Normal bending tolerances for single radius bends are in line with those specified in the National Structural Steelwork Specification.
Round Bar Bending
Because bars are solid metal, they bend very well. Bending bars is the easiest when the sections to be bent are rounds, half rounds, squares, hexagons, or rectangular, and need to be bent “the easy way.” Bending bars the easy way (y-y axis) creates a belt-like shape; bending bars “the hard way” (x-x axis) creates what looks like a giant metal washer. All else being equal, bending bars that are flat the hard way is the most difficult bar bending process.