What is the purpose of sizing a mandrel to be 1/2" smaller than the duct?

The purpose of sizing a mandrel to be 1/2" smaller than the duct is primarily to provide easier maneuverability. A mandrel that is smaller than the duct allows for more flexibility and ease when inserting it into the duct. This is particularly important in scenarios where ducts must be handled in tight spaces or where alignment is critical during installation. Ensuring that the mandrel is slightly smaller helps to avoid stressing both the mandrel and the duct, making it simpler to navigate through twists and turns without risking damage.

In other cases, sizing the mandrel larger could cause binding and make it difficult to maneuver through the assembly, leading to potential challenges during installation. The choice to size it smaller supports efficient work processes and reduces strain, enhancing the overall effectiveness of the task at hand.