For the past few prints with Prusa, I noticed strange ‘ringing’ and waves pattern- which I later learnt the issue is called ghosting. It was especially pronounced at the edge of the print like the flower patterns here.
At first, I wasn’t sure what was happening. I then started to search online what this phenomenon is. I learnt that this was a ghosting issue, which is a rather common issue with 3D printer- including Prusa i3. Quick check to Prusa website, it advised to check the belt tension for both X- and Y- axis. The belt tension should be between 240 and 300. To find the value, go to Support> Belt Status. I checked the status of my Prusa, the values for both were in 270s.- so there was no problem with the Belt tension.
I speculated that it might be the plastic, so I decided to use different plastic: same result. Next, I thought perhaps the issue is with Cura. So I used PrusaSlicer for next print: same ghosting result. Afterwards, I decided to update the printer profiles on Cura and PrusaSlicer: same results.
Getting desperate, I cleaned up the printer and greased the X- and Y- metal rods: same results. I played around with various print settings: slowing down the print acceleration, changing the infill pattern, changing wall thickness, slowing down print speed. Nothing solved the ghosting issue.
Tightening Y-axis Belt
I decided to check the Belt Tension more carefully and more thoroughly. When checking X-axis and Y-axis belt tensions, Y- belt felt somewhat looser than X- axis belt and yet they gave almost identical reading. I went on to tighten the Y- axis belt from the adjustable belt holder situated below the print bed. To do this, I needed to put the print on its side to be able to access the Y- axis belt holder. I tightened all the screws in the holder (without over-tighten them of course), and brought the holder ever slightly closer together. Once all completed, I ran the Belt Tension test and for Y-Axis, it gave a reading of 287- which is higher that previous value of 270s. The reading actually puzzled me because the higher number means the belt is looser- but I just tightened the belt!
I decided to run a test-print anyway. Lo and behold, it printed flawlessly just like a new Prusa would do! See the stark difference below.