Team

Ben Henderson & Ricky Gonzalez

For our final project, we worked on casting 8 chess pieces using a combination of prototyping and fabrication techniques we’ve learned including using the CNC mill and 3D printer as well as molding and casting techniques!

Step 1: Choose a chess piece design

The first step in the assignment was selecting an object from Thingiverse to be our chess piece. We chose the Empire State Building because of its relatively simple design and iconic status.

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Step 2: MODIFY THE SHAPEFILE IN MESHMIXER

Once we decided on our chess piece design, we downloaded the .STL file and imported it into the Meshmixer. First, we scaled the design to be the height of a king-sized (~95 mm) chess piece. Next, we vertically plane cut the object in half and discarded one half. Next, we exported the file as a binary.STL file and proceeded to SolidWorks!

Step 3: MODIFY THE FILE IN SolidWorks

In SolidWorks (SW), we imported our .STL file as a solid body so that we could create additional geometry to our object. We began by creating a rectangular base alongside the bottom portion of our object. Then, we extruded it to an ~10 mm thickness. Next, we made four equal-sized circles to be our holes/pegs, each of which had a diameter of ~5mm and an extrusion thickness of ~2.25 mm. Lastly, we made an air vent from the tip of the object to the bottom so as to prevent air bubbles in our cast. 

With our SW file made, we saved two separate SW’s files,one with the hole extrusion to be used as our 3D printed positive half and the other with peg extrusions to be used as our CNC positive half. Then we saved those same SW files as .STL files so they could be used on the 3D printer and CNC mill respectively. 

Step 4: MODIFY THE FILE IN VCARVE

Once we finalized the SW file, we opened the CNC half in Vcarve in order to generate the corresponding g-code. Next, we could select our soft wood material for the CNC half! 

Step 5: CREATE THE SILICONE MOLDS

We created a cardboard frame casing around the 3D printed and CNC cut halves in order to pour the silicon solution into. This was left out overnight and we checked that the molds looked good the next day. They turned out great and we cut down the edges of the molds so that it would be easier to make the casts. 

Step 6: CASTING

We put on 6 rubber bands very tightly in order to avoid any leaking out of the bottom. We realized that we did not need to have two air channels on both halves but it didn’t seem to cause any problems during the casting process. There was a little bit of leaking after the second cast but we added extra rubber bands to stop it – that piece did end up a little shorter (red) because some of the volume was lost. We made a variety of colors which was really enjoyable to see nearly identical objects in various different colors. 

Cost estimate

• 4 Pack Unfinished Wood (4×8″) = ~$18
• Cost to Use a CNC Mill per hour = ~$35
• Silicon mold kit = $10 
• Labor (15hrs x $20/hr) = ~$300
• TOTAL = ~$ [8 pieces so ~$45 per piece) 

**Now that the master molds are made, the cost to manufacture the casts drops dramatically when manufactured in large quantities**