Import an STL into Fusion 360 Without Scaling Issues

Here is an issue you might have run into in the past. If you go to Thingiverse, Prusa Printers, YouMagine, or any similar 3D print repository site, download a model, and upload it into Fusion 360, you might find that the scale of the model is way off. Often, an STL will end up several times larger than it should be once it is uploaded into Fusion 360.

Here’s an example. I downloaded Cali Cat – The Calibration Cat from Thingiverse.

This is a calibration object used to dial in a 3D printer so that it prints with high dimensional a accuracy. The cat’s head should measure 20mm x 20mm but if we upload the STL to Fusion 360 and use the Measure tool to inspect the actual size of the object within the software, we will see that it is around 200mm instead.

So, let’s take a look at a way of importing downloaded STLs into Fusion 360 while retaining their original dimensions.

Step 1: Create a New Design

The first step towards importing the STL at the correct size is to create a new, blank file. There is nothing special in this step. Simply navigate to File > New Design.

Then, before moving on, go ahead and save the new design (that is blank at the moment). You can name it whatever you’d like.

Step 2: Import the STL

Next we will import the STL into Fusion 360. This is different than uploading the file into Fusion 360 via the browser on the left side of the screen. Instead, select Insert from the ribbon at the top of the window, and then select Insert Mesh.

In the file manager, locate the STL file you wish to add to Fusion 360. You can move the model around or rotate it if you need to. When you have the model positioned where you want it, click the OK button in the dialog box.

Step 3: Verify Correct Scaling

Finally, we can verify that the imported STL is indeed the correct size. This is important if you plan to modify the design in any way.

Verifying the measurements of the part is easy. Simply use the Measure tool to compare the distance between two points on the model to a known distance on the reference design.

Next Steps

With your STL imported into Fusion 360 at the correct scale, there are a number of fun and interesting things you can do. You can convert the mesh into a regular body so that you can modify the design in the same way that you would work with any other part in Fusion 360.

There is a tutorial on this site for converting mesh bodies into normal solid bodies.

You could also send the design to Slicer or Meshmixer to get creative with the model.

You could use the rendering tools Fusion 360 to make a nice picture of the model.