What’s an alligator without a tail? Still an alligator, and potentially dangerous, but a lot more stubby – which is how Mr. Stubbs the alligator got his name. 10 years ago, Mr. Stubbs was found missing his tail; he was one of 32 alligators confiscated when a truck was pulled over carrying them in a trailer. While rescuers are unsure how he lost his tail, they assume it was due to a fight with another gator. He wouldn’t survive long in the wild, being unable to swim or get to food as quickly as competitors, so he was taken to Phoenix Herpetological Society. However, he still struggled without a tail, so scientists at Midwestern University, upon hearing of his problem, decided to make him a prosthetic.
In 2013, the scientists built a silicon prosthetic tail, but Mr. Stubbs outgrew it. Since he had doubled in size, the scientists didn’t want to risk getting close enough to take a plaster cast of his tail stump, so they decided to 3D scan him instead.
“We contacted the 3D-scanning and -printing company Stax3D to find out what they could do to help us,” explained Dr. Justin Georgi, associate professor of anatomy at Midwestern University. “They used an Artec3D scanner to create a high-resolution, digital model of the tail. We [were able to] manipulate that model to produce any alteration to the tail we needed. We fixed imperfections, made it exactly the correct length and size, [and] adjusted the front end so it matched Mr. Stubbs’ stump with a perfect custom fit.”
The team 3D printed the model and used it to make a silicone cast. That cast was then used to make multiple prosthetic tails for Mr. Stubbs. Why didn’t they just 3D print a wearable prosthetic? While 3D printing has been used to create numerous prosthetics for animals, an alligator tail is especially large, and the team would have needed a large-scale 3D printer to print the prosthetic all in one piece. There are certainly 3D printers that could handle the job, but it would have been a time-consuming print, especially since they wanted to make multiple prosthetics. It would be easier to make one 3D print, use it to make a mold, and quickly cast several pieces.
There’s also the fact that the team used silicone to make the tail. Silicone 3D printing only became possible two years ago, and silicone 3D printers still aren’t that common. Other animal prosthetics have been made from more common 3D printing materials like PLA or nylon – the latter lends itself well to the purpose in particular, thanks to its flexibility and toughness. Silicone made the most sense for an alligator tail, however.
With his new tails, Mr. Stubbs can swim and quickly get to food.
“[He is] doing very well,” Dr. Georgi said. “Whenever he is wearing one of his tails, he continues to show improvement. We are now in the process of building a new tail for him, based on what we have learned from the recent experiments. We expect that as his growth slows with age, and we build him a tail that he can grow into, he should soon have one that will benefit him for many years, not just the next two or three.”
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