For this assignment, we finally moved away from 2D manufacturing into the fun and fascinating world of 3D manufacturing, starting with 3D printing. After learning about different types of 3D printing and some innovative ways it was being applied, we were tasked with creating our very own “impossible object”, using two different types of 3D printing.

Selecting an Object

For an object to be deemed “impossible”, it had to be incredibly difficult to make using any method but 3D printing. I decided to find an articulated part from Thingiverse, and eventually settled on a slug model because I thought it seemed reasonable to be able to scale down. 

FDM Printing

I decided to start with the FDM printing, because it was the method I was more familiar with. In the prusa slicer, I scaled down the slug to be 50mm long. I wasn’t really sure how much it would be able to curl up to fit in the capsule, so I started on the smaller side. I messed around with the supports and brim until the slicer stopped giving me “low bed adhesion” warnings, and ended up with supports enabled and a 1 mm brim. I started by just printing one to set out the size and settings. Immediately, I knew I’d have to fix something, because the back end of the slug didn’t stick to the bed and I was left with a very wonky and not articulated sort-of slug.

To fix this, I increased the brim to 4 mm. I also changed the size to 60 mm, because once I saw what 50 mm actually looked like, I realized it was way too small. After printing one with these settings, peeling off the supports, and wiggling it a bit, I decided that it was good and printed 4 more. However, after conferring with a few of my classmates about the size, I decided to make them a little larger because there was definitely more room in the capsule.

For my final FDM prints, I increased the size to 65 mm and used the bambu printers, which didn’t require any support or brim. The difference in how the well the slugs moved on the bambu vs the prusa was drastic – no brim or supports let the joints move freely. Even after removing the excess plastic from the prusa printed slugs, they still were a little gummed up. 

SLA Printing

After completing my FDM prints, I moved onto using the SLA printer. I uploaded my slug file to the slicer, scaled the slug to 65 mm long, and auto-generated supports. I decided to print 5 after a classmate warned me that sometimes the joints don’t work properly and fuse together so I should try to make extras. 

After my print was completed, I moved the slugs to the wash. I then removed them from the build plate with some struggle and cured them at the settings for gray resin. 

After curing, I removed the supports from the slugs where it hadn’t already come off, and tried to articulate my slugs. Unfortunately, the joints had fused together  on 4 of my 5 SLA slugs, and they snapped when I tried to get them to move.

Takeaways

• For FDM printing, the bambu creates a much better final product than the prusas with less tweaking of settings
• I optimized the size of my print to work for FDM printing, and didn’t really take into account that SLA printing would be slightly different. Just like I did test prints of the FDM, I should have tested the SLA print to make sure it worked.

Cost:

• PETG Filament: about $20 per kilogram, used about 30 grams, 20*0.03= $0.60
• Gray Pro Resin: $8 per cubic inch, used about 1 cubic inch = $8.00
• Labor: $20/hour for 2 hours = $40.00
• SLA Printer operating cost: $5 for printing and processing (OEDK website)
• Total: $53.60