This blog post represents a fairly major landmark for headandhaft. It is the result of a lot of investment, time spent, and learning into a new direction, and craft for us. This is story of our first piece of commercial metal spinning.
We were approached by a longstanding client of ours, who was aware that we were now metal spinning to produce a small collection of 8 spun copper pendant shades. The lights were to be given a brushed finish, and were 250mm wide by 120mm high. If truth be told, this was just outside of what we were comfortably capable of, but we took the plunge, and decided there was no better way to learn than on the job.
The images below show the copper discs, 1mm thick, 300mm in diameter, with a water jet cut 40mm entry hole. The piece is held on the lathe with a acetal tail block which sits through the disc into a corresponding hole in the wooden mandrel, centring and holding the piece in place.
The first challenge was the material. We had never spun in Copper. Brass, Pewter, Aluminium yes, but copper no. We sourced the appropriate material and as the fittings needed to enter through a 40mm top hole we had the discs water jet cut. The next stage was to turn the mandrel over which the metal would be drawn. Back in our comfort zone we turned the mandrel from a single chunk of lignum vitae, which was repurposed from one of a large collection of 100 year old mandrels we had acquired.
So day one, we are keen to get spinning, and have vision of a bench full of spun shades adorning our benched come days end. Unfortunately not to be, the wide discs, tight radius of the form, and nature of the copper proved for an extremely frustrating, and mistake laden day. We were stretching the material far more than we should have been, and this resulted in a vastly different rim thickness to that of the original disc, as this was on the attempts that we didn't fully collapse the piece on the spin up. Back to the drawing board. We poured through every note and resource we had and began to diagnose our condition. A massive thank you must also be given to warren martin a fellow instagrammer, and metal spinner who was beyond helpful following a rather desperate email.
The main issue turned out to be that we were using a tool with a far smaller radius than was appropriate, and this was stretching the material too far. We spent half a day making a new tool, and also practicing spinning with the help of a back stick, a tapered piece of timber which when held behind the spinning disc when drawing the metal with tool, helped immeasurable to quell the buckling disc. These changes made the world of difference, and we were back in business.
The images below show the pieces after their first annealing, about a third the way up the mould. Without this process that materiel would be simply too work hardened to spin any further.
So, now we could crack on, and get the spinning going. Copper work hardens as it is spun, so it was necessary to take the metal of the lathe an anneal. This consists of bringing the metal to a certain temperature with the use of a blowtorch, which softens the copper, and allows it to be used. Annealing leaved a black fire scale on the surface of the copper. If this is left on and the spinning continued it can create an orange peel effect, and make achieving a good finish almost impossible, so it was necessary to remove this, the annealed pieces were soaked in a acid mixture, which removes the scale. From here the pieces go back on the lathe, and we can continue to spin the metal up the form.
The images below show the copper spinnings soaking in a mixture of water and sulphuric acid, a highly acidic mixture which literally burns the fire scale from the copper.
Metal spinning is an extremely particular, and in our case unintuitive craft, and forming the metal over the wooden form requires a mixture of pressure, delicacy, and understanding of what the metal want to do. The more we spun, the more competent we became. This competence happened astonishingly quickly, and we soon had the feel for the shape, and how the metal would react at each stage of the spinning. It took us two anneals, and subsequent acid baths to react the top of the form, but if we were to spend more time on these shapes, this could definitely be reduced, and make the process far more efficient.
The images below show the final spinnings. after they had been spun, all grease, and debris removed, and they were given a satin brushed finish, inside and out.
Although a relatively simple bit of metal spinning, these pieces are our first commissioned pieces, and we were delighted, and extremely proud of what we were able to achieve. They were by far the biggest things we have spun, and we learnt more on the days spent on these than the previous months of relentless practice. We are so excited for this foray into a new craft, and material base for the business, and welcome any enquiry about creating bespoke pieces. One of things we hope will set us apart is our ability as woodturners to create one off moulds for small runs or unusual shapes at almost no extra cost.
The images below are show the final shades hung in our photo studio, styled with our usual lamp holders, before being sent to the client for installation in a London restaurant next week! Please try and ignore the thumbprints all over the shades, these pictures were quickly taken with greasy fingers, before being cleaned, and packaged.