Sally Williams @ Fab Academy 2015

Assignment: 

• Design and make a 3D mould, and produce a fibre composite part in it


Testpieces

For efficiency and so that we could all share in the learning, we made some test pieces as a group. A simple foam cube was suggested as a standard shape around which to impregnate and wrap three different weave densities with Epoxy Resin.





 

It was noted that the coarse weave has much more space inter-weave to hold resin, whereas the finer weave is tightly woven.

Epoxy Resin (Super Sap)

  

Weighing the 2 parts. Ratio: 2 resin - 1 hardener

Two kinds of application were tested:

1 - by brush;
2 - thorughly pre-impregnating the fibre weaving by gloved hand.




Test vaccuming of one cube:



Cured cubes:




3D Design for Composite Week:

I wanted to see the strength and lightness of a composite structure, something that was long and put under a bit of tension.
I designed a rest to span across a 680mm bath, to hold a few bits and pieces and a glass of wine.







Milling the foam core on the shopbot:

Feeds and Speeds used for foam:

Flat End Mill : 1-4 inch (6mm)
Feed rate = 5 IPS (inch per sec)
Pass rate = 1-4 inch (6mm)
Stepover = 50%
Plunge rate = 1 IPS

Due to foam size available, the piece had to be milled in two parts. These would be glued together (using Gorilla glue or similar).





A key has been in included to help locate and give best strength back into the structure. The plastic pipe section was inserted temporarily to protect a potentially weak area whilst setting up the jig and glueing the two pieces together.





















Test engraving the jute on the lasercutter to help with cutting the material at the right places and to help "lay flow"

 

In the test piece above, I have charred the weave with the laser. I had intened to use this to provide a guide for me as to where to best cut the jute to get the best lay of the material to the form.

The lines engraved below are the lines supplied with the solidworks vector lines. This took time to engrave. In future I would create a simplified line guide for key cutting points for creating darts, folds, etc.



Applying the principles of darts in clothing to try and get better form

  






Soaking the resin into the fabric by hand:



At this stage its difficult to imagine how this could possibly work:







This is how the bathrest looked after vacuum bagging:








Design was created in Solidworks, click file below to download .stl file:

bathrestsw.stl