In January 2018, the author was addressed by Carbofun member doc. Daniela Plachá to 3D print something relevant to Carbofun summer school 2018. From that point, a collaboration between two departments, which have almost nothing common, begun.
First idea was to download a model from 3D model database available online, for example www.thingiverse.com. Luckily, the database includes a library of fluorene and graphene models. Meanwhile, it was decided to use Nylon CF15 Carbon filament from Czech company fillamentum.cz for their association with Carbofun.
Unfortunately, there was no chance to print spheres without a proper support material. Our 3D printers do not allow multi material extrusion, therefore, the support had to be created from same material as the print. This approach has two difficulties. First is the price. Compared to the commonly use filaments ABS or PLA, the Nylon Carbon fiber is expensive. One gram of this material costs 2.25 CZK, while ABS and PLA 0.5 and 0.55 CZK, respectively. Second problem is a complicated printing. This material is flexible, thermally dependent, hydroscopic, and highly abrasive.
Prusa mk3 can handle flexible materials well and thermal dependencies can be suppressed by printer casing. Nevertheless, for highly abrasive materials, it was necessary to buy, mount, and use hardened nozzle. Also, there are several ways to do this. First is to buy cheap steel nozzles which have sufficient hardness but insufficient thermal conductivity. That can lead to problems during the printing process, especially in case of nylon composites. Second possibility is to buy Olson ruby, which can be assumed as Rolls-Royce in the world of nozzles. This nozzle has copper body and head made of ruby. Copper ensures good thermal conductivity and ruby protects from abrasion of the body. This nozzle costs approx. 2500 CZK in comparison to 440 CZK for hardened steal. Based on that, the Olson ruby was bought. Meanwhile, first prints from nylon carbon was made with standard nozzle.
Expensive support made from nylon carbon has one more disadvantage it is hard to put it down from final print and it leaves some debits on the print.
Expensive support made from nylon carbon has one more disadvantage – it is hard to remove this support and the residue it leaves behind. At this point, the practical use and simplicity of this print was being sought. So, the coaster from early mentioned library was printed. It still has sphere shapes but only upwards, so the support is no longer needed. Nevertheless, the practical use of such a coaster was questioned and new ideas were demanded. The new idea came from Carbofun members. A keychain with Carbofun logo and dedication to summer school 2018 with shape reminding carbon. This model was developed and consulted with Carbofun members to incorporate their comments. Some graphical points were improved, and a small series production could start.
Because of a complicated printing there was some spoilage, but 35 keychains were produced, boxed up, and delivered to you.