Final project
Over the course of ~four weeks in EDES 210, We were tasked with creating a polyurethane cast chess piece of our choosing. We settled on Williams Tower (really nice because of the wonderful right angles), found a really nice file on Thingiverse and got to work.
Making the 3D Mold
Creating the 3D printed negative piece was relatively straightforward considering the tower is symmetrical. We simply needed to slice the tower vertically and add the base as per the instructions provided. We accidentally forgot to make a pour hole, so we needed toreprint after moving the tower down to the bottom of the base.
Making the CNC Mold
Next, we had to make the positive CNC mold using the other half of our .stl file. After importing it into Vcarve, we followed the instructions from the project document. First, a ¼” end mill was used to do a rough pass into the block of wood. Then a ⅛” finishing bit to make final smoothing passes. Looking back now, it would have been nicer to do another finishing pass with a smaller bit, because the sharp angles were somewhat lost as shown in the pictures below. But it still looked decent.
Going in with a dremel and a really light hand, we cleaned up the CNC piece and proceeded to pour the mold.
Pouring the Silicone Mold.
Since our piece was so small, measuring the volume for the mold was as simple as calculating the volume of a rectangular prism with height one centimeter greater than the height of the 3D printed (1.77”x3.85”x.79”). To create a space to pour into, we needed to seal the CNC piece and 3D printed piece with scrap cardboard and hot glue. We poured equal parts by weight of the two components for silicone and let it cure for 4 hours.
Casting our Chess piece!
It was finally time to cast our chess piece! We ran into a little hiccup as we noticed our guide holes were in the wrong place! Using a little hot glue, we swapped the positions of the two raised guides and everything was alright once more!
After joining the two halves of our mold using rubber bands, we filled it to the top with water and obtained our measurement of how much polyurethane we would need. Using 7.5 ml of Part A, 7.5 ml of Part B and dye of our choosing we cast our chess pieces! It took about 10 minutes to cure each time.
Although our pieces were beautiful, we went in with a utility knife and shaved off the side where the two halves of our mold met.
And Voila! Our mini Williams Tower chess pieces!
Photo of our last workspace!
