Making Moving Parts with a 3D Printer

3D Printers are getting more common, and are REALLY cool, but how do they work? In principle, it is quite a simple science. Most 3D printers use a plastic filament, and have a nozzle that heats up to about 200 degrees C (about 400 degrees F). This melts the plastic as it passes through the nozzle, known as an “extruder”. The 3D printer is told by a computer where and when to move its nozzle and dump out the hot melted plastic. The plastic rapidly cools, and leaves a solid behind as the extruder moves on to lay down more plastic.

The extruder will start at the bottom and make all of the things it needs to at that elevation (known as a layer), and then move up to start the next layer. Not terribly complicated. The extruder knows where to go because of a 3D file that is run through a program called a “Slicer” that decides what to do at every layer. The printer continues this process for every layer, building the entire thing from the bottom up. The unsliced file for the spinning rings seen in the video is on the left.

This allows for some cool things! These rings are one of the coolest things we have made. You may be able to see in the image above that there are some cone like pieces sticking out of the inner rings and into the outer ones. These act like axles. They cannot be cylindrical, because the 3D printer goes from top to bottom. With cylindrical axles, there would suddenly be a layer where something would be built with nothing under it to support it resulting in scary conglomerations of plastic resembling monsters from bad science fiction. Using cones in this way solves this issue.

As the printer makes its way to these axles, it prints the layer shown above. You can see the cone and the recess being formed. As the printer continues on its way, these will be locked in place. This allows that entire spinning ring assembly to be printed as a single item! In fact, it can’t be taken apart without breaking the entire structure! Understanding these constraints on 3D printing allows for some very interesting challenges, and ultimately some incredibly cool designs! Check out those spinning rings again. Can you see the axle cones?

These printers aren’t just for making cool designs. NASA is currently using a brand new 3D printer in orbit aboard the ISS. One of there astronauts needed a wrench, so they sent him the design file, and he made on on board! They even shared the plans for this wrench, allowing us to print our very own!