Image 10.12

Image 10.11

Image 10.09

Image 10.10: version 2

Image 10.06: version 1

Image 10.05

Image 10.08: large scale plastic pumping thing

Doubts.

Image 10.07: plywood pumping thing

Weight of the wooden parts: 8,5 kg. This does not include rods, screws, bearings or brackets. Those would easily add another 4 to 5 kg. This thing is getting awkwardly heavy.

Image 10.04: ready for print

The basic mechanism to make it work is to turn the disk at the bottom. There's a set of gears in the base that make the central shaft twist through 90 degrees and then back again. This turns the gears of the main hub which pushes or pulls the arms.

Image 10.03: basic mechanism 2

Changed mechanism. This new one helps to avoid problems, regarding the flexed arms colliding at the center.
Also, it’s just more elegant.
Reciprocating mechanism that can be driven by the rotation.
As standalone object it could change from one shape to another simply by pushing down on the corners of whichever shape (the cube or octahedron).

Image 10.02: basic mechanism 1

Basic mechanism. Need to ensure that all parts can fit in.
The shape is more of a cube, 120mm on each side. As long as everything fits in and works, scaling it up shouldn’t be a problem.
The cube arms extend to twice their length, so they will need to bend as they move inwards. So they’ll have to be flexible enough to follow a pathway inside the structure (and away from the mechanism in the very center)…
Flexible isn’t ideal and rather depends on the material. 3D printed polyamide does have some flex but how will the flex manifest when the arms are out and pushing the stretch fabric?
Accept this unknown and just hope it works fine…

Image 10.01: minimum volume

A drawing to figure out the minimum space within which the arms and mechanisms have to fit.