This post is provided courtesy of Scott Dellosso, middle school teacher at Perryville Middle School in Cecil County MD. Scott has been a long-time partner of DHF and consulted on Sam’s STEM project. Check out more by Scott here: 3D Printing in English Class
A STEM project written by high school student Sam Hawley.
The purpose of this experiment was to test the effect the material of 3D printing filaments has on the rotational speed of gears it prints. To carry out this experiment a gear bearing, downloaded from Thingiverse, was used to print with four different filaments, each containing different materials; Bronzefill made with bronze, LAYWOO-D3 with wood, LAYBRICK with stone, and Ninjaflex with a flexible plastic, TPE.
The alternative hypothesis stated that the bronzefill gear bearing would have the highest rotational speed. First the printing settings were adjusted using MatterControl 1.5. Then a calibration cube was printed in each filament, to test settings, before the gear bearing was printed. The axial turbine wheel file from Thingiverse was fitted with a ¼ inch hexagonal center, using Tinkercad, then printed. Next, each gear bearing was set on a table vice with a drill bit in the middle and the turbine wheel attached to the drill bit. Finally, an air compressor, set at 75 psi, was used to blow the turbine wheel, for 10 seconds. A tachometer and reflective tape were used to measure the maximum rotations per minute. However, only the Bronzefill was able to spin with just the air and turbine wheel. These results proved the alternative hypothesis to be correct, the Bronzefill gear bearing had the highest rotational speed, because it was the only filament of the four that was able to function with this experiment.
If I compare the maximum rotations per minute for a 3D printed bearing in Bronzefill, Ninjaflex, Laywoo-D3, and Laybrick, then the Bronzefill will have the highest maximum rotations per minute, because it will have the smoothest print surface with the least amount of friction on the spinning gears.
If I compare the maximum rotations per minute for a 3D printed bearing in Bronzefill, Ninjaflex, Laywoo-D3, and Laybrick, then they will all have the same maximum rotations per minute.
All of the gear bearings printed well and were able to spin. However, when applied to the test, the Bronzefill gear bearing was the only bearing to spin with the turbine wheel and air compressor. Examining the results tells us that the Ninjaflex, Laybrick, and Laywoo-D3 gear bearings have a lot of friction between the gears. This may be caused by the materials used to make them. The flexible plastic in Ninjaflex may not have worked well because the bearing needed to be harder (similar to the Bronzefill bearing). The wood in the Laywoo-D3 bearing may not have worked because the wood is not as smooth as the bronze. The Laybrick bearing may not have worked because the material is too malleable, and the surface is too rough, causing friction. The reason the Bronzefill bearing worked so well is because it had a much smoother spin than all the others and the material was metal, which works very well in gears.
The alternative hypothesis that the Bronzefill would have the highest maximum rotations per minute was accepted using a one way Anova test with a significance level .05.
Although Bronzefill worked the best, the other filaments did not yield results, so they cannot be compared to each other. The next step to improve this test would be to increase the size of the turbine wheel. This would make it easier for the given air pressure to spin the other gear bearings. Another way to improve the test would be to increase air pressure in the air compressor. This would put more pressure on the turbine wheel and increase its likelihood of spinning the other gear bearings. In conclusion, the Bronzefill gear bearing had the highest rotations per minute, but in order to rank the other filaments, the test must be improved.
Teacher/ Maker Educator
Perryville Middle School
Teacher/ STEM lead
Perryville High School
This study was completed by 11th grade STEM Academy student Sam Hawley.