Intro:

For our final project, we decided to team up once again, looking for redemption after our midterm project’s unsatisfying performance. 

The assignment this time was quite simple: create 8 chess pieces through the use of molding and casting. However, the process to get there was a little more complex than what the end goal suggests…

 

Procedure:

– Choosing Design – 

Narrowing onto a chess piece design required us to go into Thingiverse to explore options. This time around I (Daniel) was in charge of choosing the design so I went for something that was funny looking, stable and easy to manufacture. This landed us on a rook moai chess piece. 

Prior to any further progress, we first 3D printed this piece with the dimensions we wanted to check how well it would turn out. After having the 3D model printed, we confirmed that our chosen design was the one and our dimensions were perfect for a chess piece. 

With the design chosen and validated, we downloaded the stl file and went onto MeshMixer to cut our piece in half as well as ensure that the geometry of the piece wasn’t overly complex. 

From then on, we proceeded to upload our pre-processed stl file into Solidworks and built a mold rig that would allow us to create a positive of the mold. Additionally, while in Solidworks, we mirrored the image to create the other half of the positive mold. 

 

– 3D Printing – 

In order to put to practice what we learned in class, we had to use the 3D printer to create a positive half of our chosen chess piece design. With one half of the positive mold ready, we saved the file as an stl and uploaded it to 3DPrinterOS where it was sliced and queued to print. 

Once the 3D print finished, we inspected it. It turned out that the positive mold’s dimensions were too big for the wood we were going to use to CNC the other half. 

So, we went into Solidworks again to fix the dimensions and repeated the process. With a new positive mold that cleared verifications–it was now onto the CNCing! 

 

– CNCing – 

With the other half of the positive mold’s stl file, we used VCarver Pro to create toolpaths for it: one roughing path and the other a finishing path. Once we retrieved the final gcode, we opened  our file into Carbide Motion and began the CNCing process… 

We soon ran into a number of issues with the safety pin, which caused the CNCing to pose a challenge on the Nomad3, rendering it difficult to work with. After multiple failed trials, we moved on to using the Shapeoko and the difference was night and day. We were able to CNC a positive that was of high quality with our specified dimensions and tool paths. 

 

– Molding – 

The molding process was a simple procedure that required one to find the amount of solution to make in volume so that the positive molds would be filled. This was calculated by measuring the dimensions of the box the mold was going to be within with the subtraction of the 3D printed half’s volume (found on solidworks). 

The solution to be made was a 1-1 solution that created a silicon, rubbery mold when fully cured. We poured this solution into our positive molds–making sure to spray mold release onto the CNC positive to avoid the solution seeping into the pores of the wood.  

– Casting –

After allowing the mold to rest for a day, we removed the mold from our 3D printed and CNC positives. We made sure to carefully remove the tapes and cut out the excess parts to ensure clean molds that would naturally form together. This would make sure that our final product would align with both halves. 

Once we aligned the two molds (using the pegs and peg holes to keep them together), we used four rubber bands to close the two molds together. We then poured water into the mold to ensure that the mold was completely sealed. We also poured out the water in the mold into a measuring cup to calculate the volume of the final product. 

Once we knew the product’s volume, we then brought out the yellow and orange liquid plastic. We poured out half of the product’s volume of each liquid plastic to ensure a 1:1 volume solution. We then mixed the two liquids together, and then immediately poured the solution into our mold. After waiting for ten minutes, we removed the final product from our mold and repeated the process seven times.

While half of our chess pieces were white, we colored the other half of our pieces. We did this by mixing the 1:1 liquid plastic ratio along with liquid color dye before pouring the solution into the mold. While some colors were made with one dye, other colors were made by mixing multiple color dyes with the solution.

After removing all of the chess pieces from the mold, we used an X-acto Knife to trim the small excess parts that formed on the border of the 3D and CNC part of the piece. We also cleaned up the top of the crown to ensure that the crown was flat and leveled. Finally, we inspected each piece to make sure it was up to standard (and created new pieces to replace those that were subpar). 

 

Reflection:

– Brian – 

In our final project, I learned that using many different tools along an efficient tool chain can create a professional product. While it was important for me to learn how to use the 3D printer, CNC machine, and casting/molding methods, I realized that I learned much more about how to efficiently use these building techniques by designing a project that required the use of all three methods. I also learned about the difficulties when one part of the tool chain is disrupted. The CNC machine, at least for me, was by far the most challenging aspect of the project; I made many, many mistakes throughout the process. Whether it was creating the wrong G-code, using the wrong end mill, or securing the carved wood too loosely, I took account of each mishap, and greatly refined my process on the CNC machine. Some of the solutions that I learned from this experience was to read carefully through the G-codes used, switching CNC machines (from the Nomad 3 to the Shapeoko Pro) to use more secure end mills, and checking the wood used to ensure it would effectively stick to the CNC machine base. This ordeal not only taught me the importance of each step in the tool chain, but it also taught me how to effectively deal with setbacks within the tool chain. This helped develop my critical thinking and problem solving skills, which are vital for all of my future engineering endeavors.

 

– Daniel – 

This project was a useful overview of what I consider to be the engineering manufacturing process. It demonstrated how a toolchain can be effortlessly created to make an idea go from the digital space to the physical world. I feel like I now have a better understanding of what tools to use for certain jobs and ways I can mix and match them to create a flow of production. These are skills that will be beneficial when participating in future engineering design projects! That is not to say everything went well without hiccups. There were issues along the way, but we managed to figure them out and continue on with our project, which we delivered. 

 

Total Cost: $340.50

-Materials-

• Wood: $10
• PLA: $10 
• Dyes: $5
• Rubberbands: $0.50
• Molding Solutions: $90
• Casting Solution: $30

 

-Labor-

• 10 hrs x ($7.25/hr x 2) = $145

 

-Overhead (3D printing + CNCing + etc.)-

• 3D Printing: $10
• CNC Machine: $40