Over the last several years, CW Keller, Plaistow, N.H., has been using 3D modeling technology and computer numerical control (CNC) milling to create sculptural projects. Recently, they started manufacturing complex, custom concrete forms. One of the contractors they work with pulled them into a project to build two cast-in-place concrete roof canopies for the Harbor Park Pavilion in downtown Boston.

With the help of Turner Construction, S&F Concrete, SGH Engineering, and designer, Utile, the concrete roof canopies for the Boston Harbor Park Pavilion project went several steps beyond the original plan.

The pavilion was designed by carefully studying the structure from a variety of vantage points using a digital model that included the surrounding urban environment.

To create the forms, CW Keller used Rhino 3D modeling software to define the surfaces of the design, optimize the material yield, and translate the data to machine-ready files for CNC, which then mills the machined pieces for the forms. Those pieces are reassembled, laminated, and sanded smooth to create the final form. This technology allows for a much more precise, cost-effective form.

The project combined shaping plywood sheets to contoured ribs for the more subtle curves and using plywood forms for the two deeply curved, multidirectional areas. The two canopies measure 40x50 feet and 40x60 feet. CW Keller realized that after pouring the concrete, the seams and screw heads would be visible underneath the canopy, so they suggested precutting the plywood sheets with edges to create an interesting visual element, as well as creating a pattern for the screw heads and predrilling those holes. All of these pieces were shipped to the site, ready to assemble.

Because of the contours of the roof canopies and the more than 400 sheets of plywood the project required, the forms simplified the construction process, added to the overall aesthetic of the project, and saved countless hours of construction time.

The pavilion opened in June 2011. CW Keller continues to work on other concrete projects where 3D modeling technology and CNC milling are the key drivers to creating a visually stimulating work of art.

Learn more about CW Keller at www.cwkeller.com.