Access Door: flat pattern
A door over an opening in the side of a duct: the side with its opening, and the door folded as a pan, single skin or with an inner skin. A door over an opening in the side of a duct: the side with the opening cut in it, and the door folded as a pan from one blank, single skin or with an inner skin.
Open the access door in SheetMorphConfigurations
- Single skin. The door is one pan, its lip folded round the face.
- Double skin. The pan is closed at the back by a flat inner skin, for a door that is insulated.
A worked example
The single skin configuration with the sizes SheetMorph opens with, in mm. 2 plates: the duct side with its opening, the door blank: 6 parts, 4 seams.
| Blank of P1 | 500.0 mm × 400.0 mm |
| Blank of W | 800.0 mm × 600.0 mm |
| Length of cut, every outline and hole | 4600.0 mm |
| Bends (4) down, the pattern drawn outside face up | 90.0° |
| Width | 400.00 mm |
| Height | 300.00 mm |
| From the edge of the side, across | 100.00 mm |
| From the end of the side, along | 250.00 mm |
| Width | 450.00 mm |
| Height | 350.00 mm |
| Lip | 25.00 mm |
| Overall width | 500.00 mm |
| Overall height | 400.00 mm |
| Square cut out of each corner | 25.00 mm |
| P1 Base, long | 500.00 mm |
| P1 Base, wide | 400.00 mm |
| W Duct side, long | 800.00 mm |
| W Duct side, wide | 600.00 mm |
| Plates | 2 |
| Triangular facets | 12 |
| Pattern extent X | 1500.00 mm |
| Pattern extent Y | 600.00 mm |
| Area of the blanks | 677,500 mm² |
| Area cut out | 120,000 mm² |
| Net area | 557,500 mm² |
| Total cut length | 6000.00 mm |
| Longitudinal seam length | 100.00 mm |
How it is developed
True shape of flat plates; the door unfolded about its face. This is an exact development: the surface unfolds without stretching, so the pattern closes exactly.
- The opening is cut in the middle of the duct side, and the door covers it by the overlap all round.
- The door is one blank: the face with its lip laid out from each edge, a square cut out of each corner, folded up toward the side.
Checked before it can be exported
Every pattern SheetMorph draws is checked against the 3D part it comes from. For this example:
- Surface connectivity (passed): 12 facets form the door and the duct side it closes: every edge inside a part joins exactly two facets, every open edge one (V - E + F = 2).
- Developed edges equal true 3D lengths (passed): 36 facet edges compared between the 3D surface and the flat pattern (max deviation 6.25e-13).
- Shared edges and seam closure (passed): 10 internal edges are shared vertex-for-vertex between adjacent facets; 4 seam(s) have mating edges of equal true length (max deviation 6.25e-13).
- Developed facets consistently oriented (passed): All developed facets are counter-clockwise (outside face up); none is mirrored or degenerate.
- Developed area equals surface area (passed): Facet area in 3D and in the flat pattern agree (difference 0).
- Cut outlines closed and non-overlapping (passed): 2 closed outline(s); no outline crosses itself or another outline.
- HOLE-OPENING lies within its plate (passed): 4 points of the hole compared with the edges of the plate; its developed area is 120000.
Assumptions
- The pattern is developed on the mid-thickness surface; inside or outside sizes are converted to it by the thickness.
- Curves are chains of chords between division points.
- No seam, lap, weld-preparation or pressing allowance is added.
Limits of this module
- Hinges, latches, the gasket and the insulation are not drawn.
- The duct side is drawn as a flat plate; the rest of the duct is made with the straight duct.
- The corners of the door are plain square notches.
- Curves are chains of straight chords between division points.
- No seam, lap, weld-preparation or pressing allowance is added, and plates are not nested onto stock sheets.
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.
Door and side. The duct side lies in the plane Z = lip, its width along X and its length along Y, centred on the Z axis, seen from outside from -Z. The opening is cut in its middle. The door covers the opening from outside: its face at Z = 0 and its lip folded up to the side.
Door. The door is as large as the opening and the overlap all round. It is folded from one blank, the face with its lip turned up on every edge, a square cut out of each corner. A double-skin door has a flat inner skin, set in from the lip by the thickness, to close the back of the pan.
Sizes and thickness. The sizes are those of the side, the opening and the door as entered: they are flat plates and are cut as entered.
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 access doorOther dampers, doors and attenuators
- Volume Damper: A round sleeve with one blade, or a rectangular sleeve with a row of blades: the blades cut with their clearance and the sleeve with its shaft holes.
- Sound Attenuator: The casing of a sound attenuator: rectangular with a row of splitters, or round with a pod on its axis.