What causes this?

Dear experts,
So, what causes this and how do I prevent it?
Its like part of the posts some infill and some shell material.
Iris box from thingiverse.

 

What Slicer? Does the gcode preview look normal?

What are you using for the fan settings? Are you using the stock fan and bracket?

 

Um, slic3r and stock fan and mount and settings.

 

OK, I have no idea what the stock fan settings are. A screenshot of the Slic3R filament/cooling settings would help. They are pretty important for these structures.

 

That looks beyond what I would expect from any kind of stringing, which is usually just fine threads well under the diameter of the extruded filament... That looks like actual extrusion artifacts to me. What do those areas look like when you go through them in Repetier, looking at the layer range? Also, video (or a description) of what's happening when those odd bits are put down during printing might help diagnose it.

 

I agree that it looks like strange slicing. Probably not cooling because each layer should cool before it gets around to the same peg on the next layer. Did you watch these pegs print and was it extruding in mid air?

 

Didnt watch it. first one came out fine but the pegs had snapped off right at the end, this one dont know, i usually hit print then go to bed. will try and get some video or something, the sliced code looks fine.