What is the common angle for countersinking?

In the context of countersinking, a common angle used is 100 degrees. This angle is prevalent in aerospace applications because it provides a suitable shape for accommodating rivet heads or screws, allowing them to sit flush with the surface of the material. The 100-degree countersink angle offers a balanced approach, ensuring that there is enough clearance for the fastener while also maintaining structural integrity.

Using a countersink with this specific angle helps to minimize issues related to stress concentrations around the fastener during load conditions, which is particularly important in aerospace components where safety and performance are critical. The design also aids in achieving a clean, aerodynamic surface, which is a requirement for aircraft outer surfaces for minimizing drag.

Other angles may be used in different contexts or industries, but the 100-degree angle is a standard in aviation engineering for countersinking applications, making it the correct choice in this scenario.