What are two special calculations needed when bending sheet metal?

The concept of bend allowance and setback is crucial in sheet metal fabrication, especially when bending operations are involved. Bend allowance is the amount of material that is needed to account for the curvature of the bend, which is essential for determining the flat length of the sheet before the bend is made. This calculation takes into account the inside radius of the bend, the thickness of the material, and the angle of the bend.

Setback, on the other hand, refers to the distance from the bend line to the tangent line of the bend. It is important for ensuring that the metal piece fits properly in its final form and maintains the correct dimensions. Understanding these two calculations helps ensure accuracy and prevents issues like material wastage or misfits in assembly.

These factors are critical for achieving the desired shape and dimensions in the end product. Without proper calculations for bend allowance and setback, the final dimensions of the fabricated part could lead to significant errors in assembly and function.