3D scanning of auto parts and reverse engineering with Spectrum

In motorsport and tuning, there is often a problem that cannot be solved by purchasing a finished part from a catalog. There are two existing nodes that need to be connected, reinforced, or adapted to a new configuration, but there is no standard solution on the market. The classic way through manual measurements, drawings from scratch and several iterations of fitting can take a long time and still leave a risk of error.

This is where 3D scanning and reverse engineering become a practical engineering tool. They allow you to quickly obtain an accurate digital copy of existing components, design a matching part and transfer it to production, for example, to a CNC milling machine.

The scientific work of the Polytechnic University of Tirana showed the full cycle of such a process on a real automotive case: from 3D scanning of parts to reverse engineering and manufacturing of a new aluminum part for a racing car. The RangeVision Spectrum structural-light 3D scanner was used for digitization.

When a new part has to work on its own, the task is usually simpler: the engineer sets the shape, dimensions, material and calculates the loads. But in tuning, repair, customization and motorsport, something else is often required: to create a component that precisely fits between existing parts.

The study considered just such a task. It was necessary to produce a personalized aluminum part that connects two real car parts. The new part was supposed to repeat the mating surfaces of these nodes, ensure an accurate fit and withstand mechanical loads.

The following factors are critical here:

• geometry of real, not nominal surfaces;
• precise position of holes and planes;
• assembly tolerances;
• strength and service life of the part;
• no unnecessary iterations of fitting.

If there are no original CAD models, and the part has already been modified or worn out, manual measurements become a weak link. Calipers and coordinate measurements help, but they don't convey complex curved surfaces, transitions, radii, and real shape deviations well. A 3D scanner closes this gap: it transforms a physical object into an accurate digital geometry.

The case used a Spectrum 3D scanner based on structured light technology. This technology non-contact projects a light pattern onto an object and records the deformation of this pattern with cameras. Based on the data obtained, the program builds a three-dimensional surface of the part.

Before starting work, the scanner is calibrated for the selected scanning area. This is a standard stage, which directly affects the accuracy of the result. The operator then performs a series of scans from different angles to cover the entire geometry of the part.

A typical problem often occurs in automotive projects: metallic, glossy, or dark surfaces scan worse due to glare and reflections. In the study, a matting coating was used to improve the quality of the data. The authors separately note that the average thickness of such a layer was up to 18 microns. This is important: the coating helps to obtain a stable scan, but for engineering tasks, its effect on dimensions must be taken into account.

After that, the individual scans are combined and combined into a single polygonal grid. At this stage, the engineer receives a digital "cast" of the real part in the STL or OBJ format.

The STL file itself is not yet a full-fledged design model. This is a polygon grid that is convenient for visualization, analysis, and 3D printing, but not always suitable for precision design and CNC manufacturing.

Therefore, the next stage is reverse engineering, or reverse engineering. In the study, it was performed in Geomagic Design X.

The process included:

• alignment of the resulting mesh;
• cleaning and optimizing the model;
• recognition of key geometric elements;
• sketching based on scan data;
• creating CAD surfaces and a solid-state model;
• preparation of production documentation.

It is especially important that the authors used a manual approach to reconstruct the geometry. Automatic tools are useful, but in critical parts where holes, planes, axes, and junctions are important, engineering control remains necessary. In the work, the main elements, including holes, planes and contours, were restored with deviations of about ± 0.1 mm.

This is essential for an automotive assembly: a new part should not just be similar to the original geometry, but should precisely interact with neighboring parts in the assembly.

After the reverse engineering is completed, the CAD model can be exported to production formats, such as STEP or IGES. Next, it is used to prepare a control program for CNC machining.

In the described project, the final part was made of aluminum alloy AL7075-T6. It is a high-strength material that is often used in aviation, motorsport and other fields where strength, rigidity and low weight are important. For a racing car, this choice is logical: the part must withstand loads, vibrations and dynamic effects, but not add extra weight.

As a result, a functional part was produced that combined two existing automotive components and solved the customer's problem. According to the study, the total time for 3D scanning and reverse engineering was about 1.5 hours. For a task where previously long manual measurements and several refinement cycles might have been required, this is a serious reduction in time.

The practical value of 3D scanning is particularly evident in projects where you need to work not with an ideal model, but with a real detail. For vehicles, especially sports and modified ones, the actual geometry may differ from the factory documentation. Sometimes there is no documentation at all. Sometimes a part has already been finalized, damaged, or discontinued.

In such cases, Spectrum helps to solve several tasks at once.

First, it accelerates digitization. Instead of manually measuring dozens of dimensions, the engineer obtains a complete 3D geometry of the surface.

Secondly, the accuracy of the design increases. A new part is created not based on assumptions, but on a digital copy of a real object.

Thirdly, communication between the engineer, the customer and the production is simplified. At the output, you can prepare a CAD model, drawings, specifications, and production files.

Fourth, the number of physical prototypes is decreasing. The more accurate the initial data, the less likely it is that the finished part "almost fits", but needs to be improved.

The racing car case is just one example. The same approach can be used in different automotive tasks.:

• manufacture of rare or discontinued parts;
• creating adapters, brackets, and adapters;
• tuning of intake, exhaust and transmission systems;
• repairing damaged components;
• geometry control after repair;
• development of tooling and templates;
• preparing parts for CNC machining or 3D printing;
• verification of the conformity of the manufactured part to the CAD model.

A 3D scanner is especially useful where a part has a complex shape, many connections, or must fit precisely into an existing assembly.

The main mistake in the perception of 3D scanning is to consider it a separate service, after which the user receives a beautiful 3D model. In engineering practice, the value is not in the grid itself, but in the full workflow:

1. Digitize the real part.
2. Get a clean and accurate mesh model.
3. Restore the CAD geometry.
4. Check the key elements and tolerances.
5. Prepare the model for production.
6. To make and assemble the finished part.

This is exactly the cycle shown in the study. Spectrum acted as the first and critically important stage in it: without accurate source data, all subsequent reverse engineering loses reliability.

3D scanning has long gone beyond the demonstration technology. In the tasks of reverse engineering of automotive parts, it works as a practical way to quickly move from a physical object to a production model.

A case study on the manufacture of a personalized racing car part shows how the Spectrum 3D scanner helps an engineer go all the way: from scanning existing components to CAD models, documentation, and finished aluminum parts produced by CNC.

For motorsport, tuning, repairs, and small-scale production, this means less manual chore, less uncertainty, and more control over the outcome. And when a new part must precisely connect two existing nodes, such control becomes not an advantage, but a necessity.