American Dave: Vacuum-formed Dalek
Although seen here as a work in progress, Dave's Dalek is showcased because of its uniqueness. This is quite a special Dalek build, as the methods used to make many of the parts are so unusual. Dave is fortunate enough to have access to a friend's ShopBot. This is a CNC router that utilises files made from a program called ArtCam. Many of the parts have been made using the ShopBot. The larger sections, like the shoulders, are also unusual in that they have been made using vacuum-forming techniques.
How it was done...
The photo shows the ShopBot cutting a piece of twelve-pound density carving foam. The part being worked on is the pattern for the iris at the front of the Dalek's eyeball. This foam is really hard, but carves easy and leaves crisp edges. It is ideal for making parts for vacuum forming.
This is the vacuum-formed dome, made from .060 styrene. The styrene skinned beautifully over the carving foam and was used to make the original 'former'. Air travels very well through the foam, giving excellent vac-forming results.
Dalek hemispheres produced in the same way. The plastic was vacuum formed over eight plastic hemispheres bought from a craft store. They were filled with two-part urethane plastic and then sanded and finished, ready for the vac-forming process.
Here the shoulder-forming sections have been plugged top and bottom with a piece of scrap wood. Holes were drilled in all of the low points in the model. This allows air to escape from under the plastic and creates a better result, as it allows the air to escape from all of the nooks and crannies.
The photo shows the front section of the shoulders being vacuum formed. Before melting the plastic, a brush was used to spread some talcum powder over the entire model. The talc is slippery, allowing the finished piece to be removed from the original very easily.
Dave decided to cut the shoulder slats on the ShopBot. It wasn't a difficult shape to program, but each slat has several parts. Each one is in several separate pieces: The main piece, two plugs for the bolts, a middle insert piece and two angled bottom (side) pieces.
