[Stefanie Mueller]

Low-fidelity Fabrication (LOWFAB)
Speeding up Design Iteration of 3D Objects

 
 

Even though considered a rapid prototyping tool, 3D printers are so slow that a reasonably sized object requires printing overnight. This slows designers down to a single iteration per day. A typical iteration process therefore easily adds up to a week—even though the actual design work may not have taken longer than a few hours. This turns the 3D printer into the bottleneck of the workflow.

With low-fidelity fabrication, we propose to speed up design iteration by printing intermediate versions of a prototype as fast, low-fidelity previews. Only the final version is fabricated as a full 3D print.

Low-fidelity fabrication can be implemented in different ways depending on what is currently being tested.

faBrickator saves 3D printing time by automatically substituting sub-volumes with standard building blocks. After faBrickator converted a 3D model to Lego, users can mark parts of the 3D model as “high-resolution” to indicate that these should be 3D printed. faBrickator generates instructions that show users how to assemble Lego bricks and 3D printed parts. If users keep iterating on the prototype, faBrickator offers even greater benefit as it allows re-printing only the elements that changed.

WirePrint achieves its speed-up by replacing the surfaces of a 3D print with a wireframe mesh. Since wireframe previews are to scale and represent the overall shape of the 3D object, they allow users to quickly verify key aspects of their 3D design, such as the ergonomic fit. To maximize the speed-up, WirePrint instructs 3D printers to extrude filament not layer-by-layer, but directly in 3D-space, allowing them to create the edges of the wireframe model directly one stroke at a time. This allows WirePrint to achieve speed-ups of up to a factor of 10 compared to traditional layer-based printing. WirePrint runs on standard FDM 3D printers, such as the PrintrBot or the Kossel mini. Users only need to install the WirePrint software, making WirePrint applicable to many 3D printers already in use today.

Platener achieves its speed-up by extracting straight and curved plates from the 3D model and substituting them with laser cut parts of the same size and thickness. Only the regions that are of relevance to the current design iteration are executed as full-detail 3D prints. Platener connects the parts it has created by automatically inserting joints. To help fast assembly it engraves instructions. Platener allows users to customize substitution results by (1) specifying fidelity-speed tradeoffs, (2) choosing whether or not to convert curved surfaces to plates bent using heat, and (3) specifying the conversion of individual plates and joints interactively.
Platener is designed to best preserve the fidelity of technical objects, such as casings and mechanical tools, all of which contain a large percentage of straight/rectilinear elements. Compared to other low-fidelity fabrication systems, such as faBrickator and WirePrint, Platener better preserves the stability and functionality of such objects: the resulting assemblies have fewer parts and the parts have the same size, thickness, and approximate weight as in the 3D model.

Conclusion

 

The three low-fab systems presented speed up fabrication by a factor of 3-10 on average. This allows designers to have more iterations in a day, leading to a better design in less time.

Different design iterations focus on different key aspects, such as testing the technical function of an object first and then optimizing the shape for the best ergonomic fit. Different low-fab systems thus support different conversions of the original 3D model (e.g. Platener preserves the technical function of an object using plates of the same thickness, and WirePrint preserves the shape of an object by using a wireframe mesh).

Since different low-fab systems have different ways of converting the 3D model, each low-fab technique is best suited for a certain class of objects (e.g. Platener achieves its maximum speed-up for objects that have many rectilinear elements), while they are less suitable for others.

Publication

 

Mueller, S., Beyer, D., Mohr, T., Gurevich, S., Teibrich, A., Pfisterer, L., Guenther, K., Frohnhofen, J., Chen, H.-T., Baudisch, P., Im, S., Guimbretière, F.
Low-Fidelity Fabrication: Speeding up Design Iteration of 3D Objects.
CHI’15 EA, pp. 327-330. (Full Paper)
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