For our final project, our task was to use a fairly inefficient method to construct a chess piece: first to CNC mill the piece in two halves, and then to cast and mold the piece to make a final product in plastic. Nick Wolf and I choose to make a bishop, because it is nice and radially symmetrical. We didn’t want to deal with a bishop that had a hole through the top, so we found one on Thingiverse that looked nice without the hole. It is below:

I will take you through the steps we took to take this file and turn it into a plastic bishop.

1. Processing the File
   1. Nick took the .stl file from Thingiverse and, on Solidworks, split the file into its two identical halves.
   2. The file was then taken into Fusion 360. We used Fusion 360 to put the piece on a box and add holes and pins for alignment later on. We resized the piece to make it 81.5 mm tall. We also used Meshmixer to reduce the number of faces in the object to 10,000. This makes it easier for Fusion 360 to convert the file to the proper format for creating G-Code. Here’s what it looked like. 
   3. From here, we used Fusion to create G-Code for printing. I downloaded the f360-easel.cps from Easel to configure the generation of the G-Code which worked nicely (thanks for the tip, Amelia!)
   4. Lastly, using a text editor, we removed line G54 from the G-Code, as it was causing issues with homing the CNC machine. We got this tip from previous generations of ENGI210 students.
2. CNC Milling the Pieces
   1. At this point, we could cut out our piece. We decided to cut from wood, which we got by resizing 2’x4’s to be the exact size of our Fusion 360 file (roughly 100 x 60 mm). We learned we had to resize our stock the hard way, as our first attempt at cutting had an oversized stock and broke our drill bit.
   2. We then uploaded the G-Code File to Flashcut’s software, zeroed the axes, and got to work. The piece took about 50 minutes to run, and we made two.
   3. The pieces came out a little lumpy at times, which we tried to correct by using a file. Some of the skinnier parts of the piece also did not cut very well, but we decided moving forward would be the best use of our time. Below is an image of one of these pieces.
3. Making a Mold the Piece
   1. Now, it is time to make negative molds of the piece! We used a Smooth-On product called Mold Star to make two molds for the two halves of our piece
   2. We build a casing around our CNC’ed parts our of legos, and attempted to water-tight the pieces using duct tape. Here is a picture of that: 
   3. The molding went amazingly well on the first try, so we took that a positive sign and carried on. Here’s a picture.
4. Casting our Pieces
   1. Now we were finally ready to make our plastic bisshops!
   2. First, we cut out a little pour spout on our molds to be able to pour the material into.
   3. We decided to cast in Smooth On Smooth-Cast 385– it’s good stuff, since it sets in about 15 minutes which made iterating really easy.
   4. We also created a funnel out of construction paper to put the mixed up Smooth-Cast 385 into the molds. Here is what the set-up looked like. 
   5. The first few casts came out badly because of misalignment. We also forgot to add dye the first time, which made for a lumpy and deformed bishop. For the black bishop, we combined purple and brown dye, since we were out of black. Here is our progression of bishops. 
5. Post Processing
   1. Now, we took the bishops and sanded their outsides using a Dremel. This removed some of the deformities from the casting process and made sure the bishops would stand up straight

Also, we spray-painted the black bishop black since our dying technique did not come out as nicely as planned. Here are our final productsThis project was a fun way to end the semester since we got to combine a lot of different techniques to make a cool and complex object. With that said, I would not use this workflow again to make a bishop. I would opt for the much less time-consuming and much more precise method of 3D printing.