Reverse engineering of a Delage Type-S - on the road again.
In the early 20th century, as the automotive industry began to simmer, a French car manufacturer by the name of Delage was proving itself as a worthy supplier to the wealthy, and a worthy winner on the Grand Prix circuit. Its output between 1905 and 1935 earned it legendary status among automobile enthusiasts. Cars like the Delage Type S, which took part in the 1914 French Grand Prix, have been adored for more than 100 years.
Stuart Murdoch has been the proud owner of a Delage Type S since 1975, but in 2014 the engine block cracked around an exhaust valve between high temperature and high-pressure exhaust gases and the cooling water jacket enclosed in the engine block casting. It was rendered unusable.
"This crack was difficult to access, complex in topography, and impossible to repair without risk to the integrity of the block," Phil Guilfoyle, who would lead a project aiming to restore the engine block, explained. "The repair had to be perfect without affecting the surrounding area. The design of the engine made access to the crack very difficult and, although several other methods were considered, no repair was possible."
Reverse engineering a 1914 Delage Type-S engine
Guilfoyle is not only a lifelong vintage car buff but also a keen adopter of digital technology through his career as an industrial designer. The opportunity to combine a passion with his profession arose through Up The Creek Workshop (UTCW), a mechanical engineering and restoration studio who maintained Murdoch's Delage Type S. Guilfoyle and the UTCW called on the help of Keech3D, a supplier of castings, Wysiwyg, who would provide 3D scanning and modelling capabilities, as well as CSIRO Lab22, a manufacturing research centre who boast a Voxeljet VX1000 sand 3D printer.
The task at hand, to reproduce the engine block, was complicated by the lack of spare parts, design drawings, and other engines to reference. Dissembling the defective engine, 3D scanning and CAD modelling were harnessed to reconstruct the failed casting, in a quick and cost-effective manner. Guilfoyle and co didn't want to print the engine block, just the tool to recast the block with a method and materials that would allow for a true replica.
With the CAD data, a sand mould for printing was designed and validated by foundry engineers who used simulation tools to certify the casting process would work. The CAD model was successfully limited to a total of 14 mould parts - the original consisting of 42 components - and printed on the VX1000 platform in 300-micron sand layers that are selectively glued together with a binder. Then, the moulds were unpacked, excess sand cleaned away, and the subsequent casting procedure was carried out without a hitch. Including printing and mould finishing, the moulds were ready for the foundry within three days. The foundry required a further 48 hours to seal, dry and assemble the mould set.
By November 2016, after nine months of scanning, CAD modelling, mould design and then reproduction, testing was complete, the Delage Type S was once again road-ready, and the following month Murdoch was reunited with his prized asset. Since, the engine block has performed faultlessly, with the car clocking up hundreds of kilometres on country roads and completing multiple laps on the track. A vintage car has been reborn thanks to contemporary reverse engineering methods.
"3D sand printing is nearly perfect for this kind of high value, small run application of casting technology," assessed Guilfoyle. "It is efficient and flexible enough to do one-offs, which is highly relevant to vintage restoration. It is not dependant on a shrinking legacy of old parts and skills to keep heritage vehicles on the road, [and] it is extremely accurate so parts can be engineered to assemble with remaining parts.
"The Voxeljet VX1000 is still the only 3D sand printer in Australia, and the CSIRO provided both access and expertise to permit the parties in the project to take this innovative approach to a problem as old as the industrial revolution."
