Composites:

So we are at week #14 and getting closer to the end of fabacademy, and the topic of this week is composites. The assignment for this week is to design and fabricate a 3D mold (~ft2) and produce a fiber composite part in it, but of course before that we have to read the material safety data sheet (MSDS) and technical data sheet (TDS) for the resins that we are using.

Making the mold:

As am doing an electric skateboard for my final project I took the opportunity of this week in order to make the core of my project which is the board of my skateboard, and as Neil always says try to embedd everyweek into your final project and that is the goal of fabacademy. So the software that I used for this week's assignment was Rhinoceros, working with Rhino was a little annoying for me, because am used to working with Fusion360, but I chose Rhino because it has a feature (Squish) that I could not use in Fusion360 and from what I learned in fabacademy so far is that sometimes you have to get out of your comfort zone in order to achieve something.

I started by watching some Basic tutorials online on Rhinoceros, and then I began designing the skateboard and craeting the mold.

Then I created the 3d mold and used the feature which I was talking about earlier, which is Squish, this feature let you create squished layers from your 3D model which you can later cut in order to place them layer by layer in your final composite design. Looking on the web I found something similar on Fusion360 called ExactFlat, the issue with it was that whenever I tried to use it the laptop start operating slowly and I didnt get the result I wanted, but I wanted to mention it because someone might benefit from it later.

So I used the squish feature as I mentioned before on the skateboard and it created this 2D layer which has the same area of the outer surface of the 3D model (skateboard).

And then I created the two molds that am going to use to press the layers with while making the composite board .

Now it was time to create the toolpaths for the molds in order to mill them using the shopbot, so I created the toolpaths using VCarve Pro.

Then it was time to mill the mold and I used the shopbot to mill the mold because the mold was very big, and for the material, I used this material which is high density construction foam.

After that I had to prepare the working area, first I fixed the cork board to the shopbot using double tape and some clamps, after that I had to zero the three axis to start milling, for milling the rough pass I used the 1/2 inch straight and for the finish I used 1/4 inch ball nose. Then the shopbot started milling the job, when everything finished I had to sand the mold a little bit, and everything was good.

Making the composite:

The First thing to do before starting to make the composite board was to determine the material that am going to use for making the board, for that I chose 5 layers of 1.5 plywood and 3 layers of burlab and one layer of cloth, then I took the 2D shape that I generated using squish in Rhinoceros and imported it to CorelDraw to cut it using the laser cutter (Universal VLS 6.60).

To cut the burlab which is not listed in the materials data base of the machine I had to use the setting for the construction paper with a little modification, so the power was 100 % and the speed was 35% with a thickness of 0.61 mm, while cutting the burlab even after adjusting the power of the laser some of the threads were still connected so I had to use a sharp knife to cut them.

After cutting everything I ended up with 9 layers of different materials, and ready to make my composite board.

Then I started preparing everything to make my composite, after reading the data sheet I prepared all the saftey equipments and the mixing stuff.

After that I started mixing the hardner with the epoxy risin with a ratio of 1:5. after that I started applying the mix to the layers and place them one by one on top of each other, for the wood I used the brush to cover it with the epoxy risin but with the burlab I had to dip it inside the mix and then place it.

When I was done I placed the other mold on top and clamped the whole thing and left it for the next day.

The next day I opened the mold and took the board out it didnt look good because I have to sand it, so I took it and I sand it from the sides and it looked really nice and it was hard and strong, I was really proud of what I did.

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Attachements:

3D model Rhino

data sheet - 1

data sheet - 2