Hex socket head cap screw(Coarse Steel Unplated 1.4 X 3(P=0.3

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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 most commonly used without a nut.
It is also known 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, hex socket head cap screws enable work in confined spaces and allow for more compact machine designs.
Their appearance has also led to increasing use in decorative applications.


Cap Bolts　
Representative Standard Dimensions for CAP Screws　
Hex Socket Head Cap Screws　

• Hex socket head cap screw (Coarse pitch)
• Nominal diameter (d) M1.4
• Length under head (ℓ) 3.0
• Pitch (P) 2
• Thread length (b) Reference 40
• Head diameter (dk) Max(1) Nominal 21 Max(2) 21.33 Min 20.67
• Neck diameter (da) Max 15.7
• Body diameter (ds) Max Nominal 14 Min 13.73
• Hex socket width across corners (e) Min 13.716
• Head height (k) Max Nominal 14 Min 13.57
• Neck fillet (r) Min 0.6
• Hex socket width across flats (s) Nominal Nominal 12 Max 12.212 Min 12.032
• Hex socket depth (t) Min 7
• Head chamfer (v) Max 1.4
• * Max(1) Maximum diameter without knurling / Max(2) Maximum diameter with knurling