Working with steel in the metal workshop

The first stage of making the steel harmonograph was to cut out and prepare all the structural components. In a sense, the process is a bit like tailoring – you measure and cut out all the pieces, and then put them together an a logical order, investing each stage with as much care and craftsmanship as you can muster. For the flat steel components I had MDF formas cut on the college CNC machine, which David Stewart used as patterns to plasma-cut the shapes out of mild carbon-steel. We had a total of fifteen flat pieces for the basal structure, which were to be welded to a large central cylinder.

My job was to ‘finish’ the plasma-cut pieces:  I refined the curves with an angle-grinder, drilled the holes that created the delicate openwork patterns, sanded everything to smooth the edges, then repeatedly heated and quenched each piece at the forge to darken and strengthen them. When Dave first placed the angle-grinder in my hands I was terrified – the sheer speed and power and noise of the monstrous thing connecting with the steel with a shower of sparks had a brutality and violence about it that I had never before experienced. But once I got used to the heightened energy of the process it became utterly enthralling. The grinder began to feel as fluent and expressive as a brush, and the steel felt responsive and alive. Like all metalwork processes, it demands a total, immersive concentration – you can get lost in it for hours!

I enjoyed learning how to use the big industrial drill-press to make the holes in the pieces. I used drill-bits up to one-and-a-half inches in diameter, slowly and surely grinding into the 3mm steel with utter precision. The friction caused by drilling generates a phenomenal amount of heat – the steel actually smokes – which is why I had to make sure the work was constantly irrigated with machine coolant (a mixture of oil and water) trickling from its own tap.

The curved supportive components that took so long to prepare were MIG welded to the central cylinder in groups of three, braced together with curved brass rods. I bent the rods to the correct arcs on an old pipe-bender, and then drilled and tapped the ends to take the brass bolts that attach them to the steel parts. The high arch of the leg sections is a design feature governed by the clearance needed to accommodate the trajectory of the swinging pendulums. The groups of three look right, because I conceived the entire structure on the basis of the three pendulums working at angles of 60 degrees in relation to one another (forming an equilateral triangle) – so the magic number is three and its multiples. Both in music and in geometry – triplets, triangles and tetrahedra – groups of three have a distinctive dynamic energy, which is what I wanted to pervade the whole construction.