Core hole dimension tables
A core hole is a hole into which an internal thread is cut. The core hole is pre-drilled with a core hole twist drill.
A distinction is made between metric thread types and inch thread types. For metric thread types, the dimensions are given in millimetres. The pitch is calculated by measuring the distance between the first and second tooth. For inch threads, however, the dimensions are given in inches. 1 inch corresponds to 25.4 mm. Here, the pitch is determined by counting the number of threads on one inch.
Core holes have a specific dimension that is adapted to the thread to be cut. This means that the core hole dimension of the twist drill is defined by the thread diameter.
For more information on core hole drilling, please see our blog article:
Important!
For blind holes, the core hole must be pre-drilled deeper than the desired thread by the length of the chamfer.
We recommend that you lower the core hole to the thread diameter.
In the following you will find core hole dimension tables for core hole drilling for:
- Metric threads DIN 13
- Metric fine thread
- BSP
- UNC
- UNF
- BSW
- BSF
- NPT
- NPTF
- Tr
Core hole dimensions for metric threads DIN 13
The correct core hole dimensions for core drills, drilling tables and thread tables for metric ISO standard threads:
| Core hole dimensions for metric thread DIN 13 |
| |
| The metric ISO thread or standard thread is measured in millimetres and is the most commonly used in Europe. |
| |
| Nominal size mm |
Pitch mm |
Core hole mm |
| |
| M 1 |
0,25 |
0,75 |
| M 1,1 |
0,25 |
0,85 |
| M 1,2 |
0,25 |
0,95 |
| M 1,4 |
0,3 |
1,1 |
| M 1,6 |
0,35 |
1,25 |
| M 1,7 |
0,35 |
1,3 |
| M 1,8 |
0,35 |
1,45 |
| M 2 |
0,4 |
1,6 |
| M 2,2 |
0,45 |
1,75 |
| M 2,3 |
0,4 |
1,9 |
| M 2,5 |
0,45 |
2,05 |
| M 2,6 |
0,45 |
2,1 |
| M 3 |
0,5 |
2,5 |
| M 3,5 |
0,6 |
2,9 |
| M 4 |
0,7 |
3,3 |
| M 4,5 |
0,75 |
3,7 |
| M 5 |
0,8 |
4,2 |
| M 6 |
1 |
5 |
| M 7 |
1 |
6 |
| M 8 |
1,25 |
6,8 |
| M 9 |
1,25 |
7,8 |
| M 10 |
1,5 |
8,5 |
| M 11 |
1,5 |
9,5 |
| M 12 |
1,75 |
10,2 |
| M 14 |
2 |
12 |
| M 16 |
2 |
14 |
| M 18 |
2,5 |
15,5 |
| M 20 |
2,5 |
17,5 |
| M 22 |
2,5 |
19,5 |
| M 24 |
3 |
21 |
| M 27 |
3 |
24 |
| M 30 |
3,5 |
26,5 |
| M 33 |
3,5 |
29,5 |
| M 36 |
4 |
32 |
| M 39 |
4 |
35 |
| M 42 |
4,5 |
37,5 |
| M 45 |
4,5 |
40,5 |
| M 48 |
5 |
43 |
| M 52 |
5 |
47 |
| M 56 |
5,5 |
51,5 |
| M 60 |
5,5 |
54,5 |
| M 64 |
6 |
58 |
Core hole dimensions for metric fine threads
The correct core hole dimensions for core drills, drilling tables as well as thread tables for metric ISO fine thread:
| Core hole dimensions for metric fine thread |
| |
Compared to the standard thread, the fine thread has a smaller
Slope. |
| |
| Nominal dimension mm |
Pitch mm |
Core hole mm |
| |
|
|
| MF 2,5 x 0,35 |
0,35 |
2,15 |
| MF 2,6 x 0,35 |
0,35 |
2,15 |
| MF 3 x 0,35 |
0,35 |
2,65 |
| MF 3,5 x 0,35 |
0,35 |
3,15 |
| MF 4 x 0,35 |
0,35 |
3,65 |
| MF 4 x 0,5 |
0,5 |
3,5 |
| MF 4,5 x 0,35 |
0,35 |
4,15 |
| MF 4,5 x 0,5 |
0,5 |
4 |
| MF 5 x 0,5 |
0,5 |
4,5 |
| MF 5 x 0,75 |
0,75 |
4,25 |
| MF 5,5 x 0,5 |
0,5 |
5 |
| MF 5,5 x 0,75 |
0,75 |
4,75 |
| MF 6 x 0,5 |
0,5 |
5,5 |
| MF 6 x 0,75 |
0,75 |
5,25 |
| MF 7 x 0,5 |
0,5 |
6,5 |
| MF 7 x 0,75 |
0,75 |
6,25 |
| MF 8 x 0,5 |
0,5 |
7,5 |
| MF 8 x 0,75 |
0,75 |
7,25 |
| MF 8 x 1 |
1 |
7 |
| MF 8 x 1,5 |
1,5 |
6,5 |
| MF 9 x 0,5 |
0,5 |
8,5 |
| MF 9 x 0,75 |
0,75 |
8,2 |
| MF 9 x 1 |
1 |
8 |
| MF 10 x 0,5 |
0,5 |
9,5 |
| MF 10 x 0,75 |
0,75 |
9,25 |
| MF 10 x 1 |
1 |
9 |
| MF 10 x 1,25 |
1,25 |
8,8 |
| MF 11 x 0,5 |
0,5 |
10,5 |
| MF 11 x 0,75 |
0,75 |
10,25 |
| MF 11 x 1 |
1 |
10 |
| MF 11 x 1,25 |
1,25 |
9,75 |
| MF 12 x 0,5 |
0,5 |
11,5 |
| MF 12 x 0,75 |
0,75 |
11,25 |
| MF 12 x 1 |
1 |
11 |
| MF 12 x 1,25 |
1,25 |
10,8 |
| MF 12 x 1,5 |
1,5 |
10,5 |
| MF 13 x 0,5 |
0,5 |
12,5 |
| MF 13 x 0,75 |
0,75 |
12,25 |
| MF 13 x 1 |
1 |
12 |
| MF 13 x 1,25 |
1,25 |
11,75 |
| MF 13 x 1,5 |
1,5 |
11,5 |
| MF 14 x 0,5 |
0,5 |
13,5 |
| MF 14 x 0,75 |
0,75 |
13,25 |
| MF 14 x 1 |
1 |
13 |
| MF 14 x 1,25 |
1,25 |
12,8 |
| MF 14 x 1,5 |
1,5 |
12,5 |
| MF 15 x 0,5 |
0,5 |
14,5 |
| MF 15 x 0,75 |
0,75 |
14,25 |
| MF 15 x 1 |
1 |
14 |
| MF 15 x 1,25 |
1,25 |
13,8 |
| MF 15 x 1,5 |
1,5 |
13,5 |
| MF 16 x 0,5 |
0,5 |
15,5 |
| MF 16 x 0,75 |
0,75 |
15,25 |
| MF 16 x 1 |
1 |
15 |
| MF 16 x 1,25 |
1,25 |
14,75 |
| MF 16 x 1,5 |
1,5 |
14,5 |
| MF 17 x 0,75 |
0,75 |
16,25 |
| MF 17 x 1 |
1 |
16 |
| MF 17 x 1,5 |
1,5 |
15,5 |
| MF 18 x 0,5 |
0,5 |
17,5 |
| MF 18 x 0,75 |
0,75 |
17,25 |
| MF 18 x 1 |
1 |
17 |
| MF 18 x 1,25 |
1,25 |
16,75 |
| MF 18 x 1,5 |
1,5 |
16,5 |
| MF 18 x 2 |
2 |
16 |
| MF 19 x 1 |
1 |
18 |
| MF 19 x 1,5 |
1,5 |
17,5 |
| MF 20 x 0,5 |
0,5 |
19,5 |
| MF 20 x 0,75 |
0,75 |
19,25 |
| MF 20 x 1 |
1 |
19 |
| MF 20 x 1,25 |
1,25 |
18,75 |
| MF 20 x 1,5 |
1,5 |
18,5 |
| MF 20 x 2 |
2 |
18 |
| MF 21 x 1 |
1 |
20 |
| MF 21 x 1,5 |
1,5 |
19,5 |
| MF 22 x 0,5 |
0,5 |
21,5 |
| MF 22 x 0,75 |
0,75 |
21,25 |
| MF 22 x 1 |
1 |
21 |
| MF 22 x 1,25 |
1,25 |
20,75 |
| MF 22 x 1,5 |
1,5 |
20,5 |
| MF 22 x 2 |
2 |
20 |
| MF 23 x 1 |
1 |
22 |
| MF 23 x 1,5 |
1,5 |
21,5 |
| MF 24 x 0,5 |
0,5 |
23,5 |
| MF 24 x 0,75 |
0,75 |
23,25 |
| MF 24 x 1 |
1 |
23 |
| MF 24 x 1,25 |
1,25 |
22,75 |
| MF 24 x 1,5 |
1,5 |
22,5 |
| MF 24 x 2 |
2 |
22 |
| MF 25 x 1 |
1 |
24 |
| MF 25 x 1,5 |
1,5 |
23,5 |
| MF 25 x 2 |
2 |
23 |
| MF 26 x 1 |
1 |
25 |
| MF 26 x 1,25 |
1,25 |
24,75 |
| MF 26 x 1,5 |
1,5 |
24,5 |
| MF 26 x 2 |
2 |
24 |
| MF 27 x 1 |
1 |
26 |
| MF 27 x 1,5 |
1,5 |
25,5 |
| MF 27 x 2 |
2 |
25 |
| MF 28 x 1 |
1 |
27 |
| MF 28 x 1,5 |
1,5 |
26,5 |
| MF 28 x 2 |
2 |
26 |
| MF 30 x 1 |
1 |
29 |
| MF 30 x 1,5 |
1,5 |
28,5 |
| MF 30 x 2 |
2 |
28 |
| MF 30 x 3 |
3 |
27 |
| MF 32 x 1 |
1 |
31 |
| MF 32 x 1,5 |
1,5 |
30,5 |
| MF 32 x 2 |
2 |
30 |
| MF 32 x 3 |
3 |
29 |
| MF 33 x 1 |
1 |
32 |
| MF 33 x 1,5 |
1,5 |
31,5 |
| MF 33 x 2 |
2 |
31 |
| MF 33 x 3 |
3 |
30 |
| MF 34 x 1 |
1 |
33 |
| MF 34 x 1,5 |
1,5 |
32,5 |
| MF 34 x 2 |
2 |
32 |
| MF 34 x 3 |
3 |
31 |
| MF 35 x 1 |
1 |
34 |
| MF 35 x 1,5 |
1,5 |
33,5 |
| MF 35 x 2 |
2 |
33 |
| MF 35 x 3 |
3 |
32 |
| MF 36 x 1 |
1 |
35 |
| MF 36 x 1,5 |
1,5 |
34,5 |
| MF 36 x 2 |
2 |
34 |
| MF 36 x 3 |
3 |
33 |
| MF 38 x 1 |
1 |
37 |
| MF 38 x 1,5 |
1,5 |
36,5 |
| MF 38 x 2 |
2 |
36 |
| MF 38 x 3 |
3 |
35 |
| MF 39 x 1,5 |
1,5 |
37,5 |
| MF 39 x 2 |
2 |
37 |
| MF 39 x 3 |
3 |
36 |
| MF 40 x 1 |
1 |
39 |
| MF 40 x 1,5 |
1,5 |
38,5 |
| MF 40 x 2 |
2 |
38 |
| MF 40 x 3 |
3 |
37 |
| MF 42 x 1,5 |
1,5 |
40,5 |
| MF 42 x 2 |
2 |
40 |
| MF 42 x 3 |
3 |
39 |
| MF 42 x 4 |
4 |
38 |
| MF 45 x 1 |
1 |
44 |
| MF 45 x 1,5 |
1,5 |
43,5 |
| MF 45 x 2 |
2 |
43 |
| MF 45 x 3 |
3 |
42 |
| MF 45 x 4 |
4 |
41 |
| MF 48 x 1 |
1 |
47 |
| MF 48 x 1,5 |
1,5 |
46,5 |
| MF 48 x 2 |
2 |
46 |
| MF 48 x 3 |
3 |
45 |
| MF 48 x 4 |
4 |
44 |
| MF 50 x 1 |
1 |
49 |
| MF 50 x 1,5 |
1,5 |
48,5 |
| MF 50 x 2 |
2 |
48 |
| MF 50 x 3 |
3 |
47 |
| MF 50 x 4 |
4 |
46 |
| MF 52 x 1 |
1 |
51 |
| MF 52 x 1,5 |
1,5 |
50,5 |
| MF 52 x 2 |
2 |
50 |
| MF 52 x 3 |
3 |
49 |
| MF 52 x 4 |
4 |
48 |
| MF 54 x 1,5 |
1,5 |
52,5 |
| MF 54 x 2 |
2 |
52 |
| MF 54 x 3 |
3 |
51 |
| MF 54 x 4 |
4 |
50 |
| MF 55 x 1,5 |
1,5 |
53,5 |
| MF 55 x 2 |
2 |
53 |
| MF 55 x 3 |
3 |
52 |
| MF 55 x 4 |
4 |
51 |
| MF 56 x 1,5 |
1,5 |
54,5 |
| MF 56 x 2 |
2 |
54 |
| MF 56 x 3 |
3 |
53 |
| MF 56 x 4 |
4 |
52 |
| MF 58 x 1,5 |
1,5 |
56,5 |
| MF 58 x 2 |
2 |
56 |
| MF 58 x 3 |
3 |
55 |
| MF 58 x 4 |
4 |
54 |
| MF 60 x 1,5 |
1,5 |
58,5 |
| MF 60 x 2 |
2 |
58 |
| MF 60 x 3 |
3 |
57 |
| MF 60 x 4 |
4 |
56 |
| MF 62 x 1,5 |
1,5 |
60,5 |
| MF 62 x 2 |
2 |
60 |
| MF 62 x 3 |
3 |
59 |
| MF 62 x 4 |
4 |
58 |
| MF 64 x 1,5 |
1,5 |
62,5 |
| MF 64 x 2 |
2 |
62 |
| MF 64 x 3 |
3 |
61 |
| MF 64 x 4 |
4 |
60 |
Core hole dimensions for BSP
The correct core hole dimensions for core drills, drilling tables, threads per inch and thread tables for Whitworth pipe threads:
| Core hole dimensions for BSP threads |
| |
| The British Standard Pipe (BSP/ G) is a Whitworth pipe thread and is specified in inches. |
| |
| Nominal size mm |
Gears per inch |
Core hole mm |
| |
|
|
| G 1/8 |
28 |
8,8 |
| G 1/4 |
19 |
11,8 |
| G 3/8 |
19 |
15,3 |
| G 1/2 |
14 |
19 |
| G 5/8 |
14 |
21 |
| G 3/4 |
14 |
24,5 |
| G 7/8 |
14 |
28,3 |
| G 1 |
11 |
30,5 |
| G 1.1/8 |
11 |
35,5 |
| G 1.1/4 |
11 |
39,5 |
| G 1.3/8 |
11 |
42 |
| G 1.1/2 |
11 |
45 |
| G 1.5/8 |
11 |
49,6 |
| G 1.3/4 |
11 |
51 |
| G 2 |
11 |
57 |
| G 2.1/4 |
11 |
63,3 |
| G 2.1/2 |
11 |
72,8 |
| G 2.3/4 |
11 |
79 |
| G 3 |
11 |
85,5 |
| G 3.1/4 |
11 |
91,6 |
| G 3.1/2 |
11 |
98 |
| G 3.3/4 |
11 |
104 |
| G 4 |
11 |
110,7 |
The correct core hole dimensions for core drills, drilling tables, threads per inch and thread tables for the American standard thread:
| Core hole dimensions for UNC threads |
| |
| The Unified National Coarse Thread (UNC) is the American equivalent of the standard thread. Only the unit of measurement is given in inches. |
| |
| Nominal size mm |
Gears per Inch |
Core hole mm |
| |
|
|
| Nr. 1 |
64 |
1,5 |
| Nr. 2 |
56 |
1,8 |
| Nr. 3 |
48 |
2,1 |
| Nr. 4 |
40 |
2,3 |
| Nr. 5 |
40 |
2,6 |
| Nr. 6 |
32 |
2,9 |
| Nr. 8 |
32 |
3,5 |
| Nr. 10 |
24 |
3,9 |
| Nr. 12 |
24 |
4,5 |
| 1/4 |
20 |
5,2 |
| 5/16 |
18 |
6,6 |
| 3/8 |
16 |
8 |
| 7/16 |
14 |
9,4 |
| 1/2 |
13 |
10,8 |
| 9/16 |
12 |
12,3 |
| 5/8 |
11 |
13,5 |
| 3/4 |
10 |
16,5 |
| 7/8 |
9 |
19,5 |
| 1 |
8 |
22,3 |
| 1. 1/8 |
7 |
25 |
| 1. 1/4 |
7 |
28,3 |
| 1. 3/8 |
6 |
30,8 |
| 1. 1/2 |
6 |
34 |
| 1. 5/8 |
5 |
37,1 |
| 1. 3/4 |
5 |
39,5 |
| 1. 7/8 |
4,5 |
42 |
| 2 |
4,5 |
45 |
Core hole dimensions for UNF thread
The correct core hole dimensions for core drills, drilling tables, threads per inch and thread tables for American fine threads:
| Core hole dimensions for UNF threads |
| |
| The Unified National Fine Thread (UNF) is the American equivalent of the ISO metric fine thread. The unit of measurement is given in inches. |
| |
| Nominal size mm |
Gears per Inch |
Core hole mm |
| |
| Nr. 0 |
80 |
1,25 |
| Nr. 1 |
72 |
1,55 |
| Nr. 2 |
64 |
1,85 |
| Nr. 3 |
56 |
2,1 |
| Nr. 4 |
48 |
2,4 |
| Nr. 5 |
44 |
2,7 |
| Nr. 6 |
40 |
3 |
| Nr. 8 |
36 |
3,5 |
| Nr. 10 |
32 |
4,1 |
| Nr. 12 |
28 |
4,65 |
| 1/4 |
28 |
5,5 |
| 5/16 |
24 |
6,9 |
| 3/8 |
24 |
8,5 |
| 7/16 |
20 |
9,9 |
| 1/2 |
20 |
11,5 |
| 9/16 |
18 |
13 |
| 5/8 |
18 |
14,5 |
| 3/4 |
16 |
17,5 |
| 7/8 |
14 |
20,5 |
| 1 (14)” |
14 |
23,3 |
| 1 (12)” |
12 |
23,3 |
| 1. 1/8 |
12 |
26,5 |
| 1. 1/4 |
12 |
29,5 |
| 1. 3/8 |
12 |
32,5 |
| 1. 1/2 |
12 |
36 |
Core hole dimensions for BSW thread
The correct core hole dimensions for core drills, drilling tables, threads per inch and thread tables for British BSW threads:
| Core hole dimensions for BSW threads |
| |
The British Standard Whitworth (BSW/ WW) is a screw thread. It is given in inches.
|
| |
| Nominal size mm |
Gänge pro Zoll |
Kernloch mm |
| |
| 1/16 |
60 |
1,2 |
| 3/32 |
48 |
1,9 |
| 1/8 |
40 |
2,6 |
| 5/32 |
32 |
3,2 |
| 3/16 |
24 |
3,8 |
| 7/32 |
24 |
4,6 |
| 1/4 |
20 |
5,1 |
| 5/16 |
18 |
6,5 |
| 3/8 |
16 |
7,9 |
| 7/16 |
14 |
9,3 |
| 1/2 |
12 |
10,5 |
| 9/16 |
12 |
12 |
| 3/4 |
10 |
16,5 |
| 7/8 |
9 |
19,5 |
| 1″ |
8 |
22 |
| 1. 1/8 |
7 |
25 |
| 1. 1/4 |
7 |
28 |
| 1. 3/8 |
6 |
30,5 |
| 1. 1/2 |
6 |
33,5 |
| 1. 5/8 |
5 |
35,5 |
| 1. 7/8 |
4,5 |
41,5 |
| 2. 1/4 |
4 |
50,8 |
| 2. 1/2 |
4 |
57,15 |
| 2. 3/4 |
3,5 |
62,6 |
| 3″ |
3,5 |
68,95 |
Kernlochmaße für BSF
Die richtigen Kernlochmaße für Kernlochbohrer, Bohrtabellen, Gänge pro Inch sowie Gewindetabellen für das britische Feingewinde.
| Kernlochmaße für BSF Gewinde |
| |
| Das British Standard Fine (BSF) ist die englische Variante des Feingewindes. Es wird in Zoll angegeben. |
| |
| Nennmaß mm |
Gears per Inch |
Core hole mm |
| |
| 3/16 |
32 |
4 |
| 1/4 |
26 |
5,3 |
| 5/16 |
22 |
6,8 |
| 3/8 |
20 |
8,3 |
| 7/16 |
18 |
9,7 |
| 1/2 |
16 |
11,1 |
| 9/16 |
16 |
12,7 |
| 5/8 |
14 |
14 |
| 11/16 |
14 |
15,7 |
| 3/4 |
12 |
16,8 |
| 13/16 |
12 |
18,5 |
| 7/8 |
11 |
19,8 |
| 15/16 |
11 |
21,5 |
| 1 |
10 |
22,8 |
| 1. 1/8 |
9 |
25,5 |
| 1. 1/4 |
9 |
28,6 |
| 1. 3/8 |
8 |
31,5 |
| 1. 1/2 |
8 |
34,6 |
| 1. 5/8 |
8 |
38,1 |
| 1. 3/4 |
7 |
40,8 |
| 2 |
7 |
47,2 |
Core hole dimensions for NPT
| NPT- National Pipe Taper is a US-American pipe thread. |
|
|
|
|
|
| Nominal thread size |
Gradient in gears per inch/inch |
Pitch (mm) |
Outer diameter (mm)) |
Core hole (mm) |
| 1/16″ – 27 NPT |
27 |
0,941 |
7,895 |
6 |
| 1/8″ – 27 NPT |
27 |
0,941 |
10,242 |
8,25 |
| 1/4″ – 18 NPT |
18 |
1,411 |
13,616 |
10,7 |
| 3/8″ – 18 NPT |
18 |
1,411 |
17,055 |
14,1 |
| 1/2″ – 14 NPT |
14 |
1,814 |
21,223 |
17,4 |
| 3/4″ – 14 NPT |
14 |
1,814 |
26,568 |
22,6 |
| 1″ – 11 1/2 NPT |
11,5 |
2,209 |
33,228 |
28,5 |
| 1 1/4″ – 11 1/2 NPT |
11,5 |
2,209 |
41,985 |
37 |
| 1 1/2″ – 11 1/2 NPT |
11,5 |
2,209 |
48,054 |
43,5 |
| 2″ – 11 1/2 NPT |
11,5 |
2,209 |
60,092 |
55 |
| 2 1/2″ – 8 NPT |
8 |
3,175 |
72,699 |
65,5 |
| 3″ – 8 NPT |
8 |
3,175 |
88,608 |
81,5 |
| 3 1/2″ – 8 NPT |
8 |
3,175 |
101,316 |
94,3 |
| 4″ – 8 NPT |
8 |
3,175 |
113,973 |
107 |
| 5″ – 8 NPT |
8 |
3,175 |
141,3 |
134,384 |
| 6″ – 8 NPT |
8 |
3,175 |
168,275 |
161,191 |
| 8″ – 8 NPT |
8 |
3,175 |
219,075 |
211,673 |
| 10″ – 8 NPT |
8 |
3,175 |
273,05 |
265,311 |
| 12″ – 8 NPT |
8 |
3,175 |
323,85 |
315,793 |
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Core hole dimensions for NPTF
| NPTF – National Pipe Taper Fuel is a US-American pipe thread. |
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| Nominal thread size |
Gradient in gears per inch |
Pitch (mm) |
Outer diameter (mm) |
Core hole (mm) |
| 1/16″ – 27 NPTF |
27 |
0,94 |
7,87 |
6 |
| 1/8″ – 27 NPTF |
27 |
0,94 |
10,217 |
8,25 |
| 1/4″ – 18 NPTF |
18 |
1,411 |
13,577 |
10,7 |
| 3/8″ – 18 NPTF |
18 |
1,411 |
17,016 |
14,1 |
| 1/2″ – 14 NPTF |
14 |
1,814 |
21,211 |
17,4 |
| 3/4″ – 14 NPTF |
14 |
1,814 |
26,566 |
22,6 |
| 1″ – 11 1/2 NPTF |
11,5 |
2,209 |
33,195 |
28,5 |
| 1 1/4″ – 11 1/2 NPTF |
11,5 |
2,209 |
41,952 |
37 |
| 1 1/2″ – 11 1/2 NPTF |
11,5 |
2,209 |
48,021 |
43,5 |
| 2″ – 11 1/2 NPTF |
11,5 |
2,209 |
60,06 |
55 |
| 2 1/2″ – 8 NPTF |
8 |
3,175 |
72,642 |
65,5 |
| 4″ – 8 NPTF |
8 |
3,175 |
113,913 |
107 |
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Core hole dimensions for Tr
| Tr – Trapezoidal thread has the shape of an isosceles trapezoid. |
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| Nominal thread size |
Pitch (mm) |
Premachining diameter (mm) |
Core diameter (mm) |
| Tr 9 x 2 |
2 |
6,5 |
7 |
| Tr 10 x 2 |
2 |
7,5 |
8 |
| Tr 11 x 3 |
3 |
7,5 |
8 |
| Tr 12 x 3 |
3 |
8,5 |
9 |
| Tr 14 x 3 |
3 |
10,5 |
11 |
| Tr 16 x 4 |
4 |
11,5 |
12 |
| Tr 18 x 4 |
4 |
13,5 |
14 |
| Tr 20 x 4 |
4 |
15,5 |
16 |
| Tr 22 x 5 |
5 |
16,5 |
17 |
| Tr 24 x 5 |
5 |
17,5 |
19 |
| Tr 26 x 5 |
5 |
20,5 |
21 |
| Tr 28 x 5 |
5 |
22,5 |
23 |
| Tr 30 x 6 |
6 |
23 |
24 |
| Tr 32 x 6 |
6 |
25 |
26 |
| Tr 34 x 6 |
6 |
27 |
28 |
| Tr 36 x 6 |
6 |
29 |
30 |
| Tr 38 x 7 |
7 |
30 |
31 |
| Tr 40 x 7 |
7 |
32 |
33 |
| Tr 42 x 7 |
7 |
34 |
35 |
| Tr 44 x 7 |
7 |
36 |
37 |
| Tr 46 x 8 |
8 |
37 |
38 |
| Tr 48 x 8 |
8 |
39 |
40 |
| Tr 50 x 8 |
8 |
41 |
42 |
| Tr 52 x 8 |
8 |
43 |
44 |
| Tr 55 x 9 |
9 |
45 |
46 |
| Tr 60 x 9 |
9 |
50 |
51 |
| Tr 65 x 10 |
10 |
54 |
55 |
| Tr 70 x 10 |
10 |
59 |
60 |
| Tr 75 x 10 |
10 |
64 |
65 |
| Tr 80 x 10 |
10 |
69 |
70 |
| Tr 85 x 12 |
12 |
72 |
73 |
| Tr 90 x 12 |
12 |
77 |
78 |
| Tr 95 x 12 |
12 |
82 |
83 |
| Tr 100 x 12 |
12 |
87 |
88 |
| Tr 105 x 12 |
12 |
92 |
93 |
| Tr 110 x 12 |
12 |
97 |
98 |
| Tr 115 x 14 |
14 |
99 |
101 |
| Tr 120 x 14 |
14 |
104 |
106 |
| Tr 125 x 14 |
14 |
109 |
111 |
| Tr 130 x 14 |
14 |
114 |
116 |
| Tr 135 x 14 |
14 |
119 |
121 |
| Tr 140 x 14 |
14 |
124 |
126 |
| Tr 145 x 14 |
14 |
129 |
131 |
| Tr 150 x 16 |
16 |
132 |
134 |
| Tr 155 x 16 |
16 |
137 |
139 |
| Tr 160 x 16 |
16 |
142 |
144 |
| Tr 165 x 16 |
16 |
147 |
149 |
| Tr 170 x 16 |
16 |
152 |
154 |
| Tr 175 x 16 |
16 |
157 |
159 |
| Tr 180 x 18 |
18 |
160 |
162 |
| Tr 185 x 18 |
18 |
165 |
167 |
| Tr 190 x 18 |
18 |
170 |
172 |
| Tr 195 x 18 |
18 |
175 |
177 |
| Tr 200 x 18 |
18 |
180 |
182 |
| Tr 210 x 20 |
20 |
188 |
190 |
| Tr 220 x 20 |
20 |
198 |
200 |
| Tr 230 x 20 |
20 |
208 |
210 |
| Tr 240 x 22 |
22 |
216 |
218 |
| Tr 250 x 22 |
22 |
226 |
228 |
| Tr 260 x 22 |
22 |
236 |
238 |
| Tr 270 x 24 |
24 |
244 |
246 |
| Tr 280 x 24 |
24 |
254 |
256 |
| Tr 290 x 24 |
24 |
264 |
266 |
| Tr 300 x 24 |
24 |
274 |
276 |
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