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Reverse engineering and error propagation

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Reverse Engineering and Error Propagation (3D Scanning and CAD) 03:56
Reverse engineering enables us to create a copy of an object. For this purpose, the part is 3Dscanned, then the 3D scan data is converted into a CAD format, and finally, the part is manufactured. All these steps result in noticeable deviations. If an error adds up over multiple steps, then we call this error propagation.
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Error propagation between part A and B
Swann Rack / Holocreators The original parts A and B fit together like a puzzle

Error Propagation During the 3D Scan

A 3D scan is made of two parts that fit together perfectly like a puzzle. Part A and part B. Our
example 3D scanner has an accuracy of ±1 mm. This means that after the 3D scan of part A, the
resulting 3D model could be 1 mm larger or smaller than the original. The 3D model of part B could
also be 1 mm larger or smaller after the 3D scan. This means in a worst-case scenario, the whole
puzzle is shifted by 2 mm and does not fit together properly.

Even more error propagation between part A and B
Swann Rack / Holocreators After the 3D Scan, there are deviations between part A and part B

Error Propagation in Reverse Engineering

After the 3D scan, we perform reverse engineering with parametric modeling and a history tree. This
has an average deviation of up to ±0.25 mm from the original 3D scan. Adding the deviations of both
processes, the puzzle may be off by 2.5 mm.

Even more error propagation between part A and B
Swann Rack / Holocreators After reverse engineering, there are even more deviations between A and B

Error Propagation in Manufacturing

During the last step, the 3D model is manufactured with metal 3D printing. Due to manufacturing
deviations, the parts may be produced 0.2 mm larger or smaller. In a worst-case scenario, part A and
part B now have a combined total deviation of 2.9 mm, and the puzzle pieces no longer fit together.

Maximum error propagation between part A and B
Swann Rack / Holocreators After production, part A and part B no longer fit together.

Conclusion

It is not possible to eliminate error propagation in reverse engineering, but it can be minimized. At
each step of the reverse engineering process, it is important to choose the method that has the least
deviation. Therefore, the most accurate 3D-scanning technique should be chosen. And for the
reverse engineering process, it is up to the engineer to work as precisely as possible. There are also
manufacturing processes that are more precise than others. For example, CNC milling is more
accurate than 3D printing.

May we advise you on how to mitigate error propagation with your project?

Holocreators offers professional 3D-scanning and reverse engineering services. We would love to
help you with your project and advise you, for example, on how to minimize deviations in your
reverse engineering project. Please call us at +49 40 481133 or send an email info@holocreators.com

Swann has been enthusiastic about everything 3D for many years. His roots lie in analog holography, which brought him to digital 3D-modeling in 2011.

The rapid progress of various 3D-scanning techniques fascinated himso much thathe founded Holocreators together with his brother Miro Rack in 2015.

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