Reverse Engineering CAD Models

Reverse engineering a CAD model typically involves 3D scanning and measuring a part to gather data, which is then used to create a new digital model in CAD software.

Reverse engineering a 3D CAD model typically begins by measuring and inspecting a part. This measurement data, collected through methods like 3D scanning, CMM, and hand tool measurements, is used to create a new model in CAD software such as SolidWorks, AutoCAD, or Fusion. As well as gathering measurement data, it’s also beneficial to understand the part’s purpose and how it interacts with other components, to understand the design intent.

The process typically starts with a 3D scan to capture the part’s external shape in a digital mesh, which serves as a foundation for the new model. For internal features that a 3D scanner can’t capture, a CMM is invaluable, as it allows precise measurement of these areas, ensuring a comprehensive model.

How do I reverse engineer a parametric CAD model?

To reverse engineer a parametric model, start by importing the scanned mesh into your CAD software and aligning it with your coordinate system. Use the mesh as a template to guide the creation of new features, making iterative adjustments to enhance accuracy.

Depending on your software, you can take one of two approaches:
– Section the mesh to create 2D cross-section profiles by fitting lines, circles, and splines. You can then extrude or revolve these profiles to form a solid model.
– Fit surfaces such as planes, cylinders, and NURBS directly to the scan data. Once all surfaces are defined, they can be converted into a solid model.

How do I use direct modelling for reverse engineering?

Direct modelling is often used when reverse engineering cast or moulded parts, where minimal modifications to the scanned data are needed. Start by creating a watertight mesh from the scan data, ensuring there are no holes or gaps. This mesh can then be converted directly into a solid model via NURBS surfaces, which will replicate the original part’s surface, including any defects or manufacturing variations. This approach can be particularly efficient when creating models for castings or moulded components, where quickly capturing the general shape is more important than achieving perfectly uniform geometry. In some cases, direct modelling can be used in combination with parametric modelling, depending on the complexity of the part and CAD package being use.

Overchecking key features

For high-precision parts, it is good practice to overcheck critical features that impact functionality to ensure accuracy. This may involve using a CMM or other measurement tools to inspect the part and obtain more precise measurements.

Design intent vs manufacturing variation

All manufacturing processes have some variation. A key challenge in reverse engineering is determining the original design intent of a feature. This involves understanding whether a characteristic is a result of normal manufacturing variation, an intentional design feature, or due to damage or wear. Understanding the manufacturing process, the purpose and function of the part, and relying on experience in reverse engineering will help in interpreting the original design intent.

Find out more on our reverse engineering page or checkout our case studies for examples of our work.

About Us

AB Technology started out as an independent CMM Inspection & Programming company based near Nottingham, UK. Over the last 25+ years, we have expanded our services to include 3D scanning and reverse engineering, serving customers of all sizes, across an array of industry sectors, both domestically and internationally.