BendTab, a calculator for getting sheet metal bends right

Field notes

The calculator exposes four working inputs—thickness, inside radius, bend angle, and K-factor—and returns bend allowance, bend deduction, and outside setback. Its geometry view distinguishes the formed and flat states, while the accompanying method section gives both BA = α × (R + K × T) and BD = 2 × OSSB − BA. The page explicitly separates an explanatory K = 0.4 example from a production setting and recommends measured test-bend data for the actual process.