The Visual - Solid 3D Modeling Gap
3D designers hoping to 3D print 3D models had better ensure the models are indeed 3D printable.
3D designers not familiar with 3D printing fall into the trap of discovering that their favorite 3D CAD tool does not actually produce printable 3D models.
The problem lies in the fact that among the now-huge set of 3D CAD tools, the vast majority target the visual market. That is to say, they are designed to produce 3D artifacts intended to be viewed, not 3D printed. An example might be a 3D model of a helicopter that is used in a TV action show instead of an expensive “real” helicopter.
Trade schools teaching 3D design often default to this mode of design, unleashing thousands of 3D designers to the world each year, yet with relatively few knowledgeable on “solid” 3D designs that are usable with 3D printing systems. Of course, there are indeed schools that specifically teach solid 3D modeling, but they are few relative to the more popular visual approaches.
Solid 3D modeling involves the production of 3D models that are “watertight”, which ensures a completely continuous surface. Discontinuous surfaces are quite confusing to 3D print slicing software, which have to literally reproduce the ambiguous design in reality.
Meanwhile, visual 3D models can be correctly seen by viewers regardless of their watertightness. That helicopter in the TV show looked quite real, did it not? But was it watertight? Who knows?
You would find out immediately if you attempted to 3D print that model, however. And that’s the scenario when an experienced visual 3D modeler drifts into the world of 3D printing. The 3D models don’t always become printable when saved, and mayhem, repairs and rework occurs. In some cases the workflow learned over considerable time must be re-engineered to produce solid 3D models.
This trouble is not the fault of the designers, who are subject to their software and training. Many 3D CAD tools were (and still are) designed specifically to produce visual 3D assets, not solid 3D models.
The issue is that learning any 3D modeling tool to a useful level is a long process that few want to do twice. Thus, once a tool is learned, the designer really wants to use that tool for any 3D job at hand, but they’re trapped when attempting to produce printable 3D models.
Some 3D designs are so pathologically composed they simply cannot be converted into printable form: imagine a 3D tree built for a virtual reality system composed of two perpendicular 2D sheets with a tree texture on them. This approach has often been used in some 3D environments to save on processing. But could this ever be 3D printed? Not a chance. I recall one day seeking a good 3D model of a cat, only to find one made up of a similar 2D sheet.
Some visual 3D CAD tools have introduced extensions, plugins or other approaches to convert a 3D design into printable form. These work sometimes, but depend on the nature of the design.
Another approach is to simply take the visual 3D model and throw it at a sophisticated 3D model repair service like MakePrintable, for example. If you’re very lucky the repair service just might be able to convert the item into printable form.
It’s a tricky process to convert visual 3D models to solid 3D models, and usually a good result requires some alterations to the design. One 3D print service company, i.materialise, has recently published a tutorial on this process. Their tutorial focuses on using Autodesk Maya, a very popular 3D visual CAD tool, to produce printable 3D models.
The key here for visual designers is to find a printability tutorial or instructions for their tool of choice. Be it SketchUp, Maya, or other visual 3D CAD tools, there are ways to make their output printable.
But it is always a good idea to start with a true solid 3D modeling tool if you intend on 3D printing the item.