The presentation model was manufactured using a CNC milling process which involves 3D CAD modelling software and specialist CNC milling equipment.
This process uses a computer controlled router to cut predetermined shapes from a sheet of material, in this case 0.9mm aluminium and begins with a 3D CAD model :
The predetermined shapes are generated from the above 3D model which accurately models the size and shape of the design, including the width of the aluminium sheets to ensure all of the pieces fit together neatly.
Once the design has been finalised the model is digitally dismantled and each piece laid out onto a flat horizontal plane. The pieces are then arranged onto a standard size sheet to ensure minimum wastage during the cutting process.
This 3D sheet is flattened to form the final 2D cutting list which is translated by the CNC machine into x,y coordinates and used to cut the sheet of aluminium.
The sheets of aluminium come with a protective layer which is peeled off to reveal the finish. The pieces are then removed and prepared for assembly and spraying. As the tooling used to cut the metal sheets leave a serrated finish, a metal file and various grades of sandpaper can be used to smooth the edges, ready for gluing.
Other tools required for preparing the metal pieces include a file, small handsaw and masking tape. All rough edges left by the milling process are removed before glueing. A two-part epoxy resin is then used to bond the pieces together.
The masking tape is used to temporarily hold the pieces together to allow time for the adhesive to dry. The model is assembled gradually and in order so that each piece is firmly fixed before the next piece is added.
Once the glue has dried the masking tape can be removed and the excess glue sanded to leave a smooth surface for spray painting.
It isn’t possible to cut curved pieces of metal using CNC milling. To produce the rounded piece a paper template was used to produce the flat 2D shape. This flat shape is then formed around a preformed curve to make the curve. The curved shape is then gradually filed and sanded until it fits neatly.
The model is then prepared for spraying by sanding and smoothing all surfaces with a fine grade sand paper, taking care to retain sharp edges at the joints and removing all excess glue. A white primer is used as an undercoat, which allows the final coat of spray paint to adhere correctly to the aluminium and provides a base colour improving the appearance of the finished colour. Fine coats of primer are added gradually, building up thin coats of paint.
The finished model……..