3D Printed Sphere, How to Remove Roughness I have a model of an eye that I custom made in Blender 2.83 that when printed only creates roughness on the printed object near where I had the supports.  The supports are not the cause of the roughness (at least not completely) since the supports don't even touch the parts of the print where the majority of the roughness and bumps are (refer to my photos of the print)
The roughness is only near the bottom part of the sphere as it prints upwards (refer to photos)
What I'm looking for is a technique or any suggestions for printing this without the roughness so it's smooth like in the rest of the print.  I'm also curious what is causing the roughness.

Eye Model in Blender

Blender Scale Ratio: 0.001
Blender Units: mm

Eye Model in Prusa Slicer
Layer Gif

Prusa Slicer Main Settings (Higher Res)

Variable Layer Heights For Smoothness


Eye Model Prints Photos
Eye Model Small Version 3D Print (Notice it's smooth on top of print)

Eye Model Small Version 3D Print Trouble Area

Eye Model Small &amp; Large Version With Support (Notice roughness on the sphere)

Example of Support Used On Small Print

Smooth on inside of print


--------- Print Details ---------
Printer: Prusa i3 MK3s
Filament: PLA Galaxy Silver (Prusa Reserach)
Slicer Software: Prusa Slicer
Print Temperature First Layer: 205 degrees
Print Temperature Other Layers: 190 degrees
Notes: The suggested temperature for the filament is 205-215, I've adjusted after careful calibration given my environment to a lower temperature to reduce stringing.  I created a tower at different temperatures and discovered 190 was the perfect setting to reduce stringing in my case with this material.  Refer to my screenshot below.  I do not think temperature has anything to do with this since the print is smooth inside and near the top without any issues.
Temperature Tower Test For Filament Photo:
(Note stringing in the cone test areas at 225 to 205)


--------- Prusa Slicer Settings Photos ---------
Filament settings

Extruder Settings

Support Settings
While Trish is completely right that the roughness can't be completely eliminated (you can't print a perfect spherical surface with discrete layers), the situation can be improved dramatically. The most telling photo in your question is the one of the removed support structure.
The part of your sphere that's seriously rough is all severe overhang. In this region, the outer wall of layer N+1 barely overlaps the outer wall of layer N, if at all, and without support would be printed mostly or entirely over thin air, failing to attach to anything and sagging/curling down randomly according to tensions in the extruded material, air currents, etc.
Now, with support material that's not entirely the case. Every so often (looks like a 2 mm grid) there are support lines under the overhanging outer wall. These will anchor it every so often and keep it from curling or sagging too much, but they don't actually constrain it to the place the slicer wanted the wall to go, and they don't provide a surface for the extruded material to press against to get the desired (e.g. 0.4 mm wide by 0.1 mm thick) extrusion cross section; instead the cross section will tend to be circular as a result of tensions within the molten material.
In order to get a decent surface over support material, you need what slicers call &quot;Support Interface&quot; or &quot;Support Roof&quot; (these are the names Cura uses; I suspect it's similar in Prusa Slicer). This feature builds a top surface as part of the support material itself for the supported part of the model to rest upon and press against. Of course that can make support harder (potentially a lot harder) to remove, and depends on tuning the Z distance between the model and the support as a tradeoff between quality and difficulty of removal, but it should get you much better results.