Harmonograph (2005)

A harmonograph is a device used to produce interesting spirals which I believe are called harmonograms. One of the more common types of harmonographs uses two independent pendulums, one with a piece of paper above the pivot and the other with a pen on an arm. There are various other types also in existence, like my working one. I have built two harmonographs, one a success - shown below and the second more or less a failure.

My first harmonograph is made from an old shelf laden with bricks hung from my door frame with string. I used 'twiddelys' or food ties to make the string into an upside down Y shape. This enables the shelf to twist slightly which replaces the need to have a second pendulum, but produces slightly different harmonograms to the usual ones. Paper is put on the shelf, and a pen hinged using coat hangers held together with tape from a chair. To work the harmonograph I swing the shelf and gently lower the pen onto the paper. It can produce reasonably sized (around about 10/20cm across) in my opinion, beautiful, harmonograms.

(click for a larger image)

My second harmonograph was an attempt at one with two pendulums. In the absence of any good hinges, or a way to make such hinges I used string. This enabled the pendulums to twist, which meant that it didn't work properly.

The harmonograms it produced were mostly rubbish, small scribbles. However it did manage to produce these few reasonable spirals, note that these are probably larger than the originals which were roughly tuppence sized.

One day I may try to build some proper hinges and give it another shot.