Following the successful printing of the initial prototype, the next goal was to successfully print the track and cylinder using two different colors of PLA. As discussed in the 3D CAD design post, we separated the track from the cylinder. Following the failed PC cylinder prototype, we decided to print PLA in two different colors (color wasn’t important). Once again, we used an Ultimaker 3 printer with two different colors of PLA for build material using nozzles 1 and 2. The print parameters used were the same as the initial track prototype: layer height of 0.25 mm, infill density of 20%, grid infill pattern, print speed of 100 mm/s, and the same orientation. The only difference was that we applied these settings to both nozzles in the Cura setup. Nozzle 1 was set to print the cylinder and nozzle 2 was set to print the track. The first attempt to print the track is seen in Figure 1.
Figure 1. The first attempt to print the track and cylinder using two different colors.
As can be seen, the print failed. When inspecting it the next day, we assumed that nozzle 2, which was used to print the track (red part),got jammed. Without looking into it too much, we attempted to print the track and cylinder again using the same exact set up. The second attempt is seen in Figure 2.
Figure 2. The second attempt to print the track and cylinder using two different colors.
It is clear we had even less success and needed to determine what the problem was. After speaking to Professor Rudolph and some members of her lab, we learned that there are two different types of nozzles that most likely was affecting our results. According to the Ultimaker website, the build nozzle has a print core of type AA and the support nozzle has a print core of type BB. Both print core types are 0.4 mm so there is not a difference in size that could be causing problems. Ultimaker did not provide specifics on the difference between the print core types; however, it can be assumed that the difference between them affected the print.
Now that the problem was identified, we addressed the issue by replacing the print core type BB with a type AA. We ensured that there would be enough material to complete the print, and once again ran the test using the same print parameters. The results are seen in Figure 3.
Figure 3. The completed track and cylinder using two different colors.
As can be seen in Figure 3, we were able to successfully print the marble track using two different PLA colors. When examining the final part, there were quite a few stringy hairs hanging off the track that were removed during post processing. Another issue was the presence of a few small burn marks on the white portion of the track. Since they do not affect the functionality of the track, we decided to use this print for our final design.