In this week’s project of 3D printing an impossible object, I decided to print an articulated shark that I found on Thingiverse. After downloading the CAD files from the website, I uploaded the file to 3DPrinterOS to scale and print the sharks. To fit the shark in the gumball pods, I initially tried scaling the shark down so that it was 45mm in length and printed it using the Prusa i3 mk3, this made the shark way too small and delicate which made it hard to remove from the supports.
Lengths: Top: 45mm, Bottom: 80mm
I later tried scaling the shark to be 80mm in length, which ended up being the perfect size. For my FDM prints, I started out using the Prusa i3 mk3, there were a few failed prints in the beginning when I was adjusting the infill density and wall thickness but I ended up printing 3 of my sharks using the Prusa i3 mk3. The first two I made were with PLA filament, and the other one was with the TPU filament, a flexible filament, which made the shark’s articulation more springy. For the fourth shark, I used the Ultimaker which made the shark’s articulation a little stiffer because of the filament diameter size.
I decided to use the resin printer in the wet lab for the SLA print of the shark. I printed it with the same scaling as the FDM prints, however after washing, removing the supports, and curing, the SLA print didn’t move as easily as the FDM prints and had little nubs where the supports were clipped off from.
Post washing SLA print, supports haven’t been removed
Overall, I think that the FDM prints using the Prusa i3 mk3 with the PLA filament made the best articulated shark, a video of them can be found here.
(A), (B), and (C) are printed with Prusa i3 mk3, (A) and (B) using the PLA filament, and (C) using the TPU filament. (D) is printed with the Ultimaker with the PLA filament. (E) is printed with a resin printer.
Cost Analysis:
Labor: I needed a lab assistant’s help to access the wet lab and use the SLA printer for around 30 minutes. At $10/hour, the total cost of labor needed was $5.
FDM Printing Cost:
Raw Material: I had a total of 4 failed prints where the cost of the material used totaled up to be $0.19. The other 4 prints all cost $0.11 each for the 5.51grams of material used, totalling to be $0.44. The total cost of the raw material for the FDM prints is $0.63.
Machine Time: The time it took for all the prints to be made, including the failed prints, is 5.2 hours. Assuming that the machine cost for a 3D printer is $1/hour, the total machine cost for the FDM prints is $5.2.
SLA Printing Cost:
Raw Material: The weight of the resin print is approximately 8 grams. SLA prints costs approximately $0.32 per gram, so the total material cost for the SLA print is $2.56.
Machine Time: The time it took for all the resin print to be made was 1 hour 15 minutes. Assuming that the machine cost for a 3D printer is $1/hour, the total machine cost for the SLA print is $1.25.
The total cost for making all of the impossible prints is $14.64.
