Okay, so as it turns out, I needed to set the "top solid infill" to 100% and voila! Now I have a top surface. That was the same thing that I had set for my "first layer", you'd think I would have figured that one out yesterday...

I was noticing the problem with my prints and decided to take a look at the g-code in Repetier. When you look at each layer you will notice that the horizontal shells don't change, there is always one on the bottom and three on the top. I am slicing at .1 mm and I want 7 layers for my top and bottom... no such luck. It doesn't matter what number I use in the configuration, I always get the same in the g-code. 1 solid bottom layer, followed by a hollow layer, followed by three filled layers. The rest of the g-code is normal until you get near the top, then it's a filled layer, followed by a hollow layer, followed by three filled layers and no solid "shell" at all on the top.

Please take a look at the g-code in the editor and check out your layers, don't just look at the print as it might look pretty good even with this strange slicing going on. Scroll through one layer at a time and you will notice a huge difference between the bottom layer and the rest of the filled layers as the bottom is the only layer that is truly solid.

If anybody can figure this out, please let me know. Slic3r is an amazing program and I am humbled by what it can do. However, this does seem to be a bug that maybe you can only notice if you are printing in .1 mm with a .1 mm first layer and a 100% first layer width (not the default 200%).

I'd be happy to share my g-code and .ini files if anybody wants to take a closer look.

The fill looks like it does what it is supposed to now in a .1-.12" wall. The top surfaces are not any better than the infill below and are not solid as they should be. I have the horizontal shells set to 2 layers. Extrusion multiplier bumped to .9.

What other settings can I change to get the top surfaces to be solid fills?

I'm doing a rectangular part now with .12" thick walls. It does the two perimeters with no infill between them.

Why won't it do the infill? Seems to be consistant regardless of a straight wall or curved wall part.

Horizontal shells> solid layers has no effect on the top surfaces that I have found. They are left open or appear more as infill as your pictures show. I tried the default settings and they produce the same problem.

What settings are changed/set to have it work so well that Slic3r is the apparent favorite?

On the other hand, Skeinforge parts close and fill in the top surfaces completly. It does take longer to slice and has fewer settings than Slic3r, but it does produce good parts.

Note, these settings were for a layer height of 0.1mm, you might get away with less top layers if your height is different. Try printing with 6, watch it, and see if you can get away with less.