FlatBend: Sheet Metal Unfold

Bend allowance & flat pattern

Only for iPhone

$3.99 · Designed for iPhone. Not verified for macOS.

iPhone

Enter thickness, inside radius, angle and K-factor. Get bend allowance, deduction and total flat length instantly. Multi-bend, reverse solve, mm/inch fractions. FlatBend is a fast, precise flat-pattern (blank length) calculator for sheet metal workers. It runs fully offline, is a one-time purchase, and has no ads or tracking. WHAT IT DOES - Single-bend quick calc: from thickness, inside bend radius, bend angle and K-factor, see bend allowance (BA), bend deduction (BD), outside setback (OSSB) and neutral radius instantly. - Multi-bend flat pattern: lay out flanges (outside mold-line lengths) and each bend to get the total flat length automatically (Σ outside − Σ BD). - Reverse solve: fix the flat length and solve one unknown flange. - K-factor: presets 0.33 / 0.40 / 0.446 / 0.50, or an auto estimate from R/T (air-bend guide). Manual measured values are welcome too. - Units: mm and inch, with fraction display (1/16, 1/32, 1/64). - Angle: switch between bend angle and included angle. - History: name, save and reload jobs, each with a bend-profile diagram. METHOD Neutral radius = R + K*T Bend allowance BA = (pi/180)*A*(R + K*T) Outside setback OSSB = (R + T)*tan(A/2) Bend deduction BD = 2*OSSB - BA Flat length = sum of outside flange lengths - sum of BD per bend NOTE Results are geometric estimates (K-factor method). K-factor varies with material, process and tooling. For precision, enter the measured K-factor from a test bend.

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    Information

    Seller
    Yoshifumi Sato
    Size
    13.6 MB
    Category
    Utilities
    Compatibility
    Requires iOS 17.0 or later.
    • iPhone
      Requires iOS 17.0 or later.
    • Mac
      Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    English and Japanese
    Age Rating
    4+
    Copyright
    © 2026 Yoshifumi Sato
  • Developer Website
  • Privacy Policy

    • Supports

    • Family Sharing

      Up to six family members can use this app with Family Sharing enabled.

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