Rapid prototyping multitool with 6-axis robotic arm

Abstract

In this first chapter of our project, we are going to illustrate all the passages performed step by step from the beginning of the project to the delivering day in order to achieve the established targets of the project description. Furthermore, we are going to add the ways we got them, therefore we will report the employed programmes used to accomplish the tasks.Frishop.dk and the case with the NEMA attached from a private from Slovenia “AllforCNC”. Firstly, we performed the designing part, so, since we were more interested in showing the real operation of the mechanical process, we preferred drawing by Inventor very simple shapes, as for example a cube, a cube with a hole or a disk. Then, we passed to the CAM part where we had to slice our object in order to know and to settle the printing layers and passages of the injector. Thus, we used slicing softwares as CURA, Python, Skeinforge and Slic3r. The last one mentioned will be chosen as best one between the others and by consequence used in the project. So, always thanks to the slicing software we could get the G-code, which is the classical code generated by CAM programmes. At this point we had to pass from the G-code to the Hyundai one and therefore elaborating a translating programme for this operation. After having done some attempts with MathLab trying to make a finite state machine, we succeeded to achieve the target making a translating programme in Java through Eclipse software. For the knowledge of the Java language we thank Enrique, student of ICT engineering, for his help, since the operation needed a deep knowledge of the Java language. Later, having the translated code, we had to upload the part of the code related to the movements of the robotic arm alternating with the print commands by COM port in order to send the feed rate and E value to the Arduino firmware. The aim of this task is the synchronizing of the shaft of the stepper motor and the robotic arm movements. For the Arduino calibration have been made lots of tests either with an oscilloscope either with a multimeter for its correct functioning. For all the work related to the use of the robotic arm, we have to thank Hans for his help and explication about it. Besides the electronics, we developed a suitable framework to be used in the printing and deburring processes. We dimensioned the injector E3D v6, the deburring tool using a DREMEL handtool and the case of the stepper motor NEMA 17, purchased from a private seller. In addition we made a material analysis for the material of the thread to be used in our process, selecting the most suitable coming out by the performed Ashby’s plots drawn thanks to EduPack CES Granta software. Determined the components we passed to assemble them on the framework. Hence, we had to design a case which would have avoided vibrations with the purpose of not spoiling and affecting the process of FDM. The first prototype presented a moment on the corners too high therefore after suggestions of Morten, who will follow us for all the length of the construction, and the supervisor, we preferred to attach all the components only on a plate directly screwed to the robot attachment. All the drawings from the first version to the final one are made with SolidWorks CAD software. We made a FEM analysis as well, it has been performed through Ansys CAE software and compared as it is advisable doing to analytical calculations with formulas of mechanics of materials. All the calculations are reported in the appendix using MathCad software. Furthermore, for better understanding the functioning of the stepper motor and of the injector, we calculated through gear ratios the relation between the speed of the robotic arm and the angular speed of the stepper motor shaft and the thermic exchange coefficient of the winged area. For attaching the components to the framework was quite simple for the injector since the stepper motor presents a notch where you can easily trap the hot end with two small bars through two holes already realised in the case. Then, the case has to be screwed directly to the plate. Besides, more difficult has been to fasten the DREMEL to the frame. So, for this we have to thank Luca and Marco, two students of mechanical engineering, who performed their assignment for the course of Reverse CAD engineering about scanning the DREMEL and developing a suitable case to be attached to the plate. For this passage has been used the software PolyWorks dealing with *stl files, using either the functions of IMEdit either of alignment. Finally, the file got after an elaboration of SolidWorks, because with PolyWorks has been created just the surface to be put in contact with the DREMEL, the case has been 3D printed in the 3D printer of the university, offering a perfect instance of RepRap trend: a 3D printer which prints components for other 3D printers. Eventually as we said, despite of we did not analyse the part of business in our project, we had to deal with the suppliers of the components since we wanted to realise something not just in theory but concrete. The main one has been RepRap.dk for the electronics, the injector and the heat bed. Then, we purchased the DREMEL from