Tag Archives: cad

FreeCAD – some experiences

FreeCAD-logoI was looking for a 3D CAD program for OS X for a limited budget. After looking into some demo versions of commercial programs and some open source programs I decided to look into FreeCAD.

Let’s start with the good things: The parametric modeller has a steep learning curve. But when you finally understood how everything works it is extremely powerful.

Another big advantage of FreeCAD is its availability on Linux, Windows and OS X. There are only a few other CAD programs that are also available on these platforms.

If you’re not a designer, but a programmer, you will like the scripting interface. You can create, modify objects using Python. If you have experience with some programming language, it is easy to learn the Python basics needed to control FreeCAD.

Unfortunately FreeCAD has also some disadvantages:

The CAD kernel that is used is OpenCascade. Unfortunately this kernel still has some bugs. Some functions work not as expected, some will even crash the program. After filing a bug report for a specific problem, the FreeCAD team answered: “this is a bug of the underlying CAD kernel, we cannot fix it”. This can be a big risk for large design, because you never know when you will find a bug that is critical for your design.

The other big problem is speed. The whole application runs single threaded and working with models that consists of more than a few blocks can be extremely slow. I created a 3 dimensional logarithmic spiral that consists of about 500 objects. The calculations are simple, but the program stills runs more than a minute on my PC.

Conclusion: If you’re a programmer or you work with simple 3D models, FreeCAD might be a program to look into. If you work with complex models, the speed and the bugs can be serious disadvantages.

CAD for speaker design (and others)

FreeCAD-logoIn the past I used TurboCAD for loudspeaker designs. Unfortunately my TurboCAD version is extremely old and also does not run on my Mac. Therefore, I was looking for a new CAD software. Sketchup is good for some designs, but has two major problems: It is not designed for the creation of small parts (it is not usable for sub-millimeter resolution) and it does not support boolean operations in 3D (the commercial version does, but not the free version).

After looking at several open source CAD systems I decided to start using FreeCAD. FreeCAD is extremely powerful, it supports even parametric modeling. Unfortunately this also means that you need some time to learn how to use it. FreeCAD is available for Windows, Linux and Mac. Unfortunately, the Mac version is a bit less stable than the Linux and Windows version.

There is another problem for Mac users: You need a third mouse key. MagicPrefs worked well with my Magic Mouse to implement this on MacOS.

Update 16.06.2013: The parametric modeling is extremely powerful if you understand how it works. It makes changes on existing components very easy. Unfortunately the MacOS version of FreeCAD has some stability issues. Therefore save often or use the Linux version in a virtual machine.