Resurrecting a 70 year old part from 3d scans

One of our customers has an extremely rare 1951 Porsche 356 Pre-A, believed to be one of the first 500 Porsches ever built. There was a time, long before the age of investors and collectors, when these cars were discarded if they became too expensive to maintain. They went to the junk yard, got stored away in barns or, as in this case, banished to the back yard where it became a chicken coop for many decades.

This car eventually got rescued and is now in the process of being restored. One of the problem areas was the dashboard which was beyond repair as can be seen from this scan:

For some reason it was modified in the past to accommodate smaller gauges and the centre hump was replaced with a flat piece of metal, all of this in the crudest possible manner with some really rough welds.

Unlike later cars these early 356's had removable dashboards which means that a replacement part would solve the problem. However there are no new or used dashboards available for this model except for a loan one which was skew, dented and badly rusted (below):

The only good part of the original dashboard was the section at the top, directly under the windscreen. So we were asked to make a composite from the two, combining the good areas of each into a CAD model which can be printed and eventually fabricated in aluminium.

The loan part had the correct "hump" in the middle and the gauge holes were correct but the rest was almost unusable. It was dented all over and quite badly twisted.

 

It was a lot better than the original though, which was not only twisted but also concave, possibly due to an accident in the distant past.

Below is what the two parts look like when superimposed. The only two areas which corresponded were the ashtray and the speedometer hole. So we started our design from there and compensated for the differences and imperfections hoping that the final part would closely resemble what a new one in 1951 might have looked like.

In the process we found a number of quirks associated with hand made cars of the day. For instance the instrument holes didn't perfectly match between the two parts despite being from the exact same model, potentially only a few cars a part on the production line. Also, the holes under the dash, either side of the centre hump, were not symmetrical. A modern designer would normally mirror these features for practical and aesthetic reasons but in 1951 things worked differently.

The end result was a "theoretically perfect" CAD model of the original part, combining the best of both samples:

The next question was whether the theoretical design would be any good in the real world. The only way to find out was to print it and see if it fits in the 70 year old body.

We printed it in 3 parts in white ABS using a 1mm nozzle at 0.3mm layer height for speed and strength. We added large flanges at the back which helped to join the sections but also gave it some stiffness and formed part of a brace which was then printed separately to hold the gauges and add further strength.

The result was surprisingly strong for a printed part and looked better than expected.

To our great relief the part fitted without issues. The the panel gaps either side of the dashboard were just right and the mounting holes lined up perfectly with the body.

Incredible how small the dashboard is compared to modern cars

We fitted the gauges, ashtray lid and centre grille (which was designed from old photos and printed also in ABS).

The plastic dashboard will form the basis for an aluminium part which will likely be fabricated using traditional methods of the era. In the meantime it must be strong enough to act as a real dashboard in a car that's being used regularly.

The result is somewhat surreal, as cutting edge twenty first technology bolts almost seamlessly onto hand-made metal of 70 years ago. Not looking out of place either.

One can't help but wonder what one of the pioneers of automotive technology, Ferdinand Porsche, would have said about all this.

© 2020 by Martin Wiesner