The basic shape of the logo is a twisted gear, which was generated with one code line with OpenSCAD. The original object is too big to be used directly in the 3d badge. As FreeCAD does not offer so many options to manipulate stl objects (as, for example, Blender does), I decided to generate the same gear using FreeCAD tools (and to consider it for me a challenge to learn more FreeCAD features tipps and tricks, instead of a “not so skilled” way to complicate my life as a designer when a clean and easy way as software developer would be at hand 😉 ). I had available the section of the gear in svg format, easy to be imported inside FreeCAD, but as FreeCAD does not offer yet the possibility to twist a surface while extruding it, I had to find a different way to build the twisted gear.
I based my construction on FreeCAD arrays: I drew a sketch of the single element of the gearwheel rim (the “tooth”) on the x-y plane and generated the gearwheel section as a polar array of the “tooth” sketch. The basic idea was to place a copy of the gearwheel section at a different height along the z axis, rotate it, and connect the two with the “loft” tool. As there is no possibility to define a correspondence between points of the two curves, I had to play a little bit with the relative rotation of the two gear sections, to see how the “loft” tool behaved, according to the rotation angle (if it is equal to the sector occupied by a “tooth”, then the extrusion is vertical connecting to corresponding subsequent “teeth”on the two sections, not twisted to connect a “tooth”on the bottom the corresponding rotated “tooth” on the top profile).
At the end I found out that I could have the ascending anticlockwise twist with a rotation angle up to 5º.
The solution automatically became: an “ortho” array of 6 slice elements of the gear, rotated one w.r.t. the other of 5º. Considering that the gear section is a polar array of 18 “teeth”, merged in a single sketch, I created an “ortho” array of “lofts” elements connecting two copies of the same “polar” array of the single “tooth” of the gear. This is really building a whole from the single element 😀 . (Yes, I’m aware of the one code line with OpenSCAD, but where would be the 3d designer fun? I would have been the same proud as a coder, had I written myself that one code line…). No need to enter details about the inside cavity: a cylinder and a cube used as cutout tool for a Boolean “difference” with the gear.