Get started with FreeCAD

What FreeCAD is

FreeCAD is a program for 3D drawing, and what sets it apart from building something in Blender or Tinkercad is that everything you draw has dimensions. A shelf is not about 180 millimeters wide, it is 180.0, and that number stays in the model so that you can change it later. If you change the width, the holes, screws and everything else follow.

This is called parametric modeling and that is the whole point. If you draw a prototype that will be printed in a 3D printer, and it turns out half a millimeter too tight, you go back to the dimension instead of redrawing the part. FreeCAD exports to STL, the format every 3D printer wants, and to STEP if someone else needs to open the model in another CAD program.

The program is free and is under LGPL. There is nothing to pay, no trial period and nothing that stops working in the middle of a project.

Windows

Go to freecad.org and download the installation file for Windows in the 64-bit version. Run it and click through. The default choices are enough.

The first start takes a while because the program loads all its workbenches. If Windows warns about an unknown publisher, it is because the project does not pay for a signature, not because the file is dangerous, provided you downloaded it from freecad.org and nowhere else.

Linux Mint

There is something worth knowing here: FreeCAD is not in Mint's regular software repositories. If you search in the Software Manager and do not find the program among the usual packages, it is not you doing something wrong.

Two routes work. The easy one is Flatpak, which Mint has preinstalled. Open the Software Manager, search for FreeCAD and choose the version that comes from Flathub. In the terminal it is the same thing with:

flatpak install flathub org.freecad.FreeCAD

The other route is AppImage, a single file from freecad.org that you right-click, choose Properties, go to the Permissions tab and check that the file may run as a program. If it still does not start, a library is missing. On Mint 22 the package is called libfuse2t64, on Mint 21 it is called libfuse2, and both are installed with the Software Manager or with apt.

Three things to do first

1. Switch the workbench to Part Design in the drop-down menu at the top. FreeCAD is really several programs in one, and Part Design is the one you want for physical parts.
2. Draw a rectangle in a sketch and pull it out into a block. Sketch, set dimensions, extrude. If you manage that round, you have understood how the whole program works, and the rest is variations on it.
3. Change a dimension in the sketch and watch the block change. That is the second when parametric modeling becomes understandable.

The most common trap

Underconstrained sketches. FreeCAD lets you draw a line without saying how long it is or where it sits, and at first that feels great. Then half the model moves when you touch a detail further along, and nobody understands why.

Fully constrain every sketch instead. Add dimensions and constraints until FreeCAD says the sketch is fully constrained; the lines change color when it is done. It takes ten extra minutes per sketch at the start and saves a whole afternoon when the model grows.

Save often, by the way. FreeCAD is more stable than its reputation, but it has a reputation for a reason.