20mm Cube sticks out at top and bottom

I have a 20mm cube that I'm trying to print that appears to get wider at the top and bottom and I can't figure out why. It appears this way in the print preview as well as in the final print itself. I've attached (and linked) an image of the print preview. Any idea why this might be happening? It's just the standard hollow 20mm cube model.

[puu.sh]

Here's a 10mm cube. Scale it to any size you want.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Seems like it has something to do with the top and bottom solid layers..
Try disabling the top or the bottom solid fill and see if it keeps the problem away.

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Master Tinkerer

It looks like you're right Montiey. I'm currently printing out the_digital_dentist's 10mm cube that I scaled up to 20mm and it's coming out just fine. I think the difference is that the 10mm cube is solid and not hollow, so as soon as any infill is involved it does 3 perimeter walls as opposed to 1. Note: I'm using a .6mm nozzle and for some reason slic3r makes that only do 1 perimeter wall when hollow.

You should be able to change that. I use 2 perimeters, and 3-4 top/bottom layers. I recommend setting up manual extrusion widths if you use Slic3r. I switched to cura, and while it lacks filament profiles, its more reliable.
I dusted off my old slic3r settings here:

Note that this is for a 0.4mm nozzle, but should give you an idea of what seemed to work for me.

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Master Tinkerer

Just bear in mind that any time you use a percentage in the slic3r settings, that this is multiplied by layer height. So the 230% in the settings above mean an extrusion width of 0.23mm if you're using a layer height of 0.1mm.

This means a terrible first layer if you're using a 0.4mm nozzle.

I recommend a first layer extrusion width of 0.6mm, (type "0.6" into the first layer extrusion width setting in slic3r). This works really well for me, and stays constant if you start playing with layer heights.