Countersink Modeling and Selectable Sizes

Metric Thickness Gauge Standard

Modeling Rules for Countersunk Holes

When a conical shape element is detected, it will be identified as a countersink.
Countersunk Type Modeling Rules Example
Metric countersunk hole Model the angle of the conical shape to be 90°. The ratio between the outer hole diameter (D) and inner hole diameter (d) must be as follows: If d ≤ 4.0 mm, the ratio must be above 1.4, If d > 4.0 mm, the ratio must be above 1.7. Example
Inch countersunk hole Model the angle of the conical shape to be 82°. The ratio between the outer hole diameter (D) and the inner hole diameter (d) must be above 1.4, regardless of the value of d. Example

Countersunk Hole Identification

The countesunk hole is recognized through a step below.
  • The nominal diameter is determined according to the pilot hole diameter range (see table below).
  • If the detected hole diameter does not match any of the entries on the list of pilot hole diameters, the hole is treated as a through hole (or tapped hole).
  • However, you can change the hole type or hole diameter when configuring the quote settings.
Metric Countersunk Hole
Countersunk diameter Pilot hole(d) range Example
M3 3.2 ≤ d ≤ 4.0 Example
M4 4.3 ≤ d ≤ 4.8
M5 5.3 ≤ d ≤ 6.5
M6 6.3 ≤ d ≤ 7.0
M8 8.4 ≤ d ≤ 10.0
M10 10.5 ≤ d ≤ 12.0
M12 13.0 ≤ d ≤ 14.5
M14 15.0 ≤ d ≤ 16.5
M16 17.0 ≤ d ≤ 18.5
Inch Countersunk Hole
Countersunk diameter Pilot hole(d) range Example
#0 1.27 ≤ d ≤ 2.54 Example
#1 1.78 ≤ d ≤ 2.79
#2 2.03 ≤ d ≤ 3.05
#3 2.29 ≤ d ≤ 3.3
#4 2.79 ≤ d ≤ 3.81
#5 3.05 ≤ d ≤ 4.32
#6 3.3 ≤ d ≤ 4.83
#8 4.06 ≤ d ≤ 5.33
#10 4.57 ≤ d ≤ 6.1
#12 5.33 ≤ d ≤ 6.35
1/4 6.1 ≤ d ≤ 7.62
5/16 7.62 ≤ d ≤ 9.14
3/8 9.4 ≤ d ≤ 10.67
7/16 10.92 ≤ d ≤ 12.45
1/2 12.45 ≤ d ≤ 15.49
5/8 14.73 ≤ d ≤ 18.8
3/4 16.26 ≤ d ≤ 23.11
7/8 21.84 ≤ d ≤ 26.16

Countersunk Hole Size Selection for Inch Thickness Gauge Standard

  • Available sizes vary depending on material and Sheet Thickness. See the table below for details.
  • Countersunk holes cannot be selected for perforated metals or shim plate materials.

Metric Countersunk Hole

MaterialSheet Thickness
(inch)		(mm)Available Bolt Nominal Diameter
  • Cold Rolled Low Carbon Steel
  • Hot Rolled Low Carbon Steel
0.0299 (#22)0.759           
0.0359 (#20)0.912M2          
0.0418 (#19)1.062M2          
0.0478 (#18)1.214M2M2.5M3        
0.0538 (#17)1.367  M3        
0.0598 (#16)1.519M2M2.5M3M4       
0.0747 (#14)1.897M2M2.5M3M4M5      
0.0897 (#13)2.278M2M2.5M3M4M5      
0.1046 (#12)2.657M2M2.5M3M4M5M6M8    
0.1196 (#11)3.038M2M2.5M3M4M5M6M8M10   
0.1345 (#10)3.416 M2.5M3M4M5M6M8M10   
0.1495 (#9)3.797    M5M6M8M10   
0.1644 (#8)4.176    M5M6M8M10   
0.1793 (#7)4.554     M6M8M10   
0.1875 (#(3/16))4.763     M6M8M10   
0.1943 (#6)4.935  M3M4M5M6M8M10M12M14 
0.25 (#-)6.350   M4M5M6M8M10M12M14 
0.375 (#-)9.525     M6M8M10M12M14 
0.5 (#(1/2))12.700          M16
  • Cold Rolled Low Carbon Steel

    (Electrolytic Galvanized)

     
  • Cold Rolled Low Carbon Steel
    (Hot Galvanized)
0.0276 (#24)0.701           
0.0336 (#22)0.853           
0.0396 (#20)1.006M2          
0.0516 (#18)1.311M2M2.5M3        
0.0635 (#16)1.613M2M2.5M3M4       
0.0785 (#14)1.994M2M2.5M3M4M5      
0.0934 (#13)2.372  M3M4M5      
0.1084 (#12)2.753   M4M5M6M8    
0.1233 (#11)3.132   M4M5M6M8M10   
0.1382 (#10)3.510    M5M6M8M10   
0.168 (#8)4.267     M6M8M10   
0.1793 (#7)4.554     M6M8M10   
  • 304 Stainless Steel (2B)
  • 304 Stainless Steel (No.4)
  • 316 Stainless Steel (2B)
0.0187 (#26)0.475           
0.025 (#24)0.635           
0.0312 (#22)0.792           
0.0375 (#20)0.953M2          
0.0437 (#19)1.110           
0.05 (#18)1.270M2M2.5M3        
0.0562 (#17)1.427  M3        
0.0625 (#16)1.588M2M2.5M3M4       
0.0781 (#14)1.984M2M2.5M3M4M5      
0.0937 (#13)2.380  M3M4M5      
0.1094 (#12)2.779M2M2.5M3M4M5M6M8    
0.125 (#11)3.175 M2.5M3M4M5M6M8M10   
0.1406 (#10)3.571 M2.5M3M4M5M6M8M10   
0.1719 (#8)4.366  M3M4M5M6M8M10   
0.1875 (#7)4.763  M3M4M5M6M8M10   
0.25 (#3)6.350   M4M5M6M8M10   
0.5 (#(1/2))12.700          M16
  • 5052 Aluminum Alloy
  • 6061 Aluminum Alloy
0.020.508           
0.0250.635           
0.0320.813           
0.041.016M2 M3        
0.051.270M2M2.5M3        
0.0631.600M2M2.5M3M4M5      
0.082.032M2M2.5M3M4M5M6     
0.092.286M2M2.5M3M4M5M6     
0.12.540M2M2.5M3M4M5M6M8    
0.1253.175 M2.5M3M4M5M6M8M10   
0.164.064    M5M6M8M10   
0.194.826     M6M8M10   
0.256.350      M8M10   
0.31257.938       M10M12M14M16
0.3759.525        M12M14M16
0.512.700          M16

Inch Countersunk Hole

MaterialSheet Thickness (inch)(mm)Available Bolt Nominal Diameter
  • Cold Rolled Low Carbon Steel
  • Hot Rolled Low Carbon Steel
0.0179 (#26)0.455                  
0.0239 (#24)0.607                  
0.0299 (#22)0.759                  
0.0359 (#20)0.912                  
0.0418 (#19)1.062                  
0.0478 (#18)1.214#0                 
0.0538 (#17)1.367#0                 
0.0598 (#16)1.519#0#1                
0.0747 (#14)1.897#0#1#2#3              
0.0897 (#13)2.278#0#1#2#3#4             
0.1046 (#12)2.657#0#1#2#3#4#5#6           
0.1196 (#11)3.038#0#1#2#3#4#5#6#8          
0.1345 (#10)3.416#0#1#2#3#4#5#6#8#10         
0.1495 (#9)3.797     #5#6#8#10#12        
0.1644 (#8)4.176      #6#8#10#121/4       
0.1793 (#7)4.554       #8#10#121/4       
0.1875 (#3/16)4.763       #8#10#121/4       
0.1943 (#6)4.935#0#1#2#3#4#5#6#8#10#121/4       
0.25 (#2)6.350#0#1#2#3#4#5#6#8#10#121/45/16      
0.375 (#1)9.525#0#1#2#3#4#5#6#8#10#121/45/163/87/161/25/8  
0.5 (#1/2)12.700              1/25/83/47/8
  • Cold Rolled Low Carbon Steel
  • (Electrolytic Galvanized)
  • Cold Rolled Low Carbon Steel
  • (Hot Galvanized)
0.0217 (#26)0.551                  
0.0276 (#24)0.701                  
0.0336 (#22)0.853                  
0.0396 (#20)1.006                  
0.0516 (#18)1.311#0                 
0.0635 (#16)1.613#0#1                
0.0785 (#14)1.994#0#1#2#3              
0.0934 (#13)2.372 #1#2#3#4#5            
0.1084 (#12)2.753  #2#3#4#5#6           
0.1233 (#11)3.132    #4#5#6#8          
0.1382 (#10)3.510     #5#6#8#10#12        
0.168 (#8)4.267      #6#8#10#121/4       
0.1793 (#7)4.554       #8#10#121/4       
  • 304 Stainless Steel (2B)
  • 304 Stainless Steel (No.4)
  • 316 Stainless Steel (2B)
0.0187 (#28)0.475                  
0.025 (#24)0.635                  
0.0375 (#20)0.953                  
0.0437 (#19)1.110                  
0.05 (#18)1.270#0                 
0.0562 (#17)1.427#0#1                
0.0625 (#16)1.588#0#1                
0.0781 (#14)1.984#0#1#2#3              
0.0937 (#13)2.380#0#1#2#3              
0.1094 (#12)2.779#0#1#2#3#4#5#6           
0.125 (#11)3.175#0#1#2#3#4#5#6#8          
0.1406 (#10)3.571#0#1#2#3#4#5#6#8#10#12        
0.1719 (#8)4.366#0#1#2#3#4#5#6#8#10         
0.1875 (#3/16)4.763#0#1#2#3#4#5#6#8#10#121/4       
0.25 (#2)6.350#0#1#2#3#4#5#6#8#10#121/45/163/87/16    
0.5 (#1/2)12.700              1/25/83/47/8
5052 Aluminum Alloy
6061 Aluminum Alloy		0.02020.513                  
0.0250.635                  
0.0320.813                  
0.041.016                  
0.051.270#0                 
0.0631.600#0#1                
0.082.032#0#1#2#3              
0.092.286#0#1#2#3#4#5            
0.12.540#0#1#2#3#4#5#6           
0.1253.175#0#1#2#3#4#5#6#8          
0.164.064      #6#8#10#12        
0.194.826       #8#10#121/4       
0.256.350        #10#121/45/163/87/16    
0.31257.938           5/163/87/161/2   
0.3759.525            3/87/161/25/8  
0.512.700              1/25/83/47/8

Countersunk Hole Size Selection for Metric Thickness Gauge Standard

  • Available sizes vary depending on material and Sheet Thickness. See the table below for details.
  • Countersunk holes cannot be selected for perforated metals or shim plate materials (Cold Rolled Low Carbon Steel (for Shims) or 304 Stainless Steel (H) (for Shims)).
Material Sheet Thickness Countersunk Hole Bolt Nominal Diameter
  • Low Carbon Steel (Cold/Hot Rolled)
  • 1018 Carbon Steel
  • Cold Rolled Low Carbon Steel (Electrolytic Zinc Plating)
 2.0 M3
2.3 M3
3.2 M3 M4 M5
4.5 M3 M4 M5 M6
6.0 M3 M4 M5 M6 M8 M10
9.0 M5 M6 M8 M10
10.0 M5 M6 M8 M10 M12 M14 M16
12.0 M5 M6 M8 M10 M12 M14 M16
16.0 M5 M6 M8 M10 M12 M14 M16
  • 304 Stainless Steel
  • (No.1 / 2B / Single-Sided #400-Grit Polished / Single-sided hairline finish)
  • 430 Stainless Steel (2B)
  • 5052 Aluminum Alloy
  • 5052 AL Alloy Pre-Finish, Clear Anodize​
  • 5052 AL Alloy Pre-Finish, Black Anodize​
 2.0 M3
2.5 M3
3.0 M3 M4 M5
4.0 M3 M4 M5 M6
5.0 M3 M4 M5 M6 M8
6.0 M3 (*1) M4 M5 M6 M8
9.0 M5 M6 M8 M10 M12 M14 M16
10.0 M5 M6 M8 M10 M12 M14 M16
12.0 M5 M6 M8 M10 M12 M14 M16
PET Acrylic Polycarbonate PVC 3.0 M3 M4 M5
5.0 M3 M4 M5 M6 M8
8.0 (*2) M3 M4 M5 M6 M8 M10
10.0 (*3) M3 M4 M5 M6 M8 M10
Aluminum composite sheet (core material: foam polyethylene resin) *4 3.0 M3 M4 M5
  • *1 Only available for A5052 Aluminum Alloy.
  • *2 Only available in PET (standard, transparent) OR Acrylic (standard, transparent)
  • *3 Only available in Acrylic (standard, transparent)
  • *4 Click here to see the countersink machining finish for aluminum composite sheets.

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