Ugly 3D printing with high precision I am a totally beginner at 3D printing and I have this question: I see many 3D printers (at amazon) with Z precision as low as 0.1mm! To me that's amazing but what does not amaze me is this: when I see the printed objects of those 3D printers you can easily with naked eye see the "vertical steps". How?

A precision of 0.1mm should be really almost impossible to see. If a person printed using 0.1mm precision how can I see the vertical steps?

I know there are some smoothin techniques to make the surface better but that shouldnt even be needed if the printer actually printed at 0.1mm in the first case.
The 0.1mm refers to the thickness of each layer. However, it does not say anything regarding:


How precise the layers are in the XY plane
How precisely each layer is aligned with the previous in the XY plane
How consistent the extrusion is: are all the layers printed with a consistent line thickness


No matter how fine the layers (and these printers that you refer to can definitely print 0.1mm layers just fine); if they're not well-aligned with each other, or the filament extrudes inconsistently, you're going to see the layer lines. It takes a rigid printer, with low-play bearings, a well-calibrated extruder and filament with a consistent diameter to get smooth-looking prints (but you will always see some layering, especially if you look up close). Also, since filament is extruded in a round shape, the sides of the object are not perfectly flat, but consists of many small arcs, which makes it easier to see the layer lines.