Lines, circles and polyline bulges
The preview interprets LINE, ARC, CIRCLE and lightweight polyline records. A polyline bulge specifies a circular arc between vertices, including its direction. The renderer samples those curves for display and approximate length; the original arc data is retained in the DXF.
Unsupported records remain intact
Text, dimensions, blocks, hatches, legacy polylines and other entities can contain essential information. They are listed as unsupported rather than silently presented as validated. The duplicate-cleaned file preserves their original group-code records and all other sections.
A preview is not machine validation
The tool does not select power, feed, kerf, fixture position or cut order. It does not execute a file on a machine. Verify the exported drawing in the manufacturer-supported CAM workflow, particularly when unsupported entities or non-default extrusion vectors appear.
Read a lightweight polyline correctly
A LWPOLYLINE can describe straight segments and curved segments in one record. Its bulge belongs to the segment beginning at that vertex; zero means straight. The closed flag connects the final vertex back to the first. Missing that flag can leave a shape visually almost closed while its endpoint structure remains open.
The viewer samples circular geometry into short display segments. A smooth-looking preview therefore does not replace an exact CAD measurement, particularly for curved lengths. Cleaning retains the original circle, arc or bulge parameters instead of rewriting them as the sampled preview segments.
Choose a suitable export from the source application
Use a complete ASCII DXF no larger than 5 MB, with at most 10,000 entities, for this bounded inspection. Binary DXF and unsupported entities need another reader or a deliberate export from the authoring tool. Exploding a block can make its geometry inspectable, but may discard useful organization; do it only on a copy. Non-default extrusion vectors and nonzero elevation also need careful review because the preview is a two-dimensional projection.