IONIC COLUMN CAPITAL
Matthew and Joyce Walsh Family Hall of Architecture
University of Notre Dame, South Bend, IN, USA
John Simpson Architects International, London, UK
Stantec Architecture, Chicago, USA
Ordinarily, as a cast stone form designer, I work from 2D architectural drawings. From the 2D drawings, myself and my team create negative molds into which stone is poured. In many cases, it is unnecessary to take the CAD modeling into three dimensions, as the architectural elements are simple extrusions.
I prefer to work on the more challenging projects.
Ionic Column Capital specifications
Design: John Simpson Architects International
Technical Drawings: Stantec Architects
The first step in creating the Ionic column capital was to create a 3D CAD file from the 2D drawings.
This model is built in Rhino.
On a typical cast stone manufacturing project, we machine negative molds to produce positive castings.
However, when particularly high levels of detail are required, or when the geometry involves complex undercuts, (or both, as in this case), a positive master is made instead. Medium durometer rubber is then poured around the master to create a flexible, high-resolution, durable mold.
In the case of the Ionic capital, making a positive master on a 3-axis mill involved splitting the geometry into 8 individual parts, 5 of which needed to be milled from two or more directions.
The final master was milled from a combination of MDF, high-density expanded polystyrene foam, and foamed PVC sheeting.
I’m fortunate to work with a talented group of artisans who have been working in the cast stone medium for decades. For them, CAD/CAM technology is simply a new tool in a timeworn process.
In this series of images, Antonio Chavez applies release agents to the master, prior to pouring rubber over it.
Once the rubber has cured, the master will be removed to create the negative cavity into which cast stone will be poured.
A fresh casting awaits an acid wash, which will expose the aggregate mix used to resemble granite and remove the remnants of foam blockouts (used to section off the form where the casting blends into a brick façade). The “bug holes” on the vertical form faces are an unavoidable consequence of the pouring process. They will be rubbed with a patching mixture.