Designing for 3D printing with Autodesk Fusion
Autodesk Fusion (formerly Fusion 360) is a cloud-based parametric CAD software, widely used for mechanical design and 3D printing. Compared to polygonal modeling software like Blender, Fusion works with NURBS solid geometry: this means that the models are intrinsically solid and watertight, reducing many of the problems typical of preparing files for 3D printing.
However, there are some basic rules to follow to obtain an error-free printable file.
Volume and closed objects
In Fusion, each body (body) created with operations like Extrude, Revolve, or Loft is automatically a closed solid with volume. Unlike polygonal modeling software, you don't need to worry about manually "closing" surfaces.
But be careful with the surface bodies (Surface Bodies): if your model contains open surfaces instead of solids, it will not be able to export correctly for 3D printing. Check in the side browser that your elements are under the heading Bodies and not Surface Bodies.
If you have created open surfaces, you can convert them to a solid using Patch → Stitch to join them and then Patch → Thicken to give them some thickness.
Manifold and normal
Since Fusion works natively with parametric solids, meshing issues non-manifold and inverted normals are rare. These errors can appear mainly in two situations:
– when importing STL or OBJ meshes from other software
– when performing complex Boolean operations that generate problematic geometries
If you import an external mesh, Fusion offers the workspace tools Mesh to fix it: Mesh → Repair Automatically corrects holes, inverted normals, and intersections.
To verify that a solid body is valid, right-click on the body in the browser and select Properties: If the volume is displayed correctly, the body is valid.
Attention to the dimensions
Fusion works by default in millimeters. Verify that the units in your document are correct: Document Settings → Units.
You must consider the maximum overall dimensions of your object and the minimum wall thickness. Each material has different values: consult the data sheet. Technical details on the page of each 3D printing material.
To check the wall thickness in Fusion, you can use Inspect → Section Analysis to section the model and manually measure the thicknesses with the tool Inspect → Measure.
Check and correct the model
Integrity check
Before exporting, make sure your model is ready for printing:
1. Verify that all bodies are solid: in the side browser, the bodies should appear below Bodies with a filled cube icon. If you see a surface icon, the body is not closed.
2. Join the bodies: If the model is composed of several separate bodies, join them with Modify → Combine (operation Join) to obtain a single solid.
3. Solve the intersections: Bodies that overlap without being joined generate problems. Use Modify → Combine to melt them.
4. Check the dimensions: USA Inspect → Measure to check the main dimensions and wall thicknesses.
Repairing imported meshes
If you imported an STL or OBJ file into Fusion for editing, switch to the workspace Mesh and uses:
– Mesh → Repair: automatically fixes holes and normals
– Mesh → Reduce: reduces the number of triangles while maintaining the shape
– Mesh → Convert to BRep: converts the mesh into a parametric solid (only works with closed and reasonably sized meshes)
These tools are particularly useful for correcting AI-generated models, which often contain geometry errors. Read our A guide on how to 3D print AI-generated models
Export in STL format
There are two ways to export to STL from Fusion:
Method 1: Right-click on the body
1. In the side browser, right-click on the body (or component) you want to export
2. Select Save as STL
3. In the dialog box, choose the mesh resolution:
– Low: lightweight file, faceted surfaces (suitable for rapid prototyping)
– Medium: good compromise for most prints
– High: maximum detail, largest file size
4. Use Preview Mesh to preview the mesh before confirming
5. Choose the format Binary for a lighter file
6. Click Save
Method 2: From the File menu
1. Select File → Export
2. Choose the format STL
3. Set resolution options and save
Note: For most professional 3D prints, the resolution Medium It's sufficient. Too high a resolution generates large files with no visible benefits in printing, since the printer's resolution is the limiting factor.
Export to OBJ format
To export to OBJ format (useful if the model contains colors or textures):
1. Select File → Export
2. Choose the format OBJ
3. Fusion will generate an .obj file and an .mtl file with the material information
To order a full color 3D print with materials and textures, create a .zip archive containing the .obj and .mtl files and upload it to the 3D printing upload page.
Reduce the weight of the file
If the exported STL file is too large:
1. Reduce export resolution: passes by High to Medium or Low
2. Simplify the model: In Fusion, you can remove details too small to print (microscopic fillets, very small text) using Modify → Remove on unnecessary features
3. If you work with imported meshes: USA Mesh → Reduce to decrease the number of triangles by specifying a reduction ratio
Frequently asked questions
Is Fusion free?
Autodesk Fusion offers a free license for personal, non-commercial use, with some limitations. The free version allows you to export STL files for 3D printing without any problems.
What's the difference between Fusion and Blender for 3D printing?
Fusion is a parametric CAD that works with solids: each model is automatically closed and volumetric. Blender It is a polygonal modeling software best suited for organic shapes and sculpture, but requires more care to ensure that the meshes are closed and manifolds.
Which STL resolution should I choose?
For most prints, Medium it's the best compromise. High It is only useful for very small pieces with fine details. Low It is acceptable for dimensional prototypes where aesthetics are not a priority.
How do I check the wall thickness?
USA Inspect → Section Analysis to create a section of the model and then Inspect → Measure to measure the thickness. See the minimum values for each material.
Done! Now you can upload a file
or read the FAQ