WEEK
9: COMPOSITES
Interesting week in which I had time to 1)
get more confortable with the shopbot and 2) learn
how to deposit fibers and resin in a mold in order to create a composite
material.
I decided to fabricate a slot car track. As
you probably know, slot car tracks have a slot for the guidance and two
conductive lines carrying the voltage and ground, powering the car«s motor
directly from there. I used burlap (fabric) and resin (matrix) for the mix.
Also, Guillermo was kind enough to give some conductive fabric that I used for
the power.
I used solidworks
for the design and brought my model to the shopbot to
mill the surfaces. I used partworks 3D for creating
the file that the shopbot needed. I realized that
when no 3D surfaces are needed, partworks 3.0 creates
paths that are an order of magnitude faster. This time I used partworks 3D because I wanted to get comfortable with the
workflow to create interesting surfaces, but I could have created a very
similar mold just using 2.5 axis.
Once the mold was ready, time to prepare the
composite. One layer of plastic (to release the composite easier), 2 layers of
conductive fiber, 3 layers of burlap, 1 layer of bleeder (plastic with holes),
2 layers of breather (cotton).
It was quite magical to see the vacuum bag
in action.
The result was interesting. A couple of
issues:
- The part of
the mold that was gonna
create the center slot of the track was pretty weak and could not handle the
pressure, so it deformed a bit. Consequently, I was not able to get a deep
enough sharp slot for the guidance. Probably an MDF mold would have helped.
- The fiber«s
conductivity is not as good as expected. The resin probably affected its
surface«s behavior.
While I was working on the slot car track,
an interesting idea came to my mind. Robotically reconfigurable apartments are
part of my research here at the lab; robotic walls,
dropdown furniture, and so on.
When talking about dropdown furniture
such as a bed, composites can provide:
1) Lightweight
rigid structures
2) Interesting surfaces
that can add another layer of experience to apartments
In order to start exploring this potential
and get a better grasp at the mechanical properties of cheap composites such as
burlap-resin, I fabricated a beam.
The result was pretty satisfactory. I«m looking forward to doing further tests.
