Reverse-engineering: from jewelry to aircraft
The founder of the Israeli company providing reverse engineering services has told us about some of the projects carried out with the RangeVision 3D scanner and the workflow in detail.
Projects of DE-Engineering are related to production tasks requiring high accuracy. These are projects for aviation industry, manufacturers of watch mechanisms and defense enterprises. Most contracts limit the disclosure of information, but the completed projects that are published (with the clients’ consent) on the YouTube channel of Dmitry Epstein, the founder of the company, are impressive in scale and professionalism. Dmitriy is an engineer, and when asked about the projects that are especially interesting for him, he answers that he does not think about it this way: "Nothing special, you scan and work, you just need to approach the process creatively - how and in what order to scan. The main thing is to feel sure that the goal is to be reached."
Dmitry has been practicing reverse engineering since 1989. In those days he used to work with a calipers, a curvimeter, and cut out patterns from cardboard and millimeter paper. For large parts the error was about a millimeter and for small parts even worse. The accuracy increased with the advent of the 3D scanner and digital reverse-engineering. The highest requirements from the client in Dmitry's practice were to the parts of the wristwatch mechanism - 200 microns, and these requirements were met.
Since 2012 Dmitry has been using the structured-light 3D scanner from RangeVision PRO model line. In the arsenal of the company there is also Gom Atos 3D scanner.The engineer says that for his tasks the RangeVision scanner fits equally. As he puts it, RangeVision scanner is more compact and is less subject to vibrations in the customers' workshops. Among the advantages of the German competitor, Dmitry mentions the ability to remove unnecessary fragments and wipe entire sections immediately during the scanning in the scanner software.
The largest object in the practice of the DE-Engineering company was about eight meters. While scanning such "giants" Dmitry uses several tricks. He puts markers not directly on an object, but on the stripes of a paint tape, so that he does not waste any time when removing them from an object. He also adds extra geometry to minimize the loss of accuracy - he imposes three spheres on the object of digitization to align scans more accurately. Dmitry is an expert in 3D scanning of large objects. To make sure, it's enough to watch one of his videos about the fuselage of an airplane or the fuel tank of a helicopter.
The project of reverse-engineering of a car continues a series of large-scale scanned objects. The interior of the Citroen Jumpy was 3D scanned to build an armor. The 3D model completely repeated all the geometry of the car body with all the notches and cavities of the fasteners. The result was efficient: time, energy and money were saved. Based on the received 3D model, metal armored plates were manufactured and they were ideally joined to the body of the car. The bent and welded sheets had to be simply fixed on the body, without the need to cut or drill anything. The reverse-engineering of the body of the car was carried out so neatly that the final result did not require any modifications. Scanning took a couple of days and it took five days more to process scans and build a mathematical model. The client modified two cars in this way for his needs.
As we see it, the approach of DE-Engineering to the processing of scan data deserves special attention. Dmitry prefers working with a cloud of points, paying extra attention to their "thinning", and not with polygons. He reduces the amount of points locally on surfaces that do not require high detail, and leaves the maximum amount in the places where the small elements are located. He says it's easier for him and his computer to work this way with scan data. For example, in the case of a car body, the size of the scan file was about 2 GB and after "cleaning" only 150 MB.
It is convenient for an engineer to work from the start (processing of a cloud of points) to the final result (building a mathematical model) in one program, so he uses CATIA for automated modeling. It is also convenient, because the client sees the whole specification tree in the file.
Dmitry works with organic surfaces as well. We can take his project with mannequins as an example. The clothing design company provided a sample mannequin of size M with the request to make models in the range of sizes from S to XL. Dmitry 3D scanned it with RangeVision PRO on the first (large) scanning zone. By the given measures he was increasing and decreasing the volumes of different parts of the mannequin body in CATIA, it was impossible just to scale the entire model proportionally, as it contradicts the human physiology. The final CAD-models were used to cast new plastic mannequins.
At DE-Engineering the RangeVision scanner is used with all scanning zones (volumes) available, including the smallest one. Small items like jewelry or wristwatch mechanisms are scanned with scanning zone 4. A universal system with ample opportunities, as well as the experience of an engineer, are the ingredients of success in solving complex engineering tasks.