C22 / Four-panel development

C22 · Open-tray reducer · one edge aligned

Open-tray reducer · one edge aligned: calculate three true panel patterns and inspect an open U-section in 3D.

Beta · panel geometry

Plan your rise

Edit dimensions ↑
Panel 1U 200 · B 400 · S 500 mmPanel 2U 50 · B 50 · S 538.52 mmPanel 3U 50 · B 50 · S 500 mm

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Assemble the floor and two walls. Join the long seams; reference edges are assembly datums, not retained hinges.

True-size panel patterns

Panel 1U 200 · B 400 · S 500 mmPanel 2U 50 · B 50 · S 538.52 mmPanel 3U 50 · B 50 · S 500 mm
PanelUpper edgeLower edgeTrue face heightLeft corner edgeRight corner edge
1200 mm400 mm500 mm500 mm538.52 mm
250 mm50 mm538.52 mm538.52 mm538.52 mm
350 mm50 mm500 mm500 mm500 mm

Ideal sharp, zero-thickness panel geometry. Panel dimensions exclude kerf, bend allowance, seams, overlap tabs, fasteners and the openings cut in the parent tray. The assembly is a separate-panel method; confirm the actual joining detail.

Measure the two openings

The inlet and outlet widths are measured across the base; side height is constant and transition length runs along the tray. This is an open U-section: one floor and two walls, with no top panel. The left base edge stays straight; all width reduction occurs on the opposite side. The geometry is developed as three separate panels, with longitudinal joining seams.

The outlet must be narrower than the inlet. All three panels keep their true edge lengths during assembly.

How the flat patterns are calculated

Floor panel: a trapezoid with inlet and outlet widths and axial length L. For each wall, true length is √(L² + Δ²), where Δ is that wall’s lateral change. Its panel height is the tray side height. Single-sided Δ values are 0 and Wᵢ−Wₒ; centered Δ values are both (Wᵢ−Wₒ)/2.

Each four-corner panel is unfolded by an isometry: all four edges and both diagonals match the 3D panel. The assembly animation rotates each panel rigidly about a reference edge. It does not interpolate or stretch the sheet.

Default example

400 → 200 mm · L 500 mm · H 50 mm True face height: 500.00 mm / 538.52 mm / 500.00 mm.

Fabrication and assembly method

  1. Inspect three panel blanks for an open-top tray reducer.
  2. Mark the bottom plate and both side-wall outlines.
  3. Cut the three separate panels; the top stays open.
  4. Assemble the floor and two walls. Join the long seams; reference edges are assembly datums, not retained hinges.

Ideal sharp, zero-thickness panel geometry. Panel dimensions exclude kerf, bend allowance, seams, overlap tabs, fasteners and the openings cut in the parent tray. The assembly is a separate-panel method; confirm the actual joining detail.

Independent TrayNeo panel-development method. Reference-product correspondence remains under review.

Geometry references

Rectangular transition: face-height equations ↗
NPTEL · True-length development ↗

Related calculators

Other rectangular funnel method ↗
All numbered methods ↗