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How to: exchange files with other CAD software

The point of a B-Rep kernel is that the geometry survives the trip. This page is the practical checklist for getting a part out to SolidWorks, Fusion, Rhino or FreeCAD — and for bringing one back.

Import and export is the reference for the same features. This page is about the decisions around them.

Before you model: work in millimetres

STEP export writes 1 Blender unit as 1 mm, and there is no option to change it. A 10-unit box arrives as a 10 mm box.

Decide this before you build, not afterwards. There is no export scale to compensate with, and rescaling a finished feature tree means retyping every dimension.

Getting a part out

  1. Finish the model
  2. Optionally add Cleanup (Unify) as the last entry in the tree
  3. Quality & Export > Export > STEP

Cleanup merges coplanar faces, which gives the recipient a tidier model — one face where you had three. It is worth doing, and it is worth doing last: merging faces destroys the face identities that Fillet, Offset, Shell and Draft refer to, so an entry below it can break. See How it works.

Display quality settings do not matter here. STEP carries exact surfaces, not triangles, so Linear and Curvature have no effect on the file.

What the recipient will not get

Say this up front and you will save a round trip:

  • No part names — entities are unnamed
  • No colours
  • No assembly structure — the file is flat

The geometry is exact and correct. The metadata is simply not written. If someone needs a named, coloured, structured assembly, this export does not meet that need yet. See Known limitations.

Test against the actual target

If a specific application matters, open the file in that application before sending it.

"It opens in FreeCAD" is a weak test worth distrusting: FreeCAD accepts files that stricter systems reject. It tells you the file is not badly broken. It does not tell you SolidWorks will take it.

Bringing a part in

Quality & Export > Import > STEP, accepting .stp and .step.

The dialog's one option is Scale:

Source Scale
A file authored in millimetres 1.0
A file authored in metres, to keep 1 unit = 1 mm 0.001

Each solid in the file becomes its own Feature Tree entry named STEP Part …. The first one into an empty part gets Base; the rest get Add (Fuse).

Imported entries are ordinary tree entries. You can move them, change their Operation, cut them with booleans, and fillet their edges like anything else — what you cannot do is edit the parametric history of the original, because a STEP file does not carry one. It arrives as finished geometry.

The scale you chose is stored with the entry, so reloading stays consistent.

Bringing in a 2D profile

Quality & Export > Import > SVG brings in outlines, also with a Scale option. Use it when the profile already exists as artwork — a logo, a laser-cut outline, a drawing traced in Illustrator or Inkscape.

Once imported, the profile behaves like any other curve: extrude it, sweep it, loft it, or revolve it.

Going to Blender instead

If the destination is a renderer, a game engine, or anything that reads glTF, FBX or OBJ, do not export STEP. Bake to Mesh first, then use Blender's own exporters on the result.

Enable Use High Quality Bake before baking if the mesh is for a render — it re-tessellates finely rather than reusing your working display quality.

Remember that a bake is a snapshot. Change the model afterwards and you must bake again; the existing SeamlessBake object does not update.

Checklist before you send

  • [ ] Dimensions are in millimetres as Blender units
  • [ ] Cleanup (Unify) is the last entry, if you used it
  • [ ] The file opens in the recipient's actual software
  • [ ] The recipient knows there are no names, colours or assembly structure
  • [ ] For rendering rather than CAD, you baked instead of exporting

See also