What You See Is What You Get

VisionREZ and hsbCAD bridge the gap between architecture and manufacturing.

In carpentry, what is usually a good rule of thumb can sometimes result in major problems. Tony Tersigni, architectural coordinator for Great Gulf Homes, discovered this the hard way. In a project he oversaw, the architect had stipulated the height of the window headers as 7 ft. Unbeknownst to Tersigni, the construction crew at the site began second-guessing the dimensions. The carpenters felt that, for the type of windows they were installing, the header should be 8 ft, not 7 ft. So they adjusted the height at their own discretion, resulting in inaccurate quantity takeoffs. The outcome was a series of windows that didn't line up correctly.

The incident serves as a cautionary tale about the costly mistakes common in the fragmented AEC workflow, especially in a non-BIM (non-building information modeling) environment. Because design and construction occur in different phases -- in isolation from each other -- what is built sometimes doesn't match the plan.

"One of the things that drives me crazy is when our constructed homes do not match our architectural drawings," said Tersigni.

With an emphasis on collaboration, BIM encourages design and construction teams to work together more closely. But Great Gulf Homes decided to take it a step farther. Through the use of two complementary software products -- VisionREZ for building information modeling and hsbCAD, a 3D CAD/CAM solution for the timberframe industry -- the company linked its in-house fabrication operations with the 3D digital model. Walls, windows, and trusses are manufactured in its own facility, using a computer numerically controlled (CNC) machine code generated directly from the CAD file. Now, there's little chance the windows won't line up correctly. After all, what's manufactured is identical to what's in the drawing.

By using VisionREZ and hsbCAD, full-service residential architecture firm Great Gulf Homes ensures that the 3D model created in VisionREZ (top) serves as the basis for the fabrication process (bottom).

Narrowing the Gap
Although they often are used in conjunction with each other, VisionREZ and hsbCAD previously belonged to different firms. But recently, Illinois Tool Works (ITW) brought them closer through successive acquisitions. First in August 2007, ITW acquired Ameri-CAD, the creator of VisionREZ . In March 2008, hsbCAD followed. Today, Ameri-CAD and hsbCAD operate with the ITW Building Components Group (ITW BCG) division, and the effort to bridge the gap between architecture and manufacturing through digital fabrication is evident in its latest release of VisionREZ.

Announcing VisionREZ v7 in May 2009, ITW wrote, "Users can now export a VisionREZ architectural model to ITW BCG (Building Component Group) manufacturing solutions (Intellibuild, View, hsbCAD) for structural modeling of wall panels and trusses. The manufacturing-ready structural data can then be imported back into the original VisionREZ architectural DWG file."

Digital Fabrication
At Great Gulf Homes' manufacturing division, the company makes the floor panels and wall panels that are used to construct the residential homes it designs. Using VisionREZ and hsbCAD lets the company generate CNC code from the CAD model itself to produce the panels in the required sizes and shapes. This seamless integration of design and production reduces the chance of errors previously brought on by construction crews misinterpreting the drawings or making judgment calls that conflicted with the architect's plan.

"Our HVAC (heating, ventilation, and air conditioning) and structural engineers are already on AutoCAD," said Tersigni, "so an AutoCAD-based solution makes the most sense."

VisionREZ is a 3D architectural design solution developed specifically for the residential market. The technology is based on AutoCAD Architecture and AutoCAD MEP. The product is available in a stand-alone edition ($1,495 for VisionREZ Designer, $2,895 for VisionREZ Builder) or as a plug-in for AutoCAD Architecture or AutoCAD MEP ($1,495).

"By disabling some of the features that cater to the commercial market -- such as curtain walls, for instance -- we were able to offer a residential-focused price point thanks to the Autodesk OEM [original equipment manufacturer] program," said Jay Moore, Ameri-CAD business development manager. VisionREZ Stand Alone Builder or Designer, Moore pointed out, costs $2,000-$3,000 less than full seats of AutoCAD Architecture or AutoCAD MEP alone. The stand-alone version does not require a separate purchase of either Autodesk product.

hsbCAD is available in various modules: hsbWALL, hsbTIMBER, hsbPANEL, and hsbCAM, to name but a few. Many of the modules could be deployed by prefabricated home producers such as Great Gulf Homes. The wall module, for example, comes with a database of wall types, along with user-definable library items such as T-connections and wall ends. It can produce CNC codes for well-known manufacturing systems; the list includes Weinmann, Bautech, Essetre, and Hundegger. The modules are fully integrated with AutoCAD and Autodesk Architectural Desktop and are customized for specific industry segments and disciplines.

Success under the Same Roof
Ameri-CAD believes a feature that distinguishes VisionREZ from other packages is its automated roof-building tools, designed specifically for the residential market. This roof-design system, according to Ameri-CAD's Moore, was "built from the ground up."

When introducing version 7 in May, Ameri-CAD announced that "Roof Subtractive Modifier allows the user to remove an area from the roof for easier roof manipulation and design without modifying the vertices; Roof Clip and Trim allows the user to clip and trim two roofs that interfere with one another at their intersection to combine two separate roofs and let the system determine the proper intersection lines; Roof Creation from Walls enables faster roof design and development by allowing the user to simply select walls to generate a VisionREZ Roof. …"

Using the roof-design system in Ameri-CAD's VisionREZ, users can select relevant walls (top) and generate a roof object (bottom).

"Roofs are my pet peeves," admitted Tersigni. "[Ameri-CAD] understands the roofs that are suitable for the North American residential market, all the different combinations that are common."

VisionREZ's design tools let you create frames and trusses by automating layouts and anchoring the structural objects to polylines, slabs, and roof slabs.

Linking Architecture and Manufacturing
Recognizing that successful BIM implementation requires better coordination of design and construction, Autodesk also has begun offering direct fabrication tools through Revit Structure, which allows users to derive the CIS/2 data needed to produce the structural steel components directly from the BIM model (see "BIM and Digital Fabrication").

"You can create a 3D model," noted Ameri-CAD's Moore, "but if you don't pass that along for downstream use, it's just an isolated practice. BIM is about sharing." In the case of ITW BCG, it's about the company's design and manufacturing products sharing the same 3D data.