FreeCAD — Improving Quality of STL files for 3D Printing

3 min readJan 24, 2024

Recently, I made a switch to FreeCAD and have been doing some modeling of the robot parts for some of my new projects. The first time I tried to export the STL file from FreeCAD and imported it into the 3D Printer software either the Creality Print or Prusa Slicer, the 3D printing software complained about STL file have hundreds of edge problems and some additional issues.

I’m referring to FreeCAD v0.21.1 throughout this article when I say FreeCAD

I had to do some quick research to figure out what was going wrong with the STL file export from FreeCAD as I never faced that issue before. Here are some quick ways I was able to get around those errors and problems and get a really good quality STL file exported from FreeCAD.

As I started to research how to fix the STL quality problem, there were a lot of different tools recommended on web like Blender, MeshLab and such. And they are all great tools but I just wanted to find out if there is something already built into the FreeCAD that will allow me to have a standard worlflow within FreeCAD that doesn’t require another tool. Good news is FreeCAD has everything to fix those issues.

The Fix

The “fix” was actually so simple and if you want to learn more in-depth details please watch this video by MangoJelly. But I’ll save you sometime if you want to know it quickly how to do it FreeCAD.

Basically, after you have completed the model and generated a Solid body, switch to Mesh workbench from the drop down menu.

And while you have your solid body selected, click on menu Meshes → Create Mesh from Shape…

You’ll see a set of tabs on left side

You have a few options here. You can choose Standard tab and play around with surface deviation and angular deviation values, lower the value the better and smoother STL file you will get and size of file will be much larger.

My favorite thing to do is to goto Netgen tab and choose either Fine or Very Fine, its dumb simple.

You can see the differences in various tests I did side by side by importing back the STL files with various settings and moving a bit by doing transform to put them side by side and turning on View → Draw Style →Flat Lines

and you’ll see things a lot better like this

As you can see above the meshes on left were higher resolution and the ones on right were very coarse with default STL export settings which was causing issues with 3D Printing software. Once I loaded the higher resolution STL file into 3D Priting software, there were no issues reported and I was able to run the slicer simulation as normal.

Hope this helps someone who is in same situation as I ran into.

Have fun 3D printing!!!