Table Of Content
What is CSK Bolt?
CSK bolt also known countersunk bolt or flat head screw. CSK head bolt have internal hex socket for tightening, CSK anchor bolt used in furniture, automotive parts and heavy duty machinery. CSK head screw have flat head that tapers along the shaft. M4 CSK screw best for applications where a smooth surface is required. CSK allen bolt are used with a countersunk hole to provide a flush, snag free fit. Check below CSK bolt size chart.
CSK Bolt Full Form
CSK bolt stands for countersunk socket head bolt
CSK Bolt Size Chart
| Sizes Of Thread | Length Of Thread | Height Of Head | Size Of Hex Socket | Diameter Of Body | Diameter Of Head | Theoretical Diameter | Pitch |
|---|---|---|---|---|---|---|---|
| - | - | - | - | maximum | minimum | maximum | - |
| M24 | 60 | 14.22 | 14.0 | 23.96 | 38.61 | 40.42 | 3.00 |
| M22 | 56 | 13.32 | 14.0 | 21.96 | 35.61 | 37.38 | 2.50 |
| M20 | 52 | 10.11 | 12.0 | 19.96 | 35.61 | 40.32 | 2.50 |
| M18 | 48 | 9.48 | 12.0 | 17.96 | 32.61 | 36.96 | 2.50 |
| M16 | 44 | 8.80 | 10.0 | 15.96 | 29.67 | 33.60 | 2.00 |
| M14 | 40 | 8.12 | 10.0 | 13.96 | 26.67 | 30.24 | 2.00 |
| M12 | 36 | 7.44 | 8.0 | 11.97 | 23.67 | 26.88 | 1.75 |
| M10 | 32 | 6.20 | 6.0 | 9.97 | 19.67 | 22.40 | 1.50 |
| M8 | 28 | 4.96 | 5.0 | 7.97 | 15.73 | 17.92 | 1.25 |
| M6 | 24 | 3.72 | 4.0 | 5.97 | 11.73 | 13.44 | 1.00 |
| M4 | 20 | 2.48 | 2.5 | 3.98 | 7.80 | 8.96 | 0.70 |
| M3 | 18 | 1.86 | 2.0 | 2.98 | 5.82 | 6.72 | 0.50 |
Countersunk Hole Size Chart for Socket Flat Head Bolts
| Thread Size | Diameter of Countersink | Countersink Angle | Diameter of Pilot Hole (Normal Fit H13) |
|---|---|---|---|
| M24 | 41 | 90° | 26 |
| M20 | 40.71 | 90° | 22 |
| M16 | 33.99 | 90° | 17.5 |
| M12 | 27.21 | 90° | 13.5 |
| M10 | 22.73 | 90° | 11 |
| M8 | 18.25 | 90° | 9 |
| M6 | 13.71 | 90° | 6.6 |
| M5 | 11.47 | 90° | 5.5 |
| M4 | 9.18 | 90° | 4.5 |
| M3 | 6.94 | 90° | 3.4 |
CSK Bolt Standard
| Indian Standard | IS 7485 |
|---|---|
| German Standard | DIN 965 |
| International Standards | ISO 7046 |
| Japanese standard | JIS B1111 |
CSK Bolt Weight Chart
Weights are in kg per 1,000 pieces
| Diameter | M24 | M20 | M16 | M12 | M10 | M8 | M6 | M4 |
|---|---|---|---|---|---|---|---|---|
| Length | ||||||||
| 8 mm | - | - | - | - | - | - | 2.35 | 0.92 |
| 10 mm | - | - | - | - | - | 5.47 | 2.70 | 1.07 |
| 12 mm | - | - | - | - | 10.1 | 6.10 | 3.05 | 1.23 |
| 20 mm | - | - | - | 21.2 | 14.1 | 8.60 | 4.46 | 1.84 |
| 25 mm | - | - | - | 24.8 | 16.6 | 10.2 | 5.34 | 2.23 |
| 30 mm | - | - | 51.8 | 28.5 | 19.1 | 11.7 | 6.22 | 2.9 |
| 35 mm | - | 91.4 | 58.4 | 32.1 | 21.6 | 13.3 | 7.10 | 3.4 |
| 40 mm | - | 102 | 65.1 | 35.7 | 24.1 | 14.8 | 8.83 | 3.9 |
| 50 mm | 179 | 123 | 78.4 | 43.0 | 30.1 | 19.9 | 11.00 | - |
| 60 mm | 209 | 143 | 91.7 | 54.0 | 35.7 | 24.8 | - | - |
| 70 mm | 239 | 164 | 111 | 62.9 | 41.2 | - | - | - |
| 80 mm | 269 | 200 | 127 | - | - | - | - | - |
| 90 mm | 299 | 226 | 143 | - | - | - | - | - |
| 100 mm | 340 | 253 | - | - | - | - | - | - |
Applications of CSK Head Bolt
CSK Bolt Head Size
| Size | Size of Key (mm) | Diameter of Head (mm) | Height of Head (mm) |
|---|---|---|---|
| M16 | 10 | 33.6 | 8.8 |
| M12 | 8 | 26.8 | 7.4 |
| M10 | 6 | 22.4 | 6.2 |
| M8 | 5 | 17.9 | 4.96 |
| M6 | 4 | 13.4 | 3.72 |
| M5 | 3 | 11.2 | 3.1 |
| M4 | 2.5 | 8.9 | 2.48 |
| M3 | 2 | 6.7 | 1.86 |
| M2 | 1.3 | 3.8 | 1.24 |
CSK Bolt Dimensions Chart
| Size | Length of Thread (mm) | Size of Allen Key | Head Height | Head Diameter | Thread Diameter (mm) | Diameter (mm) |
|---|---|---|---|---|---|---|
| M8 | 40 | 5 | 3.2 – 3.5 mm | 15.57 – 16 mm | 7.64 | 8 |
| M5 | 40 | 3 | 2.05 – 2.5 mm | 9.64 – 10 mm | 4.82 | 5 |
| M4 | 40 | 2.5 | 1.5 – 1.8 mm | 7.64 – 8 mm | 3.82 | 4 |
| M3 | 30 | 2 | 0.95 – 1.2 mm | 5.7 – 6 mm | 2.86 | 3 |
Recommended CSK Anchor Bolt Seating Torques
| Sizes | Grade 10.9 | Grade 8.8 |
|---|---|---|
| M20 | 129.40 | 93.60 |
| M18 | 100.90 | 72.80 |
| M16 | 82.70 | 58.00 |
| M14 | 60.30 | 42.00 |
| M12 | 43.90 | 30.70 |
| M10 | 30.10 | 21.00 |
| M8 | 18.90 | 13.20 |
| M6 | 10.30 | 7.20 |
| M4 | 4.40 | 3.10 |
M6 CSK Screw Head Size
| Size | Thread Length | Allen Key Size | Head Height | Head Diameter | Thread Diameter | Diameter |
|---|---|---|---|---|---|---|
| M6 | 40mm | 4 | 2.25 – 2.5 mm | 11.57 – 12 mm | 5.7mm | 6mm |
What is the DIN Standard for CSK Bolts?
DIN 7991
Are Countersunk and CSK The Same Thing?
Yes, Countersunk also called CSK.
Can M10 CSK Bolt Be Used in All Types of Materials?
CSK bolt available in various materials, such as aluminium, high tensile steel, stainless steel, carbon steel and nickel alloy.