here’s one I made earlier :: extl lights
Katie | December 5, 2012
I met David Irwin at 100% Design this year and was fascinated by his EXTL lights for Deadgood. David explained that they had been designed to create as little waste as possible and were made from tessellating shapes cut from a single sheet of extruded aluminium so I was keen to find out more…
The project started when David was approached by Deadgood with a brief to develop a new collection of lighting which used the specialist skills of a UK based manufacturer: “The designer will be required to push the boundaries of the chosen manufacturing partner’s production capabilities, in order to create an innovative new range of products that maximize the potential of the resources at hand. The products developed will be required to offer a striking design statement to suit public, private, commercial and domestic interiors; having the ability to be specified in volume yet also retain their appeal when purchased individually.”
David was already looking into aluminium extrusion for another project and was keen to use this as his chosen manufacturing technique because he was excited about the potential he saw in the process. Extrusion is used to create objects of a fixed cross-sectional profile, from 10mm to 800mm wide in a variety of shapes. It provides an efficient and cost effective solution to many design challenges. David said, “The key thing was finding a way to utilise the efficiency of the process, while creating a product that was three dimensional and not just something linear. So I started experimenting with dissecting straight forms and reassembling them into three dimensional objects.”
“A huge variety of forms could have been produced by sacrificing a large amount of the material, but this just didn’t make sense and didn’t reflect the advantages of the process, which inherently produces very little waste. So after playing about with many forms, I brought things back to basics, by cutting a piece of flat material on a compound angle. By repeating this with equal spacing along the length of the material, you can produce components which are exactly the same but tessellate together as segments forming a three dimensional structure.”
And David realised that by changing the angles of the compound cut, he could create different versions of the same concept.
Have worked out the form, David then had to decide how to fix the pieces together. And this is where he gets delightfully geeky about the joys of aluminium extrusion! “The opportunities of the process really came into play here – the variety of features that can be added to the design of the cross sectional profile is vast. Grooves, slots and screw ports can all be incorporated into the design which means you don’t have to post fabricate these, they will already be there when the extrusion is produced.” (The image below is an example of what’s possible with this technique.)
The only constraints are things like requiring a consistent wall thicknesses to ensure an equal flow rate when passing through the die. David said, “I settled on grooves in the section which would serve two functions: firstly as a shelf for a pentagon shaped component which the cut pieces would group around; and secondly for a silicon band which would bind all the pieces together. With careful consideration of where to place these grooves relative to the angles of the cut, two forms could be created – one slim and one wide.”
“Prototyping the light was tricky. To really test the compound cut theory, first we needed the actual extrusion, so to mock that up, hundreds of individual pieces were cnc cut from mdf and then painstakingly glued together to form mock extrusion lengths.”
“Once we had this, the cut could be trialed and testing of the silicone fixing method could also be carried out.”
Once he was happy with the prototype, it was time to start production for real. To create the real extrusion, an aluminium billet is heated to 900˚C and loaded into a press where a hydraulic ram forces it through the die, producing the desired section. The extrusion then undergoes solution treatment, stretching to remove distortion and finally ageing to produce the required temper.
David told me with the great pride that the bands the hold the pieces together are available “off the shelf for pennies”.
David decided not to decorate the surface, preferring the natural ‘visual shading’ produced on the surface of any extrusion, caused by friction as its pushed through the die. To finish the lights he opted for anodising because: “it retains the crispness of the form and allows you to really see all the important elements which constitute the design and the integral structure of the lights.”
All that remained was is to assemble the pieces… et voila!
Further reading for the especially geeky: