Open contours: find the gap before closing a path

A contour can look closed at normal zoom while its endpoints remain separate. First decide whether the path is meant to enclose an area or remain an open engraving or profile line.

Match closure to the operation

Area-based operations generally need an appropriate closed boundary. Open lines can be intentional: Vectric documents open-vector profile cutting on the left, right or on the line. Offsetting an open path is not universally undefined. Do not close a slot mouth, engraving line or deliberate open profile merely because a diagnostic marks it as open.

Join the intended endpoints

Work on a copy and inspect the endpoints at high zoom. LightBurn 2.1 documents Auto-Join selected shapes for endpoints within 0.05 mm and a separate Close selected paths with tolerance operation. Choose a tolerance from the gap you measured. A larger value can connect neighbouring features that should stay separate; it is not automatically a better repair.

Check the repaired shape

Compare holes, narrow slots and part count before and after joining. DXF Medic can close or stitch supported gaps and reports the repairs it applies. Review those changes before exporting. If the gap is large or the intended connection is ambiguous, correct it in CAD rather than raising the tolerance repeatedly. Confirm closure and the resulting fill or profile in the destination application.

Sources

• LightBurn 2.1 Edit menu reference
• Vectric Aspire 12 profile toolpaths