Washington Open Object Fabricators President Matt Rogge races the teams 3-D printed boat at the Seafair Milk Carton Derby. WOOF placed second in the 14 and over racing category. Photo by Bethany Weeks
Every year, nearly 100 groups enter the Denny’s Seafair Milk Carton Derby to test the seaworthiness of their handmade boats. Washington Open Object Fabricators (WOOF), a 3-D printing club at the UW, decided to test the limits of this year’s competition by printing a boat made entirely from milk jug plastic.
The idea isn’t a new one, as a previous group of students had also attempted to convert Big Red, an old plasma cutter that was previously a piece of equipment in the mechanical engineering student shop, into a 3-D printer. But WOOF was successful where that group had fallen short.
“While it worked for many years, eventually it cost more to fix than it was worth,” said Mark Ganter, UW mechanical engineering professor and the club’s faculty advisor. “Before it went to surplus, the shopmasters asked if we had a use for it.”
As WOOF took on the project, they faced several challenges along the way. After getting permission to use a room in the Mechanical Engineering Building, the group had to configure Big Red’s plasma cutting software and completely redesign an extruder to attach to the cutter’s head. Along with these mechanical issues came problems with the actual milk cartons.
Bethany Weeks, WOOF’s lead organizer, said the main issues included how to feed the milk jugs into the printer and how to deal with the shrinkage which resulted from heating the plastic.
A chance encounter at the Seattle Mini Maker Faire with Scrapblasters, a group that salvages old stereo systems and turns them into functional art, gave the group access to industrial shredders that could turn the milk jugs into flakes that could be poured into Big Red’s hopper.
But, while the group had designed a boat with walls allowing for some change in shape, there were still problems with the printing process.
“Our biggest warp-shrink issue was when we printed a section of the boat one night and came back to it the next night to realize that our walls had moved as much as three-fourths of an inch,” said Weeks.
This was an issue, Weeks said because it would throw off the entire model. To counter this, the club had to manually move the printer head around to determine the shape of each wall.
However, after several long nights, printing the final product overnight to avoid disturbing surrounding classrooms, the boat was ready to set sail.
The boat raced in the 14-and-over racing category and took second place. For the group members, the most memorable parts of the experience varied.
“I am new to FDM (3-D) printing,” Weeks said. “I want to learn as much about it as possible, but for the boat print, I didn’t have the skills or knowledge to really help the guys out. So my favorite part of the build was watching them work. Their energy and excitement was addictive and inspiring.”
For WOOF President Matt Rogge, the experience centered around the collaborative effort.
“The best part of the project was working with the group,” said Rogge. “We have extremely creative and dedicated members.”
Reach reporter Joe Veyera at email@example.com. Twitter: @JosephVeyera
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