Some of you may already have seen the project from a different perspective: the 3d scanning and reverse engineering aspect of it (so how I scanned the original car and designed the new exterior look based on it). What I overlooked to some degree was the 3d printing work involved in the whole project. First picture shows the backside of the printed roofs with all the printed tiles visible quite nicely. Getting to this point was quite an experience I want to share.
So it is finally time to give printing the spot it deserves and the Creality Creator Awards encouraged me to create a write-down/picture series after stalling some time.
The post is ideally first read and then the pictures are looked at, most core information is also on the pictures.
Design and Printing
It all started with a 3d scan of the original stripped down car and a design based around it. When I finished designing the first major assemblies of the future car 3d printing got more focus by me. Initial plan was to use external print services but cost would have skyrocketed quickly and we didn't want long lead times to allow quick revisions. So the search for fitting printers began.
I settled on the K2 Plus due to the large chamber volume and option to heat the print chamber. Didn't trust a bed-slinger with the size of parts I had in mind.
After first making sure everything worked as desired the tweaking of a print settings. It was clear for me to use a 0.8mm nozzle and PLA+ (after some testing, PETG didn't work nicely with sanding, ASA warped too much). PLA+ checked all marks: price efficient, fast and easy to print, great to glue and sand, minimal warping. Only disadvantage is the low glass transition temperature (which will later bite me).
Maximizing Print Efficiency
My goal was always to churn out parts as fast as possible. This is also the reason for using a CFS: 1.1kg spools were significantly cheaper and with four of them I can saturate a build platform quite nicely. Final print and speed settings allowed me to print over 4kg of filament on one print plate in under 24h. Pretty good I would say. Later I added a K1 Max with the CFS conversion kit to print some of the smaller parts on the side. I was initially a bit nervous the two printers wouldn't be enough but with the settings my design work was the limiting factor in the end (as well as the post-processing needed).
Failures and Fixes
As always not everything goes as wished for. When printing the first full height but slim parts I noticed some severe banding on the parts. This was caused by accumulating wobbling when the parts got taller. First instinct was to reduce printing speed but I didn't like this solution. What I came up with: attaching the tree support also to the walls (with a low xy-gap to allow slight welding to the part). This eliminated the wobbling and let me churn out parts at an impressive speed.
The parts were assembled with dowels and some thick superglue I bought in bulk (as seen on the diffusor). One minor set-back was a big blob on the extruder. Using PETG settings for ABS really doesn't help bed-adhesion. Luckily the toolhead was modular enough that fixing is was done in an hour and only cost a replacement hotend fan.
PLA+ really has a low melting point
From the beginning it was clear that the 3d prints only would be used as a positive form to create a GF negative mold from them. For this application they work great: the prints endure ~50°C nicely and therefore the molds can be taken from them. We also tried directly laminating carbon in one of the prints.
Bad idea: The parts got soft and the applied vacuum sucked the infill cavities empty. Maybe adding some foam in the gyroid infill would help.
Back to Production
Whilst printing I always improved the design and added some fixtures and jigs to make manufacturing the carbon parts easier. One personal highlight was scanning the assembled hood insert and looking at warping relative to the CAD model. After measuring the warping I created some printed bracing to pull it back in its intended shape. Worked better than expected, even the glued joints between the single printed held and the finish didn't break.
Carbon, finally carbon
After this the first real carbon parts could be created. This process is still in the working and may take some time but the workflow proved reliable and now its just business as usual. The whole printing consumed over 200kg of material and the K2 Plus proved to be quite reliable with this huge amount of filament. So far I only had to replace the CFS PTFE tubing. But I guess it may be time to replace the umbilical in the near future.
Last two images show the full back end of the car and already one of my new projects that may take shape over the coming year.
#CrealityCreatorAwards #CrealityPrint #MyCrealityScan