What a laser needs from a DXF
Closed paths
A cut should end where it started. Open paths cut fine as single lines, but the software can't tell inside from outside, so fills, offsets and cut order break.
Real units
A DXF is just numbers. The file needs to say — or you need to know — whether 100 means millimetres or inches.
No duplicate lines
Two lines on top of each other get cut twice: extra charring on wood, melted edges on acrylic.
Sensible node count
Thousands of microscopic segments make the head stutter. Smooth curves with fewer nodes cut cleaner and faster.
The converter above takes care of the first, second and fourth automatically: every traced shape is closed, the file is scaled to the size you type (and DXF 2007 files store the unit), and curves are simplified to efficient polylines. A tracer never produces overlapping duplicates.
From image to cut file in four steps
- Start with contrastA dark design on a light background. Logos, silhouettes and lettering are ideal.
- Trace and checkRed lines in the preview are your cut paths. Adjust the threshold until they match.
- Set the finished sizeType the width you'll cut, then read the machine check for details under 0.5 mm.
- Import and assignBring the DXF into LightBurn or your laser software and set power and speed for the CUT layer.
How small can details be?
The beam removes material and heats what's around it, so very fine features char, melt or snap off. These are rules of thumb — always test on a scrap first:
| Material | Smallest practical detail (rule of thumb) |
|---|---|
| Paper and card | about 0.3–0.5 mm |
| 3 mm plywood or MDF | about 1 mm; thin strips between cuts tend to char or break |
| 3 mm acrylic | about 0.5–1 mm; tiny holes can partly melt closed |
| Sheet metal on a fibre laser | holes roughly at least as wide as the sheet is thick |
If the machine check warns about tiny parts, either make the whole design larger or raise Remove specks so they're dropped before you cut.
Kerf: why parts come out slightly small
The beam has width — typically around 0.1–0.2 mm on a CO₂ laser, depending on lens, focus and material. Cutting along a line removes half of that on each side, so an outside shape shrinks and a hole grows by roughly one kerf width. For signs and decorations you can ignore it. For finger joints, inlays or press-fit parts, apply a kerf offset in your laser software (LightBurn has one per layer) after a quick test cut.
Letters with holes, and stencils
When a shape has an enclosed area — the middle of an O, A, B or R — that inner piece is cut free. For a sign cut out of wood, that's exactly what you want: the counter falls out and the letter reads correctly. For a stencil, where you paint through the holes, the counters fall out and the letters lose their middles. The machine check counts these inner cut-outs for you. Use a stencil font, or add small “bridges” connecting the inner piece to the rest before converting.
DXF or SVG for laser cutting?
Most laser software, LightBurn included, imports both. DXF is the safer choice when the file comes from or goes into CAD, and a DXF 2007 file states its units. SVG sizes are sometimes misread because design apps disagree on pixels per inch (96 in Inkscape, 72 in older Illustrator exports). The converter gives you both formats with the same real dimensions, so use whichever your software handles best.
Checklist before you press start
- Size matches what you intend to cut (check it in the laser software, not just the file name).
- Machine check shows closed shapes and no open paths you didn't expect.
- No details under the minimum for your material.
- Inner cut-outs are intentional (sign) or bridged (stencil).
- Kerf offset applied if parts must fit together.
- Test cut on scrap with the same material and settings.
Open the DXF in your software
| Software | How to bring the DXF in | Good to know |
|---|---|---|
| LightBurn | File → Import, pick the .dxf | Shapes land on one layer; assign Cut / Line / Fill per layer. |
| Inkscape | File → Open (or Import into an existing drawing) | Handy if you want to edit, then save again as DXF or SVG. |
| Fusion 360 | Insert → Insert DXF, choose a sketch plane | Closed outlines become profiles you can extrude or use in CAM. |
| AutoCAD, DraftSight, LibreCAD | Open the file directly | The drawing starts at 0,0 in the units you chose. |
| SolidWorks | File → Open, choose DXF, import to a new part as a sketch | Use DXF 2007; pick the same units as in the converter. |
| CAM for plasma / router (SheetCAM, VCarve, Aspire…) | Use the program's import for DXF or vectors | Closed contours let the CAM offset for kerf or bit diameter. |