BendBook - bending calculator

BlackBox Design Lab

In-app purchases

About this app

BendBook is an engineering calculator for sheet-metal work: bend allowance, DXF export, sheet and bar stock nesting, and a project library - all fully offline, with no internet connection, ads, or data collection required.

WHAT IT DOES:
Bend Allowance & Springback
• Calculate bend allowance and bend deduction using any K-factor or bend-allowance method
• Predict bend radius and tonnage from material thickness, type, and V-die opening
• Measure K-factor - enter results from your own test bends and get a real K-factor for your material and press, instead of relying on a generic table

Drawings & Export:
• Build a flat-pattern layout with cutouts and features
• Export to DXF, PDF, or PNG with dimensions in place - ready for CNC and the shop floor
• 3D fold preview along bend lines before you commit

Material Nesting:
• Optimize sheet and bar stock layout against available blanks
• Per-part cycle time and cost estimate (Quote panel)

Shop Organization
• Project, part, and tooling (punch/die) library that persists between sessions
• Built-in calculator (arithmetic, fractions, arcs, unit conversion) and a part-weight calculator, both opening as floating windows without leaving your current screen
• PIN lock and a trash bin with undo

Built for engineers, programmers, and fabricators who calculate bends every day and need an exact answer immediately, without an internet connection or extra steps.

What’s new

- New: E-ink theme - fully monochrome, easy on the eyes
- New: Calculator adds Fraction, Arc, and Unit Convert modes
- New: DXF Inspector - shared MARKS layer with per-person colors, for handing a project to someone else and seeing both sets of notes
- New: Local notification reminds you to back up weekly
- Fixed: entitlement checks could incorrectly show Free after a connectivity gap
- Fixed: several smaller display and export bugs