Overview#
Every exchange loses something. The skill is knowing what, detecting the loss before it costs money, and planning the workflow so the loss is irrelevant. This page catalogs the losses format by format, then turns to the related practical problem of large files: the multi-hundred-megabyte assembly, the ten-million-triangle scan, the machine with ten thousand fasteners.
Large files and data loss belong together because the usual remedy for one (simplify, split, export a lighter format) creates the other.
Where to find it#
| Need | Where |
|---|---|
| Check what arrived | Browser tree, Inspect > Properties, Inspect > Measure |
| Detect geometry problems | Inspect > Section Analysis, Zebra Analysis, Curvature Comb (surface section) |
| Reduce an assembly | Right-click components > Isolate, Suppress (via visibility), or Save As to new design |
| Reduce a mesh | Mesh workspace > Reduce, Remesh |
| Simplify before export | Create a copy design, delete internals, fasteners, small features |
| Job and file status | Data Panel Job Status |
| Performance settings | Preferences > General > Performance / Graphics (labels vary); verify in your version |
Step by step#
An audit procedure for any exchange#
- Before export, record reference numbers: volume, surface area, bounding box, component count, face count if you can, and two or three key dimensions. Inspect > Properties provides most of these.
- Export using the best-fit format.
- Re-import into a blank design, in the same units.
- Compare the numbers. Volume within about 0.01 percent for solids is a typical bar for BRep exchange; meshes depend on refinement.
- Visually compare with Section Analysis through the same plane in both. Overlay if you can by placing both in one design with different appearances.
- List what is missing: colors, names, sketches, joints, parameters, threads, text.
- Decide: accept, fix on the sender's side, or choose another format.
Handling a very large assembly#
- Work out why it is large. Count components and bodies. Are there thousands of fasteners? Imported threaded geometry? Meshes mixed with solids? Full internal detail on purchased components?
- Ask the sender for a simplified version (envelope or outer shell) if you only need fit checks. Many vendors provide "simplified" or "shrinkwrap" models.
- Upload by sub-assembly. Upload each sub-assembly folder separately so a failure affects one job, not all.
- After import, restructure. Create a new top-level design. Insert the sub-assemblies as external references so they load on demand rather than as one monolith.
- Use Isolate and visibility during work. Only show what you need.
- Turn off expensive display features (shadows, ambient occlusion, reflections) in the Visual Style while modeling. Verify the setting names in your version.
- Save often, and keep local backups (export F3D archives) before heavy operations.
Handling a huge mesh#
- Insert the mesh into an otherwise empty design.
- Open the Mesh workspace and run Reduce to a target triangle count or percentage. For viewing, a few hundred thousand triangles are plenty; for conversion, aim lower still.
- Repair after reducing.
- If you need only a region, use Plane Cut or split the mesh and keep the part you need.
- Avoid converting the whole thing to BRep. Convert portions, or use the mesh as a reference.
Dividing an export#
- Export subassemblies individually rather than one monster file.
- If the target system cannot open a single STEP over some size, set up logical groupings (frame, drivetrain, cover) and export each.
- Provide an assembly index (a spreadsheet or PDF) with positions so the receiver can recombine.
Options reference#
What is lost, by format#
| Format | Typically preserved | Typically lost |
|---|---|---|
| F3D / F3Z (to Fusion) | Everything | Nothing within Fusion; F3Z needed for external references |
| STEP | Exact geometry, assembly structure, names, colors | History, parameters, joints, sketches, cosmetic threads, render appearances |
| IGES | Surfaces, curves | Solid identity (often arrives as surfaces), assemblies, colors can be unreliable |
| SAT / SMT | Exact geometry, some attributes | History; some color and name data; kernel version issues |
| STL | Triangles | Units, color, curvature, structure, names |
| OBJ | Triangles/quads, UVs, materials | Units, precision, BRep information |
| 3MF | Triangles, units, color, material references | Exact curvature, history |
| DXF | 2D curves, layers, text | Constraints, dimensions as parametric objects, splines may become polylines, true units |
| DWG | As DXF plus richer styles | Same; plus version limits |
| SVG | Paths, fills | Units, scale, text fonts, constraint intent |
| Visual drawing | Editable geometry; vector data may import poorly | |
| Vendor native (import) | Geometry, assembly structure | Feature tree, constraints, configurations, custom data variably |
Large file controls#
| Control | Effect | Notes |
|---|---|---|
| Mesh Reduce | Fewer triangles | Lossy; keep the original |
| Mesh Refinement on export | Triangle density | Match to purpose |
| Component visibility / Isolate | Fewer objects drawn | Does not reduce file size, only draw load |
| External references | Load by reference | Requires that referenced files stay available |
| Design history capture | Parametric timeline versus direct modeling | Turning off history (Do not capture design history) lowers overhead for imported data; verify option names in your version |
| Simplified exports | Remove internals before export | Manual step; high payoff |
| Graphics hardware | GPU and RAM | Large assemblies are memory-bound |
Specific data-loss scenarios#
Cosmetic threads. Fusion hole features with thread settings typically store thread as data on the face; many exchange formats do not carry it. The receiver sees a plain hole of the minor or nominal diameter. Add a note or a drawing callout. If a receiver needs modeled threads, they are real geometry and heavy.
Parameters and equations. Gone outside F3D. If a supplier needs to size variants, supply a table of dimensions, or hand them the Fusion design.
Tolerance and PMI. Fusion exports geometry, not semantic GD&T, to common STEP. Provide a PDF drawing.
Colors and appearances. Face colors tend to survive; textures and PBR properties do not. Name materials in a note.
Sheet metal. Bends become plain geometry. Provide DXF flat patterns and a bend table separately.
Joints. Position survives; relationships do not. Document the intended motion.
Names and metadata. Some translators drop part numbers and descriptions. Verify after import.
Mesh precision. Meshes cannot get back curvature once lost.
Sketch constraints in DXF. The receiver gets lines and arcs without dimensions or constraints. Splines may degrade to short segments.
Text. Fonts can differ; export text as geometry (outline) when exact appearance matters. Verify in your version.
Units. STL and OBJ have none; DXF's can be wrong.
Versioning. Newer native file versions cannot always be opened by older software, and the cloud translator supports a bounded range of vendor versions. Verify in the current supported-versions help.
Tips and pitfalls#
Tip: Keep an "export recipe" document per recipient: format, options, units, notes. Repeating an export becomes a one-minute task.
Tip: When a file refuses to open, try a different route: native instead of STEP, STEP instead of IGES, a repaired file from the sender, or an older version. Save the error text.
Tip: For persistent crashes on huge data, split the file and work on parts. Memory pressure is the likely cause; check how much RAM and GPU memory you have against the file's complexity.
Warning: Do not simplify a design in place. Simplify a copy. Deleting internals from your master design to shrink an export is a mistake you will make exactly once.
Warning: A mesh reduce followed by a conversion followed by a re-export compounds error. Keep the chain short.
Warning: Cloud translation and large uploads depend on your network. A dropped connection mid-upload can leave a partial job; confirm in Job Status and re-upload if needed.
Warning: Archiving: if you store only STEP or STL as the record of a design, you have lost the ability to edit it. Archive F3D as well.
Practice exercise#
- Pick a design with at least 50 components (a public assembly is fine).
- Record its volume, component count and file size.
- Export STEP; note the size and the time. Re-import and compare volume.
- Make a copy, delete fasteners and internal parts, and export again. Compare size, time and visual fidelity.
- Write down what the receiver would lose with the simplified version.
Expected result: a measured relationship between detail, file size and exchange reliability for your own hardware.
Related#
- STEP best practices (step-best-practices)
- Mesh vs BRep exchange (mesh-vs-brep-exchange)
- Upload, Open and translation (upload-open-and-translation)