Information Technology Reference
In-Depth Information
Branching out with overhangs
It is possible to have the current layer slightly larger than the previous layer
provided the overhang is not more than 45 degrees. This is because the current layer
will have enough of the previous layer to stick to.
Hence a shape like the capital letter Y
will successfully print standing up.
However, if the overhang is too great or too abrupt the new layer will droop causing a
print fail, hence a shape like the capital letter T does not print. (If the T is serif and thus
has downward dangling bits, it will fail even worse, as illustrated previously.) So it is
important to try to keep overhangs within a 45 degree cone as they go upwards.
Building bridges
If a part of the print has nothing above it, but has something on either side that it can
attach to, then it may be able to bridge the gap. But use caution. The printer makes
no special effort in making bridges; they are drawn like any other layer: outline first,
then infill. As long as the outline has something to attach to on both sides it should
be fine. But if that outline is too complex or contains parts that will print in mid-air,
it may not succeed. Being aware of bridges in the design and keeping them simple
is the key to successful bridging. Even with a simple bridge some 3D printers need a
little bit more calibration to print it well. Hence a shape like the capital letter H will
successfully print most of the time.
Of course this discussion is purely illustrative of the way overhangs work or fail.
In real life if a Y, H, or T needed to be printed the best way to do it would be to lay
them down. But for purposes of illustration it still stands that Y prints, H prints okay,
T does not.
