Plenum Box with Spigots: flat pattern

An open box folded from one blank with a row of round spigots on its back or a side: the box with every hole marked, and the spigots unrolled. An open box folded from one blank, with a row of round spigots set onto its back or onto a side: the box with every hole marked, and the spigots unrolled.

Open the plenum box with spigots in SheetMorph

Configurations

A worked example

The spigots on the back configuration with the sizes SheetMorph opens with, in mm. 3 plates: the box blank with 2 holes in its back, and 2 spigots, alike: 11 parts, 8 seams.

The flat pattern of this example: outlines to cut, with fold lines and any holes. Open it in SheetMorph for the dimensioned drawing and the files to cut it.
For the shop
Blank of P11552.0 mm × 1252.0 mm
Blank of N1630.4 mm × 100.0 mm
Blank of N2630.4 mm × 100.0 mm
Length of cut, every outline and hole8529.8 mm
Bends (4) down, the pattern drawn outside face up90.0°
Bends (4) up, the pattern drawn outside face up90.0°
Sizes on the mid-thickness surface (used for the pattern)
Length of the box901.00 mm
Width of the box601.00 mm
Height of the box300.50 mm
Spigot diameter201.00 mm
Box
Flange25.00 mm
Box blank
Overall length1552.00 mm
Overall width1252.00 mm
Square cut out of each corner325.50 mm
Spigots
Number2
Standing out from the box100.00 mm
Girth of each blank631.46 mm
Centre to centre450.00 mm
From the end of the box to the first centre225.00 mm
Plate blanks
P1 Base, long1552.00 mm
P1 Base, wide1252.00 mm
N1 Spigot 1, long630.45 mm
N1 Spigot 1, wide100.00 mm
Pattern
Plates3
Triangular facets146
Pattern extent X3588.89 mm
Pattern extent Y1252.00 mm
Area of the blanks1,645,392 mm²
Area cut out63,281 mm²
Net area1,582,112 mm²
Total cut length9791.80 mm
Longitudinal seam length1402.00 mm

How it is developed

True-shape development of flat faces about the back; parallel-line development of the spigots. This is a triangulated approximation: the curved surface is divided into small flat triangles, each laid out at its true size. The finer the division, the closer the pattern is to the surface; SheetMorph states the deviation it found.

Checked before it can be exported

Every pattern SheetMorph draws is checked against the 3D part it comes from. For this example:

Assumptions

Limits of this module

Conventions

Coordinate system. The part stands on the Z axis with End A at Z = 0. Angles round the axis are measured from +X toward +Y, counter-clockwise seen from +Z.

Divisions and thickness. A circle is divided into 4N equal chords. Sizes are inside, mid-thickness or outside sizes; the pattern is developed on the mid-thickness surface and the views show the sizes as entered.

Box. The box lies on its back at Z = 0, open face up, centred on the Z axis, its length along X and its width along Y. Corners are numbered 0 (-X, -Y), 1 (+X, -Y), 2 (+X, +Y), 3 (-X, +Y) seen from the open face; side 1 faces -Y, side 2 +X, side 3 +Y and side 4 -X. End A is the edge round the open face, or round its flange.

Spigots. The spigots are alike and stand square to the face they are on, in a row, each in the middle of its own equal share of the row: on the back along the length, pointing away from the open face; on side 2 along its width, at half the height of the box. End B is the open end of the first spigot, End C of the second, and so on. The hole for each is a true circle as large as the spigot.

Sizes and thickness. Length, width and height are those of the box, and the diameter that of the spigots, as inside, mid-thickness or outside sizes; the parts are developed on the mid-thickness surface. A flange is as wide as entered, measured from the side it is folded on.

Change the sizes to your own in SheetMorph, check the drawing, add seam and flange allowances, and export DXF, PDF, SVG, CSV or G-code. Check every pattern against your own standards before cutting.

Open the plenum box with spigots

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