This week in ENGI 210, we were tasked to print Impossible Objects using two types of 3D printers in the OEDK. These objects needed to be small enough to fit in a gumball capsule, and they needed to look intriguing enough such that the average OEDK user would want to spend $0.25 to buy one from the gumball machine.
Being a bioengineering major, my mind immediately jumped to printing an anatomical model of some part of the human body. At first, I searched Thingiverse in attempt to find a file to print a miniature kidney, since my BIOE 252 team has been doing kidney-related projects all semester. Alas, no one on Thingiverse seems interesting in kidney modelling. I searched for the next best thing – a heart – and found success. Here is the file I chose:
I had never used a 3D printer before, but purely based off my observations of friends and peers using 3D printers over the course of my time in the OEDK, it seemed like the MakerGear was a good starting point. I had a lab tech show me the right settings to get the print started, and this was the result of my first print:
I thought this was a good start, but while peeling off the raft I somehow managed to peel off a little too much of the bottom of the heart, so I decided to try the MakerGear print one more time:
From the front half this looks good, but around and especially underneath the aorta and arteries there ended up being a lot of excess support and over-extrusion. This was an issue on the original print as well, so I’m assuming that’s an artifact of the specific, weird geometry of the heart’s veins and arteries. I tried my best to cut off as much of it as I could, and was curious to see if the next printer I used would yield the same result.
I asked a lab tech to let me into the Wet Lab and to show me how to get a print started on one of the printers in there. The most simple printer that was not in use at that moment was the Fortus. Like the MakerGear, this is an FDM printer, but the lab tech explained that the Fortus is a more precise machine than a MakerGear printer. Also, it uses different material for supports than for the print itself, so the time it took to print my heart on this machine was three hours – three times as long as printing the same file on a MakerGear. After printing, my part was submersed in a bath of some sort of hot-looking chemical(s)(?). I don’t know much about the composition of the bath, but I know it removed most of the supports from my part and left me with the print itself:
I probably should have left it in the bath for a little while longer. You can kind of tell from one of the photos that a little bit of white support material is still stuck in between the left atrium and pulmonary arteries. I suppose this is the sister-issue to the over-extrusion problem I had from the MakerGear.
As a fun feature, the file I took from includes a little ring on the back of the heart. It’s advertised as being a place on which to attach a keychain. Since I made two prints on the MakerGear but only need to turn in the second one, I took full advantage of the key-chain feature:
Here are some final images of my two prints side by side and near the gumball capsules, for size reference:
Cost Analysis:
For this analysis, I will consider how much it would hypothetically cost for me to print these objects without access to a space such as the OEDK.
Printer: I found a website from which I could rent a 3d printer for $30 per day. Since I made these objects using two different printers, I will say that I rented two different printers for one day – $60
Filament seems to be available on Amazon for $19.99
The MakerGear print took about an hour, while the Fortus print took about three hours. I’ll consider the time I spent finding the file on Thingiverse negligible, so this puts me at four hours. At $1o an hour, this is $40.
Total: about $120 (a lot more than $0.25 from a gumball machine!)
