Hex socket head cap screw(GOSHO(Gosei(Coarse Steel Unplated 20 X 50 Pitch 2.5

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This is a bolt with a cylindrical head featuring a hexagonal socket.
Tightening is performed using a hex key (Allen wrench). Although classified as a bolt, it is in most cases used without a nut.
It is also referred to as a cap screw or socket screw.
Spanners and wrenches with jaws for tightening hex bolts require clearance space around the work area, whereas a hex key requires no such space.
For this reason, the use of hex socket head cap screws allows work in confined spaces and enables more compact machine designs.
Due to their appearance, they are also increasingly being used for decorative purposes.

• Hex socket head cap screw GOSEI Gosei Coarse pitch
• Nominal diameter M20
• Length under head (ℓ) 50.0
• Pitch 2.5
• Thread length (b) Reference 52
• Head diameter (dk) Max 30.33 Min 29.67
• Neck diameter (da) Max 22.4
• Body diameter (ds) Max 20 Min 19.67
• Head height (k) Max 20 Min 19.48
• Neck fillet (r) Min 0.8
• Hex socket width across flats (s) Nominal 17 Max 17.23 Min 17.05
• Hex socket depth (t) Min 10
• Head chamfer (v) Max 2
• Full thread range 70
• Strength class 12.9 (M2-M20) 10.9 (M22-M24) 10.9 (Electro zinc plating)