What File Formats Do You Need for a CNC Machining Quote?

The single fastest way to get an accurate CNC machining quote is to send the right files. The wrong format — or a 3D model without a drawing — leads to back-and-forth and delays. This guide explains exactly which file formats for CNC machining we accept, which to use, and why.

The short answer: send a STEP file (plus a 2D drawing)

For 99% of parts, a STEP file for the geometry and a 2D drawing (PDF) for tolerances is the ideal combination. STEP is a neutral, universal 3D format that every CAD system and CAM package reads reliably, so quoting and programming start immediately.

3D file formats for CNC machining

STEP (.step / .stp) — recommended

STEP (ISO 10303) is the industry-standard neutral 3D format. It preserves exact solid geometry, is software-independent, and is what our engineers prefer for accurate quoting and machining.

IGES (.igs / .iges)

An older neutral format that works well for surfaces and solids. Acceptable, though STEP is more robust for solid models.

Parasolid (.x_t / .x_b)

A high-quality solid-model format used by SolidWorks, NX, and others. Excellent fidelity and fully supported.

Native CAD (SolidWorks .sldprt, etc.)

We can often open native files, but exporting to STEP avoids version-compatibility issues and is always the safest choice.

STL (.stl)

STL describes geometry as a triangle mesh. It is fine for simple parts and 3D printing, but it loses exact dimensions and is not ideal for tight-tolerance CNC work. Use STEP when accuracy matters.

2D drawings: where tolerances live

A 3D model defines shape, but it does not communicate critical tolerances, GD&T, threads, surface finish (Ra), or inspection requirements. Provide a 2D drawing so we quote — and machine — exactly what you need:

• PDF — the easiest, most universal way to share a dimensioned drawing
• DWG / DXF — editable CAD drawing formats we also accept

Mark only the tolerances that matter; over-specifying tight tolerances everywhere raises cost unnecessarily. See our CNC machining services page for capability details.

What if I only have a sketch or a sample part?

No CAD file yet? We can still help. Send hand sketches with dimensions, photos, or a physical sample, and our team can assist with modeling or reverse engineering before quoting.

Tips for a fast, accurate quote

• Export 3D geometry as STEP
• Include a PDF drawing with critical dimensions and GD&T
• State the material grade, surface finish, and quantity
• Zip multiple parts together and label them clearly
• Note the application so we can recommend the best process

Ready to upload your files?

Send your STEP file and drawing on our Request a Quote page. Our engineers review manufacturability and return a quote with pricing and lead time — from a single prototype to low-volume production.