Enter thickness, inside radius, angle and outside flange dimensions: get the blank length, the allowance for each bend and the DIN 6935 K-factor, as in SolidWorks Sheet Metal.
Limits. Geometric flat pattern for press brake bending. The DIN 6935 K-factor depends only on r/s; the real one also depends on material, tooling and bending method, so for a production run make a test bend and enter your own K. Flange dimensions are outside, to the virtual sharp, as on a drawing.
Only the neutral fibre, K·s from the inside surface, keeps its length in a bend. DIN 6935: k = 0.65 + 0.5·lg(r/s), K = k/2.
BA = θ·(r + K·s), θ in radians: the neutral fibre length through the bend.
Matches the DIN 6935 formula and the SolidWorks Help example (s1, r1, K0.5, 90°: BA 2.356 mm).