Export 3D dwg file missing some circle

abc.skp (320.6 KB)
abc.dwg (7.0 MB)

I am using SketchUp to draw equipment diagrams for an industrial exhaust gas treatment project, primarily for gas scrubbing to achieve permissible emission standards. Typically, I draw the equipment, label it, and then break down each component of the equipment. The casing needs to be unfolded, and usually, there are holes to be made. I use the “Unwrap and Flatten Faces” plugin to unfold the casing, arrange it, and then export it as a 3D DWG file for laser cutting and fabrication. However, I am facing an issue: the unfolded layout in SketchUp appears correct, but when I export it as a 3D DWG (a format that can be opened in CAD software), many elements and circles are missing. This is the problem I am encountering.


In SketchUp, this is an ellipse compressed from a circle. Some ellipses can be exported as 3D DWG files and displayed correctly, but the ellipse pointed out by the arrow cannot be displayed correctly. I need a complete curve, not a curve composed of straight lines. During laser cutting and fabrication, a continuous curve is also required. If I can explode the curve to obtain the correct display, I can directly export it as a 2D DWG file without the need for a 3D DWG export. Therefore, the problem remains unresolved. My ultimate goal is to export all elements in SketchUp to a 3D DWG file without missing any.

Do you have an example?
What software/plugin/extension did you use to draw those ellipses?

An ellipse in SketchUp is just a polyline comprising straight segments. When exporting to DWG/DXF as a 3D model, the only geometric objects that “know” their “ancestry” are arcs and circles. All others translate to straight lines. SketchUp has no “ellipse” or “spline” type curved objects.

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123.skp (308.0 KB)
123.dwg (90.7 KB)
To create a hole on a large cylinder, you can select the face of the cylinder, right-click the model, choose “Intersect Faces,” and then unfold it to obtain a flattened plane with the hole. However, the hole on the plane is composed of straight lines, and I want it to be an elliptical curve that is continuous. So, I tried resizing a circle appropriately to get an ellipse of the same size as the polygon to cover it. However, after scaling the circle, it turns into an ellipse and the exported 3D DWG file doesn’t display this ellipse.

As @Anssi said: only constant radius entities export as curves. Single center arcs and circles. An ellipse or any shape labeled “curve” in SketchUp entity info will export as lines.

@boris.beaulant seems to have in the works something related that might help toward solving this problem.

I understand this rule, which can be exported as a polygon, but the current situation is that I don’t see the polygon being exported, and there is a blank where the polygon should appear, with no lines.

Currently in development, but here is what the OpenCutList “ellipse smoother” will be able to export with the third circle.

FACE.dxf (8,1 Ko)

@boris.beaulant Thanks for currently problem solved

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