2/20/2019 | 4 MINUTE READ

CAD/CAM Enables Rapid Turnaround for a Racing Part Rush

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CAM software enables quick design and manufacture of a custom racing part.

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Years of troubleshooting clutches for dragsters prepared Chris Nachtmann to open his own machine and engineering shop. Soon after, it became clear that he would need more CAD/CAM capabilities to advance his shop and meet the tight turnaround demands of traveling racecar teams. When a race team showed up needing a custom car component engineered in a flash, he used GibbsCAM from 3D Systems to get the job done.

Building a Foundation in Racing Machining

Working as a clutch specialist for National Hot Rod Association (NHRA)’s Alan Johnson Racing, Mr. Nachtmann learned of the challenges faced by crew chiefs, including the maintenance and rebuilding of dragster clutches. Team owner Alan Johnson encouraged him, teaching him to pursue constant improvement and inspiring him to analyze and innovate. He would take these lessons into his future design and machining operations.

After five years, he left to help run his parents’ machine shop in California. There, he developed new products, including a titanium pressure-plate cover that he offered to different NHRA teams. After race weekends, he would check with crew chiefs and use their feedback to further develop products.

In 2005, Mr. Nachtmann moved to Charlotte, North Carolina, and opened CNC Performance Engineering (CNCPE), a general engineering and machine shop in an 8,000-square-foot facility with nine employees. Though its 10 CNC machines, which include saws, lathes, wire EDMs and mills, are used for a diverse range of general engineering and machining applications, CNCPE continues to focus on high-quality clutch parts for top-fuel NHRA dragster teams. This reputation leads to occasional NASCAR and drift-racing jobs, sometimes with urgency.

Three Days to Engineer and Machine a New Part

Recently, a drift-racing team needed air filters installed on two fuel-injected Roush Yates Ford racing engines but had no way to affix the filters. Each eight-cylinder engine had a bank of four air-intake horns on each side, and there were no adapters made for the filter-runner combination. Further, the team simply could not get air-filter dimensions from the manufacturer. Making matters more urgent, an engine-tuning specialist was already scheduled to fly cross-country to optimize the engines, with filters in place, and time was running out.

The customers approached Mr. Nachtmann late on a Friday, and the engines, with filters, needed to be on the dynamometer first thing the following Tuesday. They had no concept or design for an adapter and had no filter for measurements, but they knew filters and air horns would take up all but a few millimeters of space between the runners and the hood. When the customer agreed to ship a filter overnight, CNCPE accepted the challenge of designing, machining and delivering four parts.

A major consideration for taking on this job was the improved CAD/CAM capability Mr. Nachtmann added to his company soon after revising the pressure-plate cover. GibbsCAM enables solid and surface modeling and machining, functions for machining solids and surfaces, and high-speed machining. These capabilities came in hand for the drift-racing job.

Mr. Nachtmann began as he always does when there are no CAD models, using GibbsCAM to model his concept. “I am all about the tool path,” he says. “GibbsCAM machines directly from solid CAD models, but if the part is not a simple part, I always need to extract some piece of geometry or fill in some feature for machining.”

He designed the adapter with hollow cylinders going through a thin base plate, made to fit inside the runners on one side and hold air horns in openings on the other. The cylinders on one side have cross-drilled holes for spring-loaded ball set screws, which fit into tiny indentations to be ground into each horn. The cylinders on the bottom needed no screws, as they slide right into the clamp-equipped runners.

To machine this part, Mr. Nachtmann had to hog out a lot of material to create the thin-walled standing cylinders at 3 inches in diameter while leaving a thin base. He held the aluminum billet in a vise and used GibbsCAM high-speed roughing to program rapid material removal on the first side. Beginning with a block of aluminum that weighed 27 pounds, he began to test and optimize feeds and speeds to prevent chatter. With no time to build fixtures, the second side had to be edge-gripped no deeper than the thickness to be left for the base.

CAD/CAM Enables Fast Turnaround

Mr. Nachtmann credits GibbsCAM for his ability to accept this project with such a short turnaround. With no time to build fixtures, he needed to use the vise carefully, which is where toolpath modification came into play. “GibbsCAM let me do quick edits that saved a lot of time without rebuilding anything,” he says. “You just change the amount of material you want to leave by going into the process manager. You can also try leaving more on the floor or the wall to eliminate vibration, or try machining another area first.” According to Mr. Nachtmann, the drag-and-drop interface as well as the ability to redo or replace operations with just a few clicks made the entire process that much easier.

After removing 24.6 pounds of aluminum, the finished part weighed 2.4 pounds and measured 19.25 by 7.25 by 1.95 inches. The four parts were delivered on Monday evening, with plenty of time to prepare for engine tuning the next day. Pleased with these results, Mr. Nachtmann now plans to use GibbsCAM to redesign and machine his company’s top-fuel dragster flywheel to improve its performance for increasingly powerful racing engines.


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