Sphere and Complex Surface Quality
Creating a smooth sphere is a complex task for a 3D printer as its axes are positioned on a square frame. This means that the 3D printer must make minute changes in the X and Y axis multiple times per second to maintain a good spherical print. The same applies for surfaces that feature many different curves of varying degrees.
To test the printer's performance on these parameters, I have chosen two objects that have both spherical and complex curves. The Surface Finish Calibration Test and Female Statue Test are both designed to stress the printer's calibration as well as extrusion quality.
The Surface Finish Calibration Test is one of my favorite objects to print when testing surface finish, spherical quality, and complex curves. Here you can see some seaming created by the print head starting at the same spot for every new layer. The additional flaws are derived from layers not having enough time to passively cool before the next layer is started. This is easily fixable by adding a simple fan to the extruder head. Overall, though, the surface quality is not that bad, and a few minutes with sandpaper would clean it right up.
The female form is one of the most complex shapes in nature and includes a multitude of flowing curves and radiuses that can be really tough to print. Unfortunately, as with most PLA printers, cooling time between small layers is not long enough to prevent the distortion seen here. Again, a fan would really improve print quality here. I have printed this model several times in ABS and have not experienced this issue on anything but PLA.
Another angle showing the backside of the model. You can see where the overhang became too great for the still soft plastic to retain its printed shape. You will see that this is not an issue on larger prints that have longer layer print times that allow the PLA to sufficiently cool before the next layer is started.