Week 3

Week 3: 3D Scanning and Printing

September 29 - October 6

[0] Overview
3D printing time! For the last few years, I've worked with 3D printers and materials, so I knew I could have some fun trying out dual layer materials.

This week's assignments:
(1.) design and 3D print an obect that could not be made subtractively
(2.) 3D scan an object



To prepare for my final project, I wanted to try out dual extrusion with two materials and magnetic attachemnts (I'm trying to make a toolchange that's easy for my 3 axis machine).

[1] Group Assignment
This week, we had to test out the tolerances for each printer. What better way to do this than with the brand new FlashForge 3D printer! I began the week by setting it up, and calibrating the motors to get dual extrusion. I was pleasently surprised by how easy it was to set up, but we had some initial issues with overextrusion when it was switching nozzles. This had to be fixed software wise by decreasing the heating temperature from 210°C to 200°C for PLA that was provided.

For the characterization of the machine, I tested two designs - one for bridging, and the other for angles. I printed out the angles test, which was from the HTMAA website.


What surprised me was how close to 90 degrees we could perfectly print. The angles worked up to 10 degrees without significant issues. Even 90 degree bridges were possible, something I couldn't get on my old 3D printer. I think the best part about these tests was the simplicity in running them. You just have to slice the samples into gcode (or .gx for FlashForge), and hit run with the SD card. Where it can get tricky is figuring out tolerances between joints, which is something I intend to do later on since I want to use it for my final project.

The next test I did was a dual extrusion test with the new nozzles, which was a lot more difficult than I imagined. This will be covered with the 3D printing section.
[2] 3D Scanning
In all honesty, I thought this would be the easier aspect of the week, since I figured that it was just turning a scanner around an objet. I was surely mislead by the demo, because it turned out to be a lot more finicky than I imagined.



I tried scanning various objects - my phone, my keys, and finally my face. Both my phone and keys were small, so they didn't pick up well. With my face, I was able to get my profile (albeit a little lopsided) with the help of a few people, but I still had issues with my black hair. I was eventually able to get a partial profile. While I'm not satisfied with it, I do want to come back to it with the higher quality scanner and try animating something in the foreseeable future!
[3] 3D Printing
With this unit, I focused my attention on extruding two filaments at the same time, to get ready for my final project. I hope to build interchangable blocks with the new conductive filament, so this practice would be useful. In addition, we just received soluble filament, something that would also be great for complex shapes (as I realized this week with my deisgn...)



The samples were made from a bunch of smaller subsquares, randomly chosen and then branched off from each layer upward. The algorithm will be posted soon. Using that data, I was able to model the print and export it to STL. Shown above was the FlashForge software (which has significantly improved in the last few years, but lags behind Prusa). I made 7x7 square diagrams, and each has a proper support attached.

The print took around 5 hours with the following settings:
(1) 220C
(2) PLA Blue, PLA White
(3) Heating Bed Temp: 50C.



My first few prints failed quickly, and I had to manually stop them. I quickly noticed that with two nozzles, there was a hidden feature known as idle retraction, which affected the filament. It would slowly ooze out and cause a mess, and without a brim layer this would just grab onto the print unless you pull out the strands manually. While I didn't solve the issue during my final print, I talked to several others who mentioned how the PLA might be too hot at 220 and have a lower viscosity, causing it to uncontrollably flow out. This was later tested on a smaller scale at 200C which worked much better.





This is the aformentioned threading, which was managable for this print but not suitable for long term use in the group. Taking it off the bed also took serious effort, mainly because the stock heading bed plate was not magnetic unlike the Prusas I've been used to in the Shop, so I had to pry it out. We do have an addon kit for a removable bed, which I'll attach later this week.



Post-processing was the difficult part of the 3D printing experience, and took me an hour to get the print off the bed, clean it, and remove most of the supports (more work needs to be done however). This was a very useful print to test however, since now I'm aware of the filament drip that can happen to printers when sitting idle, and I have figured out how to avoid all the threading that makes the print quality bad in some areas.

Some things I really liked:
(1) Each of the 8 subpieces managed to stay together and bind with each other during print. I was really worried that the tolerances would be off and that it would basically fall apart.

(2) The print managed to remain rigid as I intended. Some prints that have done similar shapes in the past suffer from bending parts.

Future:
(1) Testing out magnets inside of the print, using commands to stop the printer with the Prusa Slicer, as well as conductive filament. I also want to try out the soluble filament as well