Developing an open source, inexpensive, large-scale polar configuration 3D printer

Document Type

Conference Proceeding

Publication Date

Spring 2019

Department

Department of Manufacturing and Mechanical Engineering Technology

Abstract

Various 3D printer configurations, such as Cartesian printers, operate similarly to a CNC machining center and Delta printers that have a stationary build platform with the use of three motors located on pillars controlling the end effector location. A less popular configuration is a Polar system, which utilizes a rotating table, a Z translation controlled by a linear actuator located beyond the edge of the rotating table, and a horizontal arm connected to the Z-axis that translates the end effector along the center axis. The Polar 3D printer configuration, being the simplest, was chosen in order to scale up to build and test a low-cost largescale 3D printer with a build envelope of 1.83m x 1.83m x 1.53m (6ft x 6ft x 5ft). This open source hardware 3D printer (OSALS-Polar) can be produced for approximately $5,000 for materials, assuming that labor is provided by the user. To 3D print a part, any CAD software is used to output a stereo lithography (.stl) file, open source slicing software (Cura) to generate the G-code file, and open source software (Franklin) to operate the 3D printer. Testing the 3D printer requires calibration of the three axes to produce the desired positioning of the Theta-axis rotation, R-axis horizontal arm translation, and Z-axis vertical translation with the inputs into the Franklin software. Also, the system is set to start at a zero location, according to distances set from the end-stop limit switches. The final testing of the OSALS-Polar produced small extruded parts, although the accuracy and scaling up to larger parts not accomplished during this study. Future testing may encounter limitations in the size of prints, due to material cooling at various rates, causing warpage. Introduction 3D printing technology has become quite common, and increasingly applications for direct digital manufacturing are being implemented. RepRap (self-replicating machines) 3D printers (Sells, Bailard, Smith, Bowyer, & Olliver, 2010; Gibb, 2014) are open source 3D printer designs available for anyone to build. According to Wittbrodt et al. (2013), the cost of an open source 3D printer used for printing household components, such as a pierogi mold or paper towel holder, can be recuperated within a year or two if a reasonably fair number of household items are printed using the 3D printer (Wittbrodt et al. 2013; Wittbrodt, 2014). The 3D printer build envelope (printer platform times the printing height capability) can be a limitation of direct digital manufacturing, if the part exceeds this build envelope. Common desktop 3D printers have a build envelope of 203 mm (8 in.), length x 203 mm (8 in.), and width x 153 mm (6 in.) height. Larger-scale 3D printers, ranging from 5 to 10 times the size of the common desktop 3D printers, are typically very expensive to produce. Methods of joining 3D-printed parts via acetone have been successful in producing parts such as wind turbine blades (Deshpande, Rao, Pradhan, & Irwin, 2016), although this method requires several manufacturing steps and can decrease overall part accuracy. The goal of the OSALSPolar is to manufacture larger 3D-printed parts (such as wind turbine blades or propeller blades) that can be printed in a single setup without needing to be joined together. Wind turbine blades can operate at potentially high RPMs, and any structural concerns lead directly to safety concerns, making it advantageous to 3D print as one continuous part. To overcome size restrictions of desktop 3D printers, the OSALS-Polar can cost under $5,000 for materials, assuming the user provides the labor. In this paper, the authors describe the assembly and testing of the OSALS-Polar with a build envelope of 1.83m x 1.83m x 1.53m (6ft x 6ft x 5ft). The build instructions for this system are also described here. The open source software used to create the slice file was Cura; to operate OSALS-Polar, the open source software Franklin was used.

Publication Title

International Journal of Engineering Research and Innovation

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