This project is about implementing my 3D printer. 3D printing is one of the cheapest and easiest ways to realize complex objects required for projects. Due to my curiosity on how does actually a 3D printer works, and get the hands on experience, I decided to build one from scratch.
Initial Steps and Overview of the Project
Initially, I did a research on existing 3D printing technologies. The most commonly available 3D printer was that the ''cartesian'' printers. Apart from that I found about ''core-XY'' and ''delta'' printers. Delta printers are quite harder to implement compared with other two types. In cartesian printers, the printing bed moves along one of the horizontal axes, X or Y. The printing bed and its supports altogether have a considerable weight. Due to the high weight of the moving parts, it may cause the prints to detach from print surface when it changes the direction and in jerking movements at stops. When it comes to core-XY printers, their printing bed moves in a vertical axis (Z), which minimizes that effect. And also a higher printing speed can be achieved using a core-XY printer. Therefore, I decided to go for core-XY.
Goal
My goal was to build a core-XY 3D printer which gives a good print quality for a lower cost compared to commercial 3D printers.
Design & Implementation
First, I designed a CAD model of the printer. Then the frame of the printer is made using Aluminum bars. The strength of the frame and accuracy are extremely important to proceed with the project. Weight of the whole frame was concentrated more towards the bottom part in order to improve stability and reduce vibrations. Then the the Z axis setup was done. There I had to perfectly align the four metal bars which the printing bed moves along. After that, setting up X and Y axes was done. Then all the electronic components were placed and wired them properly. Then I used a customized version of Marlin firmware as firmware for the printer. This version of the printer was made using wooden parts since I wanted to minimize the cost, but having it in mind to replace them with 3D printed parts in the future. This version of the printer did not gave me that much of a print quality. But I could 3D print all the parts that required for replacing the wooden parts. So the version 2 of the printer is made by replacing wooden parts by 3D printed parts. This time time I could obtain my desired print quality. There I had to spend a considerable time to calibrate the printer for finding the best suitable values for my printer such as acceleration, print speed, jerk settings, retraction settings, printing temperatures and suitable PID values for heaters, and so many other parameters. After doing some modifications and proper calibration, I built the version 3 of my printer which gave me expected results. The cost was around 25000 Sri Lankan rupees in total.
One of the design considerations was reducing the weight of moving objects. Here I mainly considered X and Y axes since they are the axes which the print head moves along regularly. When it comes to extruders, there are mainly two types. They are direct drive and remote drive. In direct drive mode we have to use a stepper motor attached to the extruder and that stepper motor becomes a mobile part. Since a stepper motor has a considerable weight, I decided to use a remote drive which I can keep the extruder stepper motor as immobile. Further the mobile 3D printed parts also designed such that their weight becomes small while achieving the required strength. And also the stainless steel bars that used for X and Y axes were selected accordingly. There I decide to use 8mm diameter bars in order to reduce the weight while having a good strength.
By watching several videos on 3D printing, I found that vibrations are one of the major problems that affects the surface quality of prints. By making the body of printer strong and concentrating the weight towards the bottom of the printer the vibrations could be minimized. I observed that the belt tension is also responsible for vibrations. Therefore belt tensions were properly adjusted. Acceleration and jerk settings also directly affect the vibrations. Properly calibrating those also helped to reduce vibrations.
Another important fact is that reduce heat dissipation from print bed and extruder. All the heating elements used here controlled using a PID algorithm. Therefore, when the temperature of those elements go below the desired value, they power up again and again in order to maintain the desired temperature level. By reducing heat dissipation, we can reduce this where we can save power. Further, some filament types require more than 100 `C of bed temperature. Without properly managing heat dissipation, we may not be able to reach that temperature since the heat dissipation may become more than heat supply. In order to reduce the heat dissipation I used an insulated sheet below the heat bed. And also an enclosure was made to cover the printer.
For electronics good cooling system is required to function properly over a long period of time.A dedicated 12mm x 12mm fan was used for cooling main circuit board and stepper motor drivers. The enclosure was designed to have proper air inlets and outlets. A dust filter was used at the cooling fan to reduce dust going for the the main circuit board. One other think you have to make sure is that using proper wires. Most of the wires carries electrical signals in the design but there are few connections which carries high currents (10-20 Amps). They are the heat bed and extruder. Copper wires having a higher gauge need to be selected for those connections in order to prevent from overheating wires which may cause fires and many other problems.
Results and Conclusion
I could gain a lot of hands on experience by engaging with this project. Since this is not a pure electronic project, it was very interesting and challenging. I had to take so many decisions than what I listed above while doing this project. This 3D printer is actually will be a gateway for many of my future projects.
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