tensile properties of the material to form short bridges without any support.
Imagine stretching a wire like a tightrope between two posts. If you have two
points in your model with a gap between them, the extruder can stretch a
single bead of plastic between them, and once it's solidified, it can build on
top of it! This is definitely an advanced technique, so your success will vary
based on material, print speed, temperature and the phase of the moon. If
you have a lot of bridges, the plastic will tend to droop. Both of these defects
are easily corrected by cutting away the drooping plastic with a sharp blade.
MakerWare will automatically calculate the movements necessary to handle
bridging for you.
However, this 45 degree rule and the bridging problem can be easily over-
come in several ways. First, MakerWare includes the option to automatically
generate “support structures.” Support structures are small bits of extra
plastic added to your model that form an easily removed lattice structure to
support those design features that don't have any material underneath.
Figure 8-2 shows support material that was removed from the center of the
Figure 8-2. Removing support material from a print
Another option is to manually create a structure in your model that sit just
below the “unsupported” design features. Adding supports such as vertical
0.35mm walls every 1cm should be more than enough to bridge a void. If
these the other options are not viable, the designer could chop up their de-
signs into pieces that can be printed without overhangs and then just as-
semble them after printing.
But sometimes you can just rotate the object on the platform in MakerWare
before you make it, too. For example, that would have solved the problem
with the arch without the need for support material.