Why is my STL file 10X greater in Fusion 360?

Importing an STL file into Fusion 360 is easy, but it comes with several quirks.

I often get asked a variation of the following questions:

• Why is the STL file is 10x (times) the size?
• Why is my STL file 10x smaller in Fusion 360?
• Why is my STL file the wrong size in Fusion 360?
• How do I import an STL file into Fusion 360?

STL File Format

First, you should understand what data an STL file contains.

STL is short for stereolithography. Many also know it for the backronyms such as “Standard Triangle Language” and “Standard Tessellation Language.”

An STL file describes a triangulated surface and vertices using the three-dimensional Cartesian coordinate system. When STL files were created they required all coordinates to be positive numbers. However, this restriction is no longer enforced, as negative coordinates are commonly seen in STL files today.

STL files contain no scaleScales sketch objects, bodies, or components. Select the objects to scale then specify the scale factor. information and the units are arbitrary. This means if you exportExport files to your computer. Opens the Export dialog box and allows you to choose a name, file type, and location to save the file to. a mesh file that was created in millimeters then the millimeters unit of measure(keyboard shortcut “I”) Reports distance, angle, area, or position data of the selected object. Select a vertex, edge, face, body, or component. will not be tied to the file. The file size will be dictated solely by the units of measure set in the present program.

Working with Mesh (STL and OBJ) files in Fusion 360

In short, slicing software for 3D Printers usually treats units equal to 1mm. Whereas, Fusion 360 assumes all units = 1cm.

To import files in Fusion 360 most users will use the “upload” workflow that is located in the data panel. The problem is that the Upload method assumes all unitless files (.stl or .obj) are made with centimeters.

Instead, you should always use the Insert MeshInserts the selected OBJ or STL mesh file into the active design. Choose an OBJ or STL file to insert, then use the options and manipulators to orient and position the mesh. feature when you need to place a mesh file into your current design.

1. Have an STL or OBJ file

2. Insert Mesh

Start a new Fusion 360 file or open a current design. SelectThe selection mode controls how objects are select when you drag in the canvas. the Insert menu > Insert Mesh command.

3. Select Desired Units

Within the insert dialog, select whatever units provide the correct result. Often, Thingiverse files and other STL files are originally modeled in millimeters (mm). If your model is 10x smaller then you’ll need centimeters (cm) or vise versa.

4. Save the File

The mesh file is now a Fusion 360 design that should be scaled to the right proportions. Avoid using the “upload” method when working with mesh files.

Summary – Avoid These Workflows

The following two workflows will always treat the mesh file as it was created in centimeters. Avoid these workflows if your model is not intended to be in centimeters.

• File > Upload > Select Mesh
• File > Open > Select Mesh

Exporting STL Files

Exporting an STL file has the same quirks. Be sure to use the “Save asAllows you to rename a file and save a duplicate to an alternative location. STL” option instead of “File > Export”. The export option uses the same translators as the upload feature, resulting in the file is in centimeters. Instead, follow the following workflow.

1. Right-click Component

2. Select “Save as STL”

3. Choose Location

To export to your computer folders you will need to make sure “Send to 3D PrintConverts the selected body to a mesh body and outputs to STL or a 3D print utility (software). Select the body to output. Set the mesh controls and specify the print utility to output to. Utility” is unchecked.

To export to a Slicing software or another program then leave “Send to 3D Print Utility” checked and select the desired program from the dropdown list.