Fusion360 / Shopbot / Epoxy and Burlap
After the training I had a better gauge of the limits of the composite process and decided to make a clock for my bedroom in the shape of Africa. The process would be:
1) Make a Sketch of Africa in Fusion 360.
2) Export to dxf.
3) Load dxf into VCarve Pro and create a tool path for a quarter inch end mill to cut wood.
4) Cut the OSB board and keep both inside and outside pieces.
5) Dye a piece of burlap and make designs on it.
6) Make the epoxy and prepare the burlap.
7) Wrap burlap around wooden Africa.
8) Insert it back into the wooden outside so as to get good corners.
9) Assemble everything and place in airtight bag.
10) Remove as much air as possible using vacuum cleaner.
11) Leave to set for 24 hours.
12) Post process to remove extra bits.
13) Drill a hole through the middle and insert the clock mechanism.
I found a large outline of Africa image on google search and imported it to a canvas in fusion360:
Things to bear in mind when tracing the image:
1) Make sure that the image is the correct size - I had to adjust the size, this can be done by right clicking on the canvas and selecting the calibrate option.
At first I exported the Africa sketch to dxf, but VCarve Pro was complaining about a premature end of file... So after examining the file in a text editor and not finding anything wrong with it, I uploaded it to a dxf viewer online and downloaded it as a dwg file, opened it in VCarve again and this time it loaded. I made the Africa shape in fusion360 with the spline tool - I think that this may have been part of the reason for the problem, but not too sure.
As soon as I began to mill the process was completed in no time at all.
I am planning to wrap the burlap around the wooden Africa. I cut darts in the burlap to help it 'sit' better. I realized that I could use the wooden piece that I cut the Africa out of to act as a 'mold' for the composite.
I laid may burlap pieces in order to get them ready for the epoxy. The epoxy is a mix of Entropy Resins A and B epoxy in yhe ratio of two to one by volume.
I wanted to see how paint would hold up with the epoxy. I used acrylic paint to create African shapes on the front piece of the burlap.
Step 1: Make the plastic breather layer by making holes in the plastic.
Step 2: Place the top layer front first into the mold.
Step 3: Place the wraping layer into the mold.
Step 4: Place the wooden insert into the wraping layer.
Step 5: Wrap insert.
Step 6: Place back layer to cover the wrap folds.
I added the foam layer underneath and on top of the composite + mold and placed it into the vacuum seal bag.
I left the composite in the vacuum tight bag overnight to set.
It came out quite well but it still required some post-processing.