| || || || This project started after someone posted a video of a concrete truck as a giant disco ball. |
I started by thinking of a tube clad in mirrors shaped like sycamore keys and rotated by a small motor, with a light shining on it.
Then thought it would be much nicer to use existing sources of energy and light - namely the air being sucked into the exhaust system and sunlight streaming through the studio windows.
| || || ||I experimented by making a rotor from a drink can and miniature bearing and holding it in front of air vents. The air movements were really strong - the rotor spun furiously and flapped about. See this video.|| |
| || || ||After kicking around various designs I settled on a mobile comprising two concentric U-shaped rods. The inner rods had 4 rotors and the outer rods 3 rotors, making a total of 14.|
The rotors are about 360-mm long, laser-cut in 1.2-mm-thick mirror-polished stainless steel. They are welded to a 20-mm-long piece of 35-mm-dia tube, with a 32-mm-dia ball bearing race inside it.
Each piece of rod is anchored in a central hub, which is 3D-printed. The hubs accommodate another bearing race and spin around a central axis rod.
| || || ||I had to get the rotor blades cut outside because the College laser cutter isn't suitable for metal. |
I ended up buying 60 blades, double the number I really needed, because the minimum order was £80.
I also got some discs made to cover the top and bottom of the hubs.
| || || ||Here's the design of the upper hub. The central hole has a step in it so that the bearing can sit inside.|
These were 3D printed in the College Fab Lab using white PVA plastic.
As noted above, the top and bottom are clad with discs of the same material used for the rotor blades.
| || || ||I made a jig to hold the parts of the rotor in place for welding. || |
| || || ||I used the College's micro-TIG welding set to join together parts of the rotors. It was remarkably easy to use and produced really neat welds.|| |
| || || ||The first 3 of 14 rotors. || |
| || || ||I made another jig to bend the rods. I had to allow for the rods springing back, which meant that I had to halve the radius of the curves in the jig.|
| || || ||This is my design for the support system. The "jib" is 40x20mm box section, 2.4-m-long, with a pulley welded on to its tip. It's clamped to the railings at its foot.|
The stays are 2-mm-dia wire cable, as is the cable from which the mobile is hung.
| || || ||It's now installed although:|
(a) It's not in its final state. I need to put stainless bearings in the hubs, fix discs to their undersides and remove the protective film on the rotors.
(b) I need to figure out a way of making it spin and twirl. The extraction system only works when the studio is busy, and when it doesn't work, there's not enough air movement to make the rotors spin and swirl.
| || || || The framework of the mobile now rotates satisfactorily when the air extraction system is working, now that I've moved it closer to the vent. However, the rotors aren't spinning.|
See this video: https://youtu.be/2NQZYOcnjIA