Model "thickness" question

I have a Taz 6 and have been printing pretty much exclusively in PLA with the exception of the nGen sample that came with the printer. For the most part the models look really good. There are a few artifacts that I need to fine tune over time, but a nagging issue I have is the overall thickness of my printed pieces.

For example, if it’s a multi part model that requires assembly, the fittings are extremely tight. I’ve yet to get anything to fit without a considerable amount of sanding. Along the same lines, I’ve had some models that had some sort of decorative pattern on the top or bottom laters that doesnt show up. For example, the Benchy model I printed out should have some text on the bottom, but it appears solid. Likewise, I printed the following business card holder from Thingiverse and the decorative pattern on the outside is also solid and not as pictured:

My guess is that an extra shell or layer is being added, but I can’t seem to figure out how to fix it. I’ve lowered the flow % to 90 and that seems to have helped the tolerances of fitting pieces together slightly, but its still snug and the other top and bottom layer issues still remain. I’m using the default settings aside from layer height (.2), nozzle temp (200), and infill % (20).

OK! I have been were you are except for the lettering issues.

On accuracy of parts interconnecting here is a thread I started and I got a lot of really good advice on. In that thread is a link to another thread I started on filament and how it contributes to accuracy.

Another issue I have hit on that I never posted about was the thickness issue you touched on. Now the links above may well settle your thickness issue but one thing I ran into was being American, I was designing using inches and fractions of inches. Then Cura converts it to MM. I think there were rounding issues. I started designing in MM and my thickness issues went away. (I hated it at first but I am really starting to like metric)

Good luck!