Introduction

This week we learnt about making composites. Basically what we need to make a composite is a fiber and a resin. There are many examples of composites of common use, for example fiber glass or concrete (with rebars). The basic idea is to have a material that works well on traction and another that works well con compression, and by mixing them or making a fusion in order for them to work together, to have an excellent resistance with the combination.

Assignment

Make something out of a composite.

We decided to work mainly with burlap at AS220 and also with natural resins that are not as toxic as other things such as carbon fibers. I understood there were two main methods, the first one using a vacuum and the second one by making a "sandwich", I decided to make a sandwich in order to produce a surface with an interesting texture, later to be determined in what it would be used. So it was important to do a little bit of 3D design to later use the ShopBot to mill foam:

3D design, after this it became an STL file and then it went to Project Works 3D to become a readable file by the ShopBot.

Then I went to the ShopBot with 2 pieces of foam exactly the same size as the model (14"x14") and started milling the foam over two passes: the first rough pass and then a finishing pass.

The ShopBot doing what it knows best!

I had then my two pieces of foam that fit together as a key. This means that if I put something in between it should catch its shape! That's what I plan to do with the burlap.

Now they're real.

Since the resin that is going to be applied to the burlap produces an exothermic reaction, the foam would suffer from it and melt. This has happened before! This is why I coated the foam with two layers of Acrylic Matte Gel so that it would fill its pores and make it stronger and harder on the surface.

Drying times for the first layer were a little bit long.

Next, it was very important to also coat with a couple of layers of this wax I used as a mold release. I used gloves and just got my gloves dirty...

Everybody loves mold release... because it SHOULD work perfectly... right?

After I gathered other important pieces and safety equipment such as gloves, breather, goggles, the resin, clamps, amongst others, I started coating the burlap with a lot of resin but then also straighting it out with this yellow tool in the picture:

VERY messy.

I used 3 layers of burlap and then placed them on top of one of the sandwich sides. It looked so nice:

Almost finished!

After the second sandwich part was on top, I also gathered wood pieces that wood make the clamps not destroy the foam (one piece on each side) and then all of my clamps to hold the sandwich together. Some resin came from the sides as expected, because it's supposed to squeeze it and make it bleed... But not much.

24 hours like this in order to have it dry and to open the whole sandwich.

And after so much effort, this was the most frustrating part. The wax "mold release" was not good enough and the foam stuck with the resin. Also because it was too much resin and the bleeding was too little. I think that the surface I tried was too "rugged" for this sandwich method. I could have used cling wrap to prevent this but the cling wrap would have stuck with the resin. I could have also used a bleeder - breather but with this kind of surface it would have been difficult...

I had to spend a lot of time clearing the foam and I couldn't have my mold back, which is what I wanted... :(

I used a dremel to clean out and leave at least one of the surfaces the way I wanted it to be. It came out nice and, if I have enough time I will try and cover it with a nice paing because the colors are not good.

I still don't know what I will do with it...

It is very frustrating to work with resin for many reasons. One of them is that it is a very messy method, and the other one is that after doing a lot of work, there are big chances of having a failed product. I believe that if someone does this on a regular basis then the workplace would be properly conditioned and ready for the mess -- therefore not messy in the end. And also, experience would eliminate nopefully troubles such as what I had with the foam...

Files

File 1: SketchUp File here