Suburban Building Studios slashed the time required to produce detailed architectural models from several weeks to one day by switching from hand modeling to a CNC router. The CNC router, which costs only a fraction of the price of laser cutting machines also provides far better accuracy and detailing than could be achieved by hand. The use of CNC routing has dramatically improved the competitive position of the company by allowing it to produce higher quality models at a lower cost than its competitors.

Suburban Building Studios has been in the business of producing architectural models for about 10 years. For most of that time, the company has used traditional manual modeling techniques. Over the past several years, management has grown concerned about the amount of time required by this approach. About a year ago, the company began to investigate automated methods of producing architectural models.

The company first considered laser cutting machines which have been installed by a number of architects and larger modeling firms. These machines operate from a CNC program that is usually created by translating the CAD model creating during the design process. They provide a very high level of accuracy and can produce a model that is as detailed as the original CAD model. The problem is that these machines are quite expensive. A model with a four foot by four foot working surface, required to handle many larger modeling jobs, costs in the area of $100,000. The least expensive laser machines cost about $25,000 but provide only a 12 inch by 18 inch working surface. Another problem with these machines is that they are capable of taking only very light cuts.

Then, management heard about a computer controlled router that performs a similar function at a fraction of the price. The 3-axis gantry router from Techno, Inc., New Hyde Park, New York, generates an extremely accurate model based on a CAD program and provides a 4- foot by 4-foot work surface for only about $17,000. This is less than one-fifth the price of a laser cutter capable of handling the same size work piece. The router is also capable of taking much heavier cuts than a laser cutter. For example, it can easily cut ¾ inch plywood while depth of cut for a laser cutter is typically limited to about ¼ inch.

The accuracy of the router is about the same as the laser cutter and far superior to manual methods. The Techno system has an accuracy of +.1 mm (+0.004) in 300 mm and a repeatability of +0.01 mm (+0.0004). Techno routers have anti-backlash ball screws for play-free motion that makes it possible to produce accurate circles and inlays. These ball screws also make it possible to produce extremely accurate wooden or plastic parts. The ball screws have excellent power transmission due to the rolling ball contact between the nut and screws. This type of contact also ensures low friction, low wear and long life.

           Elevation of part model
A typical project on which Suburban Building Studios used the new CNC router approach is an existing primary school in New York City which was modeled to assist in a renovation and addition project. The existing building was built in the neoclassical style and contained a significant amount of detailing including windows, mullions, modulating brickwork, capstones and door openings, which the architects wanted to include in the model. The elevation of the building, which is 100 feet wide by 40 feet tall, was modeled at a scale of 1/8 inch to 1 foot. Producing a hand model of the primary school would have taken several weeks and it would have been very difficult to achieve the level of detail and accuracy that the architects required.

While architects typically supply CAD models of their projects, in this case Suburban Building Studios was asked to produce the model. The company used Mastercam CNC programming software from CNC Software, Tolland, Connecticut, which comes with the machine. While the machine is capable of full 3D contouring, the Suburban Building Studios modeler felt that the elevation was best suited to a multiple layer 2D model. He started by creating a 2D elevation drawing of the structure. Then he copied the drawing 11 times to different layers designed to represent depth in the elevation. For each layer, the modeler deleted the details that did not appear at the appropriate depth. For example, one layer focused entirely on the window mullions while several others emphasized the brick and stone work.

The layers were then combined into a CNC machining program. Each layers represented one pass of the cutting tool with the depth of cut equal to the layer spacing on the actual building when reduced to scale. A high level of detailing accuracy was achieved by using a 0.02 inch diameter cutter. Depth of cut ranged from 1/16 to 1/64 inch.

Once the program was finished, a piece of monochromatic grey plastic board was simply loaded into the machine and a few buttons were pushed to start it up. The modeler was then able to walk away while the machine finished the part. The entire process of creating the CAD model, converting to a CNC program and machining the model took just one day. The finished model had far more detail than could ever have been achieved in a hand model.

Suburban Building Studios has found many other applications for the router. It uses CNC techniques to produce architectural competition boards that stand out because the design is engraved right into the boards. It has created full-scale components for design projects such as some special clips used in the Michael Jackson kiosk at the Sony Building in New York City. It has also built some equipment for its own use such as an architectural easel.

In one year of operation, Suburban Building Studios has never had any problems with the machine. This is partly due to the strength and rigidity of the table. The Techno machine is constructed from extruded aluminum profiles that can support all architectural modeling materials and provides easy clamping capability. The machine also has four ground and hardened steel shafts and eight re-circulating bearings in each axis. This shaft and bearing system produces very smooth play-free motion and an extremely rigid system that produces high quality cuts.