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Bend Allowance Calculator — K-Factor, Deduction & Flat Length

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Length unit Sheet thickness Inside bend radius Bend angle (degrees swept) Square bend = 90°.K-factor Use validated shop data where available.Outside flange A Optional flat-length input.Outside flange B Optional flat-length input.Measured bend allowance (optional) If > 0, reverse-solves K-factor from a coupon/test bend.

Calculated result

4.4611 mm bend allowance

Bend allowance: 4.4611 mm

Outside setback: 4 mm

Bend deduction: 3.5389 mm

Neutral-axis radius: 2.84 mm

Single-bend flat length from outside flanges: 96.4611 mm

Show the working

1. θ = 90° × π ÷ 180 = 1.570796 rad.
2. BA = 1.570796 × (2 + 0.42 × 2) = 4.4611 mm.
3. OSSB = (2 + 2) × tan(45°) = 4 mm.
4. BD = 2 × 4 − 4.4611 = 3.5389 mm. Flat = 50 + 50 − 3.5389 = 96.4611 mm.

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