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MAS.863/4.140/6.9020
Lleyton Elliott

Week 4 Assignment Part 1: Design and 3D print something that cannot be made subtractively
See Part 2 of Week 4 Here!

I begin every week by looking through old Fab Class assignments in case something jumps out at me and inspires me. I wasn't sure what I wanted to do yet, and I also wanted to make sure I didn't take up too much printer time (the class page suggested our design to be on the centimeter scale). This assignment by Sal Lama from 2018 stood out to me - he connected various chain links in his design and once he took away the supporting material from the print, his print was already constructed. I thought this was a super cool concept, so I decided to try it myself.

Making the basic chain link wasn't too difficult; I'm pretty comfortable with Solidworks, so I just made a sketch of a circle and swept it around a sketch of a slot that was on a perpendicular plane:

the diameter of the cross-section of my chain the track along which I swept my cross-section

The sketches were fully defined, so I created the solid body and was happy with how it looked:

chain link with initial parameters

However, I soon ran into a problem once I decided to do a test slice of this singular chain link in Cura (I was very off with the dimensions I guessed for the first pass of the design, and it would be quite large and take way too long to print):

this would take far too long to print
So, I quickly scaled down my chain link to smaller parameters and re-sliced:
fixed
Much better!

After this, I decided to make an end link for my chain. First, I simply halved my original sketch around which I swept the circle:
beginnings of the end link
Next, I thought about what I wanted to attach at the end of it. I thought of what I could rep as I attached this chain to my backpack, a lanyard, or my keys, and settled on the Greek letters of my fraternity, Zeta Psi. Some Solidworks sketch artwork ensued and I had this:
(almost) finished end link sketch
...which didn't successfully extrude because I had overlapping contours and zero-thickness geometry:
oops
After this humbling reminder to make sure my sketches are fully defined and my lines don't overlap, I fixed the sketch and I was ready to put everything together into an assembly, which I would then export as a single stl file to be sliced! I made sure to line everything up so no solid bodies overlapped and everything was relatively close so it'd be a quicker print:
assembled!
I set up Cura to slice my design to be printed on one of the EECS lab's Prusa printers, entered my desired settings (tree supports everywhere with no build plate adhesion, plus the default Prusa infill and speed settings) and realized it was quite a quick print:
slicing my model
After double checking that everything was ready to go, I gave it a shot, and thankfully it turned out great! A quick print and some paring away of the support material later, I had a perfectly intact chain that was printed in one job.
done!

Design Files

Chain Assembly: Chain_assembly.STEP | Chain_assembly.STL

Thoughts, Lessons, and Takeaways:

I love 3D printing and am quite comfortable with CAD. I did learn a lot about printer settings and how to tune a printer to best fit the task at hand - just another piece of the puzzle! The only issue I ran into was with some sloppy Solidworks sketching, which was quickly resolved; overall, I expected this week to be one of my most comfortable assignments, and that was true, but I'd love to get into lab and continue pushing the limits of what 3D printers can do in my free time (one week later update: I was sick this week, so I'll rain check that until I get recovered and caught up on work!). I'd love to explore the possibility of printing removable end links so that I can customize my chain further, and I also intend to attempt to create more complicated designs, even simple mechanisms, within a single 3D printing job. In summary, it was a blast of a week for me and a good step towards being able to make (almost) anything!