Hi everyone!

I 3D printed a 3-ring impossible piece (Borromean rings) from thingiverse.com using the Prusa (PLA) and Formlab (SLA) printers. I downloaded the file and imported it to the 3DPrinterOS cloud and scaled the piece down to 80% to ensure it would fit in the casing.

Prusa (PLA)

Initially, I had chosen a different object that failed within 30 minutes of me putting the print in. So, I changed the design and decided to print three of them at once. The settings I used were as follows: raft with supports, layer height 0.2 mm, extruder temperature 200 degrees celsius, and heat bed temp 65 degrees celsius. After autogenerating supports and orienting the piece in the right position, I sent it to print. The print time was 4.5 hours because there were too many supports. Unfortunately, I got an email at 8:30 pm saying my part failed and then another following saying that my part is again sent to print. I sincerely want to thank whoever was at the OEDK and decided to reprint my part for me. The next morning, I had a failed part and a completed part in the two bins. The longest part of this process was removing the supports (way too many). But once I removed them, it was so great to see the three rings linked without being able to come apart.

                               
Figure 1: Failed Part                                 Figure 2: PLA part without supports

Formlab (SLA)

The resin print went a lot smoother than the PLA prints. I uploaded the same file to PreForm on the OEDK computers to print on the Form 2 using the Grey resin. I had previously used this printer so I autogenerated supports and sent two pieces to print. It took 1.5 hours to print both pieces. Once that was done, I placed it in the wash for 20 minutes before removing the supports. I decided not to cure it because these parts are not meant for structural integrity and thus would not necessarily need a cure time. I let the pieces dry overnight before putting them in the little casing.

Reflection:

This was a pretty relaxed process, besides the failed part scare. In hindsight I could have chosen something more complicated or with a different mechanism since I have used both the 3D printers in the past. Overall, I would call this a success as the object is definitely impossible. According to the owner @mathgrrl, “The Borromean rings consist of three rings with the property that no two of the rings are linked, even though all three rings together cannot come apart.” I hope to buy a 3D printer for myself in the future to make fun projects like these.

 

Cost Analysis:

PLA failed part (according to the software): $0.56
PLA successful part (according to the software): $0.72
2 Resin parts (grey resin costs $150/1L): 10mL = $1.50
Labor ($15/hr) for editing and removing supports: total 1 hr = $15
Time taken from printers (Rent cost of $1/hr): 6 hrs = $6
Prusa and Formlab printers (not included as it is provided by the OEDK)

Total cost: $23.78

This cost would be much higher if the cost of the 3D printers was included. The majority of the cost comes from labor and time spent using the printers.