1929 was a pivotal year in the Indianapolis 500 stock car race. A new formula was announced for the race in which displacement limits increased, superchargers were banned and cars returned to a two man configuration last seen in 1922. The new rules were implemented to encourage more automobile manufacturers to participate and to bring down the cost of building and maintaining Indianapolis cars. This prompted innovations in engine design and configuration that made them faster than ever before.
One of these new Indy Cars was the 1930 Sampson Special. The chief engineer and mechanic, Riley Brett, created a new configuration with two Miller 91 eight cylinder engines side by side in the chassis and geared them together to make a sixteen cylinder engine, known as the U16. The engine design resulted in the Sampson Special qualifying for the Indy-500 seven times over its long career from 1930 to 1936.
By the late 1930’s the car was obsolete and wound up engineless in a wrecking yard. It was saved from scrap drives during World War II and sold to a collector in 1960 who had no knowledge of the car, but recognized its significance as a racing artifact.
In 2001, Joe MacPherson purchased the Sampson Special from the collector and commissioned a no expense spared restoration. With the goal of bringing the car back to its 1930 condition, the restoration required a great amount of research of the feature details from timeworn photographs and modified parts.
One of these parts was the radiator, which had been altered over time and was missing the brass tag that contained a unique serial number. Greg Schneider, a member of the restoration team, knew the tag was originally produced by stamping out thin brass with a set of steel dies capable of producing thousands of parts at a time.
“I found out a set of steel dies would cost $1,500, when I only needed to create one tag, I started looking for other options,” said Schneider. He learned PolyJet 3D printing technology could build custom dies for a low cost compared to traditional manufacturing methods and contacted the experts at Stratasys Direct Manufacturing to learn more.
Greg sent his 3D CAD files to Eric Quittem, senior project engineer at Stratasys Direct Manufacturing. “The die designs were pretty thin—too thin for the application,” said Quittem. “I worked with Greg to come up with a new die design that could support the pressure and load of the embossing press.” Eric redesigned the CAD files and converted them to .STL files for printing. He advised Greg to order the dies in VeroBlue, a dimensionally stable material from the Rigid Opaque family of PolyJet materials that is perfect for fine feature details.
Greg received the female and male PolyJet dies two days after placing the order and set them up to press the brass. After embossing, he trimmed the tags and welded them to the radiator of the car.
“This radiator tag is one of those unique features you don’t see on modern vehicles,” said Greg. “Every detail is critical in car restoration. With this custom solution from Stratasys Direct Manufacturing we were able to restore this charming feature and add value to the Sampson Special.”
