Recreating BMW 328 Roadster parts using digital technology

When it comes to the BMW 328 Roadster, there are always epithets like "legend" and even "motorsport icon" — and rightly so: of the 172 races around the world in which this car participated, it won 141.
Less attention is paid to the fact that the car had an extremely short production life — it was produced with 1936 to 1940. A total of 464 copies rolled off the assembly line, and even fewer were in the back of the roadster: 403 cars.

A little over 80 years have passed, and now the BMW 328 Roadster is no longer just a legend, but a historical value. In fact, it is a real artifact. Even if only ruins remain of a particular specimen, it is still of great importance … and, of course, requires painstaking, careful restoration.
Fortunately, modern technologies — in particular, 3D scanning — make this task much easier.

In this case, only fragments of the frame and individual body parts fell into the hands of the restorers — there was a huge amount of work to restore … almost everything, including the manufacture of missing frame elements.

According to the available references, the preserved parts were carefully positioned using a laser level — relative to each other and in accordance with the original geometry of the frame — and securely fixed in the desired position.
This allowed the FivCo 3D specialist, who is engaged in 3D scanning and reverse engineering, to digitize all the preserved original elements and recreate a complete frame based on them for subsequent manufacture.

The RangeVision Spectrum 3D scanner was used for scanning, pre-calibrated for the largest capture area. In this mode, it is able to digitize fragments up to half a meter in size in one scan, which is especially convenient when working with large objects. At the same time, the scanner retains high accuracy: the resolution is about 0.2 mm, and the error remains within the tolerance limits sufficient for manufacturing parts for subsequent assembly. This is the optimal balance between speed, scale and detail — exactly what is needed in restoration, where both the overall appearance and small design nuances are important.

Taking into account all the preparatory work (warming up the garage with a heat gun to stabilize the temperature, applying markers to the object and the limited space in the room), the scan took a little more than one working day. And it took about 20 hours to create the final CAD model, taking into account the customer’s wishes, checking with the preserved archival drawings and adjusting to the original parts.

The specialist designed the missing frame elements, which perfectly fit both with the preserved original body parts and with the rest of the native frame — without fitting "by eye" and unnecessary tests.
The resulting models became the starting point for the customer in the search for a contractor to make exact copies of the lost parts and at the same time formed the basis of the entire restoration plan.