Explanation

We have compiled a selection of 3D model databases. You can download 3D models and then edit them in a 3D program or 3D print them. There are databases with free 3D models and those that sell them.

Reverse engineering is required whenever a 3D scan (STL format) needs to be converted into a CAD model (STEP format). We will give you a brief overview of three different reverse engineering techniques.

A NURBS model consists of points connected by curves. A polygon mesh consists of thousands or millions of small triangles. CAD surface models are usually created using NURBS surfaces, while 3D scans are typically exported as a polygon mesh. The conversion from a polygon mesh to a NURBS model is called "reverse engineering".

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.

Swann Rack from Holocreators gave a presentation on reverse engineering at the Rapid.tech 3D Congress 2018. Reverse engineering allows an object to be reproduced using 3D scanning and subsequent conversion into a CAD format. In his presentation, Swann Rack talked about the different 3D scanning techniques and how the reverse engineering process works.

We digitally repaired the broken clothes rail holder of an IKEA closet and then 3D-printed it in plastic. We first 3D-scanned the original broken part using a 3D CT scanner (computed tomography 3D scanner). Afterward, we reconstructed the 3D scan using reverse engineering and thus repaired it. The finished file was 3D-printed inside a laser sintering 3D printer.