Researchers at the University of Chile have explored a mobile form of 3D printing that allows a machine to produce objects bigger than itself. Named ‘Koala 3D’, the system is a combination of a climbing robot and 3D printer, capable of scaling along the object that it is printing to create an infinite fabrication loop.
In the paper, the team of researchers present the design, construction, and characterization of the Koala 3D system alongside experiments and tests on vertically fabricated columns and statues. The authors of the paper explain that, from the results, the Koala 3D has a wide range of potential applications in construction and product fabrication.
The climbing Koala 3D printer
The researchers set out by explaining that the size of parts being produced by traditional manufacturing machines are naturally bound by the dimensions of the machine itself. “For example, while a plastic injection molding machine usually occupies various cubic meters, it produces parts that are considerably smaller than itself, somewhere between several cubic centimeters. Similar situations arise with subtractive manufacturing machines, such as mills, lathes, and their CNC counterparts,” the authors write in the paper.
However, with additive manufacturing, the machine volume is often closer to the volume of produced parts compared to traditional manufacturing technologies. As such, if enabled to move freely, 3D printing can facilitate the fabrication of objects larger than itself, the researchers found. The researchers therefore designed a machine capable of navigating vertically along the object it is building by combining a 3D printer and climbing robot.
The initial design concept consisted of two central components: a printer header part and climbing part. The latter was expected to function through the implementation of a pair of robotically actuated clamps. A lower clamping mechanism was located at the bottom of the printer body while an upper clamping mechanism was free to move between the bottom and upper part of the printer. To enable an infinite range of motion, the researchers ensured that a clamp always remained attached to the beam, while the other clamp proceeded to find a new anchoring point, resulting in a repeated process of ‘printing-reanchoring-printing-reanchoring.’
“The printer can be decomposed into two major subsystems. One is the vertical climbing stage for reanchoring, precise vertical motion during printing, as well as carrying the electronics,” the authors explain. “The other subsystem is the x-y positioning stage for moving the printer extruder. This stage also carries the material impulsion system.”
The researchers set about designing a more robust positioning system compared to existing popular 3D printers, mainly regarding size and weight. The stage was designed to cover an extruder motion range of 45mm x 45mm on the x-y plane, with the aim of producing vertical beams with a sectional area of 30mm x 30mm with this motion span. Explaining the reason behind the larger motion span, the researchers state that “The extra motion span (50% larger on every dimension) was intended to allow the extruder to purge outside the printing area as well as potentially introduce some features on the surface of the produced beam.” When selecting the printing head, the research team opted for the J-Head E3D extruder due to its compact design, reduced weight, and reported performance.
After designing the system, the team then set about performing a number of experiments and tests for evaluation, demonstrating that 3D printing is possible using the proposed printing-reanchoring-printing scheme. They set about 3D printing eleven sample beams in varying sizes using the climbing system, ranging from 350 mm to 850 mm, with an additional smaller part also 3D printed.
Discussing the implications of their successful demonstration, the researchers posit potential future research and applications in construction and product development industries, as well as three problems they encountered in creating the Koala 3D climbing printer: ”The problems are (1) the machine drop after reanchoring, (2) the structural oscillation at high aspect ratios, and (3) the initial alignment between part and base. Addressing these problems will be important in developing autonomous machines that can climb along the same structures they produce.”
3D printing in the construction industry
The construction industry has recently seen an increase in the implementation of 3D printing within various projects. Notable examples include the ‘world’s first’ 3D printed community; a group of 3D printed homes in Tabasco, Mexico currently undergoing construction with the help of New Story, a non-profit organization fighting homelessness, and ICON, a Texas-based construction technologies company.
Recently, SQ4D, an offshoot of the New York-based S-Squared 3D Printers (SQ3D) completed construction of a new building, in what it claims is the “largest permitted 3D printed home in the world,” spanning 1900 square feet. Architectural design studios Precht and Mamou-Mani Architects also constructed a pair of large installations in Saudi Arabia using 3D printing.
Within projects such as these, typically the 3D printing hardware is restricted to making objects smaller than the machine structure itself, which not only limits design freedom, but also leads to a number of logistical headaches in having to transfer large equipment from one location to another. With the climbing printer concept explored by the University of Chile researchers, they open a number of avenues for alleviating the problems of large-scale 3D printing construction projects.
The paper, “Koala 3D: A continuous climbing 3D printer” is written by researchers Maximiliano Vélez, Efrén Toala, and Juan Cristóbal Zagal, and is published in Robotics and Computer-Integrated Manufacturing.
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Featured image shows Sleeping koala. Photo via Jordan Whitt on Unsplash.
