How do I import SketchUp SKP files into VCarve Pro & Aspire and set them up for CNC machining?

Overview

SketchUp .SKP files can be imported as 2D data suitable for machining with File > Import Vectors... (or the import vectors icon on the Drawing tab). You must already have created or opened a job to import into. Because a SketchUp model is usually a 3D representation of the part, the importer offers options that flatten each part and lay it out ready for machining. That makes SketchUp a useful design companion for furniture, cabinetry and architectural CNC work.

Two Layout Modes

Exploded Flat Layout

Takes each component in the model and orients it flat, ready for machining. This is the mode to use for production work. Choosing it makes extra sub-options available (below).

Three Views - Front, Top, Side

Creates an "engineering drawing" style layout of the model. The size of the model is preserved, and it is easy to pick up dimensions for parts you are going to make. Line colors come from the colors of the original SketchUp layers. It needs manual vector cleanup before toolpathing.

Step-by-Step Import

1. Open or create your job first.
2. Go to File > Import Vectors... (not File > Import Component / 3D Model). SKP imports as 2D vectors, not 3D components.
3. Select your .SKP file. The SketchUp import form opens.
4. Choose Exploded Flat Layout.
5. Set Part Orientation:

• Auto Orientate: for each part, the face with the largest area based on its outer perimeter (ignoring holes) is treated as the top and the part is rotated to face up. This works very well for sheet goods with no features on particular faces (such as pockets).
• Orientate by material: in SketchUp, paint the face you want on top with a specific material or color, then choose that material in the drop-down. It is more reliable for parts with features. If a part has no face with that material, it is oriented with its largest face on top.

6. Set Gap between parts: the space to leave between parts when first imported. After import you can use the nesting tools to lay parts out with more control and across several sheets.
7. Choose the Create Circles / Arcs options (see below).
8. Choose which layers to import under Data to Import.
9. Set the Component / Group Handling options (see below).
10. Complete the import.

Key Options Explained

Create Circles / Arcs:

SketchUp does not keep true arc or circle information for part boundaries. Its polygon representation gives poor machining results, because a fillet becomes a series of straight segments and a round hole becomes a polygon. These options refit true circles and arcs to the imported data, so fillets become single smooth arcs and holes become arcs. Both machine more cleanly. Normally leave them on.

Replace outer boundary (for flat jobs only!):

SketchUp parts are sometimes built from several components butted against each other, so the outer boundary comes in as separate segments for each feature. With this option ticked, the software tries to create a single outer boundary for every part and deletes the vectors that formed it, giving data ready to machine directly.

Limitations: it can be substantially slower, and any feature that shares an edge with the outer boundary is deleted. If your part has tabs, dadoes or rabbets on the edge, do NOT use it.

Group imported parts:

Normally selected for all but the simplest models, because it lets each part be selected, moved and nested easily after import. Ungroup afterward to machine individual features. By default each SketchUp group or component is one part, unless it contains other groups or components, in which case each lowest-level group or component becomes a separate part.

Keep components starting with two underscores (__) together:

For a complex model whose parts are made of other groups or components, name the group you want treated as one part so it starts with two underscores in SketchUp, for example __DoorPanel or __WheelAssembly. When the importer reaches a group whose name starts with __, it treats all its child objects as the same part.

Without __: sub-components import separately and are laid out independently.

Controlling What Gets Imported (Layers)

For a complex model (a cabinet with doors, hinges and hardware) you do not want to import everything at once. In SketchUp, organize the model by layer:

• Put 3/4 inch parts on one layer.
• Put 1/4 inch parts on another.
• Put hardware and non-cuttable parts on a third.

In the import dialog choose import visible data on selected layers and tick only the layers you need. The number of parts on each layer is shown next to its name. Import one material thickness group per job.

After Import

1. Ungroup grouped vectors to reach individual geometry (press U, which puts items back on their original layers).
2. Run Join Open Vectors to close any gaps between segments.
3. Run Vector Validator to check for overlaps and intersections.
4. Use Fit Curves to Vectors (Edit > Curve Fit Vectors) if you still see jagged lines.
5. Organize vectors onto named layers for toolpath templates.
6. Nest parts if needed (Edit > Nest Selected Vectors).

The options above help a lot, but in many cases additional editing is still needed before the part is ready to toolpath.

What SKP Import Cannot Do

• It imports 2D vectors, not 3D components, so you cannot use the imported data directly for 3D modeling.
• Hardware (hinges, drawer slides, knobs) should be on a separate layer and left out of the import.
• Very complex assemblies with many nested components can be difficult, so simplify the SketchUp model before importing.
• SketchUp files only open in the same bit version (32 or 64 bit) of the software that you are running.

Common Mistakes

• Importing via File > Import Component / 3D Model instead of File > Import Vectors.
• Turning off the Create Circles / Arcs options, so circles on pockets come out as polygons.
• Using Replace outer boundary on parts with edge features. Those features get deleted.
• Not organizing the SketchUp model by layer before import, so parts from all materials come in mixed together.