Variations in width of layers.

[wirlybird]

I don't know how well you can see it but the banding is the layers changing width. For instance, the lighter green is where the layers are not as wide as the darker areas. This appears on both sides.
I printed this in a different color and it came out nice. These flat sides are quite rough do to the irregular layer width.

This is a new roll of PLA, just opened.

210 nozzle
60 bed.

[CompoundCarl]

In my experience, it's almost always either the filament or a mechanical issue. Even if it's a new roll, it can still have variation in the filament diameter. And machine issues like vibration can easily cause those layer lines.

I think this page explains the common causes, although, your print is already much better than their example
https://www.simplify3d.com/support/prin ... e-of-print

[wirlybird]

Thanks Carl, I have found that the filament it very rough - lumpy on one side. I think it is a bad spool.

I am thinking under extrusion (or something similar) due to speed meaning that the extruder couldn't melt fast enough due to the irregular surface, although the bumpy surface is along all of the material so I am not sure! I wasn't printing that fast but it could have been just enough to matter. I have slowed the print way down and the base has printer much better. Now doing the main part but it takes forever!
We'll see how it goes.

Appreciate the link, I will read up on it.