Hobby CAD shootout: FreeCAD

Published on 2023-09-13 | Last modified on 2023-09-18
I explore FreeCAD for hobbyist use. FreeCAD is the most featureful of the FOSS options but it’s incredibly frustrating to use and IMO not reliable enough for the time being. However the team seems to care so I have hopes for the future.

After looking at one of the best commercial options around I decided to check out the most prominent open source option.

I already made my point in the previous article on why an open source option is important, but I want to point out some other tools that were once reviled as “convoluted garbage” and either are or are becoming everyone’s favorite option:

This is not exhaustive (there are many browsers, media players, etc.) but they are definitely the rockstars of open source and I wish for FreeCAD to enter that realm.

I’m saying this because I’m about to be say very bad things about it.

FreeCAD

The name is self explanatory, FreeCAD is CAD software that’s Free software. It uses a modular approach where every part of the application is a “workbench” and toggles part of the UI and contextual actions. The UI is very old fashioned and definitely the most jarring aspect of the first time experience.

Every other software seems to have a better idea of how to only show what’s needed when it’s needed. My first thought when looking at FreeCAD was “wow this looks so different and complicated, there’s no way I can figure this out”.

There are some forks of FreeCAD around, most notably realthunder’s FreeCAD Link which includes an assembly workbench and a sleeker UI. I will however focus on vanilla FreeCAD (0.21 at the time of writing) and I have a note later on explaining why I don’t like FreeCAD Link.

Dark mode

One of the few CAD tools that not only comes with a dark mode, but SEVERAL! You can theme the app to your heart’s content. I’m going to be using the ProDark theme as I find it cleaner than the CATIA-inspired themes it comes by default.

Part & Part Design

Inside you there are two wolves, inside FreeCAD there are two ways to make parts.

I will focus on the “Part Design” workbench as it’s the one meant to replicate a feature-based parametric CAD approach, while the “Part” workbench is a bit of a more generalized modeling that’s based on CSG and more akin to 3D modeling software (e.g. Rhinoceros).

You are generally not meant to mix the two but you totally can, the FreeCAD wiki has a document on Part vs Part design explaining in detail differences and caveats (with an example workflow in both).

Naming conventions

FreeCAD uses different names than what I’m used to. Instead of “Extrude” and “Remove” we get “Pad” and “Pocket”. For my own sake I will start using them almost interchangeably but I will favor FreeCAD terminology when I’m talking about their implementations and my own vocabulary when talking about workflow.

I don’t know if this divergence is to distinguish Part Design functions from Part functions (Part has a “Extrude” function) but it makes googling solutions even more of a problem than it already is. It’s a bit hard to nail this one down since both workflows have their distinct “Fillet” function but then there is inconsistency elsewhere (Revolve vs Revolution).

Part design is a productivity nightmare

So you finally got to do your first sketch, you draw your surfaces, try to extrude and you get a message… “Wire is not closed”, or “Multiple solids” and now the bottom half of your screen is full of red text with python tracebacks, what the heck?

You’re gonna see this a lot

You’re gonna see this a lot

You’re gonna see this a lot

Part design is too limited

Every sketch must define exactly one closed surface, which is a super slow workflow compared to what you can achieve in other tools. Errors are very opaque (an message box during the extrude step will complain “Wire must be closed” with no indication of what to do).

I don’t know if this is a technical limitation or design principle the FreeCAD developers are applying here, but it makes it incredibly frustrating to babysit the application because it can’t handle more than one surface at a time.

The “one surface per sketch” leads to a bigger number of required sketches compared to other tools which amplifies how bad sketch cross-referencing is in FreeCAD. For example, any time you want to use existing geometry for constraint you have to use the aptly named “Constrain existing geometry” function instead of being able to just click on visible existing geometry. The fact that the existing geometry is also not considered part of the surface makes it very annoying to constraint surfaces that are mostly already just there (for doing cuts, for example).

You are better off without some features

Sketch mirror outright just don’t seem to work properly. Even if it did you can only mirror on the two sketch axis, not any arbitrary line. Even when you get it to mirror the sketch it seems the pad operation just doesn’t care anyway.

You are going to lose data

Several times during my experience with FreeCAD I had constraints just poof out of existance, entire lines just stopped having relations to each others. You have to expect this, you have to actively look out for this, because it will mess every other constraint you add and leave you with a line soup.

Undo is unreliable and sometimes undoes the wrong thing, breaking the stack and leading to ruined projects, make backups regularly.

Something is wrong with keyboard shortcuts

During one of my recorded test I paused for 1 minute and 30 seconds trying to find how to turn a line from solid to construction. Wanna play that game too?

This is the sketcher’s toolbar:

The Sketcher workbench default toolbars in 3 rows

The Sketcher workbench default toolbars in 3 rows

The Sketcher workbench default toolbars in 3 rows

Now thankfully you can learn keyboard shortcuts to not have to constantly go back and forward but after cycling through my inner hotkey muscle memories of Onshape/Solvespace/etc I was at a total loss for what even is the shortcut to toggle construction lines.

It’s G followed by N.

(it was this one by the way)

(it was this one by the way)

(it was this one by the way)

The hotkey problem gets worse.

In FreeCAD, you can constraint by radius or diameter, which is actually pretty neat! You can see all the options tightly packed into a dropdown, selecting one will set it as the active button in the toolbar.

The radius constraint dropdown, showing 3 different versions of the constraint

The radius constraint dropdown, showing 3 different versions of the constraint

The radius constraint dropdown, showing 3 different versions of the constraint

All the constraints share the shortcut “R”, and which one gets selected depends on which one is in the toolbar. Why is there such a relation??

Upon further inspection, it seems all tool actually have their own shortcut (K,O / K,S / K,R) but that’s never advertised in the UI, the tooltip gives us the “R” key but you have to dig through the Customize menu to get the actual shortcuts:

The tooltips in the constraint radius/diameter buttons

The tooltips in the constraint radius/diameter buttons

The tooltips in the constraint radius/diameter buttons

The customize menu showing the actual shortcuts

The customize menu showing the actual shortcuts

The customize menu showing the actual shortcuts

I don’t know wheter I’m at fault here or there is something wrong on how this software manages shortcuts.

The trials

Lets run FreeCAD through its paces! You can check the Onshape article for a description of what trials are and how it compares to other tools.

Test drive: TooTallToby 21-03-07b-HALF SLEEVE

Today’s test drive part is another of TooTallToby’s practice drawing, specifically 21-03-07b-HALF SLEEVE.

Here’s the video of my attempt:

There are many things to note, but let’s start with the important ones:

1. I do not actually reach the correct solution

This recording was something near my 15th attempt at this. I haven’t saved recordings of all of them, but in many I had some bug that broke my flow completely while in others I forgot some details and it was basically impossible to go back and fix, if you don’t believe me, here’s one where I noticed missing one detail and went back to fix it, just to have the bottom tab sketch completely ruined and kept scrambling trying to understand why it wouldn’t fully constrain:

Maybe it was a trivial issue but it really frustrates me when I try 10 times and each time something weird ruins everything. After 15 or so tries I just gave up.

2. The trim tool destroys constraints

The trim tool works pretty well, but it seems to delete constraints… but only sometimes! Like many tools in the sketcher it seems to cause different issues every time.

3. Doing most things will over-constraint the drawing

I really don’t get this. If I’m drawing a line that connects two already horizontally aligned dots, why does FreeCAD add a horizontal constraint anyway? It creates a redundant constraint that messes up everything and it seems so easy to avoid. These issues are everywhere and make the sketcher miserable to use.

You can actually make this way less frustrating by enabling “Auto remove redundants” from the Constraint menu settings:

The “Auto remove redundants” options in the Constraints menu

The “Auto remove redundants” options in the Constraints menu

The “Auto remove redundants” options in the Constraints menu

Please make this the default!

4. The camera is ass to control

I don’t know what their problem is, but both Trackball and Turntables (they have two “turntable” options) orbit systems are very uncomfortable to use. Turntable completely blocks one axis of rotation and seems to always orbit from the wrong place (it places the origin in some imaginary spot at the center of the screen rather than say, the object) and trackball is just insanely finnicky.

I don’t know what the others are doing right but if Solvespace can do orbit right then anyone should be able to.

5. I purposely avoid using the sketcher’s mirror tool as it is basically broken

Just in case someone wanted to point it out. It’s broken and I mentioned sketcher tools generally having issues. I have at least two recordings where I try the mirror tool and while the sketch looks perfect the Pad tool just ignores the mirrored copy.

6. I constantly move the view to the right every time I’m trying to reach something on the left

Now this is a problem with an addon called Glass that creates “transparent” tree overlays (akin to Fusion, Catia etc), but it’s most notable in the realthunder’s FreeCAD fork (told you I’d come back to it), so here’s a screenshot from that version:

Screenshot from FreeCAD Link

Screenshot from FreeCAD Link

Screenshot from FreeCAD Link

This looks way better than vanilla FreeCAD, with all the floating transparent boxes wouldn’t you think?

The problem lies in the way they work. They are floating and transparent visually, but actually are not transparent to mouse-clicks.

This makes the software a nightmare to use because your instinct will be to click on a feature and half the time there’s actually something preventing you to select it. I’m not docking FreeCAD points for this but given how prominent this addon is and how nice it looks I really wish they’d just implement it in the base software without this sort of problem.

Real world part: Headphone stand

Oh god I committed to drawing TWO parts in this??

The project is simple, I have many monitor and mic stands in my desk and I would like something that clamps on one of them and keeps my headphone at desk level for me to put on and take off. I have the desk headphone stands but those are too easy to tip over (even with enough added weight).

This time even more than last I will very much spare you the video.

Behold:

Half of something, semi-trasparent

Half of something, semi-trasparent

Half of something, semi-trasparent

Something a bit unfortunate about FreeCAD is that there is no “show hidden lines” option for the 3D view, the only way to show inner details is to make the object partly transparent.

FreeCAD supports the major formats for 3D printing (STL, 3MF, STEP), I put all three side by side in PrusaSlicer and while the STEP is still above everything else (mostly because of the curve encoding) it’s really hard to notice any difference, FreeCAD’s defaults are very good!

From left to right: STL, 3MF and STEP

From left to right: STL, 3MF and STEP

From left to right: STL, 3MF and STEP

The difference, even tho barely noticeable, is completely eliminated when slicing, even at 0.05mm layer height I can’t really tell them apart.

The three versions sliced at 0.05mm with a 0.4mm nozzle

The three versions sliced at 0.05mm with a 0.4mm nozzle

The three versions sliced at 0.05mm with a 0.4mm nozzle

File sizes seem pretty good too:

FileSize
stand.STL132.0 KiB
stand.3MF31.7 KiB
stand.STEP27.3 KiB

Making drawings

Making drawing is a breeze! Once again I’m happy to not be in charge of making any kind of technical drawing cause my career would be over instantly, but so far save for having to look up a couple things I can’t really say I have had any trouble getting a page with 4 views and even a section view done!

Here’s a really bad drawing of the part above, I want to stress that the fact that the quality is atricious is completely my fault and not the program’s (also, colors were altered to avoid a flashbang effect, it’s normally black on white):

A ““Technical”” ““drawing”” of the headphone stand half-piece

A ““Technical”” ““drawing”” of the headphone stand half-piece

A ““Technical”” ““drawing”” of the headphone stand half-piece

When in the app the drawing is shown with tons of label and extra things which I assumed would end up in the final print but didn’t. I guess they are just for reference and you’re just supposed to put your own (which is good, because the built-in labels can’t be positioned around much).

Multi-part

You can have as many bodies as you want within a model file and you can import bodies from other files, it works OKish. While importing and adding bodies is quite seamless, you have to use ShapeBinders as soon as you need to have multi-body constraints and it becomes quite hairy… but still doable!

As an example this is the top half of a “keyboard controller” thingamajig I did a while ago, using Cherry MX mounts from an external file (also a FreeCAD project) applied to a surface:

The “DJMAXX”, soon to be replaced by the “DJMAXXX” which will be 18+ only

The “DJMAXX”, soon to be replaced by the “DJMAXXX” which will be 18+ only

The “DJMAXX”, soon to be replaced by the “DJMAXXX” which will be 18+ only

Export options

FreeCAD has an enormous amount of export formats. I covered STL/3MF/STEP but there are many more, though I really doubt most of these see active use and might have rather been someone just adding it for the sake of it (VRML?? what year is this??)

Surprisingly the more CAD-y format from last time don’t show up. The selection includes plenty of 3D modeling formats (Collada, OBJ, glTF) and 2D formats but the only CAD software format I could spot is .IV (Open Inventor) and… OpenSCAD? Sadly it’s not some magic way to convert your part into a procedural OpenSCAD file as much as a hardcoded list of vertices.

I assume supporting the other formats might require access to proprietary SDKs or maybe they just haven’t had anyone ask for them yet, I think supporting STEP is honestly more than enough for what I’ll ever need anyway.

Oh, and you can export a body to… a self-contained HTML page with a ThreeJS script to have a orbit camera around it, and would you believe it even there the camera works better than in FreeCAD!

The HTML export (with a darker background than normal)

The HTML export (with a darker background than normal)

The HTML export (with a darker background than normal)

Assemblies

Assemblies in FreeCAD come in two ways: the “do it yourself” way and the “addon roulette of death” way. This is because FreeCAD does not come with an assembly system of its own, but the existing tools can be used somewhat to fake having one and there are multiple competing addons trying to be the Assembly workbench:

Despite their names they are mostly unrelated and incompatible. Assembly3 is worthy of note because it’s from realthunder and their fork has it built-in.

I briefly tried A2Plus and Assembly4 and both were quite confusing to me and even after a couple videotutorials I couldn’t get a basic connection done (but then again I find struggling to mirror a part in this software sometimes). It might be that I just need to fiddle more and give it more time but I think I will just wait for FreeCAD to have a built-in assembly system before going back to it.

Sheet metal

Hey it’s that one thing I’m not good at again! Sheet metal is also not part of FreeCAD itself but there is a sheet metal add-on that’s popular enough to have its own section in the wiki, so I’m considering it for this overview.

This time, I tried replicating TooTallToby-21-01-02 and… well I succeeded!

Sheet metal part within tolerance!

Sheet metal part within tolerance!

Sheet metal part within tolerance!

It turned out to be a bit more rough than with Onshape but I managed to keep it mostly hack free, it would have been much smoother with symmetry but I didn’t wanna risk it so I took the long route.

You can even unfold it and generate proper drawings, though it’s not as straightforward and it doesn’t come with a neat list of bends like in Onshape.

Conclusion: The pieces are there but hardly a reliable pick

FreeCAD shows promise and if their last user meetup notes are anything to go by, they care. It’s just not there yet. I like to think of the current state of FreeCAD as the earlier versions of Blender (2.4 and earlier): buggy, missing core features, messy defaults (think right click select) and you had to adapt to their workflow instead of creating yours.

I’m sure the FreeCAD team can sort out the bugs, the bigger question is if they can make it not as frustrating to use in general, some of the problems are clearly due to their approach and unpolished modular system and not some hard to solve bug.

For professional use I think FreeCAD is a non-starter in its current phase, but if you’re just doing this for fun like me then it might not be so unreasonable.

I will explore other open source solutions in the future, some I’ve used already (SolveSpace) some not (SALOME) but I can tell you right away FreeCAD sits at the top of the ones I’ve tried (spoilers, I guess) and unlike Onshape and Fusion it can’t really get worse.

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