Free DXF files for plasma cutting

Why most free DXF files cut badly on plasma

A plasma arc removes a kerf of a millimetre or two and heats everything near it. Thin bridges warp or burn through, small holes come out as blobs, and every separate outline costs a pierce, which wears consumables. Artwork drawn for vinyl ignores all of that.

These designs were filtered by measurement instead of by eye. Each is a single connected piece, so nothing but the cut-outs drops through the slats. Each has at most 30 outlines, which is at most 30 pierces. And the thinnest part is at least 4 mm at the file’s 100 mm size, which becomes 12 mm at 12 inches and 24 mm at 24 inches.

Using the DXF

• The file is an ASCII DXF in millimetres, with closed polylines on one layer. Scale it to your finished size in your CAM software; if it opens in inches, scale by 25.4.
• Curves are stored as short straight segments. Most CAM programs, SheetCam and Fusion 360 among them, can cut these as they are or fit arcs to them for smoother motion.
• The outlines are drawn at true size. Apply kerf compensation and lead-ins in CAM: outside the line for the outer edge, inside for cut-outs.
• Cut the inner cut-outs first and the outer edge last, so the part stays held while the detail is cut.

How big to cut

A common rule for plasma is that a slot or hole should be no narrower than about one and a half times the plate thickness. Each design’s page lists its narrowest part at sizes up to 12 inches. For sizes beyond that, the figure scales in proportion: double the size, double the width.

Questions

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