Unless stated otherwise, what does the radius of a bend represent?

In the context of sheet metal bending, the radius of a bend typically refers to the inside radius of the metal. This is important because the inside radius is the critical dimension that affects the material's ability to bend without deforming or cracking. When a sheet metal part is formed into a bend, it experiences compression on the inside and stretching on the outside.

Understanding that the radius represents the inside radius is vital for ensuring the integrity and performance of the bent part. If you were to work with the outside radius instead, you could encounter issues with the metal’s strength or may not achieve the desired geometric tolerances. Consequently, the inside radius is the standard reference point in most sheet metal fabrication processes unless specified otherwise, which aligns with industry practices and design standards.