“It’s basically a hot glue gun on motors.”
This is how Tommy Spencer, a second year aerospace engineering major, explains his home made custom-built 3D printer. Spencer, the propulsion research lead for the UC San Diego Human-Powered Submarine Team (HPS), needed a low cost solution in order to quickly fabricate and test different versions of tail fins for the team. Buying a sophisticated printer that could accommodate many materials would have cost thousands of dollars. Instead, with the help of a Warren College undergraduate research scholarship, Spencer decided to build his own.
The 3D printer setup looks something like a mad science operation. Spencer’s personal lab, his bedroom, offers the right amount of power and space for the impressive device. About a foot long in each direction, the giant hot glue gun is quite large for a printer. The operator fills the printer with pellets or cords of any material he or she would like to use. The material is then melted inside by the filament extruder, and squeezed out like hot glue into an exact representation of the CAD (computer-aided) design.
“Starting out, I didn’t know about 3D printing at all. Now I know a lot about it, and I’ve put my own money into it because I’m really interested. It’s become kind of a hobby,” Spencer said.
He added his own customized heated chamber to make printing large fin pieces possible. This also meant that he had to create his own state-of-the-art ventilation system (an Ikea desk, ventilation ducts, and a fan) to funnel out the heat and toxic gases that are produced when melting synthetic materials.
The technology of the tail fin for the human-powered submarine uses biomimicry, modeling the flexibility off of the bone structure of a fish, which is not entirely rigid, yet not floppy. The shape of the fin is inspired by the tuna.
“The main constraint working underwater is that you have more resistance. That’s why we needed a flexible material. When you’re moving a lot of space under the water, there’s a lot of friction and force, so we found a way to engineer for that,” Spencer explained.
Having a custom 3D printer has allowed HPS to experiment with different exotic materials, which has allowed its fin to operate in a much better way.
Spencer began with a basic build-your-own printer kit, which could melt a limited number of materials. He then began experimenting with different designs, and with the help of Google, was able to build a new filament extruder that could melt any material.
Though not all the printed parts of the submarine are made in Tommy’s printer, HPS comes to him “mostly when they need an exotic material, something that needs to be really strong, or impacted a lot.”
Spencer’s newfound passion for 3D printing has led him to meet and collaborate with a graduate student who is also working in this field. Luca de Divio Nicoloso is adapting biomimicry into 3D printing techniques, specifically working with cactus structures to extract structural engineering methods from nature. Spencer met de Divio Nicoloso to confirm that his printer construction and exotic material printing projects were on the right track.
“I did finish a fin the other day. It’s the first that I’ve made that is 100 percent homemade,” Spencer said. “This means that I bought the pellets and went from that to a completed fin. We tested it in the pool over the weekend, and it it worked out pretty well.”
He credits trial-and-error and unrelenting curiosity for his success in 3D printing.
“I cranked that one out over two days, whereas before it would take maybe a week to get everything put together,” he said. “It was a very stressful two days, but still two days.”
“It’s basically just been curiosity, reading stuff online, and then combining it all to make finished products.”
What began as a “mad scientist” project in his bedroom, following his curiosity, has evolved into a possible career avenue in a new and up-and-coming field.
Betsy Meeker is a contributing writer for The Triton.