What is the purpose of setback in metal bending?

Setback in metal bending refers to the distance from the bend line to the end of the material, which is critical for accurately calculating the final dimensions of the piece being fabricated. When metal is bent, it doesn't maintain its original length, and through the bending process, the geometry of the piece changes. By knowing the setback, fabricators can account for the material stretching and compression that occurs in the bending process, ensuring that the final dimensions conform to the specifications required for the design.

Understanding how much material will be removed or added due to the bend allows for precise adjustments during the manufacturing process. This is particularly important in applications such as aircraft construction, where the exact fit and alignment of components are crucial for structural integrity and performance. Therefore, the primary role of setback is to help calculate those final dimensions accurately, making it essential for producing components that meet engineering standards and tolerances.