What is the optimal tool characteristic for a rivet set used on MS20470 rivets?

The optimal tool characteristic for a rivet set used on MS20470 rivets is that it should have a slightly greater radius than the rivet head. This design ensures that when the tool strikes the rivet, it distributes the force evenly across the rivet head. A tool with a greater radius can form a rounded contour, which is essential for properly shaping and compressing the rivet without causing damage or deformation to the rivet's integrity.

This characteristic helps in achieving a flush, strong joint while minimizing the risk of buckling or other defects during the riveting process. Furthermore, the use of an appropriately shaped rivet set aids in the effectiveness of the riveting process, ensuring a secure attachment in structural applications.

The other options do not provide the same level of effectiveness for a proper rivet joint. A set with a smaller radius may lead to uneven force distribution and potential damage to the rivet head, while a flat surface may not adequately support the rounded shape of the rivet, resulting in improper formation. Lastly, interchangeability with any rivet does not account for the unique specifications and requirements associated with different rivet types, which can vary significantly in size and design.