3D File Formats: A Practical Guide for SolidWorks Teams

The rule that decides everything

Native formats keep the intelligence. Neutral formats travel.

A native file carries features, history and parametrics, and needs the software that wrote it. A neutral file carries geometry and little else, and opens almost anywhere. Choose based on what the recipient will do with it, not on what is convenient to export.

SolidWorks: .sldprt, .sldasm, .slddrw

• Used by: mechanical engineers and product designers
• What they are: .sldprt is a part, .sldasm assembles parts into a product, .slddrw is the 2D drawing that documents it
• Strength: full design intent — features, mates, references, configurations
• Watch for: an assembly is not one file. Send the .sldasm without its parts and the recipient gets an error, not a model. Large assemblies also carry real file sizes, and newer versions do not open in older ones

To convert: open the file, File > Save As, and pick from the list — STEP and IGES for engineering, STL for print, DWG or DXF for 2D. Check the options dialog before you save; the defaults are not always what you want.

AutoCAD: .dwg and .dxf

• Used by: architects, engineers and drafters
• What they are: .dwg is AutoCAD's native drawing format; .dxf is its interchange cousin, designed to move between programs
• Strength: 2D documentation, and near-universal support
• Watch for: version compatibility. A newer .dwg may not open in older software, and .dxf is the safer choice when you do not know what the recipient runs

To convert: File > Save As, then pick the format. PDF is usually the right answer for someone who only needs to read the drawing.

Rhino: .3dm

• Used by: industrial designers and architects
• What it is: Rhino's native format, built around NURBS surfaces
• Strength: complex freeform surfaces and conceptual work, where the curve matters more than the feature tree
• Watch for: it carries surfaces, not manufacturing intent. Concepts usually get rebuilt on the engineering side

To convert: File > Save As for CAD formats, or Export for everything else. STEP is the right handoff to an engineering team; STL or OBJ for visualization and print.

3ds Max: .max

• Used by: game developers, visual effects and visualization artists
• What it is: a full scene — models, animation, materials, lighting
• Strength: presentation and animation
• Watch for: it is mesh-based, so it is not an engineering format. Nobody manufactures from a .max file

To convert: File > Export or Export Selected, then FBX, OBJ or STL depending on where it is going.

CATIA: .catpart and .catproduct

• Used by: aerospace, automotive and industrial engineers
• What they are: .catpart is a component, .catproduct is an assembly of them
• Strength: very large, very complex assemblies with high precision requirements
• Watch for: if a supplier sends you these and you run SolidWorks, ask for STEP instead of trying to open them

To convert: Save As or Export, then STEP or IGES for engineering, STL for print.

Blender: .blend

• Used by: animators, 3D artists and game developers
• What it is: an entire scene in one file — models, animation, textures, render settings
• Strength: flexibility, and it is free
• Watch for: mesh geometry again, so it belongs to visualization rather than engineering

To convert: select what you want, File > Export, then FBX, OBJ, STL or Collada.

The neutral formats: .step, .stl, .obj, .fbx

These are what you actually send.

• STEP — the engineering exchange format. Solid geometry, accurate, readable by every serious CAD system. This is what a machine shop or a supplier wants
• STL — triangulated surface mesh, the standard for 3D printing. No units, no colors, no intelligence, and once you are here you cannot go back
• OBJ — mesh with materials and textures, common in graphics
• FBX — mesh with animation, used in games and visualization

The one-line version: STEP to build it, STL to print it, OBJ or FBX to show it.

When you do not have the software

You can still convert.

• Online converters handle the common formats quickly. Check what happens to your file after upload before you send anything under NDA
• Free and open-source tools cover DWG, DXF and most mesh formats
• Conversion services exist for the specialist formats, and are worth it when the geometry has to survive intact

Seven rules that save a week

• Ask the recipient what they open before you export anything
• Send an assembly with all its parts, or send STEP instead
• Check units after conversion, every time
• Keep the original. Conversion is one-way in practice
• Expect to lose the feature tree the moment you leave the native format
• Include a short note saying what the file is and what version it came from
• For review rather than manufacture, do not send a file at all

That last one

Most of the formats above exist because someone needs to open a design in different software. If all they need to do is look at it and tell you what is wrong, a link does the job without a conversion.

Sibe keeps the SolidWorks files themselves under version control — engineers check in and out directly in SolidWorks, and every version is recorded — while reviewers open the current model in a browser and pin comments to the geometry. No format decision, no license, no account.

No servers, no VPNs, no admin hassles.

Book a free 20-minute demo.