On a sheet metal fitting layout with a single bend, how can stretching be allowed for?

In a sheet metal fitting layout that involves a single bend, considering the concept of stretching is crucial for achieving an accurate final shape. When you bend a piece of metal, the inner section of the bend undergoes compression, while the outer section experiences stretching. To account for this stretching and ensure that the dimensions remain accurate after bending, you need to adjust the layout appropriately.

Subtracting the setback from both legs of the fitting layout allows for this adjustment. The setback is the distance from the bend line to the line that indicates where the sheet metal should be cut. By subtracting this measurement, you account for the material that will be stretched and thus help to ensure that the final dimensions remain consistent with the design specifications.

This method effectively compensates for the stretching of the outer leg during the bending process, allowing for a more precise fit in the overall assembly. Using this technique helps to avoid issues like parts being too short or not fitting together correctly after bending.