Making the Exploratorium clock

The old Exploratorium at the Palace of Fine Arts

The Exploratorium which opened in 1969, was the very first ‘Science Centre’ full of interactive exhibits. It still has its wonderful exhibits, but now is also an art, science and education research institute. In 2013 it’s moved to a new home, one of San Fransisco’s piers. I am part of an Exploratorium group called ‘The Tinkering studio’ which encourages using tools and making things. The clock was a commission to decorate a column in the centre of the new tinkering studio area, on the theme of ‘people making things’

My column in the pier building

Making anything permanent for the Exploratorium is a daunting prospect because the standard is so amazingly high. When I’m there I normally work on temporary stuff which doesn’t have the same responsibility. I started with the idea of lots of small automata cartoon characters ‘making’ something big. The space around my column suited the shape of a huge vintage American road sign. I made a model while I was visiting in spring 2012 and everyone seemed to like it, but they couldn’t agree the wording on the sign. In retrospect, I can see the problem was that no other section of the new Exploratorium has an enormous sign, but at the time it was a bit frustrating.

By the beginning of August 2012, when I should have been starting work, the wording issue still hadn’t been resolved and I still hadn’t finished my previous project, an arcade game about the Somali pirates which had been dogged by bad luck. By the end of August I had started to think of the cartoon people working on numbers instead of letters and this is how it became a clock. Sitting on a train (where I often have my better ideas) I realised the numbers could swing out to form a dial. I made a new model when I got home and decided the idea was practical.

I mocked up part of the column and tower structure, made a prototype number two and then started trying different styles for the cartoon characters. I invited Paul Spooner to come and help design the mechanisms and we spent a wonderful week trying ideas out. Paul is a good friend, but we had never actually spent time making things together before. We had a great time and learnt lots of tricks from each other.

Even though I initially wanted to make the characters 3D, 2D fitted the available spaces better. Also, the 2D plywood characters looked as if they had been laser cut, even though they were actually just cut on a bandsaw. This suited the Exploratorium as they use laser cutters a lot. I never had a detailed overall master plan, I just drew cartoons characters straight on the plywood to suit the mechanisms Paul and I had made.

Column and tower mock up. An early trial character made of aluminium

By the time Paul left, I had much more confidence in the whole project. So I went to Rayman, a Far Eastern music shop in London, and bought an enormous Chinese gong for Ł1,000. There wasn’t really the budget to buy it, but I’ve wanted to make a clock with one for a long time.

After a couple more weeks I had an almost complete set of characters, mechanisms and numbers. It was then time to build the tower. I was still dithering about the width and depth an hour before we started. I finally opted for the largest of the three options, very fortunate because it later became clear that everything couldn’t have fitted if I’d made it any smaller. With the tower sections in the workshop, progress fitting the numbers went well. I could have worked out all the pivot points using CAD, but it was much more satisfying drawing it with classic Euclidian geometry. Once all the numbers were swinging out, I thought they were a bit boring so I spent an afternoon making the number three swivel upright as it swung out. I liked the effect, so then I had to think up extra pivoting mechanisms for the other numbers.

The number pivots got quite complicated

The top half of the tower in my workshop

Most of the clocks I’ve made have been outdoors so the steel had to be galvanised but for an indoor clock I wanted a raw steel finish. ‘Renaissance wax polish’ was a lucky find, super quick to apply without dismantling anything. It’s used by museums for ancient metalwork and by armourers for battle re-enactment armour.

I had decided to use an electric clock escapement as there wasn’t enough time to make a mechanical one or to test it for long enough. I had hoped to use a synchronous motor (a simple sort of stepper motor whose speed is fixed by the alternating cycles of the mains) but buying one the right spec began to seem impossible so I tried a stepper motor instead. Stepper motors are straightforward but their electronics are not. I almost gave up on the idea completely because the expensive UK driver board I’d bought wasn’t stable. Out of curiosity I’d also bought a cheap Ebay board for Ł28 from Hong Kong. I had spent so much time fiddling with the first board that I gave the cheap one a try, and it worked perfectly first time and has continued to keep time ever since.

Despite the good progress in October and November, panic started to set in because I knew I wouldn’t be able to do anything much in December. I had another job installing gates for the tiger enclosure at London Zoo, was speaking at an anthropology conference in Paris, and there was also Christmas, which is a big event in the UK when everything shuts down for two weeks. Somehow I found a few days to assemble the sections of the clock in my neighbour’s barn. Once Christmas was over, I returned to work and connected everything together. It finally all went on test (performing every three minutes, 24 hours a day) at the beginning of January.

The main problem I had during its test was the oil impregnated bronze bushes running dry and scoring the shafts. If you heat up an oil impregnated bush, an amazing amount of oil comes out, but I think there must be a capillary effect to feed it to the surface which needs priming. I replaced the shafts with really expensive induction hardened ones, and added oil and grease.

I just had time to make one final mechanism and character, the boy with the tape measure. It was hard finding the space to fit him in, but I was delighted when he ended up closely admiring the welder girl’s bottom (ass for readers in the US). So the clock not only ignores health and safety it now also has a minor element of political incorrectness.

From the size of the hole in the crate, I was convinced vital parts had fallen out, but they hadn't. The top of the crate was stoved in very close to the glass, it was amazing it was intact. Fortunately the packer, (Keiser packing, Gorleston) had done a brilliant job and there was only minor damage. I was then lucky to have a brilliant rigger to help me erect the clock round the column , we did it all in just 5 hours. It was a huge relief that it fitted, the dimensions were tight.

I then ran the clock on test again and sadly had the same problem that I'd had in the UK. The oilite bushes shafts started to run stiff, obviously my hardened shafts had not solved the problem. My return date was fixed, so I left slightly unsatisfied, but I had been training Nicole (who works at the Exploratorium) and she will have to take ownership of it, so she will fit the new roller bearings.

For me this problem rather overshadowed the fact that people obviously liked the clock. A group of journallists being shown round even clapped when the gong bonged - I've never heard of lournallists clapping, perhaps they less cynical than in the UK, where we call them hacks .

The installation was covered in greater detail on the tinkering studio's blog.