Aug 20, 2015 | By Alec

Students are often surprising the rest of us by seeing things in a fresh perspective and coming up with completely new approaches to the world around us. This is obviously also the case where 3D printing is involved, as one Australian student from the University of Melbourne reminds us. For a master’s course in Ex-Lab Digital Furniture Fabrication, architecture student Joshua Stellini employed 3D printing technology to reinvent furniture: through the strategic use of NinjaFlex tiles, he developed the Voxel cube that functions as both a table and a stool.

The Voxel cube was developed as part of the Ex-Lab Digital Furniture Fabrication program at the University of Melbourne, which revolves around using the latest digital fabrication techniques to reinvent furniture. And as anyone who’s ever worked on one of these large master’s projects will know, its an extensive process with lots of wrong turns that all contribute to the final result. While we usually only get to see the final project, this time we are fortunate enough to see what the entire development process was like.

But to begin with the result, the Voxel cube not only looks fantastic but is – unlike most stylish pieces of furniture – multifunctional. While the concept itself didn’t entirely work out perfectly, it is very clever and could definitely work. At its heart, it serves two functions depending on what the owner wants: with three functional sides, one is firm and can operate as a table, while the other two are soft and can be sat on. While the goal was to make one as comfortable as a chair and the other as a stool, the two are more or less the same – something which doesn’t harm the functionality of the Voxel one bit.

However, as Joshua explains, he didn’t start out with the idea – it simply grew on him. Really he only set out with the idea of working with innovative joint techniques this semester. Initially starting out with exploring digital design options (CNC, laser cutting…) he wisely just began to explore his options. ‘I found these tests extremely engaging and useful in order to understand the complexity of some of the projects as well as engage in the process of making with lasercut and card cut pieces,’ he says. However, he decided to shift his focus towards 3D printing, even though he had never even seen one before. This meant that the first step was getting familiar with some models from Thingiverse and trying his hand at design.

While ultimately fruitless, this helped Joshua realize he wanted to use more fascinating materials in his design. ‘A Google search yielded the image of an experimental 3D printing filament called TPU 92A- 1. The material (right) has an interesting sponge like quality to it and allows the creation of complex, light-weight structures with elastic properties,’ he says. Though that material still isn’t available to the general public, he was very impressed by the possibilities of flexible joinery and memory retention – something which would definitely make 3D printed furniture a lot more comfortable. ‘The first test to illustrate this new concept involved series of lasercut pieces stitched on top of one another with a piece of sponge sandwiched between each of the nodes. However as the elements between the nodes were rigid, the deformation was global rather than local as desired,’ Joshua says. ‘Local deformation was considered important in this case as it would allow the furniture to change shape and give rise to some interesting forms.’

Fortunately, staff at a 3D printing warehouse quickly set him on the path of ninjaflex, as many of us would’ve also advised. And with the help of a plug in called FIX UP3D, Joshua was quickly able to transform the available UP 3D printers into machines capable of working with Ninjaflex. However, as the UP isn’t the best of 3D printers, he quickly ran into some feeding issues that required very slow, fluid printing motions. ‘Due to the nature of the material, the Ninjaflex would stretch when being fed though the cog instead of being pushed like a more rigid material such as ABS would. I found that using the feeder guide was essential for the prints work correctly,’ he says. Another issue was that the UP software necessitates supports – something that limits the capacity of Ninjaflex filament. This required careful design to minimize supports.

However, Joshua was very pleased with the results and what Ninjaflex could do for him. Not only it inherently useful for budget printers as it doesn’t require a heated printbed, the parts themselves are also very very strong and flexible – perfect for use in furniture and for supporting a person’s weight. This quickly fed the idea of a piece of furniture with different pieces of Ninjaflex cushions that could provide the local deformation he was looking for. ‘After being stuck for over a week I had a brilliant idea whilst on my way home from class in what would be the beginning of my final design outcome,’ he says. ‘Frantically scribbling on the train the idea was to have a series of cubes made of Ninjaflex that would adapt to different functions based on which face they were on. For example the ‘table’ face would be more densely packed and therefore more structural than a cube on a ‘chair’ face which would be lighter and more porous.’

However, this would require clever use of other materials to limit the insane scope of 3D printing. ‘I struggled to grapple with enormity of the amount of time and filament that would be necessary in order to fabricate any 3D printed furniture piece of considerable scale. To combat this, timber was proposed to be used as infill in place of printed modules while also acting as a bracing,’ he says. By relying on a timber frame, wooden blocks with laser cut perforations and only three useable sides to the cube, this suddenly became a very feasible project.

In this scenario, the Ninjaflex parts would act as pressure plates to allow comfort and local deformation. ‘Another solution was to randomly reduce the heights of the extruded cubes. The combined reduction in height allowed for a substantially less printing time and material use and made for a more interesting, textured response,’ Joshua adds. This meant a mass of standard timber blocks, and a series of customized 3D printed cushions – something that also added to the increasingly impressive appearance of the Vortex.

In fact, there was just one issue that needed to be resolved before making this a reality: how do you cope with all the compression of separate pieces? After all, all the plastic is pushed into a direction, but they can’t all push up against each other. ‘After further research I stumbled upon an exciting field of research known as auxetics. Auxetic are materials/geometries with a negative poison’s ratio. This means that when compressed they become thinner perpendicular to the applied force. This occurs due to their hinge like structures,’ Joshua explains. ‘After a series of tests it was clear that once again density played a key role in the structural integrity of the pieces, however these structures would perform quite well for this application. As suggested in literature, these patterns did in fact behave quite unusually and shrink when compressed. From all the printed options it appeared that the re-entrant hexagon/bowtie pattern seemed to have the most drastic deformation as it would fold on top of itself leaving very little air space.’

The Vortex was thus becoming a reality. Joshua quickly purchased 2 kg of Ninjaflex, and started developing a series of STL files suitable for the modules. ‘There were 10 different modules each ranging in size and density to fulfill different functions and aesthetic requirements,’ he says. Over 200 hours of printing followed to produce the 167 modules, as well as 200 ABS caps for extra comfort.

‘Printing took approximately 7 days, with an average of 3 printers running simultaneously. At peak production 5 printers were being used purely on my job,’ the Australian student boasts. Though obviously, this entire process wasn’t without its problems as clogging was a constant issue. This meant purging the 3D printer with a rigid material like ABS between each new print. ‘Despite my best efforts often the resulting prints were quite messy, with the Ninjaflex bridging between what should be hollow sections and inhibiting the squishiness of the print. As such each and every print was thoroughly cleaned with scissors and support material removed by drilling through the part,’ he adds.

And with printing well underway, Joshua also set out cutting 192 identical blocks, as well as a cube to which all parts could be affixed. ‘The random staggered look was achieved by manually laying out the blocks on the floor and was not necessarily influenced by a parametric model. Placing the blocks became increasingly difficult as more and more pieces were installed as I had not allowed for any tolerance between the blocks,’ Joshua says of the messy assembly. ‘This became such an issue that after the first face was complete, I went back and shaved off 1-2mm of each of the old blocks to compensate for the lack of space.’

However, the results are impressive. The Voxel ended up to be a visually very impressive piece of furniture that definitely encourages reflection on efficient and multifunctional additions to increasingly smaller and crowded homes. The only caveat is, like mentioned earlier, that it doesn’t work quite as well as initially intended. ‘There is little to no observable difference between the stool face and the seat face which was not as resolved as it could have been. The table’s uneven surface also makes it unsuitable for many applications, however still functions for larger items such as books, magazines and phones,’ Joshua adds. However, it is definitely a piece that can be improved upon in further iterations.

So how did the student experience the potential of 3D printing? Just like most of us, he found them to be potent but far from perfect. ‘The printers are very temperamental often breaking down for obscure reasons. The FDM printers are also extremely limited in what they can produce as they are dependent on bed size and support material in many cases,’ he reflects.

Nonetheless, he calls them extremely powerful fabrication tools as well, that could definitely serve a purpose in the furniture world. ‘I believe there is enormous potential for flexible 3D printed furniture that is capable of varying in density. Given more time the next phase of the project would push the potentials of flexible printing even further by making every 3D printed element bespoke, as well as removing the timber entirely to develop a network which responds differently,’ he says. ‘Given a large enough print bed [furniture] could be printed anywhere by anyone.’ And in that respect, we probably haven’t seen the last of Joshua.



Posted in 3D Printing Applications



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