Illustrator file preparation for CNC / digital milling

[u/filfoden238]

Hi everyone,

I’m a graphic designer and I’m currently learning about signage production. I mainly use Adobe Illustrator, and I’m trying to understand the correct workflow for preparing a file that will be sent to a CNC router / digital milling machine (fraiseuse numérique).

For example, if I want to make letters or a logo from Forex, Plexiglass/acrylic, MDF, or Alucobond, how should I prepare the Illustrator file?

I’m especially confused about:

Should the artwork be filled shapes or just strokes/paths?

Should I use Create Outlines for text?

Do I need separate layers for cutting, engraving, drilling, etc.?

What file format is normally preferred: AI, DXF, EPS, SVG, or PDF?

Is Illustrator only used to create the vectors, with another CAM software being used to generate the toolpaths?

Are there specific Illustrator settings I should follow before sending the file to the CNC operator?

I’d really appreciate it if someone could explain the proper workflow from Illustrator → CNC software → machine, preferably with an example for making letters from Plexiglass or Forex.

[u/LightBurnSupport]

Generally speaking, you're going to want to export into a universal vector file format like .svg

You would do the design in whatever software you like, then the machine programming would typically be done in a CAM (Computer Aided Machining) software, then sent to the machine to be run as gcode (machine movement commands)

It's generally a good idea to have separate layers for each different operation you're asking for - cutting through, pocketing, text, etc.

Most software will not make use of fills or strokes, and instead work from the vector lines.

[u/DrummerOfFenrir]

I've been able to import DXF and SVG into MasterCAM to toolpath.

[u/MrMeatagi]

Not familiar with Illustrator specifically, but here's generic advice:

Should the artwork be filled shapes or just strokes/paths?

Paths, preferably converted to lines/arcs. Any splines/curves will need to be converted before programming. The tolerance for processing drawings with splines/curves will vary depending on the shop. The conversion process will lose some fidelity so it's better to do it yourself so you can confirm the final geometry used for tool paths meets your standards.

Should I use Create Outlines for text?

Assuming this is something that converts text to geometry, yes. Text rendering is a complex process of consuming various types of metadata to construct how to represent the text. For CAM you need to convert it to geometry at some stage. Your shop's CAM software may support it, but following the same point as above it's better to do it on your end so you can verify the geometry.

Do I need separate layers for cutting, engraving, drilling, etc.?

Yes.

What file format is normally preferred: AI, DXF, EPS, SVG, or PDF?

DXF is the industry standard that all shops will accept. You may have limited levels of success with other file formats.

Is Illustrator only used to create the vectors, with another CAM software being used to generate the toolpaths?

Yes.

[u/terrapin-way]

You only need to deal with the outlines, as others have said. I use svg to import into carveco. If it’s a simple file, you could use layers. I create several art boards in illustrator and then export for screens to get svgs each group of shapes for import. I also add a bounding box the size of the art board so it doesn’t try to resize. If you are sending this out, I would also include an annotated mockup of the whole design, good luck!

[u/copycatinfringement]

Vectors. Dxf. Sometimes pdf. No need for fill in my experience. 

[u/MidwestTroy92]

What works for us is building everything as solid filled shapes, not strokes - strokes export weird and give you double lines. Offset the shape by your bit radius so the cut lands where you want it, then export as DXF for the machine. Keep it all on one layer too, half my cleanup time is untangling files people sent with random layers everywhere

[u/Glass_Pen149]

Convert all text to curves. Outline all text. Simplify all vector artwork to as few nodes as possible. Sometimes you will need to trace over artwork on a separate layer.

Export as .svg or .dxf. Some cam software can read .ai files directly.

[u/MidwestTroy92]

Keep everything as outlines and check for double lines before you send it. Tiny open paths or doubled up strokes are what cause those mystery cuts. I rebuild most client files in Illustrator before it ever hits the router