The bend deduction chart generator builds a printable table of bend deduction, bend allowance or outside setback for every common bend angle and die. Choose material and thickness, and the chart fills in for standard V-dies or for your own inside radii. Copy it straight into Excel or print it for the press brake.
Print this chart for the press brake operator, or see Arcus CNC press brakes with built-in bend calculation in the controller.
How to read the chart
Each row is a bend angle and each column is a die opening or inside radius. Find your angle and die, then subtract the bend deduction from the sum of the outside flange dimensions to get the flat blank length. The 90° row is highlighted because it covers most parts.
For example, a 2 mm mild steel L-bracket with 50 mm and 30 mm outside flanges bent on a V16 die has a bend deduction of about 3.75 mm, so the flat blank is about 80 − 3.75 = 76.25 mm.
Formulas used
In V-die mode, the inside radius is estimated from the die opening for air bending (about 0.14–0.21 × V depending on material). Columns use standard die openings close to 6, 8, 10 and 12 times the thickness.
Tips for accurate charts
- Make one chart per material and thickness and post it at the machine.
- Replace the typical K-factor with a measured one from a test bend for tight-tolerance work; use our K-factor calculator.
- Bend deduction changes with the die, so always note which V-die the chart was made for.
Frequently asked questions
Why does the bend deduction grow so fast above 120°?
Outside dimensions are measured to the virtual sharp corner, and its distance from the bend grows with tan(A/2). For sharp bends that corner sits far outside the part, so the deduction becomes large. For bends over 120°, many shops dimension flanges to the tangent point instead.
Can I paste the chart into Excel?
Yes. Click "Copy table" and paste into Excel or Google Sheets; the values are tab-separated so each number lands in its own cell.