I have spent the last couple of weeks working on designs for a long bridge for my model railroad. Through the process I have tested a lot of free tools for 3-D design. There are a large variety of tools out there, from simple sketch-based software to complex, professional level, computer aided design suites. I have covered open-source software many times in the past, but this is the first time I have been surprised by the number of choices.

The first tool l tested was called FreeCAD. At first, I thought it was going to be easy to learn, but rather quickly discovered that it was rather complex. In CAD software this is not necessarily a bad thing. The complexity came from the fact that FreeCAD is a parameterized CAD software. What this means is that you cannot just draw a box, but you also must give the box an exact location in space and an exact size. Parameterization means that you must be precise in your designs. This makes FreeCAD the perfect tool for high precision work, like designing small parts such as gears, but not the right tool for designing large objects like buildings or bridges. Don’t get me wrong here, as you can definitely use FreeCAD for designing these larger objects, but it becomes painful to set all the parameters for large projects.

The second one I tested was called OpenCAD, which had a very nice user interface that was simple to use. It allowed you to create objects without having to specify exact parameters. This made it much quicker to get a rough model. However, I found two main problems with this tool. The first was a seemingly new code-base that was in need of some more serious testing; the program seemed to crash a lot, making it hard to stay focused on the design work. The second was that the models coming out of it had some pretty major issues when trying to print them with my 3-D printer. The lack of required parameterization made the models more prone to errors, like sections of the bridge that did not quite touch, or other sections that overlapped, resulting in a very ugly bridge, even though it looked good on the screen. OpenCAD would be great for 3-D models to use in video games, but not so good for real world applications.

The third tool I tested was a lot harder to use than either of the first two, but also had the most features and power. I would recommend learning it if you are looking for a career in design, or even have a serious hobby needing 3-D printing and models. The name of the software is Blender, and it combines the best features of OpenCAD and FreeCAD. Blender is the free software used by Disney and Pixar for designing all their latest animated films. Blender has the tools necessary to create complex 3-D models and combine these highly detailed models into complete scenes. You can place lights and cameras around the created stage and generate animation sequences from the scene. It is also excellent for creating objects that are easy to print on 3-D printers, but it can take years to master the tool.

The last tool, and the one I will be using to design my bridge is called OpenSCAD. Unlike any of the other tools I tested, even several I did not write about, OpenSCAD is not a drawing or drafting tool. OpenSCAD is more like a computer programming language for 3-D modeling. The end result is a very precise model like FreeCAD provided, but with what seemed to me like less work. In FreeCAD, you had to first draw the objects on the screen, in roughly the right locations, then add the parameters for giving the model precision. It took several hours to complete a fairly simple design because of the need to specify everything, after you already spent hours sketching the details of the bridge. Every point had to be parameterized by either merging it with an existing point or giving it an exact location in space. OpenSCAD allows you to skip the step of sketching and just specify the details of the model. For me this meant drawing a rough sketch on paper and labeling it with the measurements, but was still much faster than drawing it on the screen. It might be because of my long history of programming, but I liked the flexibility of OpenSCAD as well as its precision. The main issue with OpenSCAD is the lack of existing free designs available as it seems most people either design with FreeCAD or other graphical CAD software rather than coding their designs.

Until next week, stay safe and learn something new.

Scott Hamilton is an Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to shamilton@techshepherd.org or through his website at https://www.techshepherd.org.

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