The head of the robot is styled on piece of Swiss cheese. Here are some of Paul’s thought processes and insights into the mechanics of the piece.
Most of the machines I make suffer from randomness. Sometimes they work and often they don’t. I thought that this friction mechanism could be relied on to perform unpredictably.
Resting on a single driving roller and a row of three idlers, the three drums rotate about a common axis. Around the rim of each drum are 20 equally-spaced teeth.
Geared with the driving cylinder is a camshaft that brings into the paths of the rotating teeth a set of detent pins fixed at the ends of 3 levers.The pins prevent further movement of the drums, allowing the words written on them to be read. It’s a fruit machine with words instead of fruit.
I made such a machine and it seemed to generate a reasonably vivid set of phrases;
CYCLISTS – TERRORISED – LEGOLAND
JESUS – CAN’T STAND – SARAH PALIN
BIG GIRLS – STRETCHED – THE THONG
MANIACS – INVENTED – STEVENAGE
TV CHEFS – MAGNIFIED – PORRIDGE
But taking one drum at a time, it became clear that patterns of words, sometimes nine or more in a row, were repeating themselves with remarkable consistency. Tweaking of the detent pins only altered the number of words in a sequence. It was too reliable a machine to be bad enough for the purpose. I couldn’t see a way out and was thinking of instructing the person operating it to interfere manually from time to time to jumble the patterns. Then I thought of a mechanical solution that would vary the depth of penetration of the detent pins and thus introduce a new scrambling factor. A longer pin will catch on the teeth of the drum a little sooner than a short one. Half a millimeter’s difference alters the stopping position by one or two teeth. As the depth of penetration is controlled by a stop bar, moving that in and out by a small amount would produce enough variation in the stopping times to break up the patterns. I made the bar rotate by gearing it to the camshaft and fixed an eccentric cylinder to it so that the levers were arrested in a sequence of five different positions.
Here’s a photo:
You can see the 3 levers, the detent pins, the drums, driving cylinder and the eccentric on the stop bar. Is anyone still reading this or am I the only person interested enough to go through with it?
I’ve always liked puzzling through descriptions of machinery especially when the writer tells you that a glance at the diagram will clearly show how the thing works, suggesting that only an idiot would be unable to understand. If you have been, thank you for reading this.
Here is another of Paul’s ideas for a Jokebot – still on the drawing board.