Unfold

The Unfold (or AUnf) command is designed to automatically generate flat polylines based on the unfolded shape of a bent 3d-solid face.

This command is particularly useful when designing products made from sheet materials—such as furniture, facades, plywood, plastic, or sheet metal. The resulting contours are optimized for CNC milling and laser cutting.

Program capabilities:

• The program works with 3D Solids. In BricsCAD, you can use Surfaces and Regions.

• Currently, it supports the unfolding of planar, cylindrical, and conical surfaces, as well as extruded surfaces (extruded from splines and ellipses).

• The program generates contours for all holes within the selected surface.

• Adjacent surfaces (connected without a sharp break) can be combined into a single unfolding.

• Contours are always converted into closed polylines with an optimal number of segments.

• Contours can be assigned specific layers based on NC Preparation settings, or they can retain the layer of the original solid.

• The solid's name and description are copied to the xData of the unfolding polylines.

• Users can quickly switch between multiple saved unfolding styles.

Read about downloading and installing the program here.

To run the plugin, you will have to register an account and top up your account balance or receive bonuses.

Then you can activate one of the licenses:

• • Annual license - 15 EUR.

  • Unlimited license - 75 EUR. Free updates for 1 year.

  • The trial period is 20 days.

Program Limitations

• The program does not work with polygonal meshes.

• In AutoCAD, due to a long-standing, known glitch in the BRep API, it is impossible to work with Surface objects. Furthermore, AutoCAD does not allow the selection of region faces. BricsCAD does not have these issues.

• The program generates only flat contours; it does not attempt to recreate a flattened / unfolded 3D solid. Consequently, it cannot account for angled end faces or neutral-axis (middle-line) bending. However, the SolSize solid metrics tool can provide the flat pattern length along the neutral axis, accounting for angled end cuts.

• It is impossible to flatten a round pipe.

• Not all surfaces can be flattened. It is physically impossible to flatten "third-order" surfaces (spheres, tori, or NURBS surfaces curved in all directions) into a plane. One can only attempt to "stretch" them onto a plane if the material is stretchable, but the program does not support this function. However, one can attempt to unfold ruled surfaces (a loft between two arbitrary 3D curves).

• Closed surfaces created by extruding an ellipse in AutoCAD cannot be processed (though this is possible in BricsCAD). However, you can help the program identify the extrusion axis for such a shape by creating at least one linear edge along that axis.

• The flat pattern length may differ from the solid metric length measured by SolSize for parts marked as "Sweep". SolSize accounts for the opposite side of the part and angled end cuts, utilizing multiple length-calculation modes; none of these features are present in the Unfold program.

• The program does not measure the depth of blind holes in solids. Consequently, incorrect data may appear in CNC layer names; carefully verify the resulting flat pattern contour layers.

Current Version Limitations

• It is not yet possible to generate a flat pattern for a box-like shape; surfaces joined at sharp angles cannot be unfolded.

• Currently, solids must be selected one by one by clicking on the specific face. There is no integration with the Nesting command and the solids measurement command cannot use the flat pattern contours to measure conical flat patterns.

Workflow

Configure the Unfold command via the A>V>C> Options Palette. On the "NC Preparation" tab, you can set layers for outer contours, inner contours (dadoes and pockets), and an "Other" layer used for transition lines between adjacent surfaces.

You can select a solid and a specific face on it before invoking the Unfold command.

Run the Unfold command or use the AUnf second name. Select a single solid face with one click, or select a surface or region object. Note that recent versions of AutoCAD have a glitch when selecting solid faces; you may need to disable "fast" visual styles or switch to 2D Wireframe mode.

The program then verifies that the surface can be unfolded and prompts you for an insertion point for the flat pattern (the bottom-left corner of the pattern's bounding box). The prompt includes options to switch settings styles directly in the command line or to open the settings dialog.

The program generates a flat pattern of the selected and adjacent surfaces based on your settings.

For all solid faces, the outward-facing direction is taken into account and oriented upwards along the Z-axis in the flat pattern. You can reconfigure the program to lay out flat patterns "face down," just as the LAY command typically does.

The solid's "top" orientation is also considered, aligning the pattern's top with the Y-axis. The program operates within the current User Coordinate System (UCS).

For cylinders and extruded surfaces, the extrusion axis is always aligned with the Y-axis. For cones and ruled surfaces that lack a distinct axis, the program rotates the part to minimize its Y-size. However, if "Right Angle Priority" is selected in the Common Options, the program identifies a right-angled outer corner on the longest side and orients the part so that this corner aligns with the X and Y axes.

The flat pattern is laid out in the XY plane of the UCS.

If the surface is fully closed (with no distinct start or end), the program attempts to place the cut along the surface's longest linear edge.

The program will calculate and report in the command line how many surfaces were successfully unfolded, the method used, and the selected rotation variant.

Finally, the program verifies its work by comparing the area of ​​the original surface with that of the flat pattern; a warning is displayed if a significant discrepancy is found.

If continuous mode is enabled, the program will continue to prompt for new solid surfaces until you press Esc. 

Please send all surfaces that fail to unfold to avc.programming@gmail.com.

Program settings

Select Contiguous Faces

Automatically add adjacent to the selected surfaces, i.e., conjugate without a kink (kink not more than 0.1 degrees between tangents). A single flat pattern with a common outline will be generated for all these surfaces.

Run Cyclically

Continue selecting solids and their surfaces for new unfolds until you press ESC.

Approximate unfolding of ruled surfaces

Unfolding ruled surfaces that cannot be flattened exactly. Ruled surfaces are created by the LOFT command, connecting two arbitrary 3D curves with lines; a helicoid (a twisted ribbon) is one example. A ribbon triangulation method is used for this purpose. It is a rather time-consuming and complex task. An approximate unfolding requires stretching the material, and the program will issue a warning if the stretching becomes excessive. To ensure faster CAD performance and facilitate subsequent manufacturing, it is far better to remodel solids featuring such faces from scratch, without using the LOFT command.

Manage Layers

Assign layers from the current NC-Prepare style to unfolded curves. The "Outer Milling," "Dado Milling," and "Pocket Milling" layers will be used. If the part is marked as a "sweep," the part thickness derived from the solid metrics will be substituted for the %depth% contour parameter. The program does not measure the actual depth of blind holes. Other CNC contour property placeholders may remain unfilled.

Joint lines

Draw joint lines between contiguous faces. The line will be placed on the "Other" layer if such a layer is specified in the NC Preparation settings.

Innore UCS

Determine the top of the part in the World Coordinate System (WCS) rather than the current User Coordinate System (UCS). Lay out the flat pattern contours in the XY plane of the World Coordinate System.

Turn front down

Rotate the finished flat pattern so that the surface facing outward from the solid points downwards along the Z-axis.