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Machine the bodywork for a roller-coaster car

Manufacturing the bodywork for the cars of a new roller coaster

The Swiss manufacturer of large fair-attractions Giovanola had a new Roller-Coaster designed by the Swiss design bureau iDE (Innovative Design Engineering). The design of the housing of each 'cart' has been created using the Alias (tm) CAD-system, which is a very good tool for freeform designs like in the automotive industry.

The production of the housing (small series) will be done by hand using polyester layup methods, so a mould is needed. This mould should of course exactly match the CAD-design, asking for a Computer Aided route to create it. This is where DeskProto comes in: the Dutch model maker Joop Aarts calls us for assistance.

This application story is one of the earliest projects in this Gallery:
it has been completed in 1995, using DeskProto V1.0

Alias software screenshot
STL-file screenshot
A screen-shot of the Alias (tm) software showing the design, and a DeskProto V1.0 screen showing the STL-file.

Joop Aarts wants to create a negative mould (hollow), and needs a positive model in foam to create it (by casting the mould around the model). Four moulds are needed: for the first cart the bottom shell and both side-shells (different for left and right), and for all other carts the side shell. The geometry is shipped from Switzerland on diskette in the form of STL files (Alias can directly export these).

In DeskProto the STL-files are read, the geometry is correctly rotated, and NC toolpaths are calculated. These are sent out for milling to a third party (as the available desktop CNC milling machine is far too small): the Dutch moldmaker Jadima. As the illustration below shows, Jadima's milling machine in fact is not large enough too (dimensions 1,200 x 700 x 450 mm), however by milling some separate segments after one another it works out fine. The models are milled in PUR foam (quite roughly), and further finished by Joop Aarts.

NC toolpath
Milling process
Left: DeskProto window showing part of the NC toolpath (the first layer)
Right: The actual milling of the prototype, on a three axis Deckel machine.

Manufacturer of the Roller-Coaster:
- Giovanola Freres S.A. in Monthey, Switzerland

Design of the Roller-Coaster:
- Innovative Design Engineering (IDE) in Belmont, Switserland
- Creation of the production moulds:
- Joop Aarts Design in Beek en Donk, the Netherlands

Calculation of the NC milling paths:
- Delft Spline Systems in Utrecht, the Netherlands

NC milling operation:
- Jadima Fijnmetaalbewerking bv in Ede, the Netherlands.

closeup shells
The Roller-Coaster performing a test-run with two prototype bodywork shells.

In the images above the side-shells of the first two carts can be recognized. (the others are not present yet on this photo). Only after careful testing the complete series have been manufactured.