<div class="textcontainer"> <h1 style = "text-align: center;">Week 8: CNC + Molding and Casting</h1> <br> <p class = "margin"></p> The week, we were trained on the CNC machine and various methods of molding and casting. With this new skill set under our belt, we were assigned to build something using the CNC and mold+cast something. <br><br> <h2 style = "font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;">Molding & Casting</h2> Thinking forward to my final project, I knew that I wanted to this assignment mold+cast a casing for my device. I started by starting on Fusion to draw the base of the device casing and switched to blender to build onto the base (as seen below). <br><br> <p class = "margin"></p> <div style="display: flex; justify-content: center; align-items: center;"> <!-- First image --> <image style = "width: 30%; margin-right: 10%;" src = "8.4.png" alt = "Picture" class = center> </image><br> <!-- Second image --> <image style = "width: 25%" src = "8.2.png" alt = "Picture" class = center> </image><br> </div> <br><br> <p class = "margin"></p> However, thinking about the shape, I knew that I would be unable to CNC the mold for the case. I decided to resin print the mold in order to cast it with semi-flexible material so that it is easily wearable. I brought the file back to fusion to make the mold from the negative of the 3D model and adding. <image style = "width: 30%" src = "8.5.png" alt = "Picture" class = center> </image><br> The two halves of the mold and the actual 3D design of the device was brought into the resin printer and printed. <br><br><image style = "width: 70%" src = "8.7.jpeg" alt = "Picture" class = center> </image><br> After putting in all this work, I realized that a solid mold would be unfeasible for the ear cuff's shape, as its curves would make it challenging to remove without damage. Therefore, I had to try my hand around a different method of casting the ear cuff-- casting silicone in plastisol. <br><br><br> <h2 style="text-align: center; font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif; font-style: bold"> Casting with Plastisol</h2> <br><image style = "width: 80%" src = "8.8.jpeg" alt = "Picture" class = center> </image><br> Plastisol was introduced to me as method of making fish lure. Since silicone was the selected material for the cast, we had to find another material that was as flexible. Fish lure plastisol is cheap, clear, and relatively easy to use as it is melted via microwave and sets within minutes. Moreover, it is reaheatable and extremely mess free since the plastisol peels off most surfaces once its set. <br><br> We tried heating up the plastisol in the toaster oven in the Makerspace but I realized that it would heat up the substance very unevenly and take several minutes to half an hour as compared to <mark> ~1 minute</mark> in the microwave for a cup of plastisol to start reaching the desired consistancy. I figure since heat transfer through air is much slower than heat conducted through electromagnetic waves. I also noticed that the smell of the melted plastisol decreased significantly when heated up in the microwave. <br><br> <br><image style = "width: 80%" src = "8.9.jpeg" alt = "Picture" class = center> </image><br> Because so much of the plastisol can be melted at once in the micowave, I decided to cast the deired figure in layers. This worked out because it also gave me a way to suspend the model. Once the first couple layers were placed into the mold, the model cast was placed inside of the parchment paper lined cup and filled up to the top until I reached the desired height. <mark>The most important insight I gained when creating the molds was the need for a clean release mechanism to separate the mold into two halves. In the middle layer of the mold, corn starch was evenly sprinkled to form a thin barrier between the two halves. </mark> The remaining plastisol was then poured over the cast. As a result, once everything had set and cooled, I was able to effortlessly separate the two halves of the mold without hacking away with a knife. <br><br> Silicone was then casted in the plastisol mold with a syringe. I added a copper wire in the mold to add extra support and rigidity to the structure. Then I wrapped the seam with some tin foil and masking tape to prevent as much of the the silicone from leaking out. The mold was left to set overnight. <br><br><image style = "width: 20%" src = "8.6.png" alt = "Picture" class = center> </image><br> <br> Directly out of the mold, after 16 hours as specified in the silicone kit instructions, the ear cuff was sticky, with a texture similar to cheese. Disappointed with the result, I decided to switch to working with flexible resin instead. However, after allowing the mold to cure for a few weeks, the stickiness disappeared. In hindsight, this is a technique I might revisit in combination with flexible resin. <p class = "margin"></p> <br><br> <h2 style = "font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;">CNC</h2> <p class = "margin"></p> For my CNC assignment, I re-visted my design from <mark2><a href="../02_2Ddesign/index.html">Week 2: The Mr. Potatohead Box</a></mark2> and designed a small shelf to go in the dorm shower. <image style = "width: 30%" src = "8.1.png" alt = "Picture" class = center> </image><br> <br><br> CNC machining was utilized for this design to precisely engrave the screw holes into the wood, ensuring the screws would sit flush with the surface. Unfortunately, I discovered too late that the wood tends to split when screws are inserted from the side. While not ideal, the shelf is functional and now resides in the common room as it's not particularly suited for areas prone to moisture due being made of plywood. <br><br> <p class = "margin"></p> <br> <image style = "width: 20%" src = "Cnc Machine.png" alt = "End Pic" class = center> </image> <br><br> </div>