Oh - I just saw the prusa benchmark. That's completely unfair. The lighting is different. Either it's a matt black filament or you didn't position the light to maximize reflections. I see zero reflections on the benchmark.
Remember - these tiny ripples are too small to measure with a micrometer. Too small to feel. The only reason you can see them at all is because the black filament is so shiny that it shows very very tiny changes in slope as either a reflection off a ceiling light or off of the ceiling next to the light and the difference of a tiny change in angle is the difference between black and white. Literally black and white.
Wow. Okay. I could talk for 3 hours about this. I was expecting something more severe.
First of all glossy black filament shows up changes in surface angle if you hold it up to the light just right. You have to get the angle perfect to see these surface bumps. However it's extremely easy for a human to do this as we do it all the time. We just naturally are experts at holding something so the light catches it just right to see these specular reflections that show off tiny changes in surface slope. However if you tried to measure them with a micrometer you would have a lot of trouble.
So one person's "horrible quality" is another persons "fit's so beautifully - the precision is amazing!".
And again, dark glossy colors will show this the most. If you go with a matte filament you will have trouble seeing this or if you go with white or off white. With dark glossy colors you get bright reflections and in between the reflections you have vary dark so you get good contrast.
These imperfections are pretty normal for me. I don't mind them. They can be removed but it's not easy.
Okay - now to how to fix this (for black glossy).
Well I would definitely try to find a filament that is less glossy (like carbon fill) but you can still improve all these.
Issue #3, "ringing" is caused because of the tension on the belts and spring factor of the belts combined with the heavy head gives you a particular harmonic ringing frequency. The frequency is worst if you decelerate for half the period of ringing. You can fix it by setting the acceleration and speed such that you get a whole period of ringing. Think of pushing someone on a swing. If you push half the period (when they move away from you) then you can maximize the swinging. If you push equal amounts when they move away and also when they come back, the swing only swings once. If you measure the distance between lines and know the print speed for that wall you can divide speed/spacing to get frequency of ringing. Those look like 1mm and if print speed was 30mm/sec then your ringing is 30Hz. To cancel ringing you want ringing frequency = acceleration / speed. So if outer shell speed is 35mm/sec and ringing is 30Hz you want acceleration to be 1050mm/sec/sec. If you print at 100mm/sec you want acceleration to be 3500mm/s/s. UM3 can handle acceleration up to 5000 no problem.
#2 The vertical lines in the last photo are almost certainly infill showing through. If you are only printing vertical walls you can uncheck "infill before walls". Or you can do more shells. 3 shells should hide this nicely usually. 2 shells might be enough.
#2 The #2 arrow to "ghost lines" may be infill or it may be just a common oscillation related to extruder, print speed, resonances. If it's resonances, I have found lowering the print temperature helps a lot - right to the point of almost underextruding. You can play with this in the TUNE menu and keep notes such that you can test 10 different temperatures all on one part (say a cube) and use something to mark the part as you print it to know which layer had the change (like whiteout for a black part or a sharpie for a light colored part). If cooling doesn't help try slowing down also.
#1 - I'm not sure what this points to. Is this the horizontal line? it could be underextrusion but more likely it's a dirty Z screw where the bed moves down too little on a few layer changes then suddenly moves slightly more on this layer change. Using thicker layers (e.g. .2mm layers) can help with this but best is to also clean the Z screw. A dirty Z screw will create lots of horizontal layer lines like this. Typically always in the same or similar spots. Since your parts don't seem very tall you might just clean the top half of the screw or top 1/3. I use paper towels and a screw driver to get in the cracks. Or you can use q-tips. WD-40 is okay for cleaning only - not for lubricating. I recommend some limited cleaning to see if it gets better. The Z screw is a triple helix so get all 3 grooves. It helps to have one person moving the bed up and down (with power off) while the other keeps something in the groove.
In general printing slower and cooler will fix all of these issues but who wants to print everything at 10mm/sec?
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