What technique should be used to mark a rivet head before drilling?

Using a drill bit to rotate and create an indentation on a rivet head before drilling is a standard practice known as "marking" or "spot-facing." This technique helps to ensure that the subsequent drilling process will be more accurate and less likely to wander off-center. The indentation created by the rotating drill bit provides a stable reference point for the drill, significantly improving the precision of the hole placement.

This method is particularly important in aerospace applications, where precision is critical for maintaining structural integrity and ensuring safety. A properly marked rivet head allows for cleaner drilling, which minimizes the risk of damaging surrounding material or compromising the rivet itself.

The alternatives, such as making a mark with a pen or using a chisel to score the surface, often don't provide the same level of accuracy or stability for the drilling process. A punch may also seem like a viable option; however, it can leave a deeper indentation than desired, potentially affecting the rivet's integrity or alignment. Thus, creating a small, controlled indentation using a rotating drill bit is the most effective technique for this task.