In many ways, the Genetic Stair was the most demanding project Nicholas Desbiens worked on at Caliper Studio. Though small in scale, the generative design methodology employed required a synthesis of architecture, engineering and fabrication. The project has been extensively documented, perhaps most beautifully in a set of photos by Ty Cole.
The stair is the result of an in-depth research-driven design process embodying the search for a final form that inhabits the fecund territory between exuberance and rationality. To this end custom code was developed over a period of several months to marry the generative potential of 3D architectural modeling with the analytic power of structural design software. In an entirely automated evolutionary process, populations of stairs were created in compliance with strict fabrication constraints and then rated for structural performance. Then, following genetic principles, new generations were produced in which individuals showed stronger and stronger properties until a final design was deemed structurally adequate to connect two floors with no intermediary supports while making three ninety degree turns.
The collection of videos and images below were made by Nicholas Desbiens to describe the many interrelated areas of research explored during the design, development and fabrication phases of the Genetic Stair project.
CNC cut pipes
The Genetic Stair is made of 48 unique stainless steel pipes with 1400 holes and 253 connecting steel rods cut to length. Using five-axis CNC laser cutting equipment, these holes could be cut with enough precision in both position and angle to allow the pipes themselves to act as a kind of three-dimensional jig for assembling the stair. One quickly identified limitation of laser cutting technology was the relatively small range of incidence angles (< 15°) that can be precisely cut into polished stainless steel due to refraction of the beam. This constraint led to the development of highly specialized design and detailing solutions, such as fabrication-conscious generative processes and hybrid digital/analog templating procedures.
Though the laser cut pipes themselves were fabricated with a high degree of dimensional and angular accuracy, the way in which these components were joined one to the other (structural welding) was significantly less precise. To bridge the gap between the precision of digitally fabricated smart components and traditional metal shop fabrication techniques, custom jigs were made using additional digital equipment such as a CNC router, on the high end, and a standard office laser printer on the low.
Typical connection detail
Smaller diameter rod members were attached to the structural tube through a precisely-calibrated laser cut hole on the near side and a hand-finished plug weld on the far side. In addition to the 253 diagonal rods, this detail was also used to connect nineteen Corian treads, three Corian landings and eighteen planes of low-iron glass.