On Friday, Mickael gave us a lecture on composites. We would be able to work with natural linen and jute. I decided to keep it relatively simple and started to create a mold for a wastepaper bin. After reflecting about it, I wanted to use vacuum bagging in order to be able to put pressure on all sides. Made out of three thin layers of linen, the bin should be very light and look somehow out-of-the-way.
Design process and original design files of composites
To be able to laser cut the linen, the bin’s size was limited. The final dimensions were 21 × 21 × 34 cm. Using Inkscape, I created two overlapping laser cut patterns. I cut the linen with speed of 1% and power of 100%. Cutting, it was important to weight down the textile.
Using Rhinoceros, I designed and simulated the object.I considered to use the ShopBot to mill a foam based mold. As we checked, the ShopBot got a maximum milling height of 8 cm. I would have to mill 4 pieces and glue them together. Besides, I would have to remove the mold. Finally, I scrapped this concept and used 123Make to create a mold skeleton based on 3mm cardboard. In 123Make online, I imported a STL file of the mold and exported DXF laser cut patterns. To save cardboard, I limited the layers. In Inkscape, I drew some outer walls. I cut the cardboard with speed of 0,6% and power of 100%. Due to haste, I wrongly set the speed. The cardboard got partially burned. The speed should be about 2,7%.
Original design files and production of mold
I made a dry test applying the laser cut linen and putting the mold into a big vacuum bag. Vacuum bagging, the mold seemed to be stable.
I started the day cutting some more baking paper sheets as well as a breather. I put vaseline on the mold’s top layer (baking paper). We were 4 people producing fibre composite parts at the same time. We all used the same resin which had to cure 24 hours. We got 90 minutes to apply our composites. Several times, we mixed new resin. It was a real sticky and dirty job. The air smelled poisoned.
Photos of production
I applied the first layer of linen using a brush to spread resin on it. It was difficult to precisely work. Everything was wet and sticky. I applied a second and a third linen based fibre composite layer. Then I applied a layer of perforated baking paper, a layer of perforated cling wrap and finally a breather (soft material—so air is able to escape). I put the mold into the vacuum bag and start vacuuming. The mold deformed. A three layered cardboard skeleton wasn't stable enough finally. I didn't care so much because this could give my bin a less strict look. Now, I had to wait for 24 hours. I was excited to see the final result.
After 24 hours…
Though my vacuum bag didn't retain, the result turned out well. The linen fibre composite is strong. The wastepaper bin’s design is simple and subtle.
P.S.
We used two different ENTROPY RESINS. Due to hectic group working, we unfortunately interconvert the resins. Finally, this clutter didn't affect results. All our fibre composites turned out well.