Flat patterns and bend allowances · Lesson 4 of 4

Flat patterns and bend allowances: defects, verification and case study

The flat-pattern errors that make formed parts long or short, how each shows, the checks on a formed part, and a worked case from order to record.

You will be able to: Diagnose a formed part that is long or short from a flat-pattern error, choose the correction, and document the evidence for review.

9 min · 11 slides · 7 questions

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Slide 1 of 11

Where flat-pattern errors show

A blank too wide or too narrow shows after forming as legs that are long or short. Each bend adds its own error, so they build up across a profile.

Sources

Dialing in the k-factor for bending sheet metal parts (Steve Benson) - The Fabricator
Design Center Profile & bend method - Architectural Flashing Supply

Glossary

Mold-line dimension: A leg length measured on the outside faces to the theoretical sharp corner; how AFS draws and orders.
Painted face: The finished, coated side of prefinished sheet, which a drawing should mark.
Gauge range: The minimum to maximum thickness a gauge may measure; 24 ga galvanized spans 0.0236 to 0.0316 in.