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3DM STEP
Free online converter

Convert 3DM to STEP

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3DM to STEP converterFREE
Drop a .3DM file here
or pick one - we convert it to .STEP and give you the file to download

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Tested on macOS, Windows & Linux
Last verified Oct 2026

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How to convert 3DM to STEP

  1. Add your .3DM file - drop it in the box above or click to browse.
  2. Convert it to .STEP in a few seconds.
  3. Download your new .STEP file.

What to expect

  • NURBS solids transfer exactly; any mesh objects inside the .3dm export as tessellated faces, which some CAD tools may import as surface bodies rather than solid bodies.
  • Layers, display colors, render materials, and text annotations are not carried into STEP - only solid geometry and topology transfer.
  • STP and .step are the same format; rename the extension if a downstream application requires one spelling or the other.

Frequently asked questions

Does STEP preserve Rhino surface quality?
Yes. STEP stores NURBS geometry natively, keeping the exact mathematical definition of every surface - unlike STL or OBJ, which approximate surfaces as triangles.
Can I convert 3DM to STEP without buying Rhino?
Yes - use the free converter above, or Autodesk Fusion 360's free personal tier, which imports .3dm and exports .stp.
Why does the STEP file import as surfaces instead of solids in SolidWorks?
The source .3dm had open surfaces rather than fully closed shells. In Rhino, run ShowEdges with 'Naked Edges' to find the gaps, close them, then re-export.
Should I use STEP or IGES when exporting from Rhino?
STEP (AP214) is the safer default - it carries richer data and is accepted by all current CAD importers; use IGES only if a specific tool requires it.
Learn about the formats: .3DM · .STEP
Programs that convert 3DM: 3D Object Converter · CrossManager · TurboCAD · Autoconverter · TurboCAD for Mac · Autodesk Fusion 360