For Composites Week, I decided to make a simple cylindrical planter using burlap and epoxy. The shape of the model was fairly simple to figure out once I determined what size I wanted my planter. I opted for an 8-inch diameter, 8-inch high planter that will hopefully hold some fresh herbs and can site on my bench that I made during Week 8:Computer Controlled Machining.
Using the ShopBot, I milled out 5 disks. I remembered that I needed to stabilize the pieces so I screwed them down with a washer to keep from destroying the foam. Trying to be conscious of materials, I cut 3 circles from a previously used board before moving on to a new piece.
I measured and cut out my burlap pieces. To ensure I cut straight lines, I pulled out one string and was able to follow the void left behind.
I used 2-inch thick pink foam board insulation and a foam insulation base. Since I wanted the planter to be 8 inches tall, I chose to build up my mold from 5 layers of the pink foam board, making the mold a total of 10-inches tall. I wanted to give myself a little wiggle room for mitigating mistakes. I hot-glued the circle pieces together to make my form, which looked like a pink layer cake. I covered the entire thing with plastic wrap as the release.
I struggled a bit getting the burlap to stick to the mold shape while I built up the layers. Ultimately, I decided to sew the pieces together with burlap strings and that worked well. This allowed me to build up four layers of burlap.
Once the layers were sewn together, I moved forward with the AeroMarine Epoxy Resin and Hardener. I mixed them together according to the insturctions - 1 part hardener to 2 parts resin. I mixed this together and massaged the mixture to help the mixture saturate all four layers. I also used a scraper to ensure that an even application was applied to the entire form. Once I was confident that the epoxy had penetrated all the layers, I wrapped it in plastic wrap. I used the spiked roller to create protrusions in the plastic wrap; this allows for excess epoxy to bleed out. Then, I covered the form in a breather layer and put it in the space bag. I used a vacuum to remove the air from the bag and left it to cure.
The epoxy is curing! I have to leave it for 24 hours and will proceed tomorrow.
48 Hours later...
This is the exciting part! I opened the space bag and peeled off the cotton layers. My biggest concern during the curing process was the formation of large wrinkles. Luckily that did not happen and the surface is very smooth.
Once I started peeling layers off, I realized that I did not adquately design my mold to stay in one piece after the cure was complete. Orginally, I had imagined that I would be able to slide the composite off the top of the foam mold but it was held so tightly together that the only way to remove it was to destroy the mold. It took a significant amoutn of physical effort to get the two separated.
Diggin out the mold
Finally!
For my final object, I wanted the planting pot to be 8 inches tall so I built the mold up to be 10 inches tall. This gave me some extra material at the bottom that could be used as a sacrificial finish. I designed the planter so I could cut off this messy portion and be left with a very clean top edge.
Final Planter
Jessica Metz Fab Academy 2015