I designed and made this thing: http://www.thingiverse.com/thing:918608/
In itself, it's a vaguely interesting, potentially useful thing to make. More interesting are some modeling tricks to avoid supports that I'm trying out for the first time.
I came across this idea on nophead's blog some time ago. It's a way to print a hole in midair without supports, something which is not normally possible because you can't change directions while bridging. All bridges must have straight sides across the bridge. The idea is to approximate the hole as straight sided polygons on successive layers until you have enough support to continue printing normally.
In this model, I wanted a nut trap with a cavity for the nut that extended from an insertion slot towards the screw. For other support related reasons, it needed to extend upwards from the bed. This can easily be handled in Simplify3D by dropping a single manual support block under the hanging corner of the hex hole within the insertion slot, which is pretty easy to remove. It could also be handled by drawing in some manual supports to do the same thing, but I decided to try nophead's idea here, and it worked great. This is the simplest possible case, where I'm just building up one hanging corner instead of trying to draw an entire polygonal hole, so I just needed one additional layer.
A cutaway view of the model from the back, looking up:
First bridge layer:
Turning the corner in the second layer:
This is great because the recess for the nut is relatively inaccessible. For printing hanging circular through-holes without support, I used nophead's other trick of putting in a single layer diaphragm which can easily be drilled through, or even picked out with some tweezers.
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