Self Tapping Screws - hole sizes

 

 

Metric


Recommended hole sizes for metric self-tappers Type AB - to DIN 7975.

The following reference values are valid only for case hardened steel Self Tapping Screws applied in a simple fastening joint with clearance holes. The tightening torques are max. 50% of the minimum breaking torque.

Prior test must be carried out for the utilisation of other screws or other sheet metal materials. Punched pilot holes must be 0.1 - 0.3mm larger and the screws must be tightened in the direction the hole was punched.

 
Thread diameter Material strength Rm (N/mm2) Sheet metal thicknesses (mm)
0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.2 2.5 2.8 3 3.5 4 4.5 5
ST 2.2 from 100 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.8                    
approx. 300 1.7 1.7 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.9 1.9                    
up to 500 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.7 1.9 1.9 1.9                    
ST 2.9 from 101       2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.3              
approx. 301       2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4              
up to 501       2.2 2.2 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5              
ST 3.5 from 102           2.6 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.8 2.9          
approx. 302           2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.9 2.9 3 3          
up to 502           2.7 2.8 2.8 2.9 2.9 2.9 2.9 3 3 3.1 3.1          
ST 3.9 from 103           2.9 2.9 3 3 3 3 3 3 3 3.1 3.2 3.3        
approx. 303           2.9 2.9 3 3 3.1 3.1 3.2 3.2 3.2 3.3 3.3 3.3        
up to 503           3 3.1 3.1 3.2 3.2 3.3 3.3 3.3 3.3 3.4 3.4 3.5        
ST 4.2 from 104             3.1 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.3 3.4 3.5      
approx. 304             3.1 3.2 3.2 3.2 3.3 3.3 3.4 3.4 3.5 3.6 3.6 3.6      
up to 504             3.3 3.3 3.4 3.4 3.4 3.4 3.5 3.5 3.6 3.6 3.6 3.7      
ST 4.8 from 105                 3.6 3.6 3.6 3.6 3.6 3.6 3.7 3.8 3.9 4 4.1    
approx. 305                 3.6 3.7 3.8 3.8 3.9 3.9 4 4.1 4.1 4.2 4.2    
up to 505                 3.9 3.9 4 4 4 4.1 4.1 4.2 4.2 4.2 4.3    
ST 5.5 from 106                     4.2 4.2 4.2 4.2 4.2 4.4 4.5 4.6 4.7 4.8  
approx. 306                     4.3 4.4 4.4 4.5 4.7 4.7 4.8 4.8 4.9 4.9  
up to 506                     4.6 4.6 4.6 4.7 4.8 4.8 4.9 4.9 5 5  
ST 6.3 from 107                     4.9 4.9 4.9 4.9 5 5.2 5.3 5.4 5.5 5.6 5.7
approx. 307                     5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.7 5.8 5.8
up to 507                     5.3 5.4 5.4 5.5 5.6 5.7 5.7 5.7 5.8 5.8 5.8
 

 

Inch


Recommended hole sizes for inch Self Tappers Type AB.

The following reference values are valid only for case hardened steel Self Tapping Screws applied in a simple fastening joint with clearance holes. The tightening torques are max. 50% of the minimum breaking torque.

Prior test must be carried out for the utilisation of other screws or other sheet metal materials.

 
Screw size Threads per inch Hole size (inches) Drill size Drill diameter (inches)
Max Min
0 48 0.049 0.043 56 0.0465
1 42 0.063 0.055 53 0.0595
2 32 0.077 0.067 49 0.073
3 28 0.09 0.078 45 0.082
4 24 0.103 0.089 41 0.096
5 20 0.114 0.1 36 0.1065
6 20 0.124 0.108 32 0.116
7 19 0.138 0.12 30 0.1285
8 18 0.148 0.128 29 0.136
10 16 0.17 0.148 21 0.159
12 14 0.194 0.169 14 0.182
1/4 14 0.226 0.196 4 0.209
5/16 12 0.289 0.251 I 0.272
3/8 12 0.356 0.31 Q 0.332
7/16 10 0.413 0.359 W 0.386
1/2 10 0.48 0.418 29/64 0.4531