Scarceness of parts and discontinued parts can be big problem for the classic automotive restoration market. Couple this with a loss of original data and drawings, and you can almost see the frustration on the collective faces of restoration garage owners and classic car restoration enthusiasts alike.

Additive manufacturing (3D printing) is seen by automotive manufacturers as both a source of product innovation and supply chain transformation. It’s a prototyping solution, and an end-use solution when it comes to light-weighting and producing parts with complex structures that fall outside the capabilities of more traditional production methods.

It goes without saying, then, that 3D printing could have a key role to play in automotive restoration. It’s a quick, cost-effective and sustainable source of on-demand spare parts. In fact, so efficient is the process, Porsche have set up a branch of business dedicated to creating parts on demand and keeping their vintage models on the road.

Furthermore, with technology improving all the time, there is a good chance that new ‘old’ parts will be of significantly better quality than original parts. The end results? A big reduction in restoration costs, and a good chance your restoration can be completed in half the time… and will quite possibly last longer than it did the first time around.

Kings of the Road

Drop ‘3D automotive restoration’ into YouTube and you could spend many a happy hour watching delighted restorers turning their rust heaps into gleaming drive-able automobiles with the assistance of a friendly industrial 3D print service provider. There are a couple of well-documented, stand-out examples that should leave you in little doubt of the virtues and value of 3D printing.

Back in 2014, an adventurous journalist of Bimmer Magazine and the BMW Group Classic Archives set out to find Elvis’ BMW 507. It was eventually located in a garage on a pumpkin farm in the USA, covered in dust and in poor nick. The restoration team at BMW Group Classic also discovered there were very few spare 507 parts anywhere.

3D printing proved to be the answer for reproducing broken windscreen wipers, window and door handles. Without drawings to work from, the team reverse-engineered the parts, created CAD from scans and recreated the parts in one piece using a metal sintering process.

Similarly, additive manufacturing had a hand in putting systems giant Siemens’ 1920 Ruston & Hornsby back on the road almost 100 years after it was built. The Siemens Materials Solutions team scanned a broken steering box (in a disheartening 7 pieces) and ‘glued’ the resulting CAD of each broken part back together. Within 5 days they had printed the part using a fusion process and high-temperature resistant metals. The part was significantly stronger and better made than the original, having been constructed in one single piece.

Metal 3D printing is still an expensive venture, especially for an enthusiast. However, restoration experts shouldn’t be too disheartened – there are alternatives. CNC machining, for example, can be a cost-effective if there are multiple parts to be created.

Plastic Fantastic

In this article, we look at the role of composites and plastics 3D printing in automotive restoration. We’ll begin with some broad definitions and then we’ll have a look at where, even though we’re talking modern plastics, 3D printing in these materials might help you to finish your restoration project.

3D printing technologies come in several forms. The oldest is Stereolithography (SLA). A quick(ish) process, SLA is popular because it’s accurate, precise and offers very fine detailing. It’s used to make models, patterns and production parts from liquid photopolymers that harden on curing. Some SLA resins are suitable for production parts – those with ABS-like properties and those composites with ceramic powder, for example.

Selective Laser Sintering (SLS) uses high powered lasers to sinter powdered materials (metals, nylons, and even ceramics). Resultant parts in nylon, or glass filled nylon, are robust, chemical resistant and strong, making them ideal for end use parts and prototypes.

Fused Filament Fabrication (FFF, or occasionally called Fused Deposition Modelling, FDM) uses production grade thermoplastic materials. As a layered process, the CAD needs to be ‘sliced’ into multiple layers so that the part can be built in layers. This process enables composite printing as chopped carbon fibre, Kevlar, Fiberglass and other materials can be incorporated between the layers. FFF requires a fair amount of post processing, but the resultant parts are ultra-strong.

Digital Light Synthesis™ (DLS) technology (sometimes called DLP) uses a photochemical process to project light through an oxygen-permeable window into a reservoir of UV-curable resin. The resultant parts are layer free with consistent, isotropic and predictable mechanical properties. The most fabulous thing about DLS is that there is a huge range of tough, durable temperature resistant, chemical resistant resins (both hard composites and soft rubbers) that are suitable for production parts; and this technology is so sophisticated that textures can be printed onto the surface – intricate detailing that would probably have been added by hand in days gone by.

Multi Jet Fusion (MJF) is similar to Selective Laser Sintering in process. However, like DLS, it is an additive manufacturing process designed for scaled-up production. Printing in PA 11, or PA 12 nylon, parts are tough, durable, heat and chemical resistant. They can also be dyed and finished to a satin sheen.

Part by Part

Do plastics and composites really have a part to play in vehicle restoration? Perhaps not in pre-war classics; but from about 1930, plastics started to be used. It was a new concept and perhaps one that hadn’t really been thought through. Many early plastics were not the heat resistant, chemical resistant polymers available today; they would be brittle and crack quickly when exposed to heat or cold. It didn’t stop even the prestige manufacturers exploiting the economic benefits, though, and you’ll find bits of (broken) plastic both under the bonnet and on internal trim and dashboards.

Under bonnet parts that can be replaced in this way include plastic windshield-washer fluid bottles, brake fluid tanks, cable insulation, battery boxes, points covers, fluid manifold components, nozzles, dampers, air intake filters, gears, bushes, cams, bearings, weatherproof coatings, the list goes on…

Come to your interior trim and you’re looking at dashboard backings, buttons, housings, knobs, levers, carpet stud covers, badges and even lenses.

If that wasn’t enough, for parts that need to be cast, scanning and 3D printing the part first will enable your friendly caster to create a master pattern for building his casting and moulding tools.

The key to restoration, however, is getting the part exactly right in shape and size. And the parts you want to replace may well be in many pieces. And you’ll need the exact dimensions to create the CAD for printing. There are automotive archives where original drawings of a multitude of parts of a multitude of makes and models can be found. The Rootes Archive Trust in Wroxton and the Institution of Mechanical Engineers may be able to help here. Most 3D printing service providers should be able to offer you the option to turn drawings into CAD. Or they will at least will have a friendly CAD expert just a phone call away.

In the absence of drawings, it may be quicker, and possibly cheaper, to find a service provider who offers reverse engineering. Using a laser scanner such as a FAROArm, they will be able to turn the physical into digital and create new CAD for the parts. If your part is in several pieces, it can be glued back together at the digital interface.

Next, discuss with the 3D printer the most suitable options for recreating the part. Not all composites and resins are created equal, and there are a variety of simulants available. As described above, technological advantages will also need to be taken into consideration here. If your part requires a high tensile strength, and needs to be heat resistant, but doesn’t have intricate detailing, you could consider a composite printed part using fused filament fabrication (FFF). Alternatively, you might need an intricately detailed, complex, rigid component part to be produced that does require a high heat resistance. In this instance, Digital Light Synthesis™ technology could possibly be the answer.  DLS is also great for printing rubberised switches and knobs.

For Posterity

Once you’ve decided upon technology and material, and have sent the CAD to your printer, you can be sure that you’ll have your part back in a matter of days rather than weeks.

We hope that the brief insight we have provided into the merits of additive manufacturing for automotive restoration is enough to convince you that it’s worth a punt. To summarise, metal and plastic 3D printing of parts and tooling are helping to bring rare spares to the collector sooner, and cheaper, than ever before.