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How to build a car body

Manufacturing the Savage Rivale extreme sportscar

At the Top Marques auto show in Monaco (April 2009) an impressive new extreme sportscar has been unveiled by Prince Albert of Monaco. It is the Savage Rivale Roadyacht GTS, a truly amazing 4 door supercar. What about the 6.2 liter V8 motor, pulling the car from 0 to 300 in less than 20 seconds ...
The car has been developed by Dutch designers Justin de Boer and Emile Pop. Their goal was to create the "ultimate" GT sportscar, to drive from Holland to the Côte d'Azur, open the roof and enjoy driving in the sun. Read the complete story on

first sketch
scale 1:4 clay model
Sketch (left) and 1:4 clay model (right).

In fact the car is not yet in production: presented was a full size prototype, which was created using DeskProto.
The development project has started in October 2007, with lots of sketches (on paper). One design was chosen, and for this design a scale 1:4 clay model was made. Obviously while making this model many decisions on the design were made. The clay model has been sprayed and detailed, resulting in a perfect (solid) scale model.

2D drawings of the main views
Rendering of the 3D CAD model
2D drawings, and rendering of the 3D CAD model.

Based on measurements of the clay model a series of drawings has been made of all main views of the car. These sketches then were used as templates for modeling the geometry in the Catia 3D CAD system, at Design Studio Motio Development. Modeling not only involved the outer body: all internal elements like chassis, engine, drivetrain etc have been modeled as well.

Catia screenshot of the front fender
Catia screenshot: same fender, ready for millling
Front fender: left part, right mould.

As the prototype to be made was meant to be a working prototype (so not an easy solid styling model), thin-walled body parts were needed. This meant elaborately modelling every part of the external body.
In addition, for each body part a mould needed to be created: the actual thin walled parts were made by polyester layup over a mould. And such mould must contain extra geometry (the yellow surfaces in the picture above) around the actual part (the grey surfaces).

DeskProto screenshot of the toolpaths
Foam model on the CNC milling machine
The toolpaths, and a mould on the CNC machine.

All moulds (a total of 49) have been machined by Komplot Mechanics in Rotterdam, on their Dynamight CNC milling machine (working area 5.4 x 2 x 1 meter). This is a three axis milling machine: which shows that three axis machining is sufficient also for very complicated models.

It has been a complicated project though: 49 moulds, half of which needed more than one fixation in order to machine from several sides. On average six operations per part have been used. The total number of NC files was 700, total machining time ca 600 hours. Komplot Mechanics surely is a heavy user of the DeskProto software!

Plastering and sanding the foam model
Resulting fender (polyester layup)
Sanding the mould (left) and two resulting parts (right).

In order to keep the cost low the moulds have been machined in dense polyurethane (PUR) foam. After machining the PUR foam needed to be plastered and sanded (the material is cheap, however this extra labour is it's downside). Each mould has been used to produce one thin-walled plastic body part. These parts then have been finished by trimming excess material and spraying with the desired high-gloss car paint.

CAD screenshot of the frame
The resulting 1 to 1 prototype
Left the chassis in CAD, right the resulting prototype.

Parallel to building the body parts the chassis has been built, and so have all internal parts. Mounting the body parts on the chassis then resulted in a complete prototype. The prototype was ready 1.5 year after the starting with the sketches !

The Savage Rivale at the AutoRAI in Amsterdam
The Savage Rivale being unveiled at the AutoRAI show in Amsterdam.

The Savage Rivale Roadyacht GTS was one of the eye catchers at the Amsterdam AutoRAI in April 2009. It was reported to be one of the objects most photographed at the show. Also many high-ranking visitors (including the prime-minister) could not resist to enter the car and dream away about driving it to Monaco.

The Savage Rivale at the To Marques show in Monaco
Flyer for the Savage Rivale presentation at the Top Marques show in Monaco.

As indeed Monaco was the next step:
at the Top Marques auto show in Monaco (April 2009) the prototype has been unveiled by Prince Albert of Monaco.