I came up with the idea when playing around with origami, and I came across this nice origami stegosaurus design as shown below. The interlacing bony plates of this dinosaur inspired me to design the mechanical motion in 3D.
My origami inspiration (cr. Joseph Wu)
I started with creating the stegosaurus’s body using the quadball forms feature in Fusion 360º. The torso, head, and four legs are all made from quadballs, which are then connected together smoothly using combine and fillet. My first model is shown above on the right.
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A bald Giffen, first model
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Final CAD model in Fusion 360º
Then I drew out the back plates with box forms and placed them in between the split stegosaurus’s hollow body. The plates are each connected to a rod and cam, which is linked to a crank for rotational movement. Each cam is placed with a slightly slanted angle from the previous cam so that the stegosaurus’s plates rise up at different times one by one.
Printing out Giffen!
When the crank is rotated with human power, the cams attached would also rotate. With the crank’s axis placed off-center through the cams, the rods resting on the cams would move up and down to achieve the rolling plates effect. I built the box that holds the crank with a hollow design, so the audience is able to see the crank and cam mechanism inside.
Tada! Giffen is born 🐣