Achieving the Impossible | ENGI 210: Prototyping and Fabrication

This week’s assignment was to create an impossible object using 3D printing, e.g. an object that couldn’t be created in one piece using traditional manufacturing methods. Thanks to the previous work of Haruto Sasajima in an earlier semester of this class, I found and chose to try and make this lizard from Thingiverse, designed by jtronics. The design easily satisfies the impossible object constraint through its interlocked flexible sections.

Well, to be honest, I started out with the intent of trying to print a different object, an enclosed series of polyhedrons but with some guidance from the lab assistants here at the OEDK, I decided that the generated support structures would be far to difficult to remove.

I started the process of printing the lizards by uploading the .stl file to 3DPrinterOs, a cloud based printer management and slicing software. Once uploaded, I could easily center, scale, and slice the design. I chose to scale the first lizard to a size of 60mm from tail to nose, because I was hoping that with the flexibility of the design it would still fit into the gumdrop container that was provided. Due to being new to the 3D printing world, I was adverse to the idea of my print coming up from the bed and failing, so I used a brim to try and avoid that issue. I first printed one on a Prusa MK3 and then on the Ultimaker 3.

(One of the first two lizards I printed, this one on the Ultimaker printer)

While neither of the first two prints failed, I found the brim very hard to successfully remove. While I was able to cut most of it out with the sonic cutter, I ended up with a lizard that could flex up fairly well, but had interference when trying to flex it downwards. This was true of both the Prusa and Ultimaker prints. I was slightly frustrated, but excited that I had successfully printed something. Fernando suggested that I try printing one without the brim, because “the worst thing that could happen is that it fails.” Seeing no fault in his logic I gave it a try and was blessed with a beautifully printed fully mobile lizard.

(Aforementioned beauty of a flexy lizard)

I repeated the process, after which I had a collection of 4 mostly functional FDM printed lizards. It was time to learn how to use the SLA printer. Fernando helped to show me how to use the different slicing software, and explained the post-processing method for the resin print. I printed the lizard in grey hard resin, although unfortunately, the resin printing process rendered the poor guy’s joints unfunctional. It appeared as though the tolerance was too tight and the resin bonded to itself within the joint. (Unfortunately later in the day Mr. Resin Lizard lost his tail, not due to fright but weak joints)