The starting point for creating a 3D foam model of our barrio, was by creating it in rhino. Using google earth as reference, the buildings were mapped and extruded, producing the file shown above. Next the polysurfaces were transformed into meshes in order to continue work with the rhinocam plug in. Bearing in mind the dimensions of the foam panels the model was going to carved out of, the mesh was made with a thickness of 3cm. Furthermore it was necessary to split the barrio model in three, indicated by the different colors in the figure above, in order for it to not exceed the width of the panels.
After the model was finished, the settings needed to be adjusted in the rinocam in preparation for use in the CNC milling machine. It is important to choose the adequate tools for both the task at hand as well as the material to be used. In this case, three different tools were selected. The first tool (with a diameter of 26 mm) was implemented to roughly work away the superfluous material from the top of the foam model, the horizontal roughing. Next, the second tool (with a diameter of 3 mm) was used to add the detail to the 3D model. And finally, a third tool (with a diameter of 6 mm) was used to cut the borders, the parallel finishing. Each tool was set to operate at a different speed, according to the function it had to perform.
The figure to the right shows the panel which allows you to select certain specifications for each tool. Of special importance, within these settings, is the stepover control which needs to be chosen according to the sides of the tool. It is key to chose this parameter so that a satisfactory balance is achieved between the detail of the work and the time needed to perform this work.
With the correct settings in place, a block with the dimensions of the foam slab to be used was drawn. The 3D model and its borderlines were then imported into this block. In doing so it is paramount to specify to the program to work within the borderline.
The screenshot to the left, shows the setting and the simulation of the first passages with the first tool.
The screenshot to the right, shows the setting and the simulation of the second passages with the second tool.
The screenshot to the left, shows the setting and the simulation of the third passages with the third tool.
Then, the final model needs to be checked to see if there are any mistakes or any areas which may enter into conflict with the production process. The red lines indicate a potential problem during production due to the foam slab coming into contact with the holder of the tool at those places, causing the foam block to move. Therefore these red areas need to be kept to a minimum.
Once the above steps have been completed, we have 3 files to import into the CNC milling machine. There is one file for each phase of the process, ie the horizontal roughing, the parallel finishing and the horizontal finishing. With all three files loaded, the foam panel is placed on the worktop and fixed into position. Next the x, y and z coordinates of the machine need to be set, taking into consideration the tool size and the foam size among others, and the milling may begin. After the completion of each fase, the tool needs to be changed and the z-coordinate set new. As stated above, the milling of our barrio required the whole process to be repeated on three foam panels.
The milled foam panels were then perfected by sawing off pieces and sanding the surface.
Finally, our barrio was mounted on a wooden basis, alongside the other barrios of Barcelona.
