Software solves surface design

Redmond, WA--Microsoft used surface- and solid-modeling CAD systems from Alias and Surfware Inc. (Westlake Village, CA) to design the IntelliMouse trackball. In order to leverage each system's strengths, engineers predefined the product's design requirements. They concluded that the most important consideration was that the product have a smooth, comfortable external shape that also supports a user's environmental needs.

Engineers created a quick shape in Alias' solid modeler for both 2D and 3D evaluation. Then the tooling house imported the IGES files into SURFCAM and machined a prototype. Engineers refined the shape by hand, scanned the changes, and brought the data back into Alias for review. Engineers then transferred the scanned data to Surfware's SURFCAM software for final refinements.

The biggest problem encountered was developing surfaces that integrated the controls while reinforcing the visual simplicity and immediacy of the product. Using SURFCAM, engineers designed a relief area that "scoops" away from the top surface and around the ball and wheel. "This detail provides a strong visual tie for the two navigational controls," says Carl Ledbetter, senior industrial designer at Microsoft. "It also proved to be a tooling and surface-construction challenge."

Western Industrial Tooling (WIT) (Redmond, WA) also assisted in the surface development process. Engineers brought the mechanical-component designs into SURFCAM from an Alias file, and checked the surfaces for interference and clearances, in real-time. WIT also machined prototypes for Microsoft's approval. After the project was finished, Pro/E files were exported from SURFCAM to produce drawings.

During final surface development, WIT was able to quickly turn around the design changes, reducing the design cycle time. "A designer could create an updated version of the part's surface, and send it across the office to a CNC programmer who would quickly create a tool-path program for it,' says Ledbetter, "and within minutes, the new surface was created on the CNC in 3D." He concludes that this provided the best means for approving a surface--part in hand.

"SURFCAM worked great for designing this product just as it has for others in the past," comments Ledbetter. "It provides strong visuals to evaluate surfaces on-screen, and quickly transfers designs downstream for engineers to evaluate the CNC surfaces."