Overview#
Two problems account for the great majority of "my import is wrong" reports: the model is the wrong size, or it is lying on its side. Both are consequences of unit and axis conventions that differ between systems, and both are easily corrected once you know where Fusion asks.
Units. Some formats carry unit information (STEP, F3D, 3MF, DXF to a degree, native vendor files). Others do not (STL, OBJ). A format with no unit metadata is just numbers: a cube with a side of 25 might be 25 mm, 25 inches or 25 meters. Fusion must be told how to interpret it.
Orientation. Fusion's default modeling orientation is Z up; you can change it to Y up in Preferences (General > Default modeling orientation) and must restart Fusion for the change to apply. Many other tools disagree: SolidWorks and Rhino are generally Y-up in some contexts and Z-up in others; Blender and most 3D printing slicers are Z-up; many game engines are Y-up with different handedness. When data crosses these borders, an object can arrive rotated 90 degrees.
This page covers where to set units, how to reorient imported data, and how to verify the result.
Where to find it#
| Item | Location |
|---|---|
| Default up axis | Preferences > General > Default modeling orientation (Z up is the default; change to Y up, then restart Fusion) |
| Document units | Document Settings in the browser (click the gear beside the document name), Units |
| Default units for new designs | Set in Preferences or via the template; see the units page in Getting Started |
| Insert Mesh | Design workspace, Mesh tab > Create > Insert Mesh; dialog has Unit Type and Position controls |
| Insert SVG | Insert > Insert SVG |
| Insert DXF | Insert > Insert DXF |
| Move/Copy | Modify > Move/Copy (M) for repositioning |
| Scale | Modify > Scale for uniform and non-uniform scaling |
Paths are as commonly documented; verify the exact labels in your version.
Step by step#
Importing a mesh with the right size and orientation#
- Open or create a design. Check Document Settings > Units; your imports are interpreted relative to your intended working units, but the import dialog has its own unit choice.
- Choose Mesh tab > Create > Insert Mesh and select the STL, OBJ or 3MF file.
- In the dialog, pick the Unit Type matching the sender's intent: centimeter, millimeter, meter, inch or foot ("one unit from the original file equals" the chosen unit). If you do not know, guess millimeter and check the size afterward.
- Use Flip Up Direction (flips the Y and Z axes), Center or Move To Ground, or the manipulators and numeric X/Y/Z values, to position it. If the preview shows the model lying on its back, click Flip Up Direction.
- Confirm with OK. The mesh appears in the Design workspace as a mesh body.
- Use Inspect > Measure on a known dimension. If the result is off by a factor of 25.4, 10 or 1000, delete the import and redo it with the correct unit, which is cleaner than scaling afterwards.
Importing a DXF onto a plane#
- Choose Insert > Insert DXF.
- Select a planar face for the sketch, then the DXF file; the DXF origin is placed at the sketch origin.
- Set Units (scales the imported DXF), the Insert Mode (Single Sketch or One Sketch per Layer), X/Y Distance, and uncheck any DXF Layers you do not want.
- Click OK. Fusion creates a sketch containing the DXF entities. Check the overall bounding size with a Sketch Dimension against a known feature.
- If the origin of the DXF does not align with the model, use Sketch > Move/Copy on the sketch geometry, or reposition the plane.
Importing an SVG#
- Choose Insert > Insert SVG, select the SVG, then a plane.
- SVG files are resolution-independent and unit-uncertain. The Insert SVG dialog has X/Y Distance, Z Angle, Horizontal/Vertical Flip and Scale, but no unit setting; expect to scale and dimension afterward.
- Select the imported curves and use a driving dimension on a known length to fix the size. Constrain the overall shape if you will keep editing.
Fixing an already-opened model#
- If a STEP or native file opened on its side, create a Move/Copy feature on the top-level body or component and apply a rotation of 90 degrees about the appropriate axis. In a timeline-based design this becomes a recorded step.
- Alternatively, use Modify > Align to match a face to a reference plane, then move the part so a chosen datum sits at the origin.
- For an assembly, rotate the top-level component group (select the root components, not the child parts) so the internal relationships are preserved.
- Consider whether the orientation matters downstream. For CAM, you will set a WCS in the Manufacture workspace, so the design orientation is cosmetic. For 3D printing, the slicer lets you orient the model freely.
Options reference#
| Option | What it does | Notes / default |
|---|---|---|
| Unit Type (Insert Mesh) | Declares what unit the numbers in the file represent | Centimeter, Millimeter, Meter, Inch, Foot |
| Flip Up Direction (Insert Mesh) | Flips the Y and Z axes of the inserted mesh | Also Center and Move To Ground buttons |
| Insert point / position | Places the mesh at the origin, or lets you move it with the manipulator | Check that the bounding box is where you expect |
| Plane selection (Insert DXF/SVG) | Sketch plane that will host the 2D data | Pick a face for in-context placement |
| Units / Insert Mode / DXF Layers (Insert DXF) | Scales the DXF; one sketch or one per layer; layer selection | Verify the size by measuring |
| Group/Scale in Move/Copy | Rotates or translates imported bodies | Use the Free Move or Translate/Rotate tab for numerical entry |
| Scale > Scale Type | Uniform or non-uniform | Non-uniform scale distorts holes into ellipses; avoid for engineering data |
| Preferences > Default modeling orientation | Sets up axis (Z up default, or Y up) | Requires restarting Fusion |
A closer look at units#
Units trouble comes in three flavors.
1. Missing units (STL, OBJ). The only remedy is knowing the intended unit. Hints: 3D printing files are almost always in millimeters. Game and rendering assets are often meters or arbitrary. Models from architecture tools may be in inches, feet or meters.
2. Mislabeled units (DXF, STEP from poorly configured exporters). A STEP file declares its length unit in the header, so a competent translator will read it correctly. Fusion is generally reliable here, but you may still find a file whose author modeled in inches while the header says millimeters. The tell is a part that is exactly 25.4 times too large or too small.
3. Scaling intent. Sometimes the file is right and you want it a different size. Use Scale, not a unit change. A unit change reinterprets the numbers; scale changes the geometry.
Tip: Compare one dimension you know independently, such as a standard screw head or a bearing outer diameter. A single known feature validates the entire import.
Tips and pitfalls#
Tip: Import into a blank design, check the result, then copy and paste the verified body into your working design (or insert it as an external reference). This avoids corrupting a design with a bad import and having to undo through a long timeline.
Tip: Set the model's origin deliberately. Use a Move/Copy with point-to-point to place a meaningful feature (a mounting hole center, the bottom face center) at the origin. A model centered on the origin is easier to assemble, mirror and machine.
Warning: Changing Document Settings units does not rescale geometry. It changes how existing numbers are displayed and entered. A 25 mm cube displayed in inches reads 0.984 in; it is still the same cube.
Warning: Non-uniform scaling of a mesh or BRep body breaks circles and cylinders. Do not use it to compensate for a wrong unit; it will not fix the proportions.
Warning: Rotating an imported mesh body in a parametric timeline is easy; rotating an imported body in a design with external references or joints can make downstream features fail. Rotate before building on it.
Warning: Handedness differences (left-handed versus right-handed coordinate systems) can mirror a model rather than rotate it. If a rotation does not fix an import, check whether the part is a mirror image, which matters for asymmetrical parts. A part that is mirrored cannot be fixed by rotation. Use a Mirror feature, then verify with a known asymmetrical landmark.
Practice exercise#
- Model a simple L-bracket 40 mm by 20 mm by 5 mm and export it as an STL (right-click the body > Save As Mesh, Unit Type Millimeter).
- In a new design, set Document Settings units to inches. Choose Mesh tab > Create > Insert Mesh and deliberately select meters as the unit. Observe that the bracket is enormous: the file's 40 is read as 40 meters, which displays as roughly 1,575 in.
- Undo and re-insert with millimeter. Verify with Measure that the length is 40 mm, displayed as roughly 1.575 in.
- Click Flip Up Direction and observe the bracket rotating in the preview.
- Finally, in the correct import, use Move/Copy to put the bracket's lower-left corner at the origin.
Expected result: you understand that unit choice at import is a reinterpretation of the numbers, and that orientation can be corrected either at import or afterward.
Related#
- Upload, Open and translation (upload-open-and-translation)
- Mesh vs BRep exchange (mesh-vs-brep-exchange)
- Units and document settings (01-getting-started/units-and-document-settings)
- Mesh workspace and import (07-form-sculpt-mesh/mesh-workspace-and-import)