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Sunday 17 January 2021

CD Clocks Part 2


Test Joiner 1

Test Joiner 2

Test joiner 3: a bit like these house and TV models.

Dodecahedron, elastic outside

Dodecahedron, elastic inside, detail and.......

The whole thing

Octahedron. There are large spaces between some of the discs and not many edge joins, so this configuration is quite unstable and hard to build.

Cube and tetrahedral clocks.

Tetrahedral clock, front, and

From above

Cube clock

Cube clock all packaged up in a bulk cdrom container

A simple derailleur, mechanically transparent or naked


As per the last post, I have been making Cd clocks for a year or so, but left the design alone for quite a while. I did build a few models or sculptures of televisions and houses though, and these were as much experiments about how to put slabs together and fun as anything else. I put the tv’s and houses on our front gate, the closest thing to a public art space I have.

After a while, I realised that cds could be used as faces of polyhedra by attaching “edge holders” to the cd. With “N” equispaced edge holders you would get the essence of an “N” sided figure: N = 3 for triangle, 4 for square, 5 for pentagon etc. Then the faces could be put together, and all the regular polyhedra could be made.

I tried a few 3d print designs, and for a week or two had several pairs of joined cd’s on the shelves. I was after something easy to print and extract from the printer, and easy to use, and not too damaging for the cd. This included edge holders that clamp by press fit onto the CD. Some of these holders used techniques borrowed from the “house” and “television” experiments, using tubes as variable length joiners.

In the end, I borrowed parts of the clock number design to make the edge joiners, and this immediately made the edge holders compatible with the clock designs. Late last year, I made a few sets and gave a clock to my friend Deb Callister when I visited her, and gave my friend George and daughter-in-law Phoebe some as well.  The parts all pack down quite neatly, and I gave Deb the whole clock kit packaged in a bulk CD-Rom package.

In the hybrid polyhedron / clocks, the edge holders take the place of some of the numbers, so it’s a good idea to stow the left over numbers somewhere safe! 

The 1978 book " The Penguin Book of the Bicycle" describes the bicycle rear derailleur as follows, "Part of its appeal may be that it is is mechanically naked; it is easy to see how it works just by looking at it and it can be taken apart and repaired with relative simplicity". I hope I have achieved some of that design elegance and simplicity with the cd polyhedra and clocks. More to follow.


Steve Nurse

Dodecahedron as lightshade

Tetrahedron stack. From the bottom, the joins are shared edges crossing at node, shared face, shared truncation edges. Bit of dowel in the middle helps support it.

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