Data landscapes 4
Last updated
Last updated
The following section demonstrates the process of preparing a surface model for 3D printing, without going into too much detail about the complexities of the process. There are only a few points to consider here to make the transition from an abstract geometric object to a physical you can hold in your hand.
First we need to make sure the working scale is reasonable. Assuming we are working in millimetres then our grid points represent 1mm increments. The total width and height needs to fit within the printer’s work area e.g. 95mm by 95mm is reasonable.
We also need to get a sense of the depth of the object as it affects the 3d printing time and cost; a few millimetres, say 5 to 10, are also reasonable. The graph below demonstrates how to measure the surface depth by using the “bounds” component which calculates the lowest and highest “z” coordinates. Subtracting those gives us the exact depth of the surface.
After adjusting your surface for fitting with 20 mm maximum depth using the “sz” parameter of the graph. It is also a good practice to set the bottom most point at zero. This can be achieved using the “tz” parameter. At the end of this operation the vertical range should be [0, 20] or less; it is not mandatory to reach the maximum.
Thicken
Next, we need to thicken the surface into a solid object; we cannot 3D print infinitely thin objects. Thickness is related primarily to material strength. Generally, 2 to 3 mm are sufficient for plastic prototypes. Using values below 2 mm may result into fragile objects which may be damaged during print of post processing. For best results you may always consult with the FabLab staff.
There numerous approaches for creating solids from surfaces. Here, we use extrusion which amounts to making a copy of the surface along the vertical direction and filling the sides with capping surfaces. The “extrude” component requires a “base” surface and the “direction” of extrusion. We use the “z” direction scaled by the thickness. For your 3D prints use 2.5 mm of thickness.
Triangulate
3D printers can only process triangulated geometries, as opposed to what we have i.e. smooth parametric solids. We perform triangulation using the meshing component to convert the solid into a rapid prototyping ready object.
Triangulation of surfaces and solids is a fairly complex topic. To simplify the process we will use the “mesh brep” component with its default parameters. If the mesh created does not look as your surface consult with the teaching assistants for help.
Instantiate
The visual programming environment renders geometries on the screen directly for performance reasons. We first need to “bake” the triangulate geometry, ie. insert in into the CAD document, before being able to perform the last step of the process.
Right click over the “mesh brep” component and select the “bake” context menu item. This will cause the geometry to become selectable in the viewport. You may turn off the visual programming rendering mode for the next step.
Export
The file format used for 3D printers is call “STL” with stands for stereolithography, one of the earliest methods developed. We need to select the generated mesh and export an (*.stl) file we can send to the 3D printing software.
In this session we extended from planar point grids construction to spatial surfaces using the scalar fields concept. The aim was to practice with nested data forms, to introduce surface modelling and prepare for the second assignment.
Additional materials removed from this session for length, include applying the same techniques for procedural image generation. In the manner we use the x and y grid coordinate of the picture and emit pixel color values instead of vertical displacement. You may review the material for additional ideas and techniques [>].
