How to CNC machine a geographic relief model
Creating a large 3D wooden relief model of EuropeA special type of model is a relief-model, based on topographic data (heightfield data). Working with this type of data involves very large STL files (hundreds of Mb data). It also involves very long toolpaths, as for a detailed result it is needed to use a small cutter, and thus a small toolpath distance is needed for a smooth result. DeskProto is very suited on both issues: the software can handle any size of STL file, and can quickly calculate long toolpaths. Also see the DeskProto tutorial video on geographic relief models.
Architekturmodelle - Werner in Braunschweig, Germany is a specialist in this field. This model maker creates great geographic relief models in wood. These models are marketed using the brand Scopulus.de. Models are made on order: any part of the world can be processed.
The complete Relief of Europe, as exhibited at the Euromold 2002. The dimensions of this model are about 150 x 75 cm (60 x 30 inch).
Starting point is a GIS dataset, created using satellite or airplane scans, which can be bought in several qualities. Werner have developed their own software to convert these datasets to STL and to make some geometry changes that are needed for this application. For instance the Z needs to be scaled up relative to X and Y. As said the resulting STL files are huge: a file size of one Gigabyte (!) is not exceptional for this application.
The centre part of Europe in DeskProto, and as detail the "Schwarzwald"(Black Forest).
This Relief Model of Europe, in wood, was exhibited during the Euromold 2002 show in Frankfurt and attracted much attention. Some facts about this model:
- Dimensions 1.45 x 0.75 meter
- Machined in three separate parts, using three STL files
- STL file size for centre parts 260 Mb
- Total toolpath length ca 15 km
- Total machining time ca 240 hours.
Milling the relief. First operation is Roughing, using DeskProto's Block strategy.
Werner uses a CNC milling machine made by Isel in Germany.
Two machining operations are used: roughing is done using DeskProto's Block strategy, and after that finishing using parallel toolpaths. For this finishing a small cutter is used: a ballnose cutter of 1 mm or even 0.5 mm diameter. For such small cutter the spindle speed needs to be high, and the feedrate may not be very high.
Finishing the relief using a ballnose cutter of only 0.5 mm diameter.
Architekturmodelle-Werner are glad that they have discovered the DeskProto software. They state: "We do not know any other CAM software that will accept these large datasets !" The toolpath calculations still have to be done in separate segments, and even on the fastest PC will take many hours. The result, as you can see, surely makes these efforts worthwhile.
The Cote d'Azur, and next a 'satellite view': looking south-west from the Baltic.
About their relief models, Werner states as follows:
"In order to create these relief models, we have combined four distinct specialist fields: geology, software development, CNC machining technology and marketing. We offer, currently perhaps without competition, exact morphological relief models in many sizes and scales, in wood, metal and plastic. We convert pictures of the earth into 3D !"
The center part of the Europe Relief. Click on picture for a larger view