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Cone / Frustum Flat Pattern
Unfold a truncated cone — get the outer/inner radii and the sector angle to mark on plate.
How it works
- Slant Lf = √(h² + ((D−d)/2)²)
- R1 = Lf × Rb/(Rb−rb), R2 = Lf × rb/(Rb−rb)
- Sector angle = 360 × (Rb−rb) ÷ Lf
Worked example
D 400, d 200, h 300 → R1 ≈ 632.5, R2 ≈ 316.2, angle ≈ 113.8°.
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Reference tool — always validate against project specs. Not a substitute for a qualified engineer.