17. Wildcard week¶

Individual Assignment

Design and produce something with a digital fabrication process (incorporating computer-aided design and manufacturing) not covered in another assignment, documenting the requirements that your assignment meets, and including everything necessary to reproduce it.

17.1. Composite¶

This week I am going to test the composite manufacturing technique. I’m going to make the water container for my fountain.

17.1.1 Generating Gcode¶

In Solidworks, I reverse the container to make milling and laminate easier.

My mill tool has a maximum depth of 5cm, so I cut the model into 3 pieces of 5cm.

I use Aspire software to generate the gcode. I have extruded polystyrene plates of 4 cm thick, so I glue 2 plates with glue to exceed 5 cm of the model. I get an 8 cm block.

I draw a circle a little larger than the model. And I define the roughing operation by selecting that circle as the milling border to save time.

I select a milling tool 6mm in diameter, and choose 5mm depth of cut. I will select the feed rate later on the milling machine.

I also define the finishing operation. I select a 8mm diameter ball noise mill.

The simulation of both operations is shown below.

I do the same for the other sections of the model.

17.1.2 Milling¶

Our milling machine is the SW1325 by CNC Barcenas.

I select 12,000 rpm and Feed Rate 10,000 mm / min

I use double-sided tape to hold the plate.

I have had a problem in one of the sections. My mill turned into a disk.

This extruded polystyrene plate had a different glue on the inside (The 4cm plates I have bought are 2 2cm plates stuck together). This glue has stuck to the tool and has formed a very hard disk.

This glue disc has broken part of the mold.

But I’m not going to start milling again. I can fix it by covering it with a mixture of glue and shavings from the mold.

This is the complete mold.

17.1.3. Cutting cloth¶

To cut the sackcloth I design the cutting pattern in Solidworks.

I build the model as a surface instead of a solid.

I create a sketch at the base of the model, with the cuts that I will project on the surface.

Within the “Surfaces” module, I select the “Trim surfaces” operation. And I select the sketch above and the entire surface.

In “Surfaces” I select the operation “Flattening of surface”

This is the shape that I have to cut on the fabric.

I create the plane

And I cut the sackcloth in the laser cutter, but since it does not fit completely, I fold the sackcloth twice and I order to cut ¼ of the drawing.

Unfolding the sackcloth shows the complete cut.

17.1.4. Laminating¶

I put a plastic film on the mold.

Resin mix. I use Epoxylay 102 resin. It is made up of 2 parts.

I mix the following ratio: 100 from Part A -> 29 from Part B

This is the manufacturer’s SAFETY INFORMATION:

Avoid breathing fumes - use in a well ventilated area at minimum. NIOSH approved respirator is recommended. Wear safety glasses, long sleeves and rubber gloves to minimize skin contact. This material has a high exotherm (generates heat). Do not mix components in glass or foam containers.

I smear the sackcloth with the resin and place it on the mold. I put a second cloth to cover the holes in the cut of the cloth. And I paint with more resin.
I put a layer of perforated film, and a felt so that it absorbs the excess resin.

I put it in a vacuum bag and suck the air inside. And I wait 15 hours.

17.1.5. Result¶

When I take it out of the vacuum bag I discover that the felt has stuck in some areas. Maybe I’ll leave some area uncovered with the film. I also cannot remove the plastic well. I have used kitchen film, very fine. I think if I had used a thicker film I might be able to remove it better.

I use the dremel to sand the upper edge. So I can remove the plastic and the glued polyurethane more or less.

This container must contain the water from my final project fountain. I try to fill it with water and discover many leaks. So I decide to give him other layer of the same resin.