CAD to CNC

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You’ve got your CAD design. It looks great on screen, tight tolerances, clean geometry, ready to go. But now what? How do you actually turn that file into a real, CNC-machined part? If you’re staring at your .STEP, .DWG, or .DXF file wondering what the next move is, you’re not alone.

This guide breaks it all down: how to prep your CAD file, what CNC machines really need, and how to go from digital design to precision-machined reality, without wasting time, money, or materials.

What Is CAD to CNC, Really?

Let’s start with the basics.

CAD (Computer-Aided Design) is where your design lives. It’s the 2D sketch or 3D model that defines shape, size, tolerances, holes, and curves. Popular CAD programs include AutoCAD, Fusion 360, SolidWorks, and TinkerCAD.

CNC (Computer Numerical Control) is how that design gets made. A CNC machine cuts, drills, or mills your part from metal or plastic based on digital instructions.

So, when we say “CAD to CNC,” we’re talking about the full workflow: from designing on your computer to holding a physical part in your hand.

Who This Guide Is For

● Product designers who need to turn prototypes into precision metal or plastic parts.

● Mechanical engineers prepping files for CNC machining vendors or in-house teams.

● Manufacturing professionals optimizing design-for-machining workflows.

● Startup founders working on hardware MVPs and unsure how to bridge CAD and CNC.

● Anyone stuck with a CAD file and no idea how to get a perfect part made.

If you’ve ever thought, “I have the design, now how do I get this thing machined?”, this guide is written for you.

Step-by-Step: How to Convert Your CAD File for CNC Machining

1. Start with a Solid 3D Model

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Your design begins in CAD software. Some popular choices:

● AutoCAD – Great for 2D profiles and mechanical layouts

● Fusion 360 – Excellent all-in-one CAD/CAM option

● SolidWorks – Professional-grade modeling with precise tolerance control

● Rhino / TinkerCAD – For more artistic or entry-level needs

Make sure your design has no open surfaces or geometry errors. Clean models mean fewer machining problems later.

2. Export the Right File Format

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What files do CNC machines use?

CNC machines don’t use CAD files directly. You need to export your design into a format they understand.

The most common file types are:

● STEP (.step/.stp) – Universal, reliable, great for CNC machining

● IGES (.iges/.igs) – Also common, but slightly older

● STL – Mostly used for 3D printing, not ideal for CNC

● DXF – For 2D CNC cutting like laser or plasma

● DWG – Native AutoCAD files (often converted to DXF)

Pro Tip: If you're going from AutoCAD to CNC, exporting to DXF or STEP is usually your best bet depending on whether it's a 2D or 3D design.

3. Convert CAD to G-code (Toolpath Creation)

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CNC machines don’t read CAD files, they read G-code.

G-code is the language that tells the machine how to move, cut, mill, or drill. This is where CAM (Computer-Aided Manufacturing) software comes in.

For a deeper dive into specific commands, check out our detailed guide on G-Code 3D Printing Commands: Tutorial, List & How to Use Them.

Some tools for generating G-code:

● Fusion 360 (with CAM built-in)

● Mastercam

● SolidCAM

● AutoCAD with plug-ins

● FreeCAM, Carbide Create, or VCarve for simpler tasks

Using this software, you define:

● Tool paths

● Feed rates

● Spindle speeds

● Cut depth and direction

This is where design meets reality, get it wrong, and your part will too.

4. Send It to the CNC Machine

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Once you’ve got your G-code, it’s time to load it into the CNC machine’s controller (like Mach3, LinuxCNC, or proprietary systems). The machine reads the code line-by-line and starts cutting your part.

That’s it, you’ve officially gone from CAD to CNC!

CAD Software & CNC Machine Compatibility

Not all CAD software plays equally well with CNC machines. Here’s a quick compatibility chart:

If you're asking, "How do I create CNC files from AutoCAD?", you'll usually go

AutoCAD → DXF → CAM software → G-code.

How JLCCNC Helped a Startup Resolve CAD Confusion

One of our recent clients came to us with a complex CAD design but no idea how to turn it into an actual CNC-ready part. His team had just finalized their CAD designs for a custom heat sink, a crucial component of their IoT device, but every local machine shop he contacted either asked for a different file type, didn’t respond, or quoted vague timelines.

“We had our STEP files ready, but no idea what post-processing we needed or even how to prepare toolpaths. Every hour wasted was costing us our launch.”

Meet JLCCNC.

We stepped in, reviewed his files the same day, and ran a manufacturability check at no extra cost. Within 48 hours:

● We optimized the design for machining (DFM)

● Suggested better tolerances for his use-case

● Selected the right aluminum grade

● Provided an instant quote and production schedule

Within 7 working days, Zain had 15 CNC-machined prototypes on his desk, fully functional, finished, and packaged.

Why It Worked

Zain wasn’t just paying for a machine, he got:

● Design guidance from engineers who speak CAD fluently

● Instant access to production without buying machines or hiring staff

● Real-time updates and local support he couldn’t find on generic outsourcing platforms

You Might Be in the Same Spot

If you’ve got:

● CAD files but no idea how to get a quote

● Confusion about formats (.STEP vs .IGES vs .STL)

● Parts too complex for your home CNC setup

● Or you're just tired of ghosted DMs from unreliable vendors...

JLCCNC is your shortcut from design to reality.

We’re not a passive machine shop. We’re a partner in your process, whether it’s one part or one thousand.

Send us your CAD file today and get a free manufacturability review.

FAQs:

Q: What files do CNC machines use?
CNC machines use G-code, which is generated from CAD designs via CAM software. The intermediate files are typically STEP, IGES, DXF, or STL (for 3D printing).

Q: Can I go directly from AutoCAD to a CNC machine?
Not directly. You’ll need to export your design (usually as a DXF file) and run it through CAM software to generate the G-code.

Q: How to create CNC files from CAD?
Use a CAM program to convert your CAD model into toolpaths and then export it as G-code. Fusion 360 is a popular choice because it combines CAD and CAM in one.

Q: What is the best CAD to CNC software?
For beginners, Fusion 360 is ideal. It has built-in CAM and supports direct export to G-code. For professionals, SolidWorks + SolidCAM is robust and customizable.

Q: What are CNC files?
CNC files are typically G-code files (.nc or .tap extensions) that tell the CNC machine exactly how to move and cut.

Final Thoughts

Doesn’t matter if you're using AutoCAD, Fusion 360, or any other design software, turning your idea into a real machined part is more achievable than ever. Understanding the flow, from CAD software to CNC machine, puts you in control of accuracy, speed, and cost.

And if you don’t want to deal with CAM or post-processing? We can help. Just send us your CAD file, and we’ll handle the toolpaths, materials, and precision machining from start to finish.

Ready to turn your design into metal or plastic?

Contact us with your CAD file, we’ll make sure it gets CNC’d with precision.