How-to guide · how to import a dxf into a laser cutter

How to import a DXF into a laser cutter

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By Sumana Kumar · Published 4 Jun 2022 · Updated 29 Aug 2025

A DXF is the lingua franca of laser cutting: nearly every laser controller and CAM program reads it, which is why it's the format you export when a CAD block needs to become a physical part. But importing a DXF into a laser cutter is less about the import click and more about preparing the file so the machine reads it the way you intend — closed contours, the right version, correct units, and colours that map to cut and engrave operations.

This guide works from the CAD side through to the machine. We'll cover exporting the right DXF version, closing the open contours that cause half-cut parts, getting the units right so the part comes out the size you drew, and assigning layers or colours so the laser knows what to cut, score and engrave. The example software is LightBurn and RDWorks, but the principles apply to any laser.

Step 1 — Export the right DXF version from CAD

Before the file ever reaches the laser, export it well. From AutoCAD use SAVEAS and choose an older DXF version — R12 DXF is the gold standard for laser work because it predates the complex object types that confuse simple controllers, leaving clean lines, arcs and polylines. ASCII DXF (the text default) is more widely read than binary.

R12 has no concept of true splines, so it approximates curves as short polyline segments or arcs — which lasers handle perfectly. The result is a lean, unambiguous file the cutter interprets without surprises. If your CAD or laser software offers it, R12 is almost always the right export; only step up to a newer DXF if R12 drops something you actually need.

Step 2 — Close open contours

Lasers cut along paths, and an open contour — where a shape's outline doesn't quite join up — cuts as a line that stops short instead of a closed part. This is the single most common laser-cutting problem, and it usually comes from lines that look joined on screen but have tiny gaps at the corners. Before exporting, clean the geometry: in AutoCAD use PEDIT to join segments into a single closed polyline, or use the JOIN command, and check there are no duplicate or overlapping lines (OVERKILL removes those).

A closed polyline is what you want for any shape that must be cut out fully. Overlapping or duplicate lines are just as bad the other way — the laser cuts the same path twice, scorching the edge. Spend the time closing contours in CAD and the cut comes out clean.

Step 3 — Get the units right

A part that comes out half size or double size is a units mismatch between the DXF and the laser software. The blocks here are drawn in millimetres, which suits laser work since most laser software thinks in millimetres. When you import into LightBurn, RDWorks or similar, check the import units setting and confirm the part's overall size matches what you drew — measure a known dimension in the software after import.

If the part imports at the wrong scale, the import-units setting is the fix, exactly as it is in every other CAD-to-software handoff. Some laser software offers a scale-on-import option; set it so a 100 mm edge reads as 100 mm. Confirming one known dimension after import takes seconds and saves a wasted sheet of material.

Step 4 — Assign colours or layers to operations

Laser software decides what to cut, score and engrave based on layers or line colours, so set these up so the machine knows your intent. The convention in LightBurn is colour-coded layers: put cut lines on one colour, score (light cut) lines on another, and engrave/fill areas on a third. In your CAD file, draw or move the different operations onto separate layers with distinct colours before exporting, and the laser software maps them to operations on import.

This is how one DXF can drive a multi-step job — through-cut the outline, lightly score the fold lines, engrave the text — all in one file. Decide the colour-to-operation mapping your laser software expects and assign your CAD layers to match, so the import lands ready to assign speeds and powers rather than needing a sorting pass.

Step 5 — Import and set cut order, speed and power

Now the actual import: in LightBurn use File > Import (or just drag the DXF onto the canvas); in RDWorks use File > Import. The geometry appears on the work area, sorted into layers by colour. Assign each layer its operation (Line/cut, Fill/engrave) and set the speed and power appropriate to your material and machine — these are machine- and material-specific, so test on scrap first.

Set a sensible cut order too: engrave and score before cutting, and cut inner holes before the outer perimeter, so small pieces don't drop out and shift while the laser is still working on them. Position the part within the bed, set the origin, and send the job. With the file prepared properly in the earlier steps, this final stage is just assigning machine settings to clean, correctly-scaled, closed geometry.

Common laser-import problems and fixes

A handful of issues account for most failed cuts. Parts not cutting all the way through usually means open contours (step 2) — the laser followed a line that didn't close. Wrong size means units (step 3). Double-scorched edges mean duplicate or overlapping lines — run OVERKILL in CAD before exporting. Curves cut as jagged facets means the DXF approximated splines too coarsely; export with finer arc/polyline tolerance or use R12 with a tighter setting.

Text that won't cut is a frequent surprise: laser software can only cut outlines, so text must be converted to geometry (exploded to polylines or set as outlines) before export — true text entities have no cuttable path. Sorting these out on the CAD side, before the file reaches the machine, is always faster than fighting them at the laser.

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Questions

Frequently asked

What DXF version is best for a laser cutter?+

R12 DXF (ASCII) is the standard for laser work. It predates the complex object types that confuse simple controllers, leaving clean lines, arcs and polylines that every laser software reads reliably. Export to R12 from AutoCAD's SAVEAS dialog.

Why does my laser cut a line instead of cutting out the part?+

The contour is open — the outline has a tiny gap and isn't a closed loop. Before exporting, join the segments into a single closed polyline (PEDIT or JOIN in AutoCAD) and remove duplicate lines, so the laser follows a continuous closed path.

Why is my laser-cut part the wrong size?+

It's a units mismatch between the DXF and the laser software. Check the import units (the blocks here are millimetres), and after importing measure a known dimension to confirm a 100 mm edge reads as 100 mm. Adjust the import scale if not.

How do I tell the laser what to cut versus engrave?+

Use layers or line colours. Put cut, score and engrave geometry on separate coloured layers in your CAD file before exporting; laser software like LightBurn maps each colour to an operation on import, letting one DXF drive cutting, scoring and engraving in one job.

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