What is required about the bucking bar surface when forming the driven head of a rivet?

The requirement that the bucking bar surface must be at right angles to the rivet's centerline is critical to ensuring a properly formed driven head of the rivet. When the bucking bar is positioned correctly at a right angle, it allows for even force distribution during the riveting process. This alignment ensures that the rivet's deformation occurs uniformly around the shank, which leads to a strong and secure joint in the assembly.

If the bucking bar were at an angle other than perpendicular, it could cause uneven pressure on the rivet head, leading to improper forming. This might result in weaker joints or potential defects in the material being fastened. Therefore, maintaining a right-angle relationship between the bucking bar surface and the rivet’s centerline is essential for achieving the desired structural integrity and quality in the assembly process.