DaVinci CNC mills from Techno-Isel let students with cerebral palsy and other disabilities build CO2-powered race cars for a dragster design contest. "For many of these students, poor muscle control makes it unsafe for them to use conventional power tools," says Jeff Lintz, a teacher at Hialeah Middle School in Miami-Dade County, Fla. "And even if they were able to use the tools, chances are results would fall far below their expectations."
Coupled with the DaVinci tabletop machine is special software that runs along with the Mastercam CAM program. The software converts shapes to 2D splines that define the car's cross section. Students create the splines by manipulating control points with a mouse. "One student was unable to use a conventional mouse so we switched to a track ball instead," says Lintz.
The software then lofts the splines and generates a 3D version of the car shape. A Mastercam postprocessor outputs G-code tool paths to the router. Students mount balsa wood in a special fixture and the program machines one side of the car at a time with a 0.25-in. ball end mill and a 0.030-in. stepover. Wheels are turned on a manual lathe from plastic bar stock.
When completed, cars are tethered to a nylon line on a 60-ft track and propelled with a CO2 cartridge. The fastest cars run the course in about a second and reach nearly 50 mph.