Printing Conductive And Non-conductive Materials Simultaneously

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Printing Conductive and Non-Conductive Materials Simultaneously on Low-End 3D Printers Sander Klomp Supervisors: Prof. Jelle Saldien, Cesar Vandevelde Master's dissertation submitted in order to obtain the academic degree of Master of Science in de Industriële Wetenschappen: Industrieel Ontwerpen Department of Industrial System and Product Design Chairman: Prof. Kurt Stockman Faculty of Engineering and Architecture Academic year 2014-2015 Printing Conductive and Non-Conductive Materials Simultaneously on Low-End 3D Printers Sander Klomp Supervisors: Prof. Jelle Saldien, Cesar Vandevelde Master's dissertation submitted in order to obtain the academic degree of Master of Science in de Industriële Wetenschappen: Industrieel Ontwerpen Department of Industrial System and Product Design Chairman: Prof. Kurt Stockman Faculty of Engineering and Architecture Academic year 2014-2015 Foreword This thesis is written as a Master's dissertation submitted in order to obtain the academic degree of Master of Science in de Industriële Wetenschappen: Industrieel Ontwerpen. The subject of this thesis was chosen from both personal interest and the fact that 3D printing in general is a current topic, which promises for an interesting evolution in the future. At the beginning of this thesis I had little knowledge about 3D printing. However, I have been able to achieve a result I am very satisfied with. I would like to thank my supervisors from the University, Cesar Vandevelde and Jelle Saldien for giving me the opportunity to work on this project. Their valuable insights and directions gave me needful guidance to complete the research and write this thesis. I would also like to thank Maarten Vanhoucke, researcher at the Industrial Design Center in Kortrijk to share his knowledge and the best available information about 3D printing and electronics. Last but not least I want to thank Gianni Franci for sharing the design files of his dual extruder system and to guide me through the process of installing and modifying it. The author gives permission to make this master dissertation available for consultation and to copy parts of this master dissertation for personal use. In the case of any other use, the copyright terms have to be respected, in particular with regard to the obligation to state expressly the source when quoting results from this master dissertation. Sander Klomp Kortrijk, June 2015 Abstract This thesis explores the possibilities of printing conductive and non-conductive materials simultaneously on low-end 3D printers with the intention of demonstrating the potential and to stimulate further use of the technique. 3D printing has evolved in the past decades from being a sophisticated process requiring expensive machinery used only by larger companies to a considerable number of relatively cheap open source projects allowing for the technique to be used by a much wider audience. Today the average person can buy a 3D printer, draw a part in CAD or download one from the Internet and start printing it on his desktop 3D printer in the comfort of his home. With the coming of new printable materials the opportunities grow and the whole concept of manufacturing and customization changes. The development of printable, electrically-conductive materials opens up a broad avenue in the possibilities of the technique, not only does it allow the printing of sensors and circuits, it could change the whole standard of electronic devices now being able to work in a three-dimensional space instead of using the classic printed circuit board. This thesis describes the process we went through upgrading two low-end 3D printers to print two materials simultaneously. Afterwards we describe how this technique can be used for printing conductive and non-conductive materials simultaneously and we give a few demonstrations of the possibilities. Extended Abstract (See next pages) Printing Conductive and Non-Conductive Materials Simultaneously on Low-end 3D Printers Sander Klomp Department of Industrial System and Product Design, Ghent University, Campus Kortrijk Marksesteenweg 58, 8500 Kortrijk, Belgium [email protected] Cesar Vandevelde Department of Industrial System and Product Design, Ghent University, Campus Kortrijk Marksesteenweg 58, 8500 Kortrijk, Belgium [email protected] Abstract—3D printing has evolved in the past decades from being a sophisticated process requiring expensive machinery used only by larger companies to a considerable number of relatively cheap open source projects allowing for the technique to be used by a much wider audience. Today the average person can buy a 3D printer, draw a part in CAD software or download one from the Internet and start printing it on his desktop 3D printer in the comfort of his home. With the coming of new printable materials the opportunities grow and the whole concept of manufacturing and customization changes. The development of printable, electrically-conductive materials opens up a broad avenue in the possibilities of the technique, not only does it allow the printing of sensors and circuits, it could change the whole standard of electronic devices now being able to work in a three-dimensional space instead of the classic printed circuit board. This research paper explores the possibilities of simultaneously printing this new conductive material and non-conductive materials on lowcost 3D printers. Keywords — 3D printed electronics, additive manufacturing, conductive material I. INTRODUCTION Printed circuit structures To many of us, a world without electronic devices is very hard to imagine. Electronics have changed nearly every aspect of our lives. Today, nearly all circuits use discrete components that are placed on a flat, two-dimensional printed circuit board (PCB). With a big increase in popularity over the past few decades additive manufacturing or 3D printing could change the way we build electronic devices in the future. Instead of using PCBs that are mounted afterwards in the device, Printed Circuit Structures (PCS) would look at electronics from a new perspective. In a PCS the enclosure and structure of the device itself would carry the circuits and components making the usage of PCBs unnecessary. In this approach components can be smoothly integrated and even hidden inside the structure. By building the electronics into the A. Jelle Saldien Department of Industrial System and Product Design, Ghent University, Campus Kortrijk Marksesteenweg 58, 8500 Kortrijk, Belgium [email protected] structure the device would become more rigid, eliminating the use of glue, snaps, solder, wiring or bolts. This would also result in the ability to use much more components in far less space, making it possible to create smaller and less bulky devices while not sacrificing in their functionality [1]. We are evolving into a world where all electronic devices become smart and communicate with each other. With the coming of 3D printing conductive materials it will be possible to print functional components and sensors like 3D touch surfaces, integrated bend or turn sensors, optimized antennas, custom motors, speakers, solenoids and much more that can be integrated in smart devices and communicate through ‘the Internet of Things’ [2]. 3D printing 3D Printing or Additive Manufacturing (AM) is a rapid prototyping technique that lets users physically create three-dimensional (3D) objects drawn with a computer. The object is usually modelled with computer aided design (CAD) software and exported as a Surface Tessellation Language (STL) file. Slicing software slices the part in two-dimensional layers, which are sequentially printed on top of each other to create a solid object. As opposed to subtractive manufacturing (SM), a technique that takes a raw metal and creates a part by cutting or drilling sections away, additive manufacturing is less expensive, less time consuming and produces much less waste material. There are a few different techniques for 3D printing. The two techniques that are most used in low-cost 3D printers are Fused Filament Fabrication (FFF) and Stereo Lithography (SLA). B. Fused Filament Fabrication FFF is equivalent to Fused Deposition Modelling (FDM), a term and abbreviation that is trademarked by Stratasys Inc [3]. The term fused filament fabrication (FFF), was invented by the members of the RepRap project to provide a term that would be legally independent in its use [4]. An FFF 3D printer extrudes a thermoplastic material through a temperature-controlled nozzle similar to how a hot glue gun extrudes a melted cartridge of glue. The nozzle heats the material to a semi liquid state and draws the outline in ultra thin layers (typically between 0.05 mm to 0.3 mm) onto a build platform. Then it fills the outline with a raster of material creating a complete section of the object and proceeds to the next layer binding it to the previous one. The result is a plastic 3D model built up one layer at a time. Because sometimes not all the layers are touching the build platform a support structure can be created which can be removed after the print is finished. Because the printed parts are relatively strong and durable this technique is ideal for functional prototypes and the quick testing of shapes and fittings [5]. 1) layers that solidify on top of each other form the 3D object. Similar to FFF sometimes supports are required for overhangs and holes, these can be added either manually or automatically. After the product is removed from the build platform the support structure can be removed. Fig. 2. Schematic overview of the Stereolythography process [6] State of the art A three-dimensional accelerometer sensor system with microprocessor control (Fig. 3) was fabricated using a previously developed integrated layered manufacturing system that combines conductive ink dispensing with SLA. The insert itself was printed using SLA and after cleaning it rigorously, the ICs and discrete components were inserted into their designated cavities. Conductive silver ink was then dispensed throughout the design to create the circuit interconnections. After the conductive silver had cured in a convection oven, the antenna and ground plane were coated with the silver ink and again the insert was placed into a convection oven for final curing. The insert is press-fit into a helmet for the purpose of detecting Traumatic Head Injury (THI) when excessive acceleration to the head is measured. Applications could include monitoring the health of soldiers or athletes [7]. C. Fig. 1. Schematic overview of the Fused Deposition Modeling process [4] Stereolithography Stereolithography (SLA) (Fig. 2) uses a laser beam to harden the surface of a vessel of liquid resin to create a part. Where the laser beam hits the liquid, the hardening takes effect. When a layer is finished, the platform that holds the object drops a fraction of a millimetre deeper into the vessel. The different 2) Fig. 5. Quadcopter produced almost entirely on Voxel8 Developer’s Kit [9] Fig. 3. Accelerometer System Helmet Insert [7] The Voxel8 Developer’s Kit (Fig. 4) is an ‘electronics 3d printer’ that combines an FFF machine with a conductive ink dispenser. The machine starts out printing just like any other FFF 3D printer. For placing circuits into an object, a second nozzle is utilized, which is filled with highly conductive silver ink. Once the circuits are printed, the printer switches back to the FFF material. The machine pauses when an electrical component needs to be placed. The build platform can be removed and components like LED’s or sensors can be placed in place. Once placed, the machine resumes the print job [8]. At CES 2015, the company displayed a quad copter that was produced almost entirely in one piece on their machine. The PLA and connective circuits of the quad copter were 3D printed in one go, with the electronics, battery, and motors inserted throughout the printing process [9]. Carbomorph, a mixture of conductive Carbon Black (CB) and polymorph is a fairly new simple, low-cost conductive composite material able to be printed with a low-cost FFF 3D printer. The piezoresistive nature of the conductive composite was already used to sense mechanical flexing when added to an existing object and was also embedded into an ‘exo-glove’ interface device for sensing the flexing of a hand. The material was also used to create an embedded capacitive sensor in a smart vessel (Fig. 6), which is able to sense the amount of liquid placed inside. The printed sensors are simple to interface to and require no complicated electronic circuits or amplification and can be monitored using existing open-source electronics and freely available programming libraries [10]. Today Carbomorph is finding its way to the market or people even claim they improved the formula and try to crowd fund their developments using Kickstarter campaigns. Many have tried but few have succeeded. Esun, Proto-Pasta, Makergeeks, 3dxtech and Zentoolworks are a few examples of manufacturers of this conductive filament. Fig. 4. Voxel8 Developer’s Kit [8] Fig. 6. 3D printing of capacitive ‘smart’ vessel [10]. II. METHOD 3D printers We decided to focus our research on printing with low-cost FFF machines. The 3 different printers we used were an Ultimaker Original (UMO), an Ultimaker 2 (UM2) and a RepRap Prusa I3. The UM2 was mainly used to print parts for upgrading the other two printers. This section will give an overview of the upgrades we made. A. Ultimaker Original (UMO) The UMO (Fig. 7) is a Cartesian FFF 3D printer that uses 3mm filament and can print a number of different materials. The printer is well known in the Maker Community to be a ‘hackable’ printer, since it mostly uses simple laser cut or printed parts and open source software running on an Arduino Mega board. In 2012, the Ultimaker Original was awarded ‘Fastest and Most Accurate 3D printer available’ in MAKE Magazine's annual 3D printing guide [11]. For our research we did some upgrades and alterations to the printer. We installed a heated build platform, shield windows and a dual extruder. 1) results in a higher quality finish with materials such as ABS and PLA. A HBP also allows users to print without rafts, skirts and brims [13]. The heated build platform we installed (Fig. 8) is a kit we obtained from a vendor on EBay. It features a 3 mm aluminium core PCB with an integrated PCB heater, LED indicators and thermistors that allows for fast heating (20°C to 100°C in less than 5 minutes). The kit contains a power supply, which we installed to provide power to both the printer and the bed. To fit the power supply we provided the printer with some raising feet so the supply could fit snugly in the bottom of the printer next to its electronics. We also replaced the 4-point levelling system of the bed with a much easier 3-point levelling system. Fig. 8. Heated build platform b) Shield Fig. 7. Ultimaker original [12] a) Heated build platform A heated build platform (HBP) improves printing quality by helping to prevent warping. When the printed plastic cools down, it has the tendency to shrink. Because the sides of the object cool faster than the inside, mainly while printing in ABS, sometimes warping occurs. Because of this warping the corners of the part tend to come loose from the build platform. When a HBP is installed the printed part stays warm during the printing process allowing the shrinking to happen more evenly. This windows Because we wanted to be able to print with ABS we installed shield windows to make the printer case more enclosed. Extruded ABS is very sensitive for drafts in the environment surrounding it. When it doesn’t heat up or cool down evenly problems like warping or deformed parts might occur [14]. The shield windows we installed (Fig. 9) were made of laser cut 3 mm acrylic sheets with a 5mm overlap on the sides. 8 corner pieces were designed and 3D printed to keep the sheets in place. The design was also shared on Thingiverse. Fig. 9. Shield windows Dual extruder In order to be able to print two materials, being it conductive and non-conductive or not, simultaneously we added a dual extrusion system to the Ultimaker Original. Dual extrusion is a technique already used by professional 3D printers to generate support structures. Since the beginning of the RepRap project [15] people in the community have tried to implement the technique in the lowcost machines but this has proven to be fairly difficult. As of today only a handful of companies offer dual extrusion on their low cost FFF printers and these systems are still known to have quite a bit of flaws. The most common problems the systems have are ‘oozing’ and nozzle alignment. When a nozzle is inactive, it stays hot and this causes the material inside to leak out of the nozzle cluttering the print, this phenomenon is known in the Maker Community as ‘Oozing’ (Fig. 10). When using a dual extrusion system both nozzles have to be at exactly the same height. When one nozzle is lower than the other it will scratch the print or pull it off the build platform (Fig. 11). If one nozzle is higher than the other two materials printed on top of each other will not bind properly. Professional 3D printers that use the technique have much more control over the process because they use heated chambers and printing materials supplied by the same manufacturer. Ultimaker also sells an ‘experimental’ upgrade for the UMO and was planning to develop a dual extrusion upgrade for the UM2 as well but in a company update released on their community forum [16] they announced they cancelled the development of the upgrade due to technical difficulties. c) Fig. 10. Oozing effect of the inactive nozzle Fig. 11. Print being pulled loose by inactive nozzle. We decided to use E3D’s V5 all metal hot ends (Fig. 12) because we already used these for single extrusion on the UMO and have had better results with them than the standard UMO hot ends. Because some types of filaments are only available in certain diameters we chose to use a combination of a 3 mm and a 1.75 mm hot ends which would allow us to also print with these two different types of filament diameters. The design of the dual extruder (Fig. 13) consists of an XY-carriage 3D printed in ABS. In this carriage both hot ends are mounted and can be adjusted in height separately by loosening the front mounting bracket. On the backside two 30x30x10 mm fans were mounted to cool the heat breaks, this is necessary to keep the transition zone between the glass transition temperature and the melting temperature of the materials used as small as possible in order to reduce friction problems. On each side of the carriage there is a mounted fan duct that holds two 40x40x10 fans to actively cool the print area, this is particularly useful when printing bridges or small details in PLA. The two extruder motors were mounted on the back of the printer and connected to the hot ends via ‘Bowden tubes’. The Bowden tube reduces the moving mass of the extruder resulting in faster controlled motion, less shaking of the machine, less energy use and faster printing. The system has one major drawback: hysteresis. The plastic filament will compress in any extruder, but putting pressure on such a long length of filament will multiply the effects of this compression, leading to springiness. The flexibility of the PFTE tube increases this problem. It’s possible to control this problem with software calibration [17]. Because we are using two different sizes of nozzles the extruder motors both need to have their own feeding speed, the speed the extruder motor is set to in order to push the material through the nozzle. This was not possible with Marlin, the standard firmware of the Ultimaker Original. We opted for installing ‘Repetier Firmware’, another firmware solution that made it possible to assign different feed rates to each extruder. By installing the new firmware some other problems appeared; the display stopped working and the pins had to be re-assigned in the firmware, it was not possible to slice with ‘Cura’, Ultimaker’s standard slicing software, anymore because the program wouldn’t recognize the different feed rates. The solution to this problem was using ‘Repetier Host’ a slicing program made by the same developers of the new firmware we installed. Prusa I3 The Prusa I3 (Fig. 14) is the third iteration of the Prusa mendel, which was developed as a RepRap [15] project. This project started the 3D printer revolution by building low-cost, self-replicating, open-source 3D printers. It has become the most widely used 3D printer among the global members of the Maker Community (Fig. 15). The frame of our model was made of a single sheet of aluminium and uses a RAMPS 1.4 controller. It’s also a Cartesian printer and the main difference between this printer and both Ultimaker printers is that this printer moves the build platform for the Ymovement where as the Ultimaker moves the print head itself. This printer also doesn’t feature an enclosed frame making it less ideal to print ABS. We upgraded this printer with a dual extrusion system. 2) Fig. 12. E3D V5 all metal hot end [18] Fig. 14. Prusa I3 Metal Frame [19] Fig. 13. Dual extrusion system mounted on the UMO Fig. 15. Diamgram of 3D printer usage [20] a) Dondolo Dual Extruder While looking for other dual extrusion systems after what we had learnt from using our design on the UMO we came across a design shared on Thingiverse made specificly for the Prusa I3. It looked promising, using a similar technique as seen in the professional Stratasys Dimension printers [21], allowing the hot ends to pivot around an axis. The design uses a servomotor to make the hot ends pivot around the axis. The axis used as a pivot point is the axis of the single stepper motor driving the extrusion for both hot ends. The design was originally developed for E3D’s V6 all metal hot ends but after some minor modifications we were able to make it work for the V5 hot ends as well. To reduce complexity in firmware settings we decided to use two hot ends for the same 3mm filament diameter. For the extruder motor a stepper with high phase resistance and inductance was needed while still remaining a high torque. The NEMA17 42BYGHW208 stepper motor met these requirements. To drive the stepper motor we also upgraded the printer with a new DRV8825 stepper driver. Because we needed a very sharp drive gear to feed the filament we made one ourselves using a 8mm rod, which we provided with teeth on a milling machine. Later we used a UM2 drive gear, which proved to give better results. Fig. 16. CAD visualisation of the Dondolo dual extrusion system Printing Materials 1) PLA Polylactic acid (PLA) is a biodegradable polymer that is made from lactic acid, a natural substance gained from corn crops making it ideal for usage in the poorer counties of the world and a non-toxic and renewable resource. PLA biodegrades in approximately 60 days while other plastics can take up to 400 years to degrade [22]. The material is harder than ABS and has significantly less shrinking problems. It melts at a relatively low temperature (around 180°C to 220°C), and has a glass transition temperature between 60-65 °C, making it a very useful material. When printing PLA it is important to keep the distance between the glass temperature point and the melting point as small as possible because the material gets sticky in this zone and exhibits higher friction than ABS which can make it difficult to extrude and causes more extruder jams [23]. 2) ABS Acrylonitrile Butadiene Styrene (ABS) is a commonly used lightweight thermoplastic that can be used for extruding and ejection moulding. It is less brittle and requires less force to extrude than PLA but handles higher temperatures better. Therefor no active cooling is required and it does a better job at printing small parts compared to PLA. The downside of ABS is that it has more shrinking problems and has to be extruded at a higher temperature: It has a glass transition temperature of around 105 °C. Because ABS is amorphous it has no true melting point, however 230°C is the standard for printing [24]. 3) Colorfabb XT ColorFabb XT, a material manufactured by Colorfabb, is the first 3D printer filament produced from Amphora 3D Polymer, a PETG variant. It’s a strong and tough material that handles high temperatures well, has less shrinking problems and does a better job at bridging than ABS. ColorFabb XT is best printed at 240-260°C and a HBP temperature of 75°C [25]. 4) Esun Conductive filament The first Carbomorph variant we could get our hands on was Esun’s Conductive Filament. Esun is a Shenzhen based 3D printing filament supplier and one of the few suppliers of conductive filament when we started this research. It sells the conductive B. filament in a 1.75 and 3 mm variants. Our first tests were done with the 1.75 mm variant and later on we also tested the 3 mm variant. The datasheet doesn’t really specify its composition but claims the material has a surface resistance of 800 Ω and a print temperature of 220-260°C [26]. Proto-Pasta conductive PLA Proto-Pasta Conductive PLA, manufactured by a company called Protoplant, is a compound of Natureworks 4043D PLA, a dispersant and conductive carbon black. It has the same features as regular PLA but is a bit more flexible and can be printed at the same temperatures [27]. 6) Bare Conductive Electric Paint An east London based company called Bare Conductive sells a product called ‘Electric Paint’. Essentially it’s a mixture of paint and carbon, making it electrically conductive. According to the company the paint can act as a "paintable wire" that can be used on paper, cement, textiles, wood and other materials, and becomes conductive once it dries. 7) Bronzefil Colorfabb Copperfill is a filament produced with a micronized copper powder, which has been infused into a common PLA plastic. We did some tests with printing Copperfill put unfortunately the material is not conductive. 5) As a comparison we measured the resistance on all conductive materials we used. TABLE I. OVERVIEW TESTED CONDUCTIVE PRINTING MATERIALS Properties Material Technique Resistance 100 mm filament ProtoPasta FFF 987 Ω Esun 3mm FFF 172 kΩ Esun 1.75 mm FFF 123 kΩ Bare Conductive Ink 167 kΩa Bronzefill FFF ∞ a. Remarks Easy to print Lower resistance Difficult to print High resistance Difficult to print High resistance Cumbersome process High resistance Material is not conductive nozzles is not precise enough resulting in a lot of prints being scratched or pulled loose because of height difference between the nozzles. Because we installed two different diameter sizes of nozzles in our system, something we have never seen on any other printer, we suspect the slicing software confused the feed rates of the different nozzles resulting in a lot of tests with signs of over and under extrusion (Fig. 17). We also had a lot of oozing issues. We tried to solve this within the slicing software. A few options we tried were extensive retraction distances on a tool change, this helped a little but didn’t completely solve the problem. In Slic3r, a slicing program we used, there is an option to cool down the inactive nozzle after a tool change and before the active nozzle starts extruding, this solved the problems of oozing but brought some new problems with it: a print takes about five times as long to print and the nozzles were clogged all the time, especially when using the conductive material. With the Cura slicing engine an ooze shield can be added. This is a thin shell that is automatically printed around the object shielding it from oozing nozzles. At the moment of testing the dual extrusion system on the UMO the Esun conductive filament was the only conductive filament we could get our hands on. After some basic tests this material appeared to be really difficult to print with. The material doesn’t like to stick to the HBP or to other materials, it has severe oozing problems and leaves a lot of residual material in the print head, which causes a lot of print head jams and was also a big problem when we used the temperature switch technique in the Slic3r software. When printing the material together with other materials a lot of warping occurred. After weeks of tweaking and tuning both hardware and software without any significant progress we abandoned this path and decided to look for a different solution. A 100 mm long 3mm diameter channel filled with Bare Conductive Electric Paint III. RESULTS Dual extrusion on the UMO We encountered a lot of problems while trying to print the dual extrusion system we installed on the UMO. Our system to control the height of the A. Fig. 17. A printed traffic cone showing obvious signs of over extrusion. Fig. 18. Severe oozing problems Fig. 19. Dual extrusion attempts on the UMO Dual extrusion on the Prusa I3 When we came across the Dondolo dual extrusion system on Thingiverse we immediately noticed that a few of the major problems we were having with our own dual extrusion design were cleverly solved in this design. Because the inactive nozzle pivots up on a tool change it sits a few millimeters higher than the active nozzle so it can’t scratch the printed part or pull it loose. While the inactive nozzle is pivoted away it rests on a designated ‘ooze plate’ acting as a shield so no material can drip out of the nozzle when inactive. B. Fig. 20. Schematic overview of the Dondolo dual extrusion system After installing the Dondolo Dual Extrusion system on the Prusa I3 we immediately received a lot better results than our attempts with the UMO. We started off by printing calibration prints in PLA. A problem that occurred was that the material that rested inside of the inactive nozzle would heat up and become very liquid, leaving a drip mark on certain prints after a tool change. We solved this by adding a retraction before a tool change in the slicer software. Another problem we had was that the left idler didn’t give enough clearance space when the left nozzle was inactive causing the filament to be pulled up while the right extruder was extruding. After measuring and testing we discovered this was caused by a deformed part that limited the movement of the left idler. We redesigned the rocking clamp which provided the idler with some more clearance space when inactive and decided to redesign the idlers themselves enhancing the spring attachment points which allowed for more spring tension. The next problem we were confronted with was that when printing with the dual extrusion system whenever a tool change occurred, meaning that the printer switches from one extruder to the other, it took some time (or length) before the active nozzle printed consistently. We solved this by using the Cura slice engine in Repetier Host, which gave us the option to include a ‘wipe and prime tower’ (Fig. 21) in the prints. Before each printed layer the nozzle is sent to extrude a square outside of the printed object until the nozzle prints the material consistently. After the square is drawn the nozzle makes a small rapid movement over the square to wipe the nozzle clean. When all the squares are printed on top of each other this results in a tower hence the name ‘wipe and prime tower’. Fig. 21. Printing with wipe and prime tower Dual extrusion with conductive materials 1) Controller with Makey Makey On the Dondolo dual extrusion system we printed a circular controller with four buttons (Fig. 22). For the enclosure we used ABS and for the buttons we used Esun conductive filament. For testing purposes we hooked it up to a Makey Makey, a prototyping board that you can hook up to anything that is conductive and use it to control certain keys on a computer [28]. C. possibility of printing any shape you like with a 3D printer the touch pads or touch surfaces can be used in any shape. In our example the object becomes the touch pad. We used our ‘capacitive touch sphere’ to control integrated LED lights using an MPR121 Capacitive Touch Sensor Breakout Board and an Arduino. Fig. 24. 3D printed capacitive touch sphere DISCUSSION, CONCLUSION AND FUTURE WORK In this paper we looked at two different techniques to print conductive and non-conductive materials simultaneously. Although not fully optimized the second technique showed significantly better results. We spend a lot more time on getting the dual extrusion technique working than we initially planned at the beginning of this research. It proved to be the biggest challenge we had to face. The first conductive filament we tried was very difficult to print with and had a fairly high resistance making it not useable for printing electrical circuits yet. The second material we tried was already a big improvement and a step in the right direction. While the conductive materials we tested can already be used for applications that require very little current or for sensors we think that with further development of the conductive printing materials and optimized dual extrusion systems the opportunities of printing circuit structures with FFF machines will evolve rapidly. The results of this research already shed a light on what the future of printing with conductive material might offer. In a next phase research could be done to optimize the formula of conductive materials so they have less resistance and can be used for printing fully functional circuits. IV. Fig. 22. Our printed controller hooked up to a Makey Makey 2D Capacitive Wheelpad We printed a capacitive wheel pad similar to the wheel that’s used in the first generation of Apple’s Ipods [29]. To control it we used an MPR121 Capacitive Touch Sensor Breakout Board and an Arduino. This wheel pad could be used to control music, light, video games and much more. 2) Fig. 23. Printed capacitive touch wheel pad aside an existing capacitive touch wheel pad 3) 3D Capacitive Touch Sphere We printed half of a sphere with integrated touch surfaces. Most capacitive touch pads we see today are limited to a two-dimensional plane. With the ACKNOWLEDGMENT This research paper is made possible through the help and support from friends, family, teachers and fellow students but I especially would like to dedicate my acknowledgment of gratitude toward the following significant advisors and contributors: [9] M. MOLITCH-HOU, “Voxel8: 1st Electronics 3D Printer - 3D Printing Industry,” 2015. [Online]. Available: http://3dprintingindustry.com/2015/01/05/voxel8-unleasheselectronics-3d-printer-ces-world/. [Accessed: 11-May-2015]. [10] S. J. Leigh, R. J. Bradley, C. P. Purssell, D. R. Billson, and D. a. Hutchins, “A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors,” PLoS One, vol. 7, no. 11, p. e49365, Nov. 2012. First and foremost, I would like to thank my supervisors from the University, Cesar Vandevelde and Jelle Saldien for giving me the opportunity to work on this project. Their valuable insights and directions gave me needful guidance to complete the research and write this paper. [11] M. Frauenfelder, “Make: Ultimate Guide to 3D Printing 2014,” Make: Magazine, 2012. [12] “Ultimaker Original | Ultimaker.” [Online]. Available: https://ultimaker.com/en/products/ultimaker-original. [Accessed: 14-May-2015]. [13] “Heated Bed - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/Heated_Bed. [Accessed: 14-May-2015]. [14] “ABS or PLA? Choosing The Right Filament | Make:” [Online]. Available: http://makezine.com/2014/11/11/abs-or-pla-choosingthe-right-filament/. [Accessed: 14-May-2015]. Second, I would like to thank Maarten Vanhoucke, researcher at the Industrial Design Center in Kortrijk to share his knowledge and the best available information about 3D printing and electronics. [15] Last but not least I want to thank Gianni Franci for sharing the design files of his dual extruder system and to guide me through the process of installing and modifying it. R. Jones, P. Haufe, E. Sells, P. Iravani, V. Olliver, C. Palmer, and A. Bowyer, “RepRap – The Replicating Rapid Prototyper,” 2009. [16] “Company update | Ultimaker.” [Online]. Available: https://ultimaker.com/en/community/view/10344-companyupdate#entry90597. [Accessed: 23-May-2015]. REFERENCES [17] “Erik’s Bowden Extruder - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/Erik%27s_Bowden_Extruder. [Accessed: 21May-2015]. [18] “v5 HotEnd Full Kit - 3mm Direct.” [Online]. Available: http://e3donline.com/E3D-V5-3mm-Direct-All-Metal-HotEnd?search=v5. [Accessed: 15-May-2015]. [19] “Prusa i3 - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/Prusa_i3. [Accessed: 21-May-2015]. [1] K. H. Church, H. Tsang, R. Rodriguez, P. Defembaugh, R. Rumpf, and E. Paso, “Printed Circuit Structures , the Evolution of Printed Circuit Boards,” in Ipc Apex Expo Conference. [2] H. Kopetz, Real-Time Systems. 2011. [3] “FDM Technology, About Fused Deposition Modeling | Stratasys.” [Online]. Available: http://www.stratasys.com/3dprinters/technologies/fdm-technology. [Accessed: 20-May-2015]. [20] [4] “Fused filament fabrication - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/Fused_filament_fabrication. [Accessed: 17May-2015]. J. Moilanen and V. Tere, “Manufacturing in motion: first survey on 3D printing community,” 2012. [21] “Fused Deposition Modelling (FDM) | Materialise.” [Online]. Available: http://www.materialise.com/glossary/fused-depositionmodelling-fdm. [Accessed: 17-May-2015]. “Dimension 1200es 3D Modeling Printers| Stratasys.” [Online]. Available: http://www.stratasys.com/3d-printers/designseries/dimension-1200es. [Accessed: 27-May-2015]. [22] “What is Corn PLA plastic? | ecokloud.” [Online]. Available: http://www.ecokloud.com/what-is-PLA.html. [Accessed: 27-May2015]. [23] “PLA - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/PLA. [Accessed: 25-May-2015]. [24] “ABS - RepRapWiki.” [Online]. Available: http://reprap.org/wiki/ABS. [Accessed: 25-May-2015]. [25] “ColorFabb - XT Co-Polyester Filaments produced from AmphoraTM 3D Polymer by Eastman Chemical Company.” [Online]. Available: http://colorfabb.com/xt-copolyester. [Accessed: 25-May-2015]. [5] [6] J. H. Lee, “Research: Ceramic/polymer Composite Materials through Stereolithography,” 2001. [7] S. Castillo, D. Muse, F. Medina, E. Macdonald, and R. Wicker, “Electronics Integration in Conformal Substrates Fabricated with Additive Layered Manufacturing,” pp. 730–737. [8] “Voxel8 Unveils New Electronics 3D Printer At 2015 CES 3DPrint.com.” [Online]. Available: http://3dprint.com/35085/voxel8-electronics-3d-printer/. [Accessed: 12-May-2015]. [26] [27] “ESUN 3D FILAMENT CONDUCTIVE BLACK ESUN.” [Online]. Available: http://www.esun3d.net/cpxx.aspx?id=171&TypeId=15. [Accessed: 12-May-2015]. “Conductive PLA – ProtoPlant, Makers of Proto-pasta.” [Online]. Available: http://www.proto-pasta.com/pages/conductive-pla. [Accessed: 12-May-2015]. [28] “Makey Makey | Buy Direct (Official Site).” [Online]. Available: http://makeymakey.com/. [Accessed: 28-May-2015]. [29] “Apple - Products - iPod History.” [Online]. Available: https://www.apple.com/pr/products/ipodhistory/. [Accessed: 30May-2015]. Table of contents 1.! Introduction............................................................................................. 1! 1.1.! 3D printing ............................................................................................................ 1! 1.1.1.! Fused Filament Fabrication (FFF) ................................................................ 2! 1.1.2.! Stereo Lithography (SLA) .............................................................................. 3! 1.1.3.! Printing Materials .......................................................................................... 4! 1.2.! Electronics ............................................................................................................ 5! 1.2.1.! Current Electronics ........................................................................................ 5! 1.2.2.! Printed Circuit Structure (PCS) ..................................................................... 6! 2.! Market research...................................................................................... 7! 2.1.! Conductive material printing techniques ........................................................... 7! 2.1.1.! SLA with Manual Ink Dispensing .................................................................. 7! 2.1.2.! FFF with Automated Ink Dispensing ............................................................ 8! 2.1.3.! FFF with Conductive Filament ...................................................................... 9! 2.2.! Conductive material........................................................................................... 10! 2.2.1.! Bare Conductive Electric Paint ................................................................... 10! 2.2.2.! Esun Conductive Filament .......................................................................... 13! 2.2.3.! ProtoPlant Proto-Pasta Conductive PLA ................................................... 15! 2.2.4.! Colorfabb Copperfill .................................................................................... 16! 3.! Printer Modifications ............................................................................ 18! 3.1.! Ultimaker Original (UMO) .................................................................................. 18! 3.1.1.! Heated Build Platform ................................................................................. 19! 1.1.1.! LED Lighting ................................................................................................. 21! 3.1.2.! Dual extrusion system ................................................................................. 21! 3.2.! Prusa I3 .............................................................................................................. 32! 3.2.1.! Dondolo Dual Extruder ................................................................................ 33! 4.! Dual Extrusion ....................................................................................... 36! 4.1.! Preparing the Printer.......................................................................................... 36! 4.1.1.! Cleaning the Nozzle..................................................................................... 36! 4.1.2.! Seasoning the Hot-End................................................................................ 37! 4.1.3.! Calibrating the Printer ................................................................................. 38! 4.2.! Dual Extrusion with the UMO ............................................................................ 40! 4.3.! Dual Extrusion with the Prusa I3 ....................................................................... 44! 4.4.! Dual Extrusion Guide ......................................................................................... 50! 5.! Printing with Conductive Material ....................................................... 63! 5.1.! Esun conductive filament .................................................................................. 63! 5.1.1.! Controller with Makey Makey ..................................................................... 63! 5.2.! Proto-Pasta Conductive PLA............................................................................. 64! 5.2.1.! Capacitive Touch Wheel ............................................................................. 64! 5.2.2.! Capacitive Touch Sphere ............................................................................ 66! 6.! Conclusion ............................................................................................ 67! 7.! References ............................................................................................ 68! 8.! Appendixes ........................................................................................... 70! Table of figures and tables Fig. 1! Left: High-end 3D printer Stratasys Dimension [1] Right: Low-end 3D printer Ultimaker 2 [2] 1! Fig. 2! Left: Schematic overview of the Fused Deposition Modeling process [4] right: filament used for FFF machines [6] 2! Fig. 3! Left: Schematic overview of the Stereolythography process [7] Right: Resin used for SLA [8] 3! Fig. 4! Comparison of the same part printed with FFF (left) and SLA (right) [9] 3! Fig. 5! A PCB mounted in an X-box controller [14] 5! Fig. 6! A graphic rendition of future PCS [15] 6! Fig. 7! Accelerometer System Helmet Insert [16] 7! Fig. 8! Voxel8 Development Kit [17] 8! Fig. 9! 3D Printed Interface Design [18] 9! Fig. 10! First test setup with a single channel 10! Fig. 11! Bare conductive paint (left) and CAD file of the test setup (right) 11! Fig. 12! Measuring resistance on test setup 11! Fig. 13! Table showing resistance measurements on second test setup 12! Fig. 14! Esun conductive filament [20] 13! Fig. 15! Test of Esun Conductive and PLA 14! Fig. 16! Test of Esun Conductive and ColorFabb XT (warping) 14! Fig. 17! Test cube in Proto-Paste Conductive PLA for measuring resistance 15! Fig. 18! Protopasta Conductive PLA printing together with clear PLA 16! Fig. 19! Protopasta Conductive PLA printed together with Colorfabb XT 16! Fig. 20! Tests with different materials (from left to right) white PLA, Copperfill, XT and Glowfill 17! Fig. 21! Comparison table for different conductive materials 17! Fig. 22! Ultimaker original [24] 18! Fig. 23! A warped print [25] 19! Fig. 24! 3DPHK HBP installed on the UMO 20! Fig. 25! Bottom of the UMO with the power supply and rising feet in place (left) and new IEC connector and power switch added (right) 20! Fig. 26! LED light strips installed on the UMO( left) and new 24V 16.7A 400W power supply (right) 21! Fig. 27! Printed support structure on Stratasys Dimension printer [27] 22! Fig. 28! M3 threaded inserts 23! Fig. 29! Ultimaker 2 Print Head [2] 23! Fig. 30! Cad file of prototype 1 24! Fig. 31! A picture of prototype 1 24! Fig. 32! Cad file of prototype 2 25! Fig. 33! XY-carriage of prototype 2 25! Fig. 34! Prototype 2 mounted on the UMO 26! Fig. 35! Rendered exploded view of prototype 1 26! Fig. 36! Flat pattern of the heat shield 27! Fig. 37! Heat shield in 0,5 mm bent aluminium 27! Fig. 38! Backside of our second prototype 28! Fig. 39! Airtripper’s Bowden Extruder V3 29! Fig. 40! Left: oozing problem while printing with the dual extruder system on the UMO, right: the print getting pulled loose by the inactive nozzle 31! Fig. 41! Prusa I3 Metal Frame [30] 32! Fig. 42! CAD drawing of the Dondolo dual extrusion system by Gianni Franci [31] 33! Fig. 43! Schematic overview of the Dondolo Dual Extruder 34! Fig. 44! Left: Self-made drive gear right: UM2 drive gear 35! Fig. 45! Comparison teeth marks from selfmade drive gear (left) and UM2 drive gear (right) 35! Fig. 46! A piece of nylon filament we used to clean a dirty nozzle (black is Esun conductive) 36! Fig. 47! PLA jam problem solved after seasoning the hot end 37! Fig. 48! Flowchart for calibrating steps/mm 38! Fig. 49! Flowchart for fine-tuning steps/mm 39! Fig. 50! A part used for fine tuning steps/mm 39! Fig. 51! A number of test-cubes used for calibration on the UMO 41! Fig. 52! Calibration prints on the UMO 41! Fig. 53! Over extrusion on the UMO 42! Fig. 54! Over extruded traffic cone printed on the UMO 42! Fig. 55! Oozing problem of Esun Conductive Filament 43! Fig. 56! The Dondolo Dual Extruder installed and running on the Prusa I3 45! Fig. 57! Side view of the installed Dondolo Dual Extrusion System 45! Fig. 58! A view of the cable chain and the PCB cooling fan 46! Fig. 59! Dual Extrusion Calibration test when not calibrated properly 46! Fig. 60! Several calibration tests for trying to get the XY allignment just right 47! Fig. 61! Dual Extrusion Calibration in PLA(left) and ABS (right) when properly calibrated 47! Fig. 62! A drip mark on a PLA print (left) and a calibration print (right) 47! Fig. 63! Difference in clearance between right and left idler 48! Fig. 64! The redesigned dondolo extruder 48! Fig. 65! Prusa I3 printing a traffic cone with a wipe and prime tower and an ooze shield 49! Fig. 66! First model the part in Solidworks you want in one type of material 50! Fig. 67! Next model the part you want to print in the other material. Remember not to merge it with the other object 50! Fig. 68! This is your part with different solid bodies for each material 51! Fig. 69! Right click on a solid body you want in a different material and select delete/keep bodies 51! Fig. 70! Select all bodies you want to delete and click OK 52! Fig. 71! Now you are left with the pieces in one material 52! Fig. 72! Save this part as an STL 53! Fig. 73! In the delete body feature select the pieces in the other material 53! Fig. 74! Now you are left with the piece in the other material 54! Fig. 75! Save the other part as an STL giving it a different name 54! Fig. 76! Open Repetier Host and adjust the printer settings. The X and Y offset can be found using a calibration piece 55! Fig. 77! Click the + button to add the STL files 56! Fig. 78! Select both STL files and click ‘open’ 56! Fig. 79! With the STL files imported click on the settings button of the first object 57! Fig. 80! Adjust the assigned extruder and set both objects in the same object group to merge them 57! Fig. 81! Press the rotate button to oriëntate the object correctly 58! Fig. 82! Oriëntate the object and double check the assigned extruders 58! Fig. 83! In the slicer tab select the slicer engine you want to use. We like CuraEngine. Click on configuration 59! Fig. 84! Adjust the settings accordingly. These are the settings that gave us the best results. 60! Fig. 85! In the filament tab make an entry for each different filament you are using 60! Fig. 86! Adjust the settings in the slicer tab and click ‘Slice with CuraEngine’ 61! Fig. 87! Connect the printer and press print or save the Gcode file to an SD card 62! Fig. 89! The combined STL file of the controller 63! Fig. 90! Controller in ABS and Esun Conductive Filament 63! Fig. 91! Proto-Pasta and clear PLA printing on the Prusa I3 64! Fig. 92! The STL file of the buttons 64! Fig. 93! The prusa I3 prining the capacitive touch wheel 65! Fig. 94! Testing the capacitie touch wheel 65! Fig. 95! Combined STL file of the capacitive sphere 66! Fig. 96! Picture of the capacitive sphere controlling LED’s 66! List of abbreviations and symbols 3D Three-dimensional ABS Acrylonitrile Butadiene Styrene AM Additive Manufacturing FFF Fused Filament Fabrication HBP Heated Build Plate PCB Printed Circuit Board PCS Printed Circuit Structure PLA Polylactic Acid SLA Stereo Lithography SMT Surface-Mount Technology SMD Surface-Mount Device STL Surface Tessellation Language UM2 Ultimaker 2 UMO Ultimaker Original 1. Introduction 1.1. 3D printing 3D Printing or Additive Manufacturing (AM) is a rapid prototyping technique that lets users physically create three-dimensional (3D) objects drawn with a computer. The object is usually modelled with a computer aided design (CAD) software package and exported as a Surface Tessellation Language (STL) file. Slicing software slices the part in two-dimensional layers, which are sequentially printed on top of each other to create a solid object. As opposed to subtractive manufacturing (SM), a technique that takes a raw metal and creates a part by cutting or drilling sections away, additive manufacturing is less expensive, less time consuming and produces much less waste material. There are a few different techniques for 3D printing. Because this research focuses on 3D printing on low-end machines we are going to describe the two techniques that are most used in these cheaper machines: Fused Filament Fabrication (FFF) and Stereo Lithography (SLA). Fig. 1 Left: High-end 3D printer Stratasys Dimension [1] Right: Low-end 3D printer Ultimaker 2 [2] 1 1.1.1. Fused Filament Fabrication (FFF) FFF is equivalent to Fused Deposition Modelling (FDM), a term and abbreviation that is trademarked by Stratasys Inc [3]. The term fused filament fabrication (FFF), was invented by the members of the RepRap project to provide a term that would be legally independent in its use [4]. An FFF 3D printer extrudes a thermoplastic filament through a temperature-controlled nozzle similar to how a hot glue gun extrudes a melted glue-cartridge (Fig. 2). The nozzle heats the material to a semi liquid state and draws the outline in ultra thin layers (typically between 0.05 mm to 0.3 mm) onto a build platform. It then fills the outline with a raster of material creating a complete section of the object and proceeds to the next layer, binding it to the previous one. The result is a plastic 3D model built up one layer at a time. Because sometimes not all the layers are touching the build platform a support structure can be created which can be removed after the print is finished. Because the printed parts are relatively strong and durable this technique is ideal for functional prototypes and the quick testing of shapes and fittings [5]. Fig. 2 Left: Schematic overview of the Fused Deposition Modeling process [4] right: filament used for FFF machines [6] 2 1.1.2. Stereo Lithography (SLA) Stereo Lithography (SLA) uses a laser beam to harden the surface of vessel of liquid resin to create a part (Fig. 3). Where the laser beam hits the liquid, the hardening takes effect. When a layer is finished, the platform that holds the object drops a fraction of a millimetre deeper into the vessel. The different layers that solidify on top of each other form the 3D object. Similar to FFF sometimes support structures are required for overhangs and holes, these can be added either manually or automatically in the slicing software. After the product is removed from the build platform the support structure can be removed. SLA has a higher print resolution, builds quicker and can print more complex structures but the machines and the resin are much more expensive than using FFF. Fig. 3 Left: Schematic overview of the Stereolythography process [7] Right: Resin used for SLA [8] Fig. 4 Comparison of the same part printed with FFF (left) and SLA (right) [9] 3 1.1.3. Printing Materials A) PLA Polylactic acid (PLA) is a biodegradable polymer that is made from lactic acid, a natural substance gained from corn crops making it ideal for usage in the poorer counties of the world and a non-toxic and renewable resource. PLA biodegrades in approximately 60 days while other plastics can take up to 400 years to degrade [10]. The material is harder than ABS and has significantly less shrinking problems. It melts at a relatively low temperature (around 180°C to 220°C), and has a glass transition temperature between 60-65 °C, making it a very useful material. When printing PLA it is important to keep the distance between the glass temperature point and the melting point as small as possible because the material gets sticky in this zone and exhibits higher friction than ABS which can make it difficult to extrude and causes more extruder jams [11]. B) ABS Acrylonitrile Butadiene Styrene (ABS) is a commonly used lightweight thermoplastic that can be used for extruding and ejection moulding. It is less brittle and requires less force to extrude than PLA but handles higher temperatures better. Therefor no active cooling is required and it does a better job at printing small parts compared to PLA. The downside of ABS is that it has more shrinking problems and has to be extruded at a higher temperature: It has a glass transition temperature of around 105 °C. Because ABS is amorphous it has no true melting point, however 230°C is the standard for printing [12]. C) Colorfabb XT ColorFabb XT, a material manufactured by Colorfabb, is the first 3D printer filament produced from Amphora 3D Polymer, a PETG variant. It’s a strong and tough material that handles high temperatures well and has less shrinking problems and does a better job at bridging better than ABS. ColorFabb XT is best printed at 240260°C and a HBP temperature of 75°C [13]. 4 1.2. Electronics 1.2.1. Current Electronics Today most electronic devices consist of some type of enclosure with one or more printed circuit boards (PCBs) mounted inside (Fig. 5). Onto these PCBs the necessary components to make the device functional are mounted using surfacemount technology (SMT) or through hole soldering. The shape and size of the enclosure depends heavily on the shape and size of the PCB and its components. This limits the designer in shaping the device because he has to bear in mind the space needed to fit the PCB. Fig. 5 A PCB mounted in an X-box controller [14] 5 1.2.2. Printed Circuit Structure (PCS) With a big increase in popularity over the past few decades additive manufacturing or 3D printing could change the way we build electronic devices in the future. Instead of using PCBs that are mounted afterwards in the device Printed Circuit Structure (PCS) would look at electronics from a completely different angle. In a PCS the enclosure and structure of the device itself would carry the circuits and components making the usage of PCBs unnecessary. In this approach components can be smoothly integrated and even hidden inside the structure. This also makes reverse engineering much more difficult. By building the electronics into the structure the device would become more rigid, eliminating the use of glue, snaps, solder, wiring or bolts. This would also result in the ability to use much more components in far less space, making it possible to create smaller and less bulky devices while not sacrificing in its functionality. It would also open up new possibilities by making it possible to print functional components and sensors like 3D touch surfaces, integrated bend or turn sensors, optimized antennas, custom motors, speakers, solenoids and much more [15]. Fig. 6 A graphic rendition of future PCS [15] 6 2. Market research 2.1. Conductive material printing techniques Although PCSs are still at a very early stage numerous researchers have attempted to fabricate 3D and conformal electronics using different types of 3D printing techniques. This section gives an overview of the techniques already used. 2.1.1. SLA with Manual Ink Dispensing An SLA machine is used to print the structure and afterwards the components are placed and the traces are filled with conductive silver ink. This technique was used by S. Castillo et al to create a three-dimensional accelerometer sensor system with microprocessor control [16]. Fig. 7 Accelerometer System Helmet Insert [16] 7 2.1.2. FFF with Automated Ink Dispensing This technique features a machine that has two types of material dispensing systems. A nozzle that uses the FFF technique to build the structure and an automatic ink dispenser that provides the traces of the circuit. None such a machine is available on the market but at this moment a company called Voxel8 is in the final stages of developing such a machine [17]. Fig. 8 Voxel8 Development Kit [17] 8 2.1.3. FFF with Conductive Filament This technique uses a standard FFF 3D printer to print with a new type of material called ‘Carbomorph’. Carbomorph, a mixture of conductive Carbon Black (CB) and polymorph, was invented by S. J. Leigh et al and used to make a flex sensor, 2D capacitive touch buttons and a smart vessel which tracks the liquid inside [18]. Fig. 9 3D Printed Interface Design [18] Because the focus of our research was to explore a technique that can be used on low-end 3D printers we decided to mainly focus on the last technique. 9 2.2. Conductive material While looking for conductive material to print with we noticed that because this technique is so new the market supply is limited. We mainly wanted to focus on printing with FFF but also explored some other approaches as well. 2.2.1. Bare Conductive Electric Paint An east London based company called Bare Conductive sells a product called ‘Electric Paint’. Essentially it’s a mixture of paint and carbon, making it electrically conductive. According to the company the paint can act as a "paintable wire" that can be used on paper, cement, textiles, wood and other materials, and becomes conductive once it dries [19]. To measure its resistance we printed a test setup with channels in different diameters. First we printed a rectangular block with a channel running from one side to the other. Using a syringe we filled the channel with the paint and let it dry. Fig. 10 First test setup with a single channel For our next test we printed a rectangular block with different channels running through it. The hollow channels were printed with different diameters ranging from 2 mm to 6 mm in steps of 0,5 mm. Then we mixed some conductive paint with water, making the paint more liquid. We filled the channels with the thinned paint so the paint was covering the sides of the channels and then pored the thinned paint out. The result was a hollow channel with conductive sides. After drying the paint in the oven we measured the resistance of the channels (Fig. 13). We can conclude there is 10 a lot of variation in the measurements so the usage of this technique is not ideal. It was also a messy and cumbersome process. Fig. 11 Bare conductive paint (left) and CAD file of the test setup (right) Fig. 12 Measuring resistance on test setup 11 Following table shows the measurements we made using our second test setup: Diameter (mm) Resistance 2 59,7 k! 2,5 27 k! 3 34,2 k! 3,5 111,1 k! 4 49,4 k! 4,5 53.1 k! 5 31,6 k! 5,5 80 k! 6 29,4 k! Fig. 13 Table showing resistance measurements on second test setup 12 2.2.2. Esun Conductive Filament The first Carbomorph variant we could get our hands on was Esun’s Conductive Filament. Esun is a Shenzhen based 3D printing filament supplier and one of the few suppliers of conductive filament when we started this research. It sells the conductive filament in a 1.75 and 3 mm variants. Our first tests were done with the 1.75 mm variant and later on we also tested the 3 mm variant. The datasheet (Appendix 1) doesn’t really specify its composition but claims the material has a surface resistance of 800 ! and a print temperature of 220-260°C. When testing this material on our printer we noticed it was very difficult to print with it. The problems we were having were: • The material doesn’t bind to the HBP or to other materials (Fig. 15) • The material has severe oozing problems • The material leaves a lot of residual material in the print head which causes a lot of print head jams • When using the material together with other materials a lot of warping occurred (Fig. 16) Fig. 14 Esun conductive filament [20] 13 Fig. 15 Test of Esun Conductive and PLA Fig. 16 Test of Esun Conductive and ColorFabb XT (warping) 14 2.2.3. ProtoPlant Proto-Pasta Conductive PLA Proto-pasta Conductive PLA, manufactured by a company called Protoplant, is a compound of Natureworks 4043D PLA, a dispersant and conductive carbon black. It has the same features as regular PLA but is a bit more flexible and can be printed at the same temperatures [21]. We measured the conductivity by printing a 1cm cube on a Prusa I3 and soldering wires on each side so could measure the resistance perpendicular to the layers and through the layers: • Volume resistivity of 3D printed parts perpendicular to layers: 46 ohm-cm • Volume resistivity of 3D printed parts through layers (along Z axis): 84 ohmcm Fig. 17 Test cube in Proto-Paste Conductive PLA for measuring resistance Proto-Pasta prints very nicely together with regular PLA (Fig. 18). We also tried printing it together with Colorfabb XT (Fig. 19) but the two materials wouldn’t bind together. 15 Fig. 18 Protopasta Conductive PLA printing together with clear PLA Fig. 19 Protopasta Conductive PLA printed together with Colorfabb XT 2.2.4. Colorfabb Copperfill Colorfabb Copperfill is a filament produced with a micronized copper powder, which has been infused into a common PLA plastic. We did some tests with printing Copperfill put unfortunately the material is not conductive. 16 Fig. 20 Tests with different materials (from left to right) white PLA, Copperfill, XT and Glowfill To compare the different materials we measured the resistance of 100mm filament. For the conductive paint we printed a 3mm diameter, 100 mm long channel and filled it with the paint for comparison. Properties Material Technique Resistance 100 mm filament Remarks ProtoPasta FFF 987 ! Easy to print Esun 3mm FFF 172 k! Difficult to print Esun 1.75 mm FFF 123 k! Difficult to print Bare Conductive Ink 167 k! Bronzefill FFF ∞ a Cumbersome process Material is not conductive Fig. 21 Comparison table for different conductive materials 17 3. Printer Modifications The 3D printers that were used for this research are low-end FFF 3D printers. We used 3 different types of printers: an Ultimaker Original (UMO), an Ultimaker 2 (UM2) and a RepRap Prusa I3 [22]. The UM2 was mainly used to print parts for upgrading the other two printers. This section will give an overview of the upgrades we made. 3.1. Ultimaker Original (UMO) The UMO (Fig. 22) is the first model of a Dutch based company called Ultimaker BV. It’s original name was Ultimaker but the company added the suffix ‘original’ when they released their second model: the ‘Ultimaker 2’ The UMO is a Cartesian FFF 3D printer that uses 3mm filament and can print a number of different materials. The printer is also known to be a ‘hackable’ printer, since it mostly uses simple laser cut or printed parts and open source software running on an Arduino Mega board. In 2012, the UMO was awarded ‘Fastest and Most Accurate 3D printer available’ in MAKE Magazine's annual 3D printing guide [23]. For our research we did some upgrades and alterations to the printer. We installed a heated build platform, LED lights, shield windows and a dual extruder. Fig. 22 Ultimaker original [24] 18 3.1.1. Heated Build Platform A heated build platform (HBP) improves printing quality by helping to prevent warping. When the printed plastic cools down, it has the tendency to shrink. Because the sides of the object cool faster than the inside, mainly while printing in ABS, sometimes warping occurs. Because of this warping the corners of the part tend to come loose from the build platform (Fig. 23). When a HBP is installed the printed part stays warm during the printing process allowing the shrinking to happen more evenly. This results in a higher quality finish with materials such as ABS and PLA. A HBP also allows users to print without rafts, skirts and brims. The heated build platform we installed is a kit we obtained from a vendor on EBay. Fig. 23 A warped print [25] 19 Fig. 24 3DPHK HBP installed on the UMO The HBP features a 3 mm aluminium core PCB with an integrated PCB heater, LED indicators and thermistors that allows for fast heating (20°C to 100°C in < 5 minutes). The kit also provided a 24V 10A 240W DC power supply, which we installed to provide power to both the printer and the HBP. To fit the power supply we provided the printer with some raising feet so the supply could fit snugly in the bottom of the printer next to its electronics. To reduce components we used the new power supply to also provide power to the printer itself. We also replaced the 4-point levelling system of the HBP with a much easier to use 3-point leveling system. Fig. 25 Bottom of the UMO with the power supply and rising feet in place (left) and new IEC connector and power switch added (right) 20 1.1.1. LED Lighting Sometimes it’s hard to see how the printer is because of bad light conditions. In order to prevent this we provided the printer with LED light strips. We attached 3 white LED strips to the inside of the front panel of the printer, 12 LED’s at the sides and 18 LED’s at the bottom. When attaching this to the power supply we noticed the supply couldn’t handle this and the LED’s would start blinking when the heated build platform was active. It appeared that the power supply include in the heated build platform kit wasn’t powerful enough to power the build platform, the LED’s and the heaters at once. Therefore we installed a more powerful 24V 16.7A 400W DC power supply that could handle feeding all of the components without a problem. Fig. 26 LED light strips installed on the UMO( left) and new 24V 16.7A 400W power supply (right) 3.1.2. Dual extrusion system In order to be able to print two materials, being it conductive and non-conductive or just two different colours or materials, simultaneously we added a dual extrusion system to the UMO. This was not an easy task because the dual extrusion technique itself is still pretty new and few companies have managed to make it work on these low-cost machines. Professional 3D printers use the technique to generate support structures but they have much more control because they use heated chambers and all their printing materials come from the same manufacturer. Ultimaker sells an ‘experimental’ upgrade for the UMO and was planning to develop a dual extrusion upgrade for the UM2 as well but in a company update released on their community forum [26] they announced they cancelled the development of the upgrade due to technical difficulties. 21 Fig. 27 Printed support structure on Stratasys Dimension printer [27] The hot ends we used were E3D’s V5 all metal hot ends. Because some types of filaments are only available in certain diameters we chose to use a combination of a 2.85 and a 1.75 mm hot ends which would allow us to also print with these two different types of filament diameters. Our first prototype was inspired by the print head used by the UM2 (Fig. 29), a printer we obtained great results with. While the UM2 is sold with only one nozzle the print head is also equipped to hold 2 nozzles. The design of the dual extruder consists of a XY-carriage 3d printed in ABS. In this carriage both hot ends are mounted and can be adjusted in height separately by loosening the front mounting bracket. On the backside two 30x30x10 mm fans were mounted to cool the heat breaks, this is necessary because there is a short transition zone between the glass transition temperature and the melting temperature of the materials used. On the bottom of the print head is a bended aluminium plate which acts as a heat break between the hot end and the cooled part and on each side the plate was bend to act as a fan duct, holding two 40x40x10 fans to actively cool the print area, this is particularly useful when printing bridges or small details in PLA. For connecting the different parts together we used M3 threaded inserts (Fig. 28). 22 Fig. 28 M3 threaded inserts In our second prototype we opted to also print the fan ducts because it was too complicated to bend the aluminium plate the way we wanted. Fig. 29 Ultimaker 2 Print Head [2] 23 Fig. 30 Cad file of prototype 1 Fig. 31 A picture of prototype 1 24 Fig. 32 Cad file of prototype 2 Fig. 33 XY-carriage of prototype 2 25 Fig. 34 Prototype 2 mounted on the UMO Fig. 35 Rendered exploded view of prototype 1 26 Fig. 36 Flat pattern of the heat shield Fig. 37 Heat shield in 0,5 mm bent aluminium 27 Fig. 38 Backside of our second prototype The two extruder motors were mounted on the back of the printer and connected to the hot ends via ‘Bowden tubes’. Because the extruder motors are not attached to the print head the moving mass of the head is reduced, hereby allowing the head to make faster controlled motions. As a result the machine will shake less, use less energy and print faster. The system has one major disadvantage: hysteresis. By putting pressure on such a long length of filament a lot more compression occurs, leading to a dynamic lag between the input and output of the tube. The flexibility of the Bowden tube increases the problem. It’s possible to control this problem with software calibration [28]. For the feeding of the 3mm filament head we used the original feeding mechanism of the UMO and for the 1.75mm filament head we used a design we found on Thingiverse called Airtripper’s Bowden Extruder V3 (Fig. 39) uploaded by the user ‘Airtripper’ [29]. 28 Fig. 39 Airtripper’s Bowden Extruder V3 Because we are using two different sizes of nozzles the extruder motors both need to have their own feeding speed, the speed the extruder motor is set to in order to push the material through the nozzle. Unfortunately this was not possible with Marlin, the standard firmware of the UMO. Here for we opted for installing ‘Repetier Firmware’, another firmware solution that made it possible to assign different feed rates to each extruder. By installing the new firmware some other problems appeared; the display stopped working and the pins had to be re-assigned in the firmware, it was not possible to slice with ‘Cura’, Ultimaker’s standard slicing software, anymore because the program wouldn’t recognize the different feed rates. The solution for this was using ‘Repetier Host’ a slicing program made by the same developers of the new firmware we installed. These are the changes that needed to be made in the UIconfig.h file of Repetier Firmware in order to make the UMO display work (also see Appendix 4-7): 29 #define UI_DISPLAY_TYPE 1 #else // Direct display connections #define UI_DISPLAY_RS_PIN 20 #define UI_DISPLAY_RW_PIN -1 #define UI_DISPLAY_ENABLE_PIN 17 #define UI_DISPLAY_D0_PIN 59 #define UI_DISPLAY_D1_PIN 64 #define UI_DISPLAY_D2_PIN 44 #define UI_DISPLAY_D3_PIN 66 #define UI_DISPLAY_D4_PIN 16 #define UI_DISPLAY_D5_PIN 21 #define UI_DISPLAY_D6_PIN 5 #define UI_DISPLAY_D7_PIN 6 #define UI_DELAYPERCHAR 320 30 With the hardware installed and all software and firmware problems solved some new problems occurred, it appeared to be very difficult to install both nozzles at exactly the same height and aligning the HBP accordingly. Also, when printing, a lot of ‘oozing’ occurred, when one hot end is inactive it stays hot resulting in material dripping out of the nozzle and cluttering the print (Fig. 40). Additionally, because both nozzles were at the same height, the inactive nozzle would scratch the print while printing or even pulling it loose from the HBP. After weeks of frustration trying to solve the problems by tweaking the software and hardware we abandoned this path and decided to look for a different solution. Fig. 40 Left: oozing problem while printing with the dual extruder system on the UMO, right: the print getting pulled loose by the inactive nozzle 31 3.2. Prusa I3 The Prusa I3 (Fig. 41) is the third iteration of the Prusa mendel, which was developed as part of the RepRap [22] project. This project started the 3D printer revolution by building low-cost, self-replicating, open-source 3d printers. It has become the most widely used 3D printer among the global members of the Maker Community. The frame of our model was made of a single sheet of aluminium and uses a RAMPS 1.4 controller. It’s also a Cartesian printer and the main difference between this printer and the UMO is that this printer moves the build platform for the Y-movement where as the UMO moves the print head itself. This printer also doesn’t feature an enclosed frame making it less ideal to print ABS. We upgraded this printer with a dual extrusion system. Fig. 41 Prusa I3 Metal Frame [30] 32 3.2.1. Dondolo Dual Extruder While looking for other dual extrusion systems after our failed attempt on the UMO we came across a design shared on Thingiverse called ‘Dondolo V1.0b’ [31]. It was uploaded by user Gianni Franci and made specifically for the Prusa I3. It looked promising, using a similar technique as seen in the more expensive Stratasys Dimension printers, allowing the hot ends to pivot around an axis. This not only solves the problem of the nozzle scraping the print but also reduces oozing due to the inactive nozzle being blocked by an ‘anti-oozing’ plate. The design uses an RC servo to make the hot ends pivot around the axis. The axis used as a pivot point is the axis of the single stepper motor driving the extrusion for both hot ends. The design was originally made for E3D’s V6 all metal hot ends but after some minor modifications we were able to make it work for the V5 hot ends as well. To reduce complexity in firmware settings we decided to use two hot ends for the same filament diameter; 2,85 mm. For the extruder motor a stepper with high phase resistance and inductance was needed while still remaining a high torque. The NEMA17 42BYGHW208 (Appendix 2) stepper motor met these requirements. Fig. 42 CAD drawing of the Dondolo dual extrusion system by Gianni Franci [31] 33 Fig. 43 Schematic overview of the Dondolo Dual Extruder For driving the filament through the extruder we needed a drive gear with sharp teeth. We made one ourselves (Fig. 44) from an 8mm rod that we machined. The teeth we carved using an M5 thread tap on a milling machine. Later on we noticed this gear was not driving the filament consistently so we used the gear from the UM2, which also has sharp teeth and extruded more consistently (Fig. 45). 34 Fig. 44 Left: Self-made drive gear right: UM2 drive gear Fig. 45 Comparison teeth marks from selfmade drive gear (left) and UM2 drive gear (right) 35 4. Dual Extrusion Before we could begin printing with conductive materials it was important the dual extrusion system worked properly. As mentioned before printing with a dual extruder setup is easier said than done. Because you now have two extruders, which have to be at precisely the same distance from the build platform, levelling the build platform is a bit more complicated. If one extruder head is too high it will not properly attach the extruded material to the build platform or to the previous layers. Two extruders also mean double the chance of a nozzle being clogged. When printing a part with two different materials both nozzles have to work perfectly or the print will be ruined. 4.1. Preparing the Printer 4.1.1. Cleaning the Nozzle We found a good way to clean out dirty nozzles along the way. Nylon filament worked particularly well for this job. We heat the nozzle to 240°C. Feed some nylon filament through the nozzle. Let the nozzle cool down to 130°C and gently pull out the nylon filament. When you do this right you can see the shape of the nozzle and a very thin piece of wire that was in the top end (Fig. 46). Repeat this process until all the other material is gone and you just pull out clean nylon. Fig. 46 A piece of nylon filament we used to clean a dirty nozzle (black is Esun conductive) 36 4.1.2. Seasoning the Hot-End For some reason our printer (UMO with E3D all metal hot end V5) had problems with printing PLA. This problem also occurred before installing the heated bed so this couldn’t be the cause of the problem. We went online looking for answers and found that a lot of people were having the same problem with this E3D all-metal setup. We tried a lot of different things: higher temperatures, lower temperatures, retraction settings, updated the firmware, bed leveling. Shortening the retraction made it a little better but the result wasn’t as it should be yet. On a few forums people suggested ‘seasoning’ the hot end; dipping the filament in some olive oil (or other oil) and then pushing it through the nozzle. This creates a small film inside of the nozzle so the PLA gets through easily. At first we thought this was a joke but after thinking about it this actually made sense because PLA is made of corn. In the kitchen when something is cooked oil i also used for not sticking it to the pan. So we tried ‘seasoning’ the hot end and our PLA jam problem is solved. Fig. 47 PLA jam problem solved after seasoning the hot end 37 4.1.3. Calibrating the Printer Before we started printing with two extruders we decided to first test each extruder individually. For calibrating the steps/mm on each extruder we used Triffid Hunter's Calibration Guide (Fig. 48 & Fig. 49) [32]. This is the code that needs to bee changed in the configuration.h file of Repetier Firmware to change the steps/mm: #define EXT0_STEPS_PER_MM 836 #define EXT1_STEPS_PER_MM 135 As you can see, after calibration, extruder 1, which feeds the 3mm filament, was set to 836 steps/mm and extruder 2, which feeds the 1.75mm filament was set to 135 steps/mm. Fig. 48 Flowchart for calibrating steps/mm 38 Fig. 49 Flowchart for fine-tuning steps/mm Fig. 50 A part used for fine tuning steps/mm 39 4.2. Dual Extrusion with the UMO We encountered a lot of problems while trying to print the dual extrusion system we installed on the UMO. Our system to control the height of the nozzles is not precise enough resulting in a lot of prints being scratched or pulled loose because of height difference between the nozzles. Because we installed two different diameter sizes of nozzles in our system, something we have never seen on any other printer, we suspect the slicing software confused the feed rates of the different nozzles resulting in a lot of tests with signs of over and under extrusion. We also had a lot of oozing issues. We tried to solve this within the slicing software. A few options we tried were extensive retraction distances on a tool change, this helped a little but didn’t completely solve the problem. In Slic3r, a slicing program we used, there is an option to cool down the inactive nozzle after a tool change and before the active nozzle starts extruding, this solved the problems of oozing but brought some new problems with it: a print takes about five times as long to print and the nozzles were clogged all the time, especially when using the conductive material. With the Cura slicing engine an ooze shield can be added. This is a thin shell that is automatically printed around the object shielding it from oozing nozzles. At the moment of testing the dual extrusion system on the UMO the Esun conductive filament was the only conductive filament we could get our hands on. After some basic tests this material appeared to be really difficult to print with. The material doesn’t like to stick to the HBP or to other materials, it has severe oozing problems and leaves a lot of residual material in the print head, which causes a lot of print head jams and was also a big problem when we used the temperature switch technique in the Slic3r software. When printing the material together with other materials a lot of warping occurred. After weeks of tweaking and tuning both hardware and software without any significant progress we abandoned this path and decided to look for a different solution. 40 Fig. 51 A number of test-cubes used for calibration on the UMO Fig. 52 Calibration prints on the UMO 41 Fig. 53 Over extrusion on the UMO Fig. 54 Over extruded traffic cone printed on the UMO 42 Fig. 55 Oozing problem of Esun Conductive Filament 43 4.3. Dual Extrusion with the Prusa I3 After installing the Dondolo Dual Extrusion system on the Prusa I3 (Fig. 56) we immediately received a lot better results than our attempts with the UMO. We started off by printing with PLA. We found a design on Thingiverse that was better suited for calibrating the distance between the two nozzles: ‘the ‘Dual Extrusion Calibration Print’ uploaded by walter [33]. A problem that occurred was that the material that rested inside of the inactive nozzle would heat up and become very liquid, leaving a drip mark on certain prints (Fig. 62). We solved this by adding a 10mm retraction before a tool change in the slicer software. Another problem we had was that the left idler didn’t give enough clearance space when the left nozzle was inactive causing the filament to be pulled up while the right extruder was extruding (Fig. 63). After measuring and testing we discovered this was caused by a deformed part that limited the movement of the left idler. We decided to reprint all of the extruder setup parts. We redesigned the rocking clamp which provided the idler with some more clearance space when inactive and decided to redesign the idlers themselves enhancing the spring attachment points which allowed for more spring tension (Fig. 64). We also opted to use M3 bolts to hold the spring instead of the original printed fixations. The next problem we were confronted with was that when printing with the dual extrusion system whenever a tool change occurred, meaning that the printer switches from one extruder to the other, it took some time (or length) before the active nozzle printed consistently. We solved this by using the Cura slice engine in Repetier Host, which gave us the option to include a ‘wipe and prime tower’ in the prints. Before each printed layer the nozzle is sent to extrude a square outside of the printed object until the nozzle prints the material consistently. After the square is drawn the nozzle makes a small rapid movement over the square to wipe the nozzle clean. When all the squares are printed on top of each other this results in a tower hence the name ‘wipe and prime tower’. Cura engine also gives the option to include an ‘ooze shield’. This is a thin layer that’s printed around the object before printing the object’s layer providing a shield for possible oozing that might occur (Fig. 65). 44 Fig. 56 The Dondolo Dual Extruder installed and running on the Prusa I3 Fig. 57 Side view of the installed Dondolo Dual Extrusion System 45 Fig. 58 A view of the cable chain and the PCB cooling fan Fig. 59 Dual Extrusion Calibration test when not calibrated properly 46 Fig. 60 Several calibration tests for trying to get the XY allignment just right Fig. 61 Dual Extrusion Calibration in PLA(left) and ABS (right) when properly calibrated Fig. 62 A drip mark on a PLA print (left) and a calibration print (right) 47 Fig. 63 Difference in clearance between right and left idler Fig. 64 The redesigned dondolo extruder 48 Fig. 65 Prusa I3 printing a traffic cone with a wipe and prime tower and an ooze shield 49 4.4. Dual Extrusion Guide This section will be a guide for using dual extrusion with Solidworks and Repetier Host. Fig. 66 First model the part in Solidworks you want in one type of material Fig. 67 Next model the part you want to print in the other material. Remember not to merge it with the other object 50 Fig. 68 This is your part with different solid bodies for each material Fig. 69 Right click on a solid body you want in a different material and select delete/keep bodies 51 Fig. 70 Select all bodies you want to delete and click OK Fig. 71 Now you are left with the pieces in one material 52 Fig. 72 Save this part as an STL Fig. 73 In the delete body feature select the pieces in the other material 53 Fig. 74 Now you are left with the piece in the other material Fig. 75 Save the other part as an STL giving it a different name 54 Fig. 76 Open Repetier Host and adjust the printer settings. The X and Y offset can be found using a calibration piece 55 Fig. 77 Click the + button to add the STL files Fig. 78 Select both STL files and click ‘open’ 56 Fig. 79 With the STL files imported click on the settings button of the first object Fig. 80 Adjust the assigned extruder and set both objects in the same object group to merge them 57 Fig. 81 Press the rotate button to oriëntate the object correctly Fig. 82 Oriëntate the object and double check the assigned extruders 58 Fig. 83 In the slicer tab select the slicer engine you want to use. We like CuraEngine. Click on configuration 59 Fig. 84 Adjust the settings accordingly. These are the settings that gave us the best results. Fig. 85 In the filament tab make an entry for each different filament you are using 60 Fig. 86 Adjust the settings in the slicer tab and click ‘Slice with CuraEngine’ 61 In the preview tab you can see the estimated time and filament length required Fig. 87 Connect the printer and press print or save the Gcode file to an SD card 62 5. Printing with Conductive Material 5.1. Esun conductive filament 5.1.1. Controller with Makey Makey With the dual extrusion system up and running on the Prusa I3 we could finally start 3D printing with conductive material. We started off with printing a small controller, which we hooked up to a Makey Makey to control the arrow keys of a PC. The case of the controller was printed in ABS and the buttons were printed with the Esun Conductive Filament. It was not a clean print but it worked. Fig. 89 The combined STL file of the controller Fig. 90 Controller in ABS and Esun Conductive Filament 63 5.2. Proto-Pasta Conductive PLA We had much better results printing with the Proto-Pasta Conductive PLA. It binded really good with regular PLA so it was much easier to print. Fig. 91 Proto-Pasta and clear PLA printing on the Prusa I3 5.2.1. Capacitive Touch Wheel We printed a capacitive wheel pad similar to the wheel that’s used in the first generation of Apple’s Ipods. To control it we used an MPR121 Capacitive Touch Sensor Breakout Board and an Arduino. This wheel pad could be used to control music, light, video games and much more. Fig. 92 The STL file of the buttons 64 Fig. 93 The prusa I3 prining the capacitive touch wheel Fig. 94 Testing the capacitie touch wheel 65 5.2.2. Capacitive Touch Sphere We printed half of a sphere with integrated touch surfaces. Most capacitive touch pads we see today are limited to a two-dimensional plane. With the possibility of printing any shape you like with a 3D printer the touch pads or touch surfaces can be used in any shape. In our example the object becomes the touch pad. We used our ‘capacitive touch sphere’ to control integrated LED lights using an MPR121 Capacitive Touch Sensor Breakout Board and an Arduino. Fig. 95 Combined STL file of the capacitive sphere Fig. 96 Picture of the capacitive sphere controlling LED’s 66 6. Conclusion In this thesis we looked at two different techniques to print conductive and nonconductive materials simultaneously. Although not fully optimized the second technique showed significantly better results. We spend a lot more time on getting the dual extrusion technique working than we initially planned at the beginning of this research. It proved to be the biggest challenge we had to face. The first conductive filament we tried was very difficult to print with and had a fairly high resistance making it not useable for printing electrical circuits yet. The next material we tried was already a big improvement and a step in the right direction. 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[Accessed: 25-May-2015]. 69 Appendix 1 Tel: 86-755-26031978 electric property thermal property mechanical property physical property ASTM D-256 3.2 mm 1.8 Mpa notch impact strength heat distortion temperature flammability ASTM D-257 HB 100 354 2400 85-90 45 50 1 1.5 1.2 800 220-260℃ Better nature, better life! www.brightcn.net surface resistivity UL 94 ASTM D-648 ASTM D-790 ASTM D-790 ASTM D-638 Elongation at Break flexural modulus Tensile Strength ASTM D-638 Tensile Strength ASTM D-1238 ASTM D-792 Data Black 3mm,1.75mm 0.5kg/roll Test Standard ASTM D-955 230oC/2.16k g Test Conditon Shinking rate Melt Flow Index Print Tem. [email protected] Data Sheet of Esun 3D Conductive Filament Shenzhen Esun Industrial Co., Ltd. Relative Density Color Diameter Packing Item Contact: Kevin Yang Fax: 86-755-26031982 Ohm ℃ J/m Mpa Mpa % Mpa % g/10min g/cm3 Unit 8. Appendixes Esun conductive filament datasheet 70 http://www.openimpulse.com 42BYGHW208 Stepper Motor Datasheet Model Step Angle ( ° ) 42BYGHW208 1.8 Motor Length L(mm) 34 Rate Voltage (V) Rate Current (A) Phase Resistance ( Ω) Phase Inductance (mH)   Holding Torque (g.cm) 12 0.4 30 37 2800   Lead Wire (NO.) 4  Rotor Inertia (g. cm2) 34  Detent Torque (g.cm) 200   Motor Weight (kg) 0.2 http://www.openimpulse.com Appendix 2 NEMA17 42BYGHW208 Datasheet 71 Appendix 3 NEMA17 42BYGH4803 datasheet 72 Class B 100Mohm Holding Torque Pull-in Rate Insulation Class Dielectric Strength Insulation Resistance Operation Temp Range 8 9 10 11 12 13 N/A 0.34Kg(Max) Lead Wire MFG of Terminal Weight 20 21 Life Stepping Accuracy Rotor Inertia Detent Torque -20 ~ +40° C 19 18 17 16 15 Storage Temp Range 5.5Kg.cm Current Per Phase 7 14 4.8 1.5A Inductance Per Phase 6 ± 20% 2.8 ± 10% Resistance Per Phase 4 5 1.8° ± 5% Step Angle No.of Step per Revolution NO of Phase 3 4.2V 2 Rated Voltage 500VDC SPECIFICATION CONDITION 1 2 ITEM 4.5 C GRN A B 21.0 D BLU 24.0± 0.5 2.0 48.0Max 750 NO. 4-M3 Sara 9/2 9/2 42BYGH4803 Q.A. MFG APPR. ENG APPR. Ma Yunlei DRAWN CHECKED AWG22 deep4.0min Weight(kg): 0.34 DWG.NO. 1504 Kysan Electronics SCALE: 1.5 : 1 SIZE A4 Revision Update UNIT: mm 31.0± 0.1 42.3Max Rev. 01 31.0± 0.1 SHEET 1 OF 1 REV 01 Date 9/2 42.3Max Ø22.0 Ø5.0 Appendix 4 Repetier Firmware changes in configuration.h for UMO 73 Appendix 5 Repetier Firmware display changes in Uiconfig.h 74 Appendix 6 Repetier Firmware display changes in Uiconfig.h 75 Appendix 7 Repetier Firmware controller keys changes in Uiconfig.h 76