As always, having a new assignment in ENGI 210 requires us to learn new skills and apply them in sometimes an unforeseen manner. In this case, we as a class had to learn how 3d printing works as an additive manufacturing process and how to use the 3d printers here at the OEDK. The only available processes that the printers that the OEDK allows us to use at the moment were Fused Deposition Modelling printers and Stereolithography printers provided by the PRUSAs and the Form printers respectively.
Our main goal for this assignment was to learn how to download and scale a premade design so that it would fit inside of one of these plastic gumballs and still maintain a semblance of what the object is supposed to be. The object also had to be impossible, meaning it couldn’t have possibly been made without 3d printing, like interlocking 3d parts or making things with hinges and printing them already put together.
I chose for my object a Fidget Star, which would continuously create boxes and stars as you keep opening it. I found it to be fun and pretty decently sized so I made this my chosen print.
For my first prints, I found that I had forgotten to set a brim or raft to increase the adhesion of the object to the build plate, resulting in sliding of the first layer after it had built some. I added a raft/brim to my object and it printed successfully. Getting the supports out was difficult at first, but I found using one of the scrapers to slide in between the cracks of the cube and leveraging it open was most effective. As it turns out, the full size object was actually quite small and fit inside of the gumball with quite a bit of extra space, so I decided to scale the object up ever so slightly.
My failed yellow print in the back, with my new smaller print with lots of supports
After raising the scale up to 108%, I once again printed the object in a set of 3 with the FDM printers. After cleaning out the supports from the inside and outside of the objects, I surprisingly found that the object didn’t fit when folded up as a cube, but when inverted into a star, it fit inside the gumball perfectly.
I continued on with the stereolithography printers. I scaled the object up using the Preform software and then sent the object to the Form 3 and waited approximately 4 hours for a single print to finish. After cleaning the print and post processing it with both an isopropyl alcohol bath and cooking it inside a UV chamber for 20 minutes, I found the print to be very brittle. Unfortunately, the print broke into pieces at the hinges. This is more than likely due to the fact that the resin is sticky throughout the process and more than likely the insides of the hinges became stuck to the walls of the hinge. This particular object is definitely much more suited for FDM printing rather than stereolithography.
The cost analysis of making these prints are as follows:
The PRUSA and FORM printers were free for me because I didn’t purchase them, the OEDK did.
The filament for the FDM printers cost about 35 cents per box, so the total cost for them was about $1.40.
The resin for the stereolithography printers cost about $100 per 1L tank, and assuming I used about 40 mL, the resin cost me about $4.
The time spent making the prints were about 8 hours mostly due to long queue times. This time could have been spent with other things, so I will say minimum wage is fair to estimate the cost. Thus, the cost would be $58.
In total, the cost of the 3d prints would be: $63.40.
