These are general instructions for making the Hoberman spheres. I've designed several different part/kit versions (4 or 5) with varying success. These instruction will guide you to the overall assembly of the sphere. There will be other documentation on the actually assembly of the parts in a given kit version.

This design is based upon a star dome (icosidodecahedron). It has 60 edges of the same length and 30 verticies. Each edge will be comprised of a pair of curved arms joined together by a pivot joint at their midpoints. Each vertex will be comprised of a pair of hubs (an inner hub and an outer hub), each connected to 4 arms allowing pivotal motion in the plane of the arm.

You will need:
60 pairs of arms (120 arms)
60 sets of arm pivot point pins/fasteners
30 hub pairs (60 hubs) (if used)
240 sets of hub pins/fasteners (if used)

The dome is made up of pentagons and triangles using the arms as sides and the hubs as corners.

Every side of every pentagon must also be the side of an adjacent triangle and visa-versa.

Every pair of inner and outer hubs will be the intersection of the corners of 2 pentagons and 2 triangles.

The arms are pinned together in pairs through their middle holes.

Every pair of arms goes between two sets of an inner and outer hub at both ends of the arms.

A given arm will be connected to an inner hub at one end and an outer hub at the other.

The curvature of the arms goes towards the center of the dome.

The hubs are not symmetrical - if you put a strait edge across a hub from where one arm attaches, through the center of the hub, to the place where the opposite arm attaches - you would see that the two arms across from each other will attach on opposite sides of the strait edge.

The pair of arms across from each other must always be attached to the hubs such that one arm of each pair is on either side of the line defined by the above mentioned strait edge.

To accomplish this the inner and outer hubs of each hub pair must be flipped relative to each other (opposites sides of a coin).

If you follow these rules it will eventually form an expandable/collapsible geodesic dome.

If you have any questions email me at johann@fablab.no

Good Luck,
Johann