I'm using Slic3r 0.8.4 with a parimeter count of "1". Slic3r automaticaly adds more parimeters if it thinks it has to. Most of the time it uses 2 perimeters. If Slic3r notices that there are too thin walls in the object for placing 2 or more perimeters there it switsches back to 1 perimeter. The resulting thin wall seems not to be connected to the rest of the object and looks like perforated.

Disabling the generation of extra shells leads to a perfect result.(see last image)





I had this issue on several objects (for example objects with nut traps and so on).

This is a known bug and is being worked on.

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Great to hear! thanks for your information.

I noticed something similar. When extra permimeter is on, on small objects especially pins that need to fit into a hole (thingiverse thing:23030) they do not fit at all. the holes are printed to small and the pins are printed to big.
When scaling this thing to 35% and printing with a 0.2mm nozzle, the holes in the small gears disappear completely and are filled. when deactivating extra perimeter, it seems fine (at least in pronterface preview).
Maybe this helps in fining the bug.