Cut the red wire or the blue wire? Unfortunately, defusing a bomb is a lot more complicated than that, often involving tiny, intricate, delicate mechanical fuses that more closely resemble the inside of a geared clock than the wick of a bottle rocket.
In response, the Golden West Humanitarian Foundation–an international nonprofit that clears mines and bombs lingering after war–has collaborated with MIT and the Singapore University of Technology and Design on a better way to train specialists in bomb disposal. It’s called the Advanced Ordnance Teaching Materials (or AOTM), and it’s a collection of 3-D printed models representing the 10 most common fuses found in bombs.
“The problem with using the real thing (with the explosives removed, called ‘inert ordnance’) is that the mechanisms are normally too small and obscured by physical features to gain an understanding of how they work,” writes Golden West’s design lab director, Allen Tan, via email. “Unlike a car engine, ordnance fuses were designed to be manufactured and then used (exploded). They were never intended to be taken apart. When you do, they become fragile and fall apart easily.”
That leaves the most obvious solution, which is what most people who are trained to defuse bombs use today: printed schematics, like textbooks. But Tan insists that these schematics are problematic for two more reasons: First, they’re 2-D, not 3-D. And furthermore, organizations like Golden West and the UN perform a majority of their bomb disposal work in places like Cambodia, where they need to train locals on the ground who’ve often had no formal education. “For them, learning a technical hands-on job from a line drawing just doesn’t make sense,” Tan explains.
Tan’s team spent over 1,000 hours translating fuses into larger scale mechanical replicates, modeling each of the 144 pieces used across the 10 models from scratch. Their gears and pistons actually move as they do in real fuses, and the models can be assembled and disassembled over and over again. If the color scheme reminds you of a Playskool toy, there’s at least some reason. The palette of basic colors is derived in part by international standard rubrics. Each color defines part of the bomb structure. The blue is the fuse body itself, the white designates arming components, the red designates firing (or explosion-inducing) components, and the yellow, the explosives themselves.
The injection molding used in traditional manufacturing could have built the same thing, but 3-D printing offered Tan and his team the chance to rapidly refine their builds, tweaking files to make new models quickly. Plus, given that their market of customers is relatively small, 3-D printing was actually more cost-effective than bringing designs to the production line.
“For us the impact will be determined by how many new bomb-disposal technicians benefit from using these tools,” Tan explains. “It’s not strictly about units sold; a center that trains 300 bomb disposal techs a year may only need one of our sets; that’s okay with us as long as it’s of benefit.”
Tan and his team have received two rounds of funding from the U.S. Department of State, Office of Weapons Removal and Abatement, allowing them to develop their project without relying on per-unit profit margins to keep the lights on. Five months into the project, Golden West has sold their AOTM models to the U.S. and Swiss governments, the UN, and a handful of other commercial and nonprofit groups around the globe.