Week 14: Composites

Making a Laptop Hardcase

For the assignment we have to design and make a 3D mold (~ft2), and produce a fiber composite part in it. After thinking about surfboards, I decided to make a this laptop case instead. The design includes two cases, the top and the bottom of the laptop, jointed by a zipper.

Software: Rhino, PartWorks
Textile Experiments: Jute, cotton mixture (one coloured, one white); Resin, Proxy
Machines: Milling ShopBot; Vacuum Press; Lasercutter

Overview - Working Process

* generate Rhino design of casting form
* generate 3D milling strategy in PartWorks; mill form
* experiment with different textiles and how they harden with Resin & Proxy
* Inkscape, Blender: laser cut textile / cut by hand
* apply chosen textile on laptop form

Design Casting Form

I drew a rectangle in Rhino in the laptop measurements (230mm x 330mm x 15mm) extruded planar curve and rounded the upper corners with the fillet edges command. I safed the file as stv and opened it in PartWorks to define 3D milling strategy.

laptop-shaped box

3D Milling of Foam

I actually made two (identical) forms to speed up the process

Experiment with Textiles

Together with Edgar and Cansu, I experimented with four different textiles (two are cotton/synthetic mixtures; one is jute; one is 100% cotton) that we put over wooden blocks. They all absorbed the resin/hardener mixture well. The resin epoxy (super sap) and hardener epoxy (super sap) mixture is 1:2 (by volume) or 100:47 (by weight). The form needs to be layered in foils, this is the layering bottom up: * plastic foil (protects vaccum press)
* cotton material (to absorb exess resin)
* breathing material (perforated red foil)
* form + textile (plastic foil between form and textile allows to reuse the form)
* breathing material (perforated red foil)
* cotton material (to absorb exess).

the workbench

mixing resin & hardener with a scale...


soaking the textile, putting textile in its "foil bed"

wrapping it on object


ready for the vacuum press and in there for 20 hours

all four pieces are solid. theys consist of: 100% cotton textile & cardboard, I tried to incorporate the mold of an arrow, but it didn´t came out; top right is three leyers of a thin white cotton/synthetic textile; bottom left is one layer of jute with the white textile underneath; bottom right is two layers of the white textile and a coloured cotton/synthetic one on top

taking out the forming wood

there is a lot of resin/proxy left over. while this adds to the stability, it is also a waste of material. the lapop case surely can do with less

I like the jute and colourful fabric best

Lasercut the Textile

Next task is unwrapping the surface in order to laser cut the textile. Following this tutorial turning the model in a nurb in a mesh and back into a nurb did not work and produced the result below. I also tried to explode the surfaces and unroll them individually, however, Rhino let´s me do the arrangement on the plane, which basically results in unprecise guesswork on my part.


In a next step, Ferdi helped me produce the textile cut layout in Blender, which I used as a guide to draw the outline in Inkscape.

Blender guide

Inkscape cutting pattern

I made a mistake in the Inkscape drawing. In consequence, the corner ears are cut out instead of being part of the textile. Instead of going back to the design, I decided that it would be quicker to just cut the pieces by hand.

Using a ruler, a pen and the first lasercut piece, I drew the shape on each of the 12 pieces and cut them out by hand.

Final Result

While during the testing we worked in a group of three, for the final laptop case I went through the Resin process by myself, which was not the best idea. Mixing new resin in a precise measurment, while wearing gloves sticky with resin and 12 layers of textile to be soaked without getting stuck to the wrong side of a foil really requires more hands. However, the outcome looks nice:

The final case, still missing the zipper and nice textile inlay.

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