Fusion 360 SLDASM import problems usually are not caused by Fusion itself. They come from the structure of the SolidWorks assembly: the top-level .sldasm depends on referenced parts and subassemblies, and those references have to stay intact through the conversion step.
That is why the CADExchange Fusion add-in supports an optional support ZIP. It gives you a clean way to pass the assembly plus its referenced files into the conversion job without leaving Fusion.
1. What to Put in the ZIP
- The top-level .sldasm file.
- All referenced .sldprt files.
- Any nested subassemblies.
- The same folder structure and relative paths the assembly expects.
2. Fusion Workflow for Assemblies
- Open the add-in command inside Fusion.
- Select the main .sldasm file.
- Attach the support ZIP.
- Run the conversion and let the add-in insert the STEP result.
3. Common Failure Modes
- Parts are missing from the ZIP.
- Folders were flattened, so relative paths changed.
- Files were renamed after zipping.
- The upload included a random subset of references instead of the original assembly tree.
If you are troubleshooting a conversion that already failed, the broader SLDASM to STEP troubleshooting checklist is still worth keeping nearby.
4. Why the Add-In Helps
The add-in does not magically fix a broken assembly package, but it removes the friction around account auth, entitlement, upload, polling, download, and insertion. That makes it easier to focus on the real issue: whether your source ZIP is complete and faithful to the original assembly.
Start from the Fusion add-in page, then review pricing if you are rolling this out to a team.