69
M5.0×0.8
4.56
4.60
4.64
M6.0×1.0
5.45
5.50
5.55
M7.0×1.0
6.45
6.50
6.55
M8.0×1.25
7.31
7.38
7.44
M10×1.5
9.18
9.25
9.32
M10×1.25
9.31
9.38
9.44
M12×1.75
11.04
11.12
11.21
M12×1.25
11.31
11.38
11.44
Note: The drilling diameter of the non-grooved wire tap is the value listed in the above table. Due to the influence of the material, hardness, shape, size, etc. of the processed material, it will vary somewhat. Therefore, please refer to the above table at the same time. Increase or decrease several.

 

American pipe thread
Specification (UNEF) Standard diameter
Grade 2 teeth drilling diameter
maximum
The smallest
NO.12 -32 4.70 4.826 4.623
1/4 -32 5.60 5.690 5.486
5/16 -32 7.10 7.264 7.087
3/8 -32 8.70 8.865 8.661
7/16 -28 10.20 10.338 10.135
1/2 -28 11.80 11.938 11.709
9/16 -28 13.20 13.386 13.132
5/8 -24 14.80 14.986 14.732
3/4 -20 17.80 17.958 17.678
7/8 -20 21.00 21.133 20.853
1 -20 24.00 24.308 24.028

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