A digital chair for a historic landmark: Developing the prototype design

            Having experimented with Asian inspired joinery in the first chair prototype Ali Alwayel, with feedback from Professor Stevens and the project team developed makeLab’s Affleck House chair design in a new direction. Moving away from their original design which had separate frame, seating surface and back rest—reminiscent of the Wright designed dressing table chair originally in the home—to a more integrated laminated design that better combined CNC construction methods, material properties and form.

            The team progressed toward a final prototype in rapid succession with Ali performing three dimension modeling in Rhinoceros and preparing tool paths to drive makeLab’s ShopBot in RhinoCAM. The final prototype design incorporates a series of profile cut plywood members and a single acrylic plastic member that are laminated together to create the chair.     

            Each of the router cut half-inch veneer plywood profiles was assembled over a quarter-inch hardwood locating dowel. Wood glue was used to bond each of the layers to each other and to the dowel. Minor variations in the bore diameter of the holes in several of the laminated plywood layers made assembly more challenging. Even though the CNC router is precise there are still variations in machine and material tolerances that cause the parts to vary slightly. The acrylic member proved especially challenging to route, breaking one bit in the process and necessitating the modification of the tool path settings to run the ShopBot at slower cut speeds than originally programmed. The acrylic layer was also registered over the wood dowels and bonded to the wood components using a two-part epoxy. Lastly, the bonded components were sanded to blend the layers, creating a smooth continuous surface. The assembled prototype is not only sturdy but relatively comfortable (for a hard-seating-surface chair with no cushion) as well. 

Jason M. Colon

jcolon@LTU.edu

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