a guide, for the laser bed

Preparing Cut Files for Laser Cutting: SVG Text and DXF from PDF Drawings

A laser follows lines, so a cut file is only as good as its paths: right size, hairline strokes, closed outlines, text turned into shapes. Below are the checks that apply to every file, then the two places files usually come from — lettering from a text tool and a part from a PDF drawing — and what goes wrong with each.

What a laser actually reads

A laser cutter does not look at a picture. The software takes a vector file, turns every path into a toolpath, and drives the head along it. Preparing a cut file therefore means one thing: clean lines the machine can follow, at the right size, with nothing in the file that should not be cut.

The two formats you will meet are SVG, which design and browser tools produce, and DXF, which CAD programs and engineering drawings produce. Laser software such as LightBurn opens both. The trouble is not the format; it is that lettering from a text tool and a part from an engineer’s PDF each arrive with their own way of being wrong.

Five checks that apply to every cut file

1. Units and scale. SVG has no fixed physical unit: one program assumes 96 pixels per inch, another 72, and the same file opens at two sizes. Put a known dimension in the file — a 100 mm square you delete before cutting — and measure it after import. DXF carries units in its header, but only if the writer filled them in.
2. Line width. Most laser software reads a hairline stroke as “cut” and a filled shape as “engrave”. A thick stroke does not cut thicker; it is ignored or traced as two lines. Cut lines get the thinnest stroke your software recognises and no fill.
3. Closed paths. A part that should fall out of the sheet must be one closed outline. A gap of a fraction of a millimetre leaves a bridge of material. Run the join or close-path command on anything that came from a trace or a conversion.
4. No duplicate lines. Two identical paths cut the same line twice, which chars the edge and can ignite thin wood. They are invisible on screen; Inkscape (via an extension) and LightBurn both have a delete-duplicates tool.
5. Text converted to outlines. Live text depends on a font the laser computer may not have. Convert every text object to a path before export, and keep an editable copy.

Lettering: getting curved or straight text into a cut file

Route A: set the text in a vector program and convert it

In Inkscape, type the text, use Text → Put on Path if it needs to curve, then Path → Object to Path. Hairline stroke, no fill, save as plain SVG. LightBurn and several other laser programs have their own text-on-path tool, which skips the export entirely. This gives the cleanest edges, because the outline comes straight from the font’s own curves.

Route B: a browser tool, then a trace

If you only want the words bent and do not want to learn a vector program, a browser tool — this site included — curves the text and exports it (the guide on curving text without Photoshop compares the options). To be clear: the generator on this site exports a transparent PNG, not an SVG, so the laser software still has to turn pixels into a path. Making that trace reliable is the same recipe as for a vinyl cutter: a solid dark colour, the Outline width at zero, Transparent background on, the largest export size (3200 × 2000). Then Path → Trace Bitmap in Inkscape, or the trace-on-import in LightBurn, gives a closed outline of every letter. A traced edge is never quite as smooth as a font outline, so check the smallest letters at 400% before you cut.

Two things that only matter once the laser is on

• Counters fall out. The inside of an O, A, B or D is a separate closed shape and drops onto the bed. For a stencil, use a stencil font or draw a small bridge to each counter.
• Kerf eats thin strokes. The beam removes a fraction of a millimetre either side of the line, so a fine script hairline can vanish. Heavier faces cut more reliably, and letter spacing on a strong curve stops neighbouring letters merging into one shape.

Drawings: getting a DXF out of a PDF

The other common starting point is a PDF: a part drawing from a client, a plan from a supplier. First work out what kind of PDF it is. Zoom to 800%. If the lines stay crisp, the PDF holds vector line work and can be converted. If they go blocky, it is a scan — a picture of a drawing — and the only options are tracing, which gives outlines around the ink rather than lines, or redrawing.

Route 1: open it in Inkscape and clean up by hand

Inkscape imports PDF directly. Ungroup everything, delete the title block, dimensions and border, join the remaining segments, set a hairline stroke and save as SVG or DXF. It is free and it works, but curves usually arrive already chopped into short straight segments, so a circle becomes a polygon you cannot snap to or resize cleanly; the scale is the page size, not the part size; and on a dense drawing the clean-up takes longer than the cut.

Route 2: import it in a CAD program and save as DXF

Some CAD programs import PDF directly — AutoCAD’s PDFIMPORT is the well-known one — and then save as DXF with real CAD geometry. If you already own and know such a program, this is the cleanest route for a drawing you will keep editing, and the most expensive one if you do not.

Route 3: a dedicated PDF-to-DXF converter

The third way is a tool built for exactly this step. One example is the PDF to DXF Converter from DrawingFox, a Chrome extension that reads a vector PDF and writes a DXF inside the browser tab, so the drawing is not uploaded to a server — relevant for a client file under NDA. What sets it apart from a generic online converter is what survives: it fits real curves, so a circle comes out as a CIRCLE and an arc as an ARC rather than a chain of segments, and it keeps the original CAD layer names when the PDF carries them. Output is the paper size at 1:1, in millimetres or inches, as a DXF R2007 file.

Its limits are stated on its own site and worth knowing before you install. It handles vector PDFs only and refuses scans. Text and dimension labels come back as geometry, not editable text. Layer names survive only if whoever exported the PDF ticked “include layer information”; otherwise everything lands on layer 0. And it requires a Google sign-in even on the free tier, which allows three conversions a day; a one-time $29 payment removes the daily limit, with a seven-day refund window. For one drawing a month the free tier is enough; for a batch it is not.

Route 4: redraw it

For a bracket with six lines and two holes, redrawing in any vector or CAD program is faster than any conversion and gives you a file you fully understand. Conversion earns its place on drawings with dozens of arcs or hundreds of entities.

After the conversion, before the laser

• Check one dimension. Measure a labelled feature in the converted file. If it is off by a fixed factor, the units were guessed wrong; scale the whole file.
• Strip what should not be cut: dimension lines, arrows, centre lines, the title block, hatching. If layers survived, that is one click per layer; if not, it is manual.
• Separate cut from engrave onto different layers or colours, so each can get its own power and speed.
• Allow for kerf. If two parts must fit together, offset the mating edges by half the kerf width, or cut a test slot first.

Cutting on a Cricut instead? The trace steps are on the curved text for Cricut page.

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