The first articulated design that started it all.
Photo: Javier Rodríguez (McGybeer)
The first tentacle Javier Rodríguez designed moved only a few degrees at each section. His Cute Mini Octopus had printed on the first try, but the movement still needed work.
“So I did a few iterations, adjusting sizes, gaps, and fillets,” Rodríguez said in an email interview. “I was amazed at how small changes, just tenths of a millimeter, caused huge changes in the mobility.”
Rodríguez designs articulated 3D-printable models as McGybeer. The octopus was his first articulation, and the problem it presented still runs through his account of designing a character: the shape has to leave room for the movement he imagines.
“It depends on the model; there are always exceptions,” he said. “But usually, I pick up my to-do list and do a quick brainstorming about how that character should move.”
He considers possible joints, their orientations and whether the object can print. An idea may become workable later that day or week; he then uses the sketchbook to check whether it makes sense before beginning the 3D model.
“If there’s a new articulation, that goes first,” Rodríguez said. “Then, the rest of the character.”
Image credit: Javier Rodríguez (McGybeer)
That order gives the movement a place in the design before the remaining form is built around it.
“Prototyping, prototyping, and more prototyping,” he said of checking a design. Experience helps him anticipate a joint’s behavior, but a new one still has to go through a prototype.
“But new ones rarely work as intended on the first try,” he said. “I look for printability (no supports), strength, and mobility.”
He described checking parts at half scale with a high-quality print profile, and at 60% scale with a low-quality profile. Those smaller tests are part of his own process for deciding whether the model is ready at its original size.
“If they move and don’t break, then they are ready to go at original size,” Rodríguez said.
Image credit: Javier Rodríguez (McGybeer)
His octopus gives that testing a concrete measure. A gap or curve can change by a fraction of a millimeter while the difference in the hand is much larger: a tentacle that barely bends gains more freedom to move.