What does DXF mean in fabrication?

DXF stands for Drawing Exchange Format, and Autodesk introduced it with the first version of AutoCAD in 1982 so other programs could read AutoCAD drawings, and almost every CAD, CAM and quoting program can open one today.

A DXF is usually saved as plain text. Inside, it holds:

• geometry: lines, arcs, circles, polylines and splines
• layers that group the geometry, often by purpose (cut, bend, etch, dimensions)
• text, dimensions and title blocks, if the drafter left them in
• header settings such as the drawing units

What a DXF doesn't reliably carry is the job information. Material, grade, thickness, quantity and finish might appear as text notes on the drawing or not at all, so they usually arrive in the email or on a PDF of the drawing.

How is a DXF file used?

In a profile cutting shop, the detail in the DXF drives the pricing and material requirements for the job, and once the order is placed, the programmer imports the same file into CAM software, nests it onto a sheet and generates the toolpath the machine follows.

A few practical points come up again and again:

• DXF vs DWG: DWG is AutoCAD's own binary format. It holds the same geometry in a much smaller file, so it's worth asking for a DWG if a DXF is too big to email or upload.
• Versions: DXF files are saved in versions tied to AutoCAD releases (R12, 2000, 2018 and so on). If older CAM software won't open a file, ask for it saved as R12 or 2000.
• Units: a DXF may or may not record its units. A part drawn in inches and read as millimetres comes out 25.4 times too small, so check one known dimension on every new file.

Why does a DXF file matter?

The DXF is the starting point for both the price and the part, so its quality decides how much work happens before either is right. A clean file can go from inbox to quote in minutes. A messy one needs cleaning first, and if the mess isn't spotted, it inflates the quote or causes problems on the machine.

The usual problems:

• duplicate lines stacked on top of each other, which double the cut length and can make the laser cut the same path twice
• open contours, where lines don't quite meet, so the shape can't be cut as one closed path
• title blocks, dimensions and notes mixed in with the cut geometry
• several views of the same part (top, side, section) that look like extra parts
• text that hasn't been converted to outlines, which most CAM software can't cut
• bend or etch lines on unclear layers, so it isn't obvious which lines get cut

What makes a DXF laser-ready

A DXF that can go straight to quoting and cutting has:

• the part drawn at 1:1 scale, in stated units
• only the geometry to be cut, etched or bent, with nothing else in the file
• closed outer and inner profiles, with no gaps or overlaps
• no duplicate or overlapping lines
• each part separate, with no parts drawn inside other parts' cut-outs
• text converted to outlines (sometimes called exploding text or converting to curves)
• bend and etch lines on clearly named layers, such as BEND or ETCH

Ask customers for a PDF of the full drawing as well. It carries the dimensions, notes, material and finish that should be kept out of the DXF itself, and it's the reference when a dimension in the file looks wrong.

DXF files and quoting

A quote is only as accurate as the DXF it's measured from. Measure a file with duplicate lines and a title block still in it, and the cut length and pierce count come out high, along with the price. Clean it up by hand first, and every quote waits on whoever knows CAD.

Tempus Tools quotes straight from DXF and DWG files. Its Drawing Doctor finds and fixes the common problems, such as double lines, leftover dimensions and tiny gaps between line ends, before the part is priced, so the cut length and pierce count come from the geometry that will actually be cut.

Further reading: What is a DXF file? A practical guide for laser cutting and fabrication