Guide: From CAD Parts to DXF Files to Inkscape for Laser Cutting - dairyking98/leonards-wiki GitHub Wiki

Guide: Exporting CAD Parts to DXF and Preparing in Inkscape for Laser Cutting

Preparing parts for laser cutting involves exporting 2D profiles (outlines) from your CAD software (e.g. SolidWorks or Fusion 360) as DXF files, then refining those vectors in Inkscape. This guide details the workflow and best practices to ensure smooth production.

1. Export from SolidWorks to DXF

Create a 2D Drawing or Flat View

  • Open Your Part: Open the 3D part in SolidWorks.
  • Generate a 2D View: Create a 2D drawing or flat pattern of the face you want to cut. Ensure the view is orthogonal (normal) to the part for an accurate outline.
  • Set Scale: Set the drawing scale to 1:1 (full scale) so that the DXF remains true to size.
  • Clean the Drawing: Remove any title blocks, dimensions, or annotations that might export as extra lines.

References:
SolidWorks Blog
Instructables Tutorial

Save As DXF

  • Export: Go to File → Save As and choose DXF.
  • Select Geometry: In the export options, select the 2D view (or face) representing your cut geometry. Deselect any unnecessary layers or hidden entities.
  • Quick Export: Alternatively, right-click a face and choose “Export to DXF/DWG” to export just that face.

Reference:
SolidWorks Blog – DXF Export

Verify the DXF Output

  • Review the File: Open the DXF in a viewer or CAD program.
  • Check Details: Ensure only the desired profile is present with no stray construction lines or text.
  • Confirm Units: Verify that the geometry reflects the part’s actual size and that the units are correct.
  • Standard Format: Use a standard DXF format (e.g. AutoCAD R12/R14) for broad compatibility.

2. Export from Fusion 360 to DXF

Prepare the Sketch

  • Create/Identify Sketch: In Fusion 360, create or select a 2D sketch containing the outline of the part.
  • For 3D Designs: Project edges onto a sketch or use the Sheet Metal flat pattern if applicable.
  • Ensure Completeness: Make sure the sketch is complete (no open profiles) and at the correct size.

Save Sketch as DXF

  • Export Sketch: Right-click the sketch in the Fusion 360 browser and choose "Save as DXF."
  • Address Issues: If extra geometry (like construction lines or splines) appears, consider using an add-in (e.g. Shetter/Shepper Utilities) to produce a cleaner export, even if it means exporting as an SVG and then converting to DXF.

References:
Fab Academy Tutorial – DXF Export
Fab Academy – Alternative Workflow

Troubleshoot Export Issues

  • Remove Extra Geometry: Edit the sketch to remove or hide construction lines, points, etc., if they appear in the DXF.
  • DXF Option Missing: If Fusion’s personal license omits the DXF option, use a plugin or update.
  • Conversion Option: If the export produces an SVG, open it in Inkscape and re-save as DXF.

Confirm Scale and Units

  • Unit Consistency: DXF files do not embed units. Fusion will assume the DXF is in your design’s units upon import into another program.
  • Double-Check Dimensions: Verify that a part intended to be 100 mm is not misinterpreted as 100 inches.
  • Stick to One Unit System: Use consistent units across all programs to avoid scaling issues.

Reference:
Fab Academy – Scale and Units

3. Importing and Preparing the DXF in Inkscape

Open or Import the DXF

  • Launch Inkscape: Open Inkscape and import your DXF file via File → Import.
  • Set Correct Units: When prompted, select the same units or scale factor used in your CAD software.
  • Verify Dimensions: Use Inkscape’s measurement tools (e.g., draw a reference rectangle) to ensure the dimensions are accurate.

Set the Document Layout

  • Adjust Document Size: In File → Document Properties, set the page size to match your laser cutter’s bed or the material sheet (e.g. 32″ x 18″).
  • Optimize Layout: Arrange multiple DXF outlines within the document to optimize material usage and cutting order.

Reference:
MIT Fab Lab – Document Layout

Combine and Edit Paths

  • Convert to Paths: Ensure all shapes are converted to paths (use Path → Object to Path for text).
  • Ungroup & Combine: If imported as separate segments or groups, ungroup them (Ctrl+U) and combine paths if necessary.
  • Remove Duplicates: Delete any overlapping or duplicate paths to avoid the laser cutting the same line twice.

Reference:
Harvard Fab Lab – Editing Paths

Assign Stroke Properties for Cutting

  • Set Stroke Width: Use a very thin “hairline” stroke (commonly 0.001 inch or 0.0254 mm) for cut lines.
  • Choose Stroke Color: A common convention is to use red (RGB 255,0,0) for cutting operations.
  • Remove Fill: Set Fill to “none” (transparent) to ensure only the stroke is processed.

References:
Virginia Tech Build LAB

Layering for Order (Optional)

  • Use Layers or Colors: If your laser cutting software supports it, use separate layers or colors to designate different operations (e.g., inner details vs. outer profiles).
  • Plan Cutting Order: Cutting inner details first helps keep parts stable until the final outer cut.

Reference:
Harvard Fab Lab – Layering

Final File Check and Export

  • Review the File: Ensure all geometry is correctly placed, scaled, and styled.
  • Remove Unwanted Elements: Delete any guides, notes, or non-cut elements.
  • Export Format:
    • PDF/SVG: Useful if you plan to print to the laser’s driver or further edit in another program.
    • DXF: If required by your laser software, save as AutoCAD DXF (R14) and uncheck options like ROBO-master splines or LWPOLYLINE.
  • Test Import: Import the file into your laser software to verify that the scale and stroke settings are correctly interpreted.

References:
MIT Fab Lab – Exporting Files
Comakingspace Wiki – DXF Format

4. Best Practices and Considerations

  • Maintain 1:1 Scale:
    Always export and work at real size. Avoid scaling in the laser software. Verify that 1 unit in your file equals 1 unit on the machine.
    Reference: Fab Academy – Scale

  • Clean Geometry Only:
    Remove auxiliary data (construction lines, points, etc.) and hidden layers or guides to ensure the laser cuts only the desired paths.
    Reference: Harvard Fab Lab – Clean Geometry

  • Use Simple Polylines:
    Convert complex spline data to simpler paths if necessary. An older DXF version (R14) can help maintain compatibility with legacy laser programs.
    Reference: Comakingspace Wiki – Simple Polylines

  • Convert Text to Path:
    Convert all text to outlines (via Path → Object to Path) to avoid font issues during laser cutting.

  • Color Code for Multiple Operations:
    Use different colors or layers for tasks such as engraving versus cutting. This allows you to assign different power/speed settings in the laser software.
    Reference: Harvard Fab Lab – Color Coding

  • Inside-Out Cutting Order:
    Plan the cutting sequence so that interior features are cut before the outer perimeter, ensuring the piece remains stable until all cuts are completed.
    Reference: Harvard Fab Lab – Cutting Order

  • Test a Small Section:
    Run a small test cut (e.g., a square of known dimensions) to verify the scale and stroke settings before committing to the full job.

Sources

  • MIT “How to Make (Almost) Anything” Class Example – Exporting CAD faces to DXF and using Inkscape
    fab.cba.mit.edu
  • Fab Academy Tutorial (Jeancome Picot) – Fusion 360 to DXF workflow and Inkscape adjustments
    fabacademy.org
  • Virginia Tech Build LAB Guide – Inkscape settings for laser cutting (stroke width 0.001″, red for cut lines)
    mlsoc.vt.edu
  • Harvard GSD Fab Lab Guidelines – Layer conventions and avoiding duplicate lines
    fablab.gsd.harvard.edu