• Srabanti Chakrabarty

The third part of Yethinder's Journey

In the last month, I have made a lot of progress and tasted success after the logistics impeded my progress. The majority of my work was to design and construct the obstacles, for which I used 3d printing. While I was able to complete the job, I faced some issues with the 3D printed objects.

One of the issues of FDM 3D printed objects is precision. Many variables affect the quality of the print, such as flow rate, bed level, printer calibration, temperature, and so on. It also depends on the printer's class, but since the printer cannot be changed much after it has been bought, it is not worth discussing. In the process of improving precision, first, the present print quality has to be known. There are many free models available online named "Tolerance test," which, when printed, provides a clear picture of the printer's current capability in either X-axis or Y-axis. A good printer has a tolerance value of as low as 0.15 mm.

The first layer is essential and has a significant effect on the rest of the print. To get the first layer right, the bed should be as level as possible. Often, low-quality print beds bulge or sag in the middle due to the change in temperatures. This issue can be minimized by adding glass on top of the existing bed. In addition to that, glass also provides a smooth surface finish on the first layer. However, there's also a disadvantage to it as the first layers do not stick properly and may lead to a disastrous print. One cheap and easy solution is to spread glue on the glass; this holds the first layer in place for the entire print.

The next step is to adjust the flow rate or extrusion multiplier. A mark is made on the filament, 10 cm away from the extruder inlet. Printer controller software such as Pronterface is used to command the printed to extrude 10 cm. After it has finished extruding, look for the mark which was made on the filament. If it is visible, measure the distance of the mark from the extruder inlet, this implies under extrusion and that the steps of the motor are mismatched. If the mark is not visible, it may have over extruded. In either of the cases, steps (of the stepper motor) per millimeter has to be changed. Increase the step value using the M command if it under extruded or vice versa. Repeat the process until the desired result is obtained. After following the above steps, if still, the printer is not able to achieve low tolerances, other print settings such as extrusion width, layer height have to be altered. These can be changed from any slicer software. Too much extrusion width and layer can also cause a problem, so it is recommended to experiment with and reduce the values to get better results. Of course, lowering the width and height will increase the print time, but it mostly improves the print quality. Reducing the print speed will certainly help along with a good part cooling fan. If neither of the above changes works, it is time to revisit the temperature setting as each brand is different from others even though they are the same material.

Yethinder Ragav

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