What are the two different degrees for countersink rivets?

What are the two different degrees for countersink rivets?

• A. 82 and 100
• B. 100 and 120
• C. 60 and 82
• D. 90 and 120

Answer: (A)

Countersunk rivets need a matching conical recess so the head sits flush with the surface. In aviation practice there are two standard countersink angles: 100 degrees and 120 degrees. The 100-degree countersink is the most common for standard flush rivets, giving a typical seating depth that fills the head nicely within the skin thickness. The 120-degree countersink is used for certain rivet sizes or materials when a different seating depth is required to maintain a flush finish and proper load distribution. Other angles like 82, 60, or 90 aren’t standard for rivet countersinks, so they wouldn’t provide the correct seating geometry for these fasteners.

Countersunk rivets need a matching conical recess so the head sits flush with the surface. In aviation practice there are two standard countersink angles: 100 degrees and 120 degrees. The 100-degree countersink is the most common for standard flush rivets, giving a typical seating depth that fills the head nicely within the skin thickness. The 120-degree countersink is used for certain rivet sizes or materials when a different seating depth is required to maintain a flush finish and proper load distribution. Other angles like 82, 60, or 90 aren’t standard for rivet countersinks, so they wouldn’t provide the correct seating geometry for these fasteners.