Raised lines on top layer surface Ender 3

Question

I have an Ender 3 for two weeks now, my first 3D printer. I think I have a problem with top layers. See the left 3 stones on the first picture. It looks like lines and it feels like raised lines. The outer lines (walls) are perfectly flat, but the surface in between has heavily raised lines. I started with the standard Cura profile for the Ender 3 and tried .2 and .12 mm layer height, 2-5 top layers, 1 to 2 top surface skin layers and 5-20 % infill, all gave similar results. The only setting that solved it is the ironing feature (the fourth stone). While this solved it, it feels like I'm hiding an error in my printing with this feature and I would like it to print decently without ironing. The cat shows that my printer prints fine if no top surface is present. I have an Ender 3, upgraded with some fan guards and bowden clips and use Cura 4.5. SKR mini E3 and upgraded bowden tubes are on the way.

1. Is this normal?
2. What could be wrong?
3. Is ironing a commonly used solution?
4. Any idea what might fix it (apart from ironing)?

Answer 1

I would firstly do a flow rate calibration:https://www.thingiverse.com/thing:2490893

print this using: 0.2 mm layer resolution;0.4 mm layer width; wall count= 2; infill=100% print it at the same temperature you printed the cat. measure the walls width a couple of times in different places, get the average and then do : 100*0.8/average. the result is your new flow rate or extrusion multiplier.

I would then do a E-step calibration, use this:

Once you have this two parameters, re-print the block. I would suggest to print not faster than 50 mm/s and raise it by 5 mm/s if you see the thing is going right. Try a typical grid-20 % infill with 3 top layers and 1 superficial layer (usually you shouldn't need more than one). For these trials try scaling the blocks by 50% so you don't waste that much material. Try not to use the ironing function yet, you should get a uniform surface without it.

The weird thing is the holes pattern you get in all the pieces. Just in case, tighten your x and y belts, re-level your bed and try moving the extruder with your hand (gently) to see it doesn't wobbles.