Choosing between 2D and 3D CAD isn’t about tools—it’s about how clearly your design communicates what really matters. The file you send decides who holds responsibility when something goes wrong—or when everything goes right.
We’ve seen it too many times. A customer uploads a part and assumes the job is done. But whether it's a clean DXF or a polished STEP file, what’s missing is rarely the file itself—it’s the intent.
When you only send a 2D drawing, you’re saying:
“Here’s the shape I want. You figure out how deep, how tight, how clean.”
When you only send a 3D model, you’re saying:
“This is what it looks like. I’ll assume you know which holes need threading and which dimensions matter.”
And when something is machined wrong—when your part arrives with the perfect geometry but the wrong fit—it’s not just a file issue. It’s a communication breakdown.
Some engineers prefer 2D because it's precise, controlled, and familiar. Every detail is labeled. Every edge is defined. There's comfort in the clarity. But here's the catch: CNC machines don’t read DXF files. People do.
And people—no matter how experienced—make assumptions.
We’ve machined “flat” plates with undimensioned holes, assuming through-holes, only to find out the customer wanted counterbores. We’ve received DXFs with perfect contours and zero thickness specs. These are avoidable mistakes—if you include intent, not just geometry.
Others lean into 3D. And we get it. A STEP file is clean. It loads directly into CAM. It defines volume, depth, even fillets. But it tells us nothing about priority.
Does that tapped hole need ±0.05mm? Or is it just cosmetic? Should this boss be reamed? Or is it just a mount?
Without a 2D drawing—or at least a note—these questions stay unanswered. And unanswered questions on a CNC floor usually become conservative guesses. That means more cost, more time, and sometimes, wrong assumptions.
The truth is, you’re not choosing between 2D and 3D—you’re choosing between guessing and being understood.
When you send both, something changes. Suddenly we’re not interpreting—we’re confirming. The 3D model gives us shape, and the drawing gives us priority. Together, they form a full conversation between you and the machine.
We’re no longer guessing about your design. We’re executing it.
Can I just send a 2D drawing?
Yes—for flat parts like brackets, plates, panels. But without thickness, depth, and thread notes, mistakes happen easily. We always recommend adding a 3D model if available.
Is 3D enough on its own?
No. A STEP file shows shape, but not tolerances, material specs, threads, or surface finish. You still need to clarify what matters.
Why do shops ask for both?
Because 2D and 3D serve different purposes. One shows geometry. The other shows intent. Together, they reduce risk and speed up machining.
What if I only have STL?
STL is not ideal. It’s faceted, lacks units, and isn’t editable. We’ll try to help—but STEP is much safer.
Not sure what to send?
Send what you have. We’ll review it and help you improve it. Better to clarify now than to remake the part later.
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How to prepare a CNC drawing properly →
Use our ISO Tolerance Calculator →
If you truly want to avoid mistakes, miscommunication, and unnecessary cost:
Send both. Save time. Be understood.
Whether you're designing a flat aluminum plate or a complex 5-axis part, 2D and 3D files are not competitors—they’re teammates. The best outcomes come when they work together.
And if you’re not sure what to include, talk to us. We’ll guide you through it. Not because it’s our process—because we’ve seen how easy it is to get it wrong when you guess.
This article was written by the EKINSUN CNC team, based on real conversations with customers across aerospace, hardware, medical, and rapid prototyping industries. We’ve reviewed over 10,000 part files, and what we’ve learned is simple: files don’t make parts—clarity does.