Graphics Programs Reference
In-Depth Information
milling). 3-D printing involves the extrusion of micron-thin layers of plastic to build up an object layer-by-
layer inside a 3-D printer. Milling is performed by a robotic arm with a cutting head that effectively carves
away a shape based on 3-D data.
3-D printing allows for far more delicate pieces and retains fine details. The drawback can be that the size
is limited to the size of the printer bed. Milling, on the other hand, works very well for large objects. Because
the machine head tends to carve out of foam, your detail can be limited to the size of the smallest mill head.
This can work just fine, especially for very large figures where details would actually be much larger than
they would be on a smaller maquette. Often a 3-D mill is further finished with real-world sculpting before
being molded and cast. A 3-D print may be reworked but often with the newer high-quality machines, the
piece off the printer is ready for molding after a light cleaning.
3-D Printers
There are a few different manufacturers who produce 3-D printers. The two most common machines I have
encountered are 3-D systems Thermojet and the Objet “Eden.” I have worked with both and I find the Objet
printer to be stunning in its detail and quality of print.
Figure 11-1
shows the Objet Eden printer.
Figure 11-1:
Objet Eden printer
These printers work by a process called stereolithography. This process involves the extruding of a thin
layer of plastic called acrylic-based photopolymer, which is catalyzed by a UV light. Each layer is so thin it
must be measured in microns (or micrometers) rather than millimeters. The Eden machines from Objet lay
down layers of plastic that are merely 16 µm thick (the symbol µm means microns, or micrometers—i.e.,
a millionth of a meter; you will encounter this in the documentation for these kinds of machines). As each
layer is extruded and cured, a new layer emerges, effectively growing the part from the printer bed (
Figure
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