The CLUFIX® range of blind rivet nuts is also available in Unified Screw Thread profiles (UST), standard in the United States, Great Britain and Canada. This type of profile is coded UNC or UNF, depending on the pitch value:
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C: Coarse
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F: Fine
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Designation of a UST thread:
- Diameter in inches or fractions of inches (for example: ¼” - 1 inch= 25.4 mm)
- The specified pitch in number of threads to the inch (for example: 28)
- The UN symbol
- A letter, in accordance with pitch type (for example: C)
- A number designates the tolerance class, and the letter A or B indicates whether it is an internal or external thread.
For a screw or bolt: ¼” -28 UNF 2A
For a nut: 6-12 UNC 2B
The profile shape is identical to that of the metric profile. |
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Diameter in inches
Examples : ¼", 6... |
Pitch (in number of threads per inch)
Examples : 28, 12... |
 UN symbol
 Pitch type
F = Fine
C = Coarse |
Tolerance class (1 to 3)
Tolerance thread gap
A = For threads
B = For internal threads |
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Tolerances:
For threads, there are 3 classes: 1A, 2A, 3A
For internal threads, there are 3 classes: 1B, 2B, 3B
Tolerance positions for the pitch diameters: |
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The two tables below contain standardized dimensional data (ANSI B1-1-1974 standard) for inch-dimension UNC and UNF threads: |
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Thread
designation |
Pitch in mm |
nominal Ø |
Ø pitch ? |
| N° 1 - 64 f |
0.3069 |
1.854 |
1.598 |
| N° 2 - 56 f |
0.4536 |
2.184 |
1.890 |
| N° 3 - 48 f |
0.5292 |
2.515 |
2.172 |
| N° 4 - 40 f |
0.6350 |
2.845 |
2.433 |
| N° 5 - 40 f |
0.6350 |
3.175 |
2.764 |
| N° 6 - 32 f |
0.7938 |
3.505 |
2.990 |
| N° 8 - 32 f |
0.7938 |
4.166 |
3.650 |
| N° 10 - 32 f |
1.0583 |
4.826 |
4.138 |
| N° 12 - 32 f |
1.0583 |
5.486 |
4.798 |
| 1/4" - 20 f |
1.2700 |
6.350 |
5.525 |
| 5/16" - 18 f |
1.4111 |
7.938 |
7.021 |
| 3/8" - 16 f |
1.5875 |
9.525 |
8.494 |
| 7/16" - 14 f |
1.8143 |
11.113 |
9.934 |
| 1/2" - 13 f |
1.9538 |
12.700 |
11.430 |
| 9/16" - 12 f |
2.1167 |
14.288 |
12.913 |
| 5/8" - 11 f |
2.3091 |
15.875 |
14.376 |
| 3/4" - 10 f |
2.5400 |
19.050 |
17.399 |
| 7/8" - 9 f |
2.8222 |
22.225 |
20.391 |
| 1 - 8 f |
3.1750 |
25.400 |
23.338 |
| 1 1/8" - 7 f |
3.6286 |
28.575 |
26.218 |
| 1 1/4" - 7 f |
3.6286 |
31.750 |
29.393 |
| 1 3/8" - 6 f |
4.2333 |
34.925 |
32.174 |
| 1 1/2" - 6 f |
4.2333 |
38.100 |
35.349 |
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Thread
designation |
Pitch in mm |
nominal Ø |
Ø pitch ? |
| N° 0 - 80 f |
0.3175 |
1.524 |
1.318 |
| N° 1 - 72 f |
0.3528 |
1.854 |
1.626 |
| N° 2 - 64 f |
0.3969 |
2.184 |
1.928 |
| N° 3 - 56 f |
0.4536 |
2.515 |
2.220 |
| N° 4 - 48 f |
0.5292 |
2.845 |
2.502 |
| N° 5 - 44 f |
0.5773 |
3.175 |
2.799 |
| N° 6 - 40 f |
0.6350 |
3.505 |
3.094 |
| N° 8 - 36 f |
0.7056 |
4.166 |
3.708 |
| N° 10 - 32 f |
0.7938 |
4.826 |
4.310 |
| N° 12 - 28 f |
0.9071 |
5.486 |
4.897 |
| 1/4" - 28 f |
0.9071 |
6.350 |
5.761 |
| 5/16" - 24 f |
1.0583 |
7.938 |
7.249 |
| 3/8" - 24 f |
1.0583 |
9.525 |
8.837 |
| 7/16" - 20 f |
1.2700 |
11.113 |
10.287 |
| 1/2" - 20 f |
1.2700 |
12.700 |
11.875 |
| 9/16" - 18 f |
1.4111 |
14.288 |
13.371 |
| 5/8" - 18 f |
1.4111 |
15.875 |
14.958 |
| 3/4" - 16 f |
1.5875 |
19.050 |
18.019 |
| 7/8" - 14 f |
1.8143 |
22.225 |
21.046 |
| 1 - 12 f |
2.1167 |
25.400 |
24.026 |
| 1 1/8" - 12 f |
2.1167 |
28.575 |
27.201 |
| 1 1/4" - 12 f |
2.1167 |
31.750 |
30.376 |
| 1 3/8" - 12 f |
2.1167 |
34.925 |
33.551 |
| 1 1/2" - 12 f |
2.1167 |
38.100 |
36.726 |
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For specific applications, LA CLUSIENNE-CLUFIX offers custom-made thread profiles (gas, trapezoid, etc.). |
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