How to Prepare a DXF or SVG File for Laser Cutting

A fiber laser follows your drawing exactly — right size or not, closed or not, cut or etch. This guide covers preparing a DXF or SVG for fiber laser cutting: scale, closed outlines, hole, slot and web sizes for the metal’s thickness, which lines cut and which etch, and the notes the quote raises before you order. Routed parts follow the same basics with a different tool; the CAD file prep guide covers those.

DXF or SVG: which to send

Either works. A DXF exported from CAD — Fusion 360, SolidWorks, Onshape, AutoCAD, Rhino — suits brackets, plates and other mechanical parts, because it carries real units and true arcs. An SVG from Illustrator, Inkscape or Affinity Designer suits signs, logos, lettering and decorative screens. The laser quote reads STEP models too. DWG and PDF files aren’t read directly, so export a DXF, and save Illustrator (.ai) artwork as SVG. Parts cut from tube are a separate, three-dimensional job: CNC tube laser cutting is quoted on request from a STEP model and a cut list.

Units and scale: make an inch mean an inch

A part cut at the wrong scale is scrap. Export at 1:1 — never “fit to page” or a plotted scale — and set the units on purpose:

• DXF: units travel in the file’s header, so set inches or millimeters before exporting. A DXF with no units is read as inches. One that only makes sense in another unit — smaller than a coin, or too big for any machine — is re-read in that unit, and the cleanup notes name both sizes so you can check.
• SVG: the size comes from the document’s width and height, so set the artboard to inches or millimeters. Without real units the drawing is read as pixels — 96 to the inch, or 72 for Illustrator’s exports — and the notes say which reading was used.
• After upload, “Size wrong?” on the part re-reads the whole file in millimeters, in inches or at a width you type, and every hole, cut length and price follows.

A ten-second check: note the part’s longest edge in your drawing program, then compare it with the size the quote shows.

Close every outline

The laser cuts closed shapes. An outline with a gap has no inside or outside, so it can’t be cut as a part. On upload the importer joins segments that meet end to end, closes hairline gaps and removes lines drawn twice, listing each repair; a gap too wide to bridge safely becomes an error that names it, and the part waits for the shop’s review before you can pay. The usual causes:

• Trimmed lines that stop just short of each other — run Join in AutoCAD or Illustrator, or join the end nodes in Inkscape, before exporting.
• Stacked shapes meant as one outline, like a rectangle drawn over a circle — merge them with Union or Unite so the laser cuts the combined shape.
• Construction lines, borders and title blocks on a cutting layer — delete them or move them to a layer named NO CUT. DXF dimension, note and non-plotting layers are skipped automatically.
• SVG clipping masks — a mask hides artwork on screen, but the cut follows the paths themselves, so trim the artwork to its visible shape. Hidden layers aren’t cut.

Holes, slots and webs scale with thickness

The beam pierces before it cuts, and its heat has to go somewhere, so thicker metal needs bigger holes, wider slots and more metal between cuts. The quote checks every feature against these rules for the metal and thickness you pick:

• Holes: make them at least about half the material thickness across; below that they can come out rough or out of round.
• Slots and narrow cutouts: no narrower than the material thickness, or the slug can tilt and jam instead of dropping free.
• Webs: leave at least the material thickness of metal between cuts, and between any cut and the edge. Thinner bridges warp or burn away — a common problem in dense decorative screens.
• Tiny parts: anything under 1″ both ways may stay attached by small tabs so it can’t fall between the bed’s slats; expect a nub to file off.

These are notes, not refusals: the part still prices, and the shop checks it before cutting. If a hole truly has to be smaller, etch a cross at its center and drill it afterward. For a threaded hole, draw the tap-drill diameter, not the thread size.

Kerf: draw the finished size

Kerf is the width of metal the beam removes — narrow on a fiber laser, a little wider in plate than in sheet. Don’t offset your drawing for it. The kerf is compensated when the job is programmed, with the beam running just outside each outline and just inside each hole, so parts come out at the size you drew. Offset the file yourself and the correction happens twice: parts small, holes large.

Fits still need clearance you draw: slots for tab-and-slot metal parts at the tab’s real thickness plus a little, and bolt holes at clearance size rather than the bolt’s exact diameter. Send parts as separate shapes in one file, not laid out on a sheet — the quote splits the file into parts and nests them with the laser’s own spacing.

Etch or cut: tell the file which is which

Every line either cuts through or marks the surface. Closed shapes inside a part are cut out unless you say otherwise. To mark instead — part numbers, logos, bend lines, assembly marks — put the lines on a layer named ENGRAVE or ETCH (SCORE works too). Open lines inside a part, such as a centerline or a signature, come in as etch lines on their own. The quote labels them “Etch line,” and you can switch any shape between cut and etch before you confirm the part.

An etch traces each line once, so outlined text etches as the outline of every letter — fine on sign lettering, faint on a small label. For part numbers, a single-line engraving font gives one clean stroke per character; explode it to lines before exporting. Cut-through lettering is the opposite problem: the islands in letters like O, A and R fall out with the scrap unless they’re bridged, which is what stencil fonts are for.

Text, images and strokes that don’t cut

• Live text isn’t geometry, so it isn’t cut; the cleanup notes list it as “Not cut.” Convert it with Create Outlines in Illustrator, Object to Path in Inkscape or TXTEXP in AutoCAD.
• Placed photos and bitmap logos aren’t cut — only vector paths are. Trace them, then delete the specks and doubled edges tracing leaves behind.
• A stroke is cut along its path, not its painted width. When the width is the design, use Outline Stroke in Illustrator or Stroke to Path in Inkscape.
• DXF shapes tilted out of the flat plane are reported as drawn in 3D and aren’t cut — flatten them, or upload the STEP model.

What the quote flags, and what to do

Every laser part is checked before it’s priced. Errors mean the part can’t be cut as drawn, so it waits for the shop before you can pay; everything else is a note the shop checks before cutting.

• “A laser cuts all the way through” (error) — pockets or dados, usually from a STEP model or a POCKET or DADO layer. Remove them, or make the part in wood or plastic on the CNC router.
• “Set to a depth” (error) — a blind hole. Make it a through-hole or remove it.
• “Small for … stock” or “narrow for … stock” — holes, slots or cutouts under the sizes above.
• “The metal between cuts is …” — a web under the rule; spread the features apart.
• “The outline isn’t closed” (error) — fix the gap and upload again, or send the part to an engineer from the quote.
• “Does not fit any … sheet we stock” — the bed takes parts up to 72 × 144″, but stock sets the real limit: today, 72 × 144″ in mild steel 3/16″ and thicker. Choose another metal or thickness, or split the part.

A pre-upload checklist

• 1:1 scale, units set, longest edge checked against the quote
• Outlines closed, overlaps merged, construction lines gone or on NO CUT
• Holes, slots and webs sized for the thickness
• Marks on an ENGRAVE or ETCH layer
• Text outlined, images traced, strokes expanded
• Finished sizes, no kerf offset, parts as separate shapes
• Any gauge callout converted to inches with the sheet metal gauge chart

Then upload the file to the laser quote. Each part shows its notes before it’s priced, and its price covers its cut length, each hole by its size, its pierces and any etched lines, plus setup and programming once per design, handling for each piece and loading for each sheet the job uses, with the metal billed by the area your parts use. Then you pay online once the shop confirms the price and pick up at the shop or get local delivery in the Las Vegas valley. Still choosing a metal? The metal guides compare them.