Laser File Check

DXF open polyline checker

Find open contours in a DXF: polylines that aren't closed and chains of lines and arcs with gaps between them.

Drop your SVG or DXF hereFrom Inkscape, Illustrator, Affinity, Fusion, LibreCAD and more · up to 30 MB

Checked entirely in your browser. Your file is never uploaded.

Machine and material (optional)

Only used to compare against your file. Leave blank to skip those checks.

How contours are traced

DXF files often describe a shape as separate LINE and ARC entities rather than one closed polyline. The check joins every entity end to end, allowing 0.01 mm of tolerance, and treats a line that ends on another line as connected, so parts that share a cut edge aren't reported. An end that meets nothing is loose, and the report gives the coordinates of loose ends so you can find them in your CAD program. A lone straight line that touches nothing, such as a hinge slit or score line, is listed as a note instead.

Fixing open contours

  • AutoCAD: PEDIT with Multiple → Join and a fuzz distance joins segments that don't quite touch. Joining doesn't close the shape, so set the polyline's Closed property to Yes in the Properties palette.
  • LibreCAD and QCAD: snap the endpoints together, then create a polyline from the existing segments.
  • Fusion and other CAD: fix the sketch so every profile is closed (it usually shades closed profiles), then export again.
  • LightBurn: Edit → Auto-join selected shapes after import.

Questions

My polyline looks closed. Why is it reported as open?

The last vertex may sit exactly on the first without the polyline's “closed” flag being set, or be slightly off. Some software treats that as open. The check reports both: truly open chains and ones whose ends nearly meet.

What tolerance is used to connect lines and arcs?

Endpoints within 0.01 mm of each other, or of another line, are treated as connected. If every loose end is within 0.1 mm of another end or line, the shape is reported as nearly closed.

Does it handle arcs and bulges?

Yes. Arcs, circles, ellipses, polyline bulges and splines are converted to line segments within 0.05 mm of the true curve before endpoints are compared. Splines stored only as fit points are drawn as straight lines through those points, and the report says so.