Since we had a great 2nd semester with more 3-D prototyping and fabrication, it made sense to utilize all we have learned (3-D printing, casting and molding, and the CNC milling) to create something that can be sold in bulk if we were an at home business. Chess pieces seemed like a lovely decision to implement these techniques into one project.

 

Step 1: Picking our design

When it was time to pick our design, we had one criteria: one it had to be Pokemon themed. Therefore, we embarked on our journey to find the perfect chess piece. However, finding one on Thingiverse that did not have overhangs (since we knew the CNC machine would not be able to recreate those) and that showcased a Pokemon we both loved proved to be difficult. Therefore, we decided to design our own by utilizing two already existing Thingiverse files and stacking them on each other in 3dprinteros, and it worked! For recreation of this product, the base file is from Low Poly Pokemon Chess Set (https://www.thingiverse.com/thing:2672945) by Izzhang10 and the Ditto figurine is from Happy Ditto (Pokemon) (https://www.thingiverse.com/thing:1932974) by MaddieLee3D. 

 

Step 2: Creating the MeshMixer and SOLIDWORKS files

First, we needed to create the files for our chess pieces by first going into MeshMixer in order to cut the piece in half to work on it in SOLIDWORKS. By going through the instructions in the STL processing document, we were able to make a perfect half cut in the middle of our object and save both sides as binary stl files. Then, for SOLIDWORKS, we followed the instructions to create the bases for the pieces along with the extruded piece holders and the cut ones. However, we ran into trouble regarding the placement of the chess piece on the block and, in order to find a method to decrease the odds of the objects not aligning, we relied heavily on measurements from the measure function in SOLIDWORKS along with just vocalizing many of the measurements and making them as simple as possible. Then, we were ready to start making our chess pieces a reality:)

 

Step 3: 3-D printing our first piece! 

For our first piece, we decided to have a 0.2 mm layer height and had no raft for the build plate adhesion type with no supports to create our back of the chess piece block! It was easily created and we got to print out two of them (one with original settings and the other one was with us modifying the measurements a bit from the SOLIDWORKS perspective).

Step 4: Cardboard the 3-D piece

After having Dr. Wettergreen inspect our 3-D printed piece, he made the suggestion of encasing it with cardboard and shrinking the top of the block to ensure that we would not spend more time on the CNC machine since it would have to go through more layer of milling, which would increase the time we are on the machine. It turned out to be a great decision since we ran into trouble later regarding the length of our cut and timing based on how long our reservation for the machine was (1 hour and like 10 minutes with an hour of a reservation remaining did not prove to be a good feeling:(). Therefore, we created a cardboard barrier, but unfortunately we glued it on with superglue instead of using the hot glue gun:/ After presenting our new version of the 3-D printed piece, Dr. Wettergreen asked us to lather the object in hot glue to ensure that it would be tight enough to prevent any of the mold liquids from escaping the encasing. Therefore, also since hot glue is very inexpensive, we covered what we thought was every inch of the object in hot glue that might have had an opening. With this done, we were ready to focus on our CNC piece.

     

Step 5: CNC our other half:)

Setting up our settings on Vcarve for our piece proved to be relatively straightforward as we read and watched the tutorial while completing the steps. However, while realizing after setting up toolpaths, the unfortunate issue of the time to mill the piece was greater than the time remaining on our reservation for the Nomad machine. Therefore, we started exploring other options with a bigger size bit end, such as the ¼ inch. However, when we started the machine, it ended up tossing around the block and not creating the cuts in the places we desired, making it unusable for our project. We decided to come back later and focus on our initial idea of just using the ⅛ inch for the roughing path and the 1/16 inch for the finishing path, and it turned out beautiful and well done except for needing to sand a little bit on the face to gain those finer details for our chess pieces.

     

Step 6: Sand

For the CNC piece, some parts of the surface were a little bit fuzzy and uneven after coming out from the machine. Therefore, we wanted to sand the surface to make it more even so that the mold turns out smoother in the end. We used up to 220 grit sandpaper to sand the uneven parts until relatively smooth.

   

Step 7: Make our mold!

After the sanding was complete, we replicated the process with the 3-D printed piece’s cardboard barriers and inserted them on the CNC piece, creating those walls so leakage would hopefully not occur. With everything prepared and having the correct height to be able to pour in the molding ingredients, we began the process of making our mold! By following the videos in the Media Gallery by Dr. Wettergreen, we replicated the process of calculating how much volume we need to insert into the encapsulated piece. With using our 3-D printed piece as our example since that would be more shallow than our CNC piece (because of the milling create that extra depth), we found that we wanted the box to be 7.4 cm in length, 7.5 cm in width, and 3.4 cm in height, creating a volume of 188.7 mL. Then, for our whole object in the middle of it, we settled on the dimensions of 6.23 cm in length, 3.94 cm in width, and 2.5 cm in height to get a volume of 61.3655 mL, which cut to 30.68 mL in volume since it is half the object. Therefore, the volume we gained for the pouring was 158 total mL, so we had ~79 mL of Part A and ~79 mL of Part B in the molding ingredients mix. Then, since it is around a 15 minute life duration for the mixture, we went ahead and mixed it and then poured it in a specific corner in the box so as to ensure not many air bubbles came about. After repeating this process for the CNC piece with the same calculations, we had them set, but unfortunately the fear of leakage occurred and we got creative with stopping it (lots of hot glue and a popsicle stick glued to the bottom of the block where the hole was). The leakage then stopped and we were able to come back later to remove our molds!

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Step 8: Cast our pieces!

It was finally time to cast our pieces. Again, we followed the video instructions in the Media Gallery to cast our chess pieces. Since the volume of our object was roughly 60 mL, we poured around 30 mL of Plastic A and 30 mL of Plastic B to achieve the 1:1 ratio estimate. We tied the two molded halves together with rubber bands tightly, poured the plastic inside, and waited for about 10 minutes to take out our first chess piece. The alignment of the first chess piece was not ideal; there were some sticking out portions on the sides. So from there, we focused on aligning the two molds more precisely, making sure the interior edges aligned well with each other. Finally, we casted our eight ditto chess pieces successfully!

   

Step 9: Model them:)

Here are our gorgeous chess pieces! We created 4 of them without color and then the other 4 we wanted to maintain a pastel theme, so we chose pink and blue to maintain that theme. Perfect for anyone and can be utilized at any chess tournament (as the Queen piece, of course!).

Step 10: Finding out if it was worth it and reflecting on what we learned

 

Cost Analysis:

Raw materials:

• wood ~ $6
• tape ~ $1
• 3d printing PLA ~ $0.65
• wood stain ~ $10
• sandpaper ~ $5
• hot glue ~ $1
• cardboard ~ $1
• casting material (polyurethane) ~ $8
• molding material (silicon) ~ $35

Labor, machine, overhead:

• 3D printer: ~ 3 hr ($20/hr) = $60
• CNC machine: ~ 3 hr ($40/hr) = $120
• labor: ~ 20 hrs ($7.25/hr) = $145

Total: $392.65 (for 8 chess pieces total)

 

Reflection:

We learned a lot in this project regarding many of the 3-D related techniques, but it was also intriguing to see how they can come together to form a finished product. Although none of the project was centered around SOLIDWORKS, it was a bit of a pain to use since even though we had instructions to follow, implementing the steps were somewhat difficult at times for users with not much experience with the program. Also, it was fun to learn of a new way to create our files for the CNC machine, but it became evident that we should plan ahead for the cutting a bit better in the future so as to not run into time constraints. However, it became a good experience to work through it together and get to see our desires become a reality!