FreeCAD 3D design software

By | June 1, 2016

Our club has been (slowly) constructing a SatNOGS 3D printed satellite ground station. It uses a bunch of parts that have been designed on a platform called 3D CAD. This is a free (as the name suggests) 3D CAD solids modelling tool. For those not familiar with mechanical design here’s a very quick and simple run through.

The good old days gave you 2 dimensional CAD packages. One of the most famous was AutoCAD. There have been many releases and it still has a place today (you can even get a free version called Draft Sight).

Perfect for producing 2D drawings in the traditional was. Also ideal for those .dxf files for laser cutting front panels for example. These are simple tools to get your head round but ultimately very powerful. This technology has been used to deliver some pretty complex engineering so don’t underestimate its usefulness

3D CAD design can look like a complex business but as tools develop the proliferation of simple to use applications exist and as expected they use their own language. 2D drawings are no longer the standard and so 3D parametric CAD systems are available from a number of big players like AutoCAD and SolidWorks. They range from very expensive professional packages that have features that only the very keen would need (like finite element analysis, animation and computational fluid dynamics) through to offshoots that are particularly aimed at home users. In amongst these packages are offerings such as FreeCAD and SketchUp which are completely free and very well supported. There is only one preferred standard and that is for the .stl file type although there are key differences between types.

Solids modelling and Surface modelling. As the names suggest one type produces solid shapes which are determined through sketching a part in 2D then turning that into a 3D part by stretching or revolving it around and axis for instance. These are generally referred to parametric modelling tools and they produce solid shapes. Examples of these types are FreeCAD, AutoCAD inventor and Solidworks. SketchUp on the other hand produces hollow surfaces. An easy analogy is between a dice and a cardboard box. Both are cubes, one is hollow and the other is solid. 3D printers for example need to think in terms of solids. This doesn’t mean you can’t use a surface modelling tool to produce a part, it means there are some additional bits of computer based thinking that needs to be done.

FreeCAD falls squarely into the 3D parametric solids modelling camp (for the purists, yes it does do sheet and mesh work but stay with me on this). It is also nice and simple once you get your head round the basic premise. Sketch something in 2D then pad it to make a solid and perhaps put in a pocket for a bolt hole for example. I have been working my way through a few tutorials on YouTube and can recommend theses…..

Once you get into the workbench idea and the language used it is relatively straightforward producing designs. I think the issues are that the assembly workbench isn’t quite there yet and it isn’t as polished as commercial alternatives, but hey it doesn’t cost thousands.

There are also a number of developing online packages like 123D CAD and Onshape but I haven’t had a look at those in any detail. The premise is still the same. draw a 2D sketch, constrain it with dimensions, symmetry, equality etc and extrude, revolve, pocket to your hearts content. It is a really great step to see such powerful tools available for free.

It wouldn’t be fair to mention the extremely accessible surface modelling package that is SketchUp. A Once Google product that instead of producing solids models faces and uses clever tricks to make you thinks they are solids. This is a great tool and is good enough for 3D printing parts. Just beware of its limitations and well aware of the huge amount of models available in its warehouse.

Well worth considering for anything from shack layout to 3D parts design.

Hopefully I will get re-antiquated with this new tools as its been a while sine I behaved like a clanky (that is a mechanical engineer to you lot). There are some truly staggeringly clever products available that you only need invest a bit of time in learning.

 

6 thoughts on “FreeCAD 3D design software

    1. Alex Post author

      Hi Jim, 3D printers or rather the slicer software like .stl files. They can all generate these files one way or another. Either by exporting or with some clever trickery in the case of Sketchup

      Reply
  1. Jim Isbell W5JAI

    I was talking specifically about FreeCAD 3D software. With that particular package AND a small 3D Printer and, of course a computer. either Linux or Windows, what more would I need to produce an item on the Printer?

    Reply
    1. Alex Post author

      FreeCAD is just the design software, but it will give you a .stl file. This will need to passed to the printer through a package like CURA. This will translate the solid into thin slices that the printer translates into movement in the x,y and z planes as well as feed for the polymer.

      In simple terms there is an intermediate step in between your FreeCAD 3D design and a part in your hand

      Reply
  2. Jim Isbell W5JAI

    Yes, I understand that. I just wanted to know if the output of FreeCAD would be comparable with my 3D printer driver software. I see that it will be. Thank you.

    Reply
    1. Alex Post author

      Ok Jim, hope you enjoy using FreeCAD. It has a different work flow than other systems I’ve used with its workbenches. Once you get your head round that it really is very good, and free as well. The YouTube videos are really useful too.

      Reply

Leave a Reply