Availability of open CAD tools


#1

Hi all,

After this second edition of OSCW, someone mentioned again that, among all the required tooling to do a cubesat mission (and probably the same goes for rockets, cc @concretedog) the most pressing limitations are in CAD tools.

I am extremely interested about this topic and would like to learn more about specific problems. To begin with, these are the open/libre 3D mechanical design tools that I’m aware of:

There are probably others. There is a very interesting (and sad) story about formats that perhaps is affecting the interoperability of these tools, nicknamed the “libredwg drama”. However, I have no idea whether this is the main problem that others face when trying to use these tools.

Can you please comment what kind of issues you have had in the past? Formats, interoperability, features (which?), usability, installation, stability (buggy behavior), lack of support from the community (or even hostile/not welcoming responses), bad documentation, integration with mechanical/thermal analysis, others…?

I would really like to understand what’s going on in this space and what can be done about it. Thanks everyone!


#2

OpenSCAD has worked very well for me in design if 3D printed antennas and pipe organ pipes, flues, and fittings It doesn’t gave a GUI. All model parts are programmatically described.


#3

I too love openSCAD and use it to generate lots of parts for rocketry projects… nosecone geometries etc. Its great how well it integrates into Freecad which I am slowly learning. I also might add I looked at Blender as an opensource CAD environment. I struggle to find CAM solutions in opensource that are useable and stable… I have to confess I have struggled to get LinuxCNC to control my homebrewish router consistently and also find the 2D/2.5D toolpathing one can achieve in Inkscape utterly painful to use! I do therefore, despite using opensource CAD and opensource Gcode senders, resort to proprietary CAM environments… :frowning:


#4

Although I’m not a professional user of 3d myself I do get the pleasure of instructing my designers to work faster :wink: We use non open source products as you might imagine and whilst it’s not fair to compare the paid for mega bucks products we use in terms of features with the current crop of open source offerings there are a few big differences.

2D is ok but the world has moved on, for a good reason. 3D offers a much more robust way of working. 1 model 1 assembly one thing to maintain, not multiple drawings on multiple sheets.

Autodesk and Solidworks are great products, really great products as are browser based bits of software like Onshape. They are generally really easy to pick up and are far easier to swap between which unfortunately is not the case with FreeCAD.

I think I’m a bit confused with the open source thing sometimes. Is it better to have an open source end product (file extension I guess) that can be modified with user users software of choice providing the changes are ‘open’ or is it better to do the whole lot in open source software?

I just couldn’t get on with FreeCAD,Too many workbenches and just too far removed from the stuff I see almost daily. I tried, honest, but I found Onshape to be far easier to use. OpenSCAD give me the heebeejeebies so have avoided it. It reminds me of DOGS 2D software I used years ago.


#5

Thanks all for your responses! @g7kse it’s been a while since I last used a CAD tool but Onshape looks impressive (also, being a web app is the right way to go IMHO).

We’ll have to add CAM to the list then.

I guess it dependes on your definition of “better”. At this point, I guess I would put the threshold on using open formats, so in principle anybody can edit them with their tool of choice, even if it’s a closed one.


#6

As for the file format .STEP I think that is an open standard and is integrated in almost any CAD program.
As for the software now I am big fun of FreeCAD. OK, maybe is a bit unstable, and maybe it has a bit steep learning curve, but is getting better day by day, it has a very good potential and even now is usable and can be the main software for fairly complex projects like SatNOGS rotator. FreeCAD also nowadays include a large collection of different workbenches for different operations including a FEM workbench, for finite element analysis (mechanical, thermal as I know), a path/CAM workbench to generate Gcode for cnc machines and lot more.
Lot people are afraid of it because it was really unstable some years ago but now is getting more spable and more capable. FreeCAD it will definitely my software of choice if I had to start to design a cubesat now. (FreeCAD has used to design UPSat’s antenna deployment system)


#7

Thanks @manthos you have reminded me to look at the CAM stuff in freecad again… It seems to me that Freecad can pretty much mirror fusion with a little work. I’ve never played with the FEA/FEM stuff… but I must get to grips with it. A friend of mine uses fusion and eagle which is now integrated into the fusion workflow… ,makes me wonder if KiCAD could similarly be linked to FreeCad?


#8

I would really like to make use of FreeCAD but it kills me every time I go to use it. Too many years using AutoDesk products and getting used to their workflow makes it hard to use. I’m sure given enough time it would get easier.

You mean you don’t do FE Anaylsis by hand? Whatever next…you youngsters and your 1N loads tsk :slight_smile:

On a serious note there is a good reason why we get stuck into one type of software or another, sometimes the way a person works makes it harder to learn. We all have to admit that Eagle for example is great for PCB design, KiCAD is different in many ways and takes a bit of getting used to but is just as capable now. As long as you practice enough then it gets easier. Once or twice a year isn’t enough.


#9

Not sure I agree on eagle! I really value the footprint/component approach in KiCAD and the freedom to multi layer and go over 100*100mm. :slight_smile:


#10

I am always really missing the command line of eagle. sigh


#11

Some things work for some people and not for others. I’m sure you can go over 100mm*100mm in Eagle, you’ve just got to pay for it.

AutoCAD 2D has a really useful command line Although it was the beginning of the end of draughtsmen’s licence…it meant you actually have to get the dimensions and tolerances correct, tsk!


#12

The biggest problem I see in opensource CAD software currently is the lack of a good parametric CAD system. Parametric as in I have sketches on coordinate planes or surfaces which I can extrude, loft,… and then put other sketches on their surfaces rinse, repeat. Changes to sketches should automatically propagate through the part if possible. Just like in professional tools e.g. Creo or SolidWorks. (This is also one thing where Fusion360 fails spectacularly or at least it fails to guide me on the correct workflow where this just works,)

Sure there is FreeCAD which I try once a year, but I usually run into stability issues or the one feature I need to model the part quickly is not quite done yet. Or even worse I end up fighting the constrains solver for hours.

I do a lot of stuff in OpenSCAD, because it is really VCS friendly. The problem there is that it is hard to write maintainable OpenSCAD files, which are not write-only-code. Especially when want something parametric and have to express the decencies between dimensions via trigonometry equations. Also some operations get really computing expensive. For example recently I designed a part for a fluid mixing system, which had multiple spiral channels in it. Designing a continuous downward spiral in OpenSCAD really takes up a lot of resources.

LibreCAD is quite okay for 2D stuff assuming you ever use autocad in the early 2000s. If that’s not the case it takes quite a while to get used to the workflow and still it can feel cumbersome some times. I mainly use it to construct complex shapes to extrude in OpenSCAD. It works fine for everything I could also draw up on paper. However it completely lacks the ability to do anything parametric with it.

Other then that I don’t know of any good method to put CAD files under version control. OpenSCAD works fine with git, as most source code files do, but other than that, this is an unsolved problem.


#13

I love OpenSCAD for designing single objects for 3D printing, but I can’t imagine trying to do complex, multi part assemblies in it. Sounds painful.

I’ve been learning FreeCAD, and really liking it so far. It also can take objects back and forth to OpenSCAD, which is nice. It also supposedly works well with KiCAD, though I’ve not tries it.