A good DXF for laser cutting is drawn at 1:1 in millimetres, has closed outlines, and contains only the lines you want cut. Get those three right and most files go straight from your inbox to the machine.
Get them wrong and the job stalls. Someone has to email you to ask whether that 25 is millimetres or inches, why there are two lines on top of each other, or whether the title block is meant to be cut out of steel. This guide walks through the checks we'd do on your file anyway, so you can do them first and get a price sooner.
Why the DXF matters so much
A laser cutter doesn't read your drawing the way a person does. The cutting software takes every line in the file as a path for the beam. A dimension line is a cut. A border is a cut. Two overlapping lines are two cuts, which burns the edge.
So a DXF that looks fine on screen can still be a bad cutting file. The goal is a file where every line is a real edge of the part, and nothing else.
Set the scale and units first
Draw the part at full size, in millimetres. South African suppliers buy and sell sheet in millimetres, and that's what the cutting software expects.
Two common traps:
- Exported in inches. A 100 mm plate becomes a 2,540 mm plate, or a 3.9 mm one, depending on how the software guesses. Check the export settings and the units in the file header.
- Exported from a scaled layout. If you export from a drawing sheet at 1:5, everything comes out a fifth of the size. Export from model space, or the part itself, not the printed sheet.
A quick sanity check: measure one known dimension in the DXF before you send it. If your 120 mm bracket measures 120 mm, you're good.
Clean up the geometry
This is where most files need work.
Close every outline
Every cut shape should be one closed loop: the outside profile, and each hole or slot. Tiny gaps where two lines nearly meet are the classic problem. The software sees an open shape and doesn't know which side is scrap. Join lines into polylines, or use your CAD program's "join" or "close" command.
Delete duplicates and overlaps
Imported files, especially ones that have passed through a few programs, often have lines stacked on top of each other. The laser will cut the same edge twice, which leaves a rougher, burnt edge and wastes time. Use an "overkill" or "delete duplicates" tool if your CAD has one.
Convert splines where you can
Freeform curves (splines) can come through as hundreds of tiny segments or odd shapes. If your CAD lets you convert splines to arcs and polylines, do it. Text and logos are the usual culprits.
Remove everything that isn't a cut
Delete dimensions, centre lines, hatching, notes, title blocks, and borders. If you need to send that information, put it in a separate PDF. The DXF should just be the part.
Check your features against the material
A clean file can still describe a part that won't cut well. Before you send it, look at the smallest features.
- Holes: a good starting rule is a hole diameter at least equal to the material thickness. A 2 mm hole in 3 mm steel is pushing it. More on that in our guide to minimum hole sizes for laser cutting.
- Narrow slots and webs: keep them at least one material thickness wide.
- Features near edges: keep holes and slots at least one thickness away from the edge, or the thin bridge can distort.
- Tight inside corners: the beam has a width, so a perfectly sharp inside corner will have a tiny radius. If a square part has to fit into that corner, add a small relief.
Draw everything at finished size. Don't try to offset lines for the laser beam yourself. The cutting software already compensates for the kerf, and doing it twice makes holes too big.
One part per file, or clearly separated
If you're ordering several different parts, either send one DXF per part or space them out clearly in one file with a label next to each in your PDF. Name files so they make sense: bracket-left-3mm-ms-qty20.dxf tells us more than Drawing1.dxf.
For parts that will be bent, a flat DXF alone can be ambiguous. Mark the bend lines on a separate layer, or send a STEP model of the folded part too. Our post on DXF, DWG, STEP, and PDF files explains when each one is the better choice.
A quick pre-send checklist
- Drawn at 1:1, in millimetres
- One known dimension measured and correct
- All outlines closed
- No duplicate or overlapping lines
- No dimensions, text, borders, or title blocks (unless text is meant to be cut)
- Holes at least material thickness, webs at least one thickness wide
- Bend lines on their own layer, or a STEP file included
- A sensible file name with material, thickness, and quantity
Sending it to us
Upload the DXF on the quote form along with the material, thickness, and quantity. The form takes DXF, DWG, STEP, PDF, or a photo up to 10 MB. Larger files can go to ctrlcutsa@gmail.com.
If you're not sure your file is clean, send it anyway and say so in the notes. It's quicker to sort out a question at quote stage than after the sheet is cut. Start a laser cutting quote, or read more about our laser cutting service.