What is the recommended size of the shop head of a rivet in relation to its shank?

The recommended size of the shop head of a rivet is one and one-half times the diameter of the shank. This standard ensures that when the rivet is properly set, the shop head provides adequate surface area for a secure connection without compromising the integrity of the materials being joined.

A larger shop head increases the bearing surface against the materials, which helps distribute the load over a wider area. It also prevents the rivet from pulling through the material under load, ensuring a strong, durable connection. This proportion has been established through industry standards and practices to promote the effectiveness and safety of riveted joints in various applications, particularly in aviation where structural integrity is critical.

Choosing a shop head size smaller or equal to the diameter of the shank may not provide sufficient surface area or strength, leading to potential joint failure. Thus, specifying a shop head that is one and one-half times the diameter of the shank is a crucial rule of thumb in rivet design and application.