Between November 15th and 21st, Mia came into the OEDK to work on creating the 3D and CNC stl files. On the 17th, there were lots of opportunities for learning that she experienced. First, she failed to save the file (aka email it to herself) twice, so there was some frustration at constantly restarting. Then, after some instructor feedback, she realized that the Death Star design should be split in half behind the face rather than right through the face. This is so that the 3D printer can work with the front face piece and get that design in rather than the CNC which may struggle with the overhang of the Death Star. 

 

Later, there was lots of struggle with working on creating the back half stl for the CNC machine. Because we had to split it behind the face, the pieces are no longer symmetrical and we can’t just “mirror” the pieces for the 3D and CNC file. It was difficult to position the faces in the exact same spot on the base that had the exact same dimensions and exact positioning of button clasps. However, it eventually got done, and the V-Carving of the CNC half file was handed over to Alana. 3 different 3D prints were done throughout this time since there was a cycle of design -> print -> feedback -> redesign -> print. 

 

When it came to creating the VCarve file, Alana ran into a few mishaps as well. First, she ended up actually doing the entire file in Fusion360 first, which ended up being extremely difficult and the reason why that program isn’t used for this project too. This was definitely frustrating because Alana had to get familiar with an entirely different program again. After a while though, we successfully had a ready file. 

 

Once Alana finished the file, Mia went into the OEDK on December 1 to get the cut. However, after a few passes, it was clear that the machine would begin cutting in the air. After some troubleshooting, the source of the issue wasn’t clear and the machine reservation was running out, so we knew we had to return another day. After speaking with Doug, we realized that it was a simple orientation problem; the VCarve file shows the material as vertical, and Mia positioned it horizontally. Also, the material dimensions in this file were a little off so we adjusted them and saved a new file. 

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On December 5th, 6th, and 7th, we returned to the OEDK and consistently ran into problems with the machine and file, and the limited time reservations inconveniently had us returning day after another. Our problems included:

• not knowing the source of the problems in general
  • we couldn’t figure out if the new file was causing issues
    • this new file was in .tap form rather than .gcode for some reason
• machine cutting in the air after repeated zeroing and jogging
  • we weren’t sure if this was due to the toolpath set up in VCarve having the z-zero as machine surface or material bed
• constant Limit Switch errors
• constant errors where the machine didn’t ask for a tool change after pressing start
  • if I didn’t change the tool, it would have cut with the probing tool
    • when I did change the tool, it never did the measuring action, so it didn’t know how long the 1/8th bit was
• time reservations were slim; our cuts were over 1.5 hours, so we only had 30 minutes within each reservation for set-up and troubleshooting
• other people (Doug, Fernando, Danny, Rafe) honestly not knowing the source of the problems either

Finally, on December 7th, we got a cut CNC piece. However, we immediately noticed that the size of the pawn in this piece looked much smaller than the size of the pawn in the 3D piece. This may have been due to the finishing pass which cut the surface of the pawn for 30 minutes and cut out a lot of details; the Death Star’s defining lines were almost entirely gone. 

 

After the piece was cut, Alana made the cardboard walls for both the 3D and CNC pieces, and Mia poured the molds. They rested overnight, so we could return to check on them and make a first cast.

Unfortunately, this first cast made it very, very clear how different the sizings were. The CNC-mold pawn was much, much smaller, leading to a very asymmetrical and odd looking Death Star. This was extremely worrisome. We had been working on this project since it was introduced in the middle of November, so we couldn’t tell if we would be able to back track that far in the process to fix this mistake. Also, with the other responsibilities of Finals season, it was unclear if we would be able to fit redoing half of the project into our busy study schedules.

 

We sent a message to Dr.Wettergreen and were greatly relieved that he was satisfied with and impressed with our work so far, and that we can continue forward with the project. All that matters is that we are learning and building ENGI and non-ENGI skills, and we are definitely doing both. 

 

Finally, we had 8 pawns and successfully completed our project (with only a few ups and downs). 

Total Costs:

• Orange PLA = 17.59
  • https://www.matterhackers.com/store/l/polymaker-polylite-pla-orange-175mm-1kg/sk/M3EKRR7Z?rcode=PMAX_PMax1&gclid=CjwKCAiAs8acBhA1EiwAgRFdw3YGaRBFpy5dFoP7VxikY7sRnn-mqx0gLgIplythFpE0dAoMW_85BxoCHIIQAvD_BwE
• FTM Printer: 6 hours @ $30/hour = 180
• CNC rental: 8 hours @ $30/hour = 240
  • https://www.routespaceatx.com/ 
• Scrap wood from wood shop = Free
• Molding and casting kit = $120
  • https://www.brickintheyard.com/products/7320moldcastkit
• Mia total time = ~17 hours @ $20/hour = 340
• Alana total time = ~17 hours @ $20/hour = 340

Total = $1237.59

 

Final thoughts:

• Encountering lots of mistakes and redesigns allowed us to feel very comfortable using Meshmixer, Solidworks, Fusion360, and VCarve.
  • Even though having to spend constant, extra time on these programs was frustrating, it feels nice to be able to see our growth with these programs. Each time we readdressed a file, we worked faster and faster. Looking back, if we got the files in one go, we probably wouldn’t have felt so confident in our skills. 
• Always double check a file.
  • Mia constantly had to change the file due to failing to double check and get some feedback. After getting a 3D print out of the printer and being ready to move on, it always seemed like there was something off about the file; there was always room for improvement. 
  • Somewhere along the way, the size of the item in the VCarve file must have changed (or the finishing pass was too intense). We should have double checked this before starting with the CNC machine. 
• Having a partner to work with is extremely helpful.
  • Alana and I are both busy students and individuals. It was so helpful to constantly have an open line of communication about our availability and schedules. Splitting up work whenever one of us had an exam or an event helped relieve us of the time-sensitive aspect of this project. It was so helpful to be able to lean on each other. 
• Push through and persist. 
  • This project definitely wasn’t a smooth one. It seemed like every work day we wanted to give up or come back another day (which means avoid it until the due date becomes too threatening). We even considered doing a simple pawn design rather than the Death Star that we were both excited about because it seemed like a simple pawn would go much easier. 
  • When it came to the CNC aspect of this project, we were completely dumbfounded and exhausted. Seeing the errors happen over and over for 3 days straight was so frustrating and it felt like somehow we got unlucky and our project was doomed. After countless emails and questions to the Lab Assistants and Danny and Fernando, we really felt hopeless and couldn’t imagine getting to easily finish the project in time. Of course, we persisted and moved on with what we had and it worked out for us in the end.
  • Though our pawns are a little funky, they have lots of character and make us laugh in relief. We are pretty proud of them; they prove to us that we had resilience in this project and definitely learned a lot. Never would we have thought we’d be so comfortable and familiar with CAD programs and the CNC machine, but we are now and it feels great. 
  • Everything we learned is also definitely applicable beyond classes and academics. We feel like stronger individuals who are satisfied with our work and efforts.